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Evolution of upper crustal magmatic plumbing systems: comparisons of geochronological, petrological, geochemical and structural records in the Cretaceous Fangshan pluton, Beijing, China, the Meso...

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Evolution of upper crustal magmatic plumbing systems: comparisons of geochronological, petrological, geochemical and structural records in the Cretaceous Fangshan pluton, Beijing, China, the Meso...

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Content EVOLUTION OF UPPER CRUSTAL MAGMATIC PLUMBING SYSTEMS: COMPARISONS OF GEOCHRONOLOGICAL, PETROLOGICAL, GEOCHEMICAL AND STRUCTURAL RECORDS IN THE CRETACEOUS FANGSHAN PLUTON, BEIJING, CHINA, THE MESOZOIC CENTRAL SIERRA ARC, CA, USA AND THE MIOCENE SILVER CREEK CALDERA, AZ, USA by Tao Zhang A Dissertation Presented to the FALCULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (GEOLOGICAL SCIENCES) May 2012 Copyright 2012 Tao Zhang ii ACKNOWLEDGEMENTS Accomplishment of my PhD dissertation won’t happen without enough financial, technological and emotional support from different people and organizations. For each chapter in this dissertation there is a group of people who have been my solid support from the beginning till the end of these projects. I would like to give thanks to all of them before I start the main chapters of the dissertation. I would like to firstly thank my PhD advisor and committee chair, Scott Paterson. It is him who brought me from China to this country and this wonderful Earth Sciences Department at USC. Since my research background was not about plutons, it was hard for me get my research here started at the beginning. Scott has always been patient and encouraged me a lot both when we were doing field work and daily research at school. With his innovative ideas and directive guidance, my PhD projects became more and more fulfilled and were carried out gradually even with all those unexpected difficulties from different parties. I really appreciated his hard work on getting me through every step of my research including the hardest writing process. In addition to my academic life at school, Scott also helped me a lot with my culture adaption in the US. As we know that international students always have more difficulties in terms of language and cultural difference, Scott has been very considerate to me so I can be gradually getting used to American culture and comfortably communicating with others. Without Scott’s help I would not be able to go through graduate school. Thanks also need to go to my other two PhD dissertation committee members, Steve Lund and Edwin, McCann from Earth Sciences and Philosophy department. They also iii served in my oral exam committee as well. Steve helped me to build up my AMS project and taught me the technique patiently. I also need to thank Prof. Olivier Bachmann from and Lawford Anderson who served in my oral exam committee and been always available to me for all kinds of help. Lawford has also been both an academic advisor and life advisor to me. Without his encouragement and help I could not go through many different things. Dr Roland Mundil from Berkeley geochronology center (BGC) did a great job teaching me the CA-TIMS technique and different aspects about U/Pb dating and 40 Ar- 39 Ar dating. I have been to Berkeley three times doing different project, Roland, Roland’s friend and my friend Su-chin Chang all have provided residence for me during these trips to make my tight budget relaxed a bit. I appreciated all the help and warm host from BGC. Without your help, the geochronology in my dissertation could not be accomplished and be fantastic. For my Fangshan project, I received help from Prof. He Bin and his student Yan Bo both in the field and during later research. For my Silver Creek project, I need to thank Charles Ferguson from Arizona Geological Survey, who is the discoverer of this wonderful caldera and helped me a lot during multiple field trips with mapping and sample collecting in the caldera. His aunt’s cake was the best gift for my 2009 New Year. Prof. Calvin Miller from Vanderbilt University gave me general financial support from his NSF grant (NSF-EAR-0911726 , "Supereruptions," magma chambers, & plutonic residue: Insights from Peach Spring Tuff, significance of sphene (collaborative with Jonathan Miller, San Jose State Univ.), 2009-2012) to do CA-TIMS dating in BGC for iv my intracaldera rocks. He also organized fieldtrips for us and other geologists working on the same project to get us together to share data. Prof. Jonathan Miller from San Jose State University also helped with communication between members in this project and helped with my writing of abstract as well. Other than projects in this dissertation, I also did some interesting field work with our research group in Inner Mongolia, China. Prof. Zhou Zhiguang, Zhang Da provided general financial and field assistance to us. I had a great time for those summers with them. Their students: Liu Changfeng also helped a lot with everything in China. I would also like to thank our department, especially Cindy Waite, John McRaney, Barbara Grubb, John Yu for their consistent support for the whole six years. I have been TA for the department for most of the time I have been here, which is the main financial support I have had for my PhD program. I would like to say that without this generosity from our department, nothing is possible. Every summer, I got financial support from Barbara and this allowed me to do field work without being worried about other stuff. John Yu has always been available to me for any type of technical support to make sure that my computer work well and efficient. Then I have to mention my wonderful fellow students and friends around me for years. Vali Memeti, both as a fellow student and a big sister for me, plays an important role in mentoring me through graduate school. Almost every hard step I have been experienced here I received smart advice from her and this is so important to me to get things done efficiently. Geoffrey Pignotta, David Farris, Rita Economos, Adam Ianno, Wenrong Cao, Katy Johanesen, Whitney Behr, Leonardo Xia all gave me help whenever I need it. There v are also friends from other schools that generously provide help to me at different times. Tamara Carley, Susanne McDowell from Vanderbilt University, Su-chin Chang from Berkeley, you are all so great to work with. Now, I want to give a very special “thank you” to my fiancé Peter Hsu, and my parents. Peter is the most wonderful gift for my life. He has been standing by me during ups and downs during the last year of my PhD program. His emotional support made me strong and brave enough to face anything in my life. My parents have always been the solid pillar of support in my life, and their generosity makes my life a lot easier. This dissertation is for all of you. vi TABLE OF CONTENTS ACKNOWLEDGEMENTS ............................................................................................... ii LIST OF TABLES .............................................................................................................. x LIST OF FIGURES .......................................................................................................... xi ABSTRACT .................................................................................................................... xiv CHAPTER 1: INTRODUCTION ....................................................................................... 1 CHAPTER 2: HIGH PRECISION U-PB ZIRCON GEOCHRONOLOGY OF THE FANGSHAN PLUTON, BEIJING, CHINA: IMPLICATIONS FOR THE INCREMENTAL GROWTH OF ZONED PLUTONS AND TIMING OF REGIONAL TECTONICS ..................................................................8 1.0 Abstract ....................................................................................................................... 8 2.0 Introduction ................................................................................................................. 9 3.0 Geological Setting ..................................................................................................... 12 3.1 Metamorphism ..................................................................................................... 13 3.2 Structures and deformation history ...................................................................... 14 4.0 Description of the Fangshan pluton .......................................................................... 17 5.0 Geochronology .......................................................................................................... 20 5.1 Previous Geochronologic studies ......................................................................... 20 5.2 Sampling .............................................................................................................. 23 5.3 Analytical Method ............................................................................................... 23 5.4 Age calculation .................................................................................................... 24 5.5 Geochronology results and interpretation ............................................................ 26 6.0 Geochemistry ............................................................................................................ 27 6.1 Previous geochemistry studies ............................................................................. 27 6.2 New Geochemistry............................................................................................... 28 7.0 Discussion ................................................................................................................. 29 7.1 Temporal history of the Fangshan pluton ............................................................ 29 7.2 Necessity of the re-evaluation of the previous K-Ar and 40 Ar- 39 Ar ages ...................................................................................... 31 7.3 Nature of magma source of Fangshan pluton ...................................................... 33 7.4 Growth of the magma chamber below Fangshan pluton .................................................................................................... 34 vii 7.5 Significance for regional tectonics ....................................................................... 35 8.0 Conclusions ............................................................................................................... 37 CHAPTER 3: TEMPERAL AND SPATIAL GEOCHEMICAL EVOLUTION OF MESOZOIC MAGMATISM IN THE CENTRAL SIERRA ARC, CALIFORNIA ..................................................................... 50 1.0 Abstract ..................................................................................................................... 50 2.0 Introduction ............................................................................................................... 51 3.0 New field studies....................................................................................................... 53 3.1 Virginia Canyon area ........................................................................................... 54 3.2 Saddlebag Lake .................................................................................................... 57 3.3 Waugh Lake ......................................................................................................... 60 3.4 Cinko Lake ........................................................................................................... 67 3.5 Jackass Lakes area ............................................................................................... 69 4.0 Summary of Regional Geochronology ..................................................................... 75 5.0 Geochemistry data collection and processing ........................................................... 76 6.0 Summary of Geochemistry and Isotopes .................................................................. 77 6.1 Geochemistry ....................................................................................................... 78 6.2 Strontium-Neodymium Arrays ............................................................................ 82 7.0 Discussion ................................................................................................................. 83 8.0 Conclusions ............................................................................................................... 86 CHAPTER 4: LIFETIME OF AN UPPER CRUSTAL PLUTONIC-VOLCANIC PLUMBING SYSTEM: INSIGHTS FROM CA-TIMS, U-Pb ZIRCON GEOCHRONOLOGY OF INTRACALDERA TUFF AND INTRUSIONS IN SILVER CREEK CALDERA, ARIZONA, USA............................................................................................................. 101 1.0 Abstract ................................................................................................................... 101 2.0 Introduction ............................................................................................................. 102 3.0 Geological background ........................................................................................... 105 4.0 Description of Peach Spring Tuff and Silver Creek caldera ........................................................................................................... 107 4.1 Peach Spring Tuff outflow ................................................................................. 107 4.2 Description of Silver Creek caldera ................................................................... 108 4.2.1 Intracaldera Tuff ........................................................................................ 109 4.2.2 Intracaldera Shallow Intrusions ................................................................. 111 4.3 Geochemistry summary ..................................................................................... 112 4.4 Structure ............................................................................................................. 114 viii 5.0 Geochronology ........................................................................................................ 116 5.1 Previous geochronology of PST and Silver Creek caldera ........................................................................................... 116 5.2 Sampling ............................................................................................................ 117 5.3 Sample preparation ............................................................................................ 118 5.4 Analytical method .............................................................................................. 118 5.5 3-D “Total Pb/U isochron” ................................................................................ 119 5.6 Results ................................................................................................................ 121 6.0 Discussion ............................................................................................................... 122 6.1 The lifespan of the Silver Creek caldera ............................................................ 122 6.2 Crystal budget of this upper crustal magmatic system ...................................... 124 6.3 Chemical variations between the intrusion and the tuff..................................... 127 6.4 Difference between the evolution of long-lived and short-lived magmatic systems ..................................................................... 129 7.0 Conclusions ............................................................................................................. 129 CHAPTER 5: MAGNETIC FABRICS OF THE INTRACALDERA PEACH SPRING TUFF AND SHALLOW INTRUSIONS: IMPLICATIONS FOR THE REACTIVATION OF THE SILVER CREEK CALDERA, ARIZONA, USA ........................................................................................ 148 1.0 Abstract ................................................................................................................... 148 2.0 Introduction ............................................................................................................. 149 3.0 Geological setting of Peach Spring Tuff (PST) and Silver Creek caldera ......................................................................................... 152 4.0 Previous AMS study of PST outflow ..................................................................... 154 5.0 Description of Silver Creek caldera ........................................................................ 154 5.1 Intracaldera Tuff ................................................................................................ 155 5.2 Intracaldera Shallow Intrusions ......................................................................... 156 5.3 Geochronology ................................................................................................... 158 5.4 Structure ............................................................................................................. 159 5.5 Alteration ........................................................................................................... 160 6.0 Reactivation models of Silver Creek caldera .......................................................... 161 6.1 Ring Dikes Model .............................................................................................. 161 6.2 Resurgent Diapir Model ..................................................................................... 162 6.3 Resurgent laccolith Model ................................................................................. 162 7.0 Magnetic susceptibility and AMS data ................................................................... 163 7.1 Magnetic susceptibility methodology ................................................................ 163 ix 7.2 Sampling strategy............................................................................................... 164 7.3 Magnetic mineralogy ......................................................................................... 165 7.4 AMS measurements and data processing .......................................................... 166 7.5 AMS results ....................................................................................................... 167 8.0 Discussion ............................................................................................................... 170 8.1 Complications about the interpretation of the magnetic fabrics ........................................................................................... 170 8.2 Different AMS and magnetic fabrics between the intracaldera PST and the shallow intrusions ................................................ 173 8.3 Magnetic fabrics and inferred resurgent models ................................................ 175 8.4 Influence from regional stress field ................................................................... 176 8.5 Comparison of intracaldera and outflow AMS .................................................. 176 9.0 Conclusions ............................................................................................................. 178 CHAPTER 6: SUMMARY............................................................................................. 190 REFERENCES ............................................................................................................... 196 APPENDICES ................................................................................................................ 221 APPENDIX A: MAJOR ELEMENT DATA ............................................................... 221 APPENDIX B: REE AND TRACE ELEMENT DATA .............................................. 240 x LIST OF TABLES Table 2.1. Different deformational history models of Fangshan area .............................. 45 Table 2.2. Geochronology summary of the Fangshan pluton ........................................... 46 Table 2.3. Isotopic measurements and calculated 238 U- 206 Pb and 235 U- 207 Pb ages of all zircons .................................................................... 47 Table 2.4. Geochemistry data of Fangshan pluton and averages of typical types of adakite from literature ........................................................ 48 Table 4.1 Major elements summary................................................................................ 145 Table 4.2 Age summary of both outflow PST and intracaldera PST and intrusions ............................................................... 146 Table 4.3 U/Pb data for all zircons ................................................................................. 147 Table 5.1 AMS results of 21 out of 23 samples with statistical averages ...................... 188 Table 5.2 Shape factors and magnetic fabrics ................................................................ 189 Table 5.3 Comparison of the major AMS results and fabrics between the intracaldera and outflow PST ..................................................... 189 xi LIST OF FIGURES Fig.2.1 Geological map of Fangshan pluton ..................................................................... 39 Fig.2.2 Simplified structure map of Fangshan area .......................................................... 40 Fig.2.3 Field photos .......................................................................................................... 41 Fig.2.4 Photos of zircons under plane-polarized light ...................................................... 42 Fig.2.5 Concordia plots and weighted mean age of Fangshan samples............................ 42 Fig.2.6 Comparison of the precision and the range of the geochronology data of Fangshan pluton ....................................................................................... 43 Fig.2.7 (a) Comparison of the REE pattern of Fangshan samples and other samples from literature ......................................................................... 44 Fig.2.7 (b) Comparison of TE (trace element) pattern of the two units of Fangshan pluton ................................................................................................ 45 Fig.2.8 Cartoon of Fangshan pluton incremental growth model and the recycling of zircons within the whole magmatic system ................................ 45 Fig.3.1 Outline of central and southern Sierra Nevada ..................................................... 88 Fig.3.2 Central Sierra map ................................................................................................ 89 Fig.3.3 Virginia Canyon geologic map ............................................................................. 90 Fig.3.4 Saddlebag Lake geologic map .............................................................................. 91 Fig.3.5 Waugh Lake geologic map ................................................................................... 92 Fig.3.6 Cinko Lake geologic map, redrafted after Memeti et al. (2010) .......................... 93 Fig.3.7 Preliminary Quartz Mountain geologic map ........................................................ 94 Fig.3.8 Geochemical classification plots .......................................................................... 95 xii Fig.3.9 Shand’s alkali-aluminum classification diagram (Shand, 1943) of Triassic, Jurassic, and Cretaceous plutonic and volcanic rocks in central Sierra ....................................................... 96 Fig.3.10 Harker variation diagrams .................................................................................. 97 Fig.3.11 Trace elements patterns of plutonic and volcanic rocks ..................................... 98 Fig.3.12 Chondrite-normalized REE patterns ................................................................... 98 Fig.3.13 Sr (ppm) versus SiO 2 , Sr/Y versus La/Lu plots .................................................. 99 Fig.3.14 ƐNd-Sr i plot ...................................................................................................... 100 Fig.4.1 Location of the Silver Creek caldera and the distribution of the outflow Peach Spring Tuff .................................................................................. 131 Fig.4.2 Simplified geological map of Silver Creek caldera with Geochronology sample locations ........................................................................ 132 Fig.4.3 Photo taken from an outcrop close to Kingman showing the deposition sequence of PST and previous tuffs .................................................. 133 Fig.4.4 Photo of PST outflow showing both the pre-eruption blasts and the major eruptive deposit ............................................................................ 134 Fig.4.5 Comparison of the intracaldera and outflow PST .............................................. 135 Fig.4.6 Field photos from Silver Creek caldera .............................................................. 136 Fig.4.7 Thin section photos from units in the Silver Creek caldera ............................... 137 Fig.4.8 Classification of intracaldera intrusions, intracaldera PST and outflow PST ................................................................................................. 138 Fig.4.9 Magma series plots of intracaldera intrusions, intracaldera PST and outflow PST.......................................................................................... 139 Fig.4.10 Harker diagram of intracaldera intrusions, intracaldera PST and outflow PST ....................................................................................... 140 Fig.4.11 Sample thin sections ......................................................................................... 141 Fig.4.12 Zircons from two analyzed samples ................................................................. 142 xiii Fig.4.13 3-D plots of samples ages ................................................................................. 142 Fig.4.14 Comparison of all available ages related to PST with error bars .......................................................................................................... 143 Fig.4.15 238 U/ 206 Pb ages of individual zircons from every sample ................................. 144 Fig.4.16 Comparison of crystallization age time between intracaldera plutonic and volcanic rocks........................................................... 144 Fig.5.1 Location and geological setting maps of the Silver Creek Caldera..................................................................................................... 180 Fig.5.2 Silver Creek caldera geological map .................................................................. 181 Fig.5.3 Field and thin section photos from Silver Crek caldera ..................................... 182 Fig.5.4 End-member caldera reactivation models and the Fabrics that we expect to see in both the volcanic and plutonic regims ............................................................................................. 183 Fig.5.5 Stereonet plots of the AMS data for each sample with confidence ellipses .............................................................................................. 184 Fig.5.6 Shape factor diagrams ........................................................................................ 185 Fig.5.7 Magnetic fabrics plotted along the two transects and the stereonet plots of both lineations and foliations within both rock types ......................................................................................... 186 Fig.5.8 Comparison of the outflow and intracaldera fabric ............................................ 187 xiv ABSTRACT Magmatism is the most important process to form crust in Earth’s history. Both volcanic and plutonic rocks are major components of Earth’s current crust and their geochronologic, geochemical and structural features provide key information for rock sequence, source reservoirs, tectonic environments and emplacement mechanisms of igneous rocks. In order to better picture the igneous rocks as a whole I picked three upper crustal magmatic systems in different tectonic environments to study. Fangshan pluton is an intraplate pluton that emplaced at the depth of about 10-15; Central Sierra plutons and correlated volcanic rocks are subduction related magmatism with the plutons emplaced at about the same depth as Fangshan; Silver Creek caldera is a much shallower magmatic system with intralcaldera tuff and subvolcanic plutons. High-precision CA-TIMS (chemical abrasion thermal ionization mass spectrometer) geochronology of Fangshan pluton rocks indicated a much longer history of the magmatic system below the pluton than what people realized before. The existence of antecrystic zircons shows the intense recycling of crystals by multiple magma pulses. The same technique was used on Silver Creek plutonic and volcanic rocks. No antecrystic zircons have been found so far in both the volcanic and subvolcanic plutons, which indicates a relatively simpler history for this magmatic system and the existence of possible filtering mechanisms of older zircons. Considering all single zircon ages from oldest to youngest, the lifespan of this system is only about 1.5 m.y. that is a lot shorter than those deeper magmatic systems. Regional geochemistry study done on the Central Sierra Mesozoic igneous rocks show a close link between the two rock types and the important roles magma fractionation, mixing and xv mingling played during the formation of these magma bodies. The magma source below this area did not change much through the whole Mesozoic though. In order to see the rock fabrics in Silver Creek caldera, AMS study was carried on for 23 samples from this caldera. The results show extremely weak fabrics in both shallow intrusions and volcanic rocks. Although the randomly oriented magnetic lineations in the intracaldera tuff can’t be well connected with the outflow magnetic lineations, it does agrees well with the typical caldera forming model of mechanically collapsing of the magma chamber roof after the chamber drained. Magnetic fabrics in the plutonic rocks do not form any noticeable pattern. More data need to be collected to make sure whether there is pattern or not. Multiple data sets from different magmatic systems do show the complications involved in this process and correlated study of both plutonic and volcanic rocks of the same system is a powerful way to understand any single magma plumbing system. There is still some fundamental difference between the plutonic and volcanic rocks, so the correlation of them needs careful evaluations still. 1 CHAPTER 1: INTRODUCTION Ever since the mid-20 th century, numerous efforts have been made to bridge the gap between our understanding of the plutonic and volcanic regimes (Buddington, 1959; Smith, 1960; Lipman, 1984; Wyborn and Chappell, 1986; Miller and Miller, 2002; Clemens, 2003; Metcalf, 2004; Lipman, 2007; Bachmann et al., 2007). Plutonic rocks record long term evolution of the upper crustal magma chambers while volcanic rocks play the role of recording snapshots of short lived magma batches. In order to get a better understand of the evolution of upper crustal magmatic system, a coalescence study of both rock types within one system and across different systems is necessary. To evaluate the potential connections between these two realms, researchers explored their spatial, petrological, geochemical and geophysical relationships. there are more and more important and interesting questions about this kinship that need to be answered. Here are some examples: 1. Are the volcanic and plutonic rocks from one system derived from the same batch of parent magma? 2. If both rock regimes are from one magmatic system, do they share the same isotopic signatures? Are they geochemically identical? If not, are there any fundamental differences? 3. How long can magma chambers stay active? How often do they get refill? 4. Do crystals as zircons recycle in all magmatic systems? If yes, how intense this process can be in different systems? 5. What do the fabrics in a plutonic-volcanic system look like? 2 To answer these questions, we need not only well exposed, linked plutonic and volcanic systems but also need to apply multiple modern geological tools to different magmatic systems. This PhD research project was motivated by my interests in both rock types and the desire to try to answer the above questions. The three field areas in this dissertation provide natural laboratories for this project. High-precision U/Pb zircon geochronology, geochemistry, and AMS (anisotropy of magnetic susceptibility) studies were applied to these areas on both plutonic and volcanic rocks. In Chapter 2 I present the high-precision geochronology study done on Fangshan pluton. Recent high-precision geochronology studies on several batholiths revealed that different zircon populations occurred in single rock samples (Coleman et al., 2004; Miller et al., 2007; Matzel et al., 2005; Memeti et al., 2010). Miller et al., 2007 classified these different zircon populations as (1)Autocrysts: zircons crystallized from the magma pulse analyzed; (2)Antecrysts: zircons that crystallized from early pulses and were recycled into the current pulse; (3) Xenocrysts: zircon crystals inherited from the host rock. The Age of autocrysts is used as the crystallization age of a certain magma pulse, while the age of the antecrysts can reveal early intrusive history that might or might not exposed to us. Age of the xenocrysts can give us information about country rocks of the intrusion. In Chapter 2 of this dissertation, I applied the same high-precision U/Pb CA-TIMS (chemical-abrasion-TIMS) method to the zircons from a Mesozoic pluton SW of Beijing, China. This pluton is called Fangshan pluton, and it is located right at the intersection of the NNE trending Taihang Mountains and the EW trending Yanshan-Yinshan oregenic belt. Two main units of quartz-diorite and granodiorite from the margin to the center of 3 the pluton were mapped out. This pluton has been studied intensely by Chinese geologists and biotite and hornblende from this pluton have been used as the Chinese geostandard of K-Ar and 40 Ar/ 39 Ar geochronology labs. It is also a field geology study base camp for many Geosciences departments in China. And even though many geochronology studies have been completed on this pluton, no high-precision U/Pb dating has been done here. Previous U/Pb geochronology studies are mostly micro-sampling methods like SHRIMP, SIMS and ICP-MS. These zircon ages have relatively larger errors and did not reveal much detail about different zircon populations. Another problem about the geochronology is the systematic reverse discrepancy between the U/Pb zircon crystallization ages and the K-Ar, 40 Ar/ 39 Ar cooling ages. Our high-precision results can help to better constrain the ages of the two exposed units and broaden our view about the unexposed history of this pluton and the evolution of the magmatic system below it. The two new ages we achieved indicate a more complicated evolution history of the magmatic system below Fangshan area than any other geochronology studies have concluded so far. This Chapter was written as a paper which is almost ready to submit for now. Text and figures of Chapter 3 of this dissertation are directly from a review paper of the geology of the central Sierra arc, California, USA. My advisor Scott Paterson is the first author and this paper has been submitted to Geosphere. As a coauthor of this paper, I focused on the geochemistry section especially the major and trace element portion of this collaborative paper. By using geochemistry data from NAVDAT (North America Volcanic rocks Database), from USC undergraduate team research, and from graduate 4 research projects I was able to gather data from over 700 whole rock samples from the central Sierra area. I then grouped the data by age (Triassic, Jurassic, Cretaceous) and rock types (volcanic and plutonic). By comparing the geochemistry evolution through time I evaluated whether there is a temporal evolution of this arc and whether there is overlap between different time periods. Combined with field studies, geochronology studies, Sm-Nd, Rb-Sr, Pb and O isotope studies, a composite temporal magmatic and tectonic history of this Mesozoic arc is formed. The geochemistry study shows that the both plutonic and the volcanic components of Mesozoic age along this arc are spatially, temporally linked and parts of the same magmatic system below the arc. Chapter 4 and chapter 5 are both dealing with a Miocene caldera in Arizona. This remnant caldera is called Silver Creek caldera and is located right at the triple boundary of Nevada, California and Arizona. It was proposed as the source of the famous Peach Spring Tuff by Ferguson, 2008. Peach Spring Tuff that used to be called Peach Springs Tuff (PST) is a regional stratigraphic marker from Barstow to the western margin of the Colorado plateau. The outflow tuff has been studied by many authors and was dated as about 18.5 Ma (Young and Brennan, 1974; Glazner et al., 1986; Neilson et al., 1990; Hillhouse and Wells, 1991; Carley et al., 2010). For a long time, people had trouble finding the eruptive source of this large ignimbrite sheet. Predictions have been made about the location of the source based on different evidence as thickness variance of the outflow, AMS (anisotropic of magnetic susceptibility) study on outflow fabrics. The location of the Silver Creek caldera is located roughly within the region of these predictions and based on more reliable phenocrysts studies by Thorson (1971) and 5 Ferguson, Ferguson concluded that it is the source of PST. Silver Creek caldera now only consists of the eastern half of the caldera, the western half has been faulted away by a left-lateral strike slip fault and now is located tens of kilometers to the SW (from personal communication with Charles Ferguson). In the caldera, thick intracaldera tuff was intruded by shallow intrusions along the eastern margin of the caldera. This is a perfect natural lab to study connected plutonic and volcanic rocks from one magmatic system. I have done two small projects on this caldera for my PhD. One is the high-precision geochronology studies of both plutonic and volcanic regimes in the caldera and another one is AMS study of both rock types in the caldera. These two studies were done to try to make stronger connection between the caldera and the outflow PST, and explore more about the magmatic plumbing system below the caldera. Chapter 4 is written as a dissertation chapter for now and it will be part of a collaborative geochronology paper on Peach Spring tuff and Silver Creek caldera. Previous grochronology studies mostly used either the conventional K-Ar method or 40 Ar- 39 Ar method. A lot of these previous ages are even discordant within the same sample site. In order to accurately determine the crystallization age of the intracaldera tuff and the shallow intrusions, four samples from the caldera were collected with one from the tuff and three from the intrusions. By applying CA-TIMS method, any Pb loss domains within the zircons were removed and this assured the high-precision of the ages. For this study, accurate ages will increase the possibility for us tell the time sequence of the emplacement of the tuff and the intrusions. Analyzing multiple grains for one sample also allows us to find different zircon populations if they exist. In this chapter I discussed 6 the ages themselves, comparison of our high-precision ages and previous ages, and the possible reasons filtering older zircon crystals from the magmatic system. Because our zircons have a relatively high common Pb component we used a different mathematical method called “3D-Total U/Pb isochron” to present the zircon ages. This 3D presentation method considers not only the concordance of the zircon ages but also the common Pb effect on young zircons. Chapter 5 of this dissertation is about my AMS study of both rocks types in the Silver Creek caldera. This chapter will become a paper. In this chapter, I will present AMS data from 21 samples, compare the magnetic fabrics between the plutonic and the volcanic rocks, compare the fabrics between the intracaldera rocks and the outflow, and discuss the meaning of our new fabrics and the complications we need to consider when trying to connect fabrics and flow. Before we try to use fabrics to infer flow patterns in any magmatic system, we have to be clear about that fabrics are strain that preserved in the rock and flow is a process that can create all different types of fabrics. It needs to be very careful when we try to connect these two. The new AMS results show very low magnetic anisotropy, which agrees well with the previous AMS data from the outflow PST and also explains why the fabrics do not show much in the field and even under microscope. I also found that the volcanic rocks generally have higher magnetic anisotropy than the plutonic rocks, which means that the volcanic rocks deformed more during the formation of the caldera. Current magnetic fabrics within the shallow intrusions are not very consistent for us to conclude that they show a certain pattern. In comparison to the 7 outflow PST, intracaldera tuff does not show a consistent lineation pattern pointing to the exact center of the caldera. All these observations will be discussed in this chapter. The three magmatic systems I picked for this project are representations of two different levels of magmatic systems. Fangshan pluton and central Sierra plutons were both emplaced at a depth of about 10-15km, while the intrusions and tuff in the Silver Creek caldera are representatives of a very shallow or even surface cooling magmatic system. The three field areas also represent three different types of tectonic environment. Fangshan pluton is an intraplate pluton which is very far from the Mesozoic subduction along the east coast of China. Central Sierra is part of a subduction-related, Mesozoic continental margin arc. Silver Creek caldera formed during tectonic extension caused by lithospheric thinning at the beginning of Basin and Range. This variety gives us a more complete picture about upper crustal magmatic systems at different depths and in different tectonic environments. Although we need to be careful when directly comparing any of these two systems since they all have quite different scales, it will still be helpful to try to put the observations we made together and see whether there is any similarity or difference we can find. Chapter 6 of this dissertation is a summary of all three areas. Conclusions from each chapter will be summarized here. The difference between different magmatic systems will be explored here based on the studies in the three field areas. At the end of the dissertation, there is an appendix of all the geochemistry data for Chapter 2 listed in an excel spreadsheet. 8 CHAPTER 2: HIGH PRECISION U-PB ZIRCON GEOCHRONOLOGY OF THE FANGSHAN PLUTON, BEIJING, CHINA: IMPLICATIONS FOR THE INCREMENTAL GROWTH OF ZONED PLUTONS AND TIMING OF REGIONAL TECTONICS 1.0 Abstract: High-precision U-Pb zircon geochronology is a powerful way to test incremental growth of zoned plutons and to reveal important details about the evolution of magma plumbing systems. The Fangshan pluton, located at the intersection of the NNE trending Taihang Mountain and the E-W trending Yanshan fold and thrust belt, is an ideal place to test incremental growth models and to use the age of the pluton to constrain the regional deformation history. The pluton consists of two mappable concentric units of an outer quartz-diorite and inner granodiorite with some internal gradations within these units. One sample from each unit has been analyzed using CA-TIMS (chemical abrasion- thermal ionization mass spectrometer) method. Zircon populations yield weighted mean ages of 131.06±0.43 Ma (MSWD=2) and 131.02±0.26 Ma (MSWD=1.4) for the outer and inner unit, respectively. Both populations contain antecrystic zircons with ages ranging 132-145 Ma, which indicates that older magmatic units exit in the magmatic plumbing system below the Fangshan pluton, that this magma system has a prolonged history of about 15 Ma and was built up by multiple magma pulses of different ages. Our field measurements of steeply dipping magmatic foliation, steeply plunging but variably trending magmatic lineation, and steeply plunging stretching lineation in the host rock immediately next to the pluton show strong vertical movement of the magma. New major and trace elements geochemistry agree well with previous studies and again support 9 magma mixing and mingling between different units and between magma and host rock during the emplacement of the pluton. Units in this pluton are typical high Sr low Y adakite developed in eastern China. The time sequence of major Mesozoic deformation events and magmatism in Fangshan area is based on both field relationship and geochronology studies. The two new high precision crystallization ages indicate that the ESE (110°-130°) stretching lineation (what SE shearing?) happened before 131 Ma and the related regional crustal thinning and proposed melting of the base of the thickened crust occurred as early as 145 Ma when the oldest antecrystic zircon formed. 2.0 Introduction Structural, geochemical and geochronologic studies of large magmatic sheeted complexes show clear evidence of the incremental growth of magmatic systems. It is often less clear to what degree incremental growth played in the formation of large, zoned plutons. A number of recent high resolution geochronologic studies of large, zoned granitic magmatic intrusions such as the Tuolumne batholith, Sierra Nevada, the Mt Stuart and Tenpeak plutons in the Cascades, the Vinalhaven Intrusive Complex, Maine have established that at least some zoned plutons do consist of multiple pulses and grew over durations between 2 to10 million years (Kistler et al, 1986; Coleman et al. 2004; Hawkins and Wiebe, 2004; Matzel et al., 2005, 2006; Memeti et al. 2010). However questions about the size and number of pulses, internal processes within and interactions between pulses, and chamber growth scenarios remain uncertain. Part of this uncertainty comes from the lack of 3D control on the overall size and architecture of plutons, sufficiently good exposure to allow detailed studies of the lateral changes in these 10 batholiths, and studies specifically aimed at addressing the above questions. High- precision zircon geochronology provides a powerful tool for evaluating the processes involved and durations of chamber growth and indirectly the size and age(s) for the existence of the unexposed portions of batholiths. The Fangshan pluton, located 40 km to the southwest of the city of Beijing, China, is a well exposed, normally zoned pluton ranging from an outer quartz-diorite to inner granodiorite unit (Fig.2.1). This pluton has played a rather pivotal role in a number of Chinese studies of plutons, and thus the geology, geochemistry, structure, and geochronology has been examined in detail since 1936 (Ho, 1936; Ma, 1989; Zhang and Li, 1990; Ma et al., 1996; He et al., 2005; Cai et al., 2005, Sang et al., 2006; Yan et al., 2006; Sang et al., 2007; He et al., 2009, Sun et al., 2010; Yan et al., 2010; Wang et al., 2011). Furthermore, since the Fangshan pluton is located at the intersection of the NNE- trending Taihang Mountain and the eastern part of the intraplate Yanshan orogenic belt, deciphering the age and emplacement of the pluton is very useful for the accurate interpretation of regional tectonics. Numerous field studies have been completed on this pluton and its surrounding host rocks and the region is now used as a classic teaching locality for many geologic departments in the Beijing area. Samples from the pluton are presently used in China as the K-Ar and Ar-Ar geostandards. Well developed rim synclines, steeply plunging magmatic lineations, steep magmatic fabrics along the margin, shear zones along the northwestern margin of the pluton, and the dramatic thinning of local stratigraphy has suggested to previous researchers that this pluton is a classic example of a diapir (He et al., 2005, He et al., 2009). It has been suggested that this 11 pluton was constructed by two main diapiric pulses with the second pulse consisting of three increasingly younger phases (Wang et al., 2002; He et al., 2005). Because of the need to better understand the growth histories of zoned plutons, the timing of regional tectonics of this portion of China, and because of the high impact in China of studies of the Fangshan pluton, we have pursued high-precision geochronology to test interpretations of the growth of this pluton. Combined with geochemistry studies, recent zircon U-Pb CA-TIMS analysis of the two main intrusive units of the Fangshan pluton provide precise ages and additional constraints on the growth of this pluton and evidence of the existence of older, unexposed parts of this batholith. In this paper, we report (1) new, high precision, CA-TIMS, U-Pb, single zircon ages from zircon populations from two samples: one age for the outer quartz-diorite unit of 131.06±0.43Ma and another age of about 131.02±0.26 Ma for the inner granodiorite unit and discuss the significance of older zircons present in each sample; (2) a small amount of new geochemistry; and (3) a compilation of our field studies. A compilation of these and previous data do support an incremental growth history for the Fangshan pluton and also require a source of slightly older zircons, presumably at deeper levels. It also draws attention of the need to reevaluate some existing K-Ar and 40 Ar- 39 Ar ages from this pluton, which are typically older than and thus not compatible with the new zircon ages. Finally we will revisit the implications of our results for previous emplacement models and for regional tectonic interpretations. 12 3.0 Geological Setting: The Fangshan pluton is located in the Western Hills area to the southwest of Beijing. Western Hills belong to the hinterland of the North China Craton (NCC). The pluton was emplaced at the intersection of the NNE trending Taihang Mountain and the E-W trending Yanshan orogenic belt and is part of the Mesozoic magmatic arc in eastern China (Fig.2.1). Local stratigraphy in Fangshan area is typical for this portion of the NCC. The NCC consists predominantly of Archean and Early Proterozoic crystalline basement covered by a passive margin sequence about 4 km in thickness (He et al., 2005). Archean rocks are mostly gneiss, amphibolites and granulites and are only exposed as tectonic slivers along the northern and southern margins of the Fangshan pluton. Most of the Archean rocks were mylonitized during Phanerozoic deformation and metamorphism. Regionally Middle and Upper Proterozoic strata unconformably overlie the crystalline basement and are slightly metamorphosed to greenschist facies. Lower Paleozoic rocks include Cambrian and Lower Ordovician carbonaceous rocks. Like much of the NCC, while Upper Paleozoic strata in Fangshan area lack Devonian and Lower Carboniferous units. Part of the Middle and Upper Carboniferous and Permian rocks were metamorphosed and deformed by the emplacement of the Fangshan pluton. Upper Permian rocks are unconformably overlain by Lower Triassic red-beds and conglomerates, which in turn are unconformably overlain by middle-late Jurassic and Cretaceous (174±8 Ma for basalt, 147.6±1.6 Ma for andesite, 144.7±2.8 Ma for clastic rocks) volcanic and clastic deposits (Shao et al., 2003). The oldest country rock intruded by the Fangshan pluton is the 13 intensely metamorphosed Archean complex sparsely distributed along the northern and the southern margins of the pluton and the youngest is the Jiulongshan group of middle Jurassic age (Cai et al., 2005). The stratigraphic thickness and characteristics of the strata in the broader Fangshan area are equivalent to regional strata away from the pluton but dramatically thinned and altered by emplacement related deformation and metamorphism near the pluton (He et al., 2005; He et al., 2009). Compared to the undeformed strata farther away from the pluton, country rock stratigraphy close to the pluton has been thinned by about 4-5 km by the emplacement of the pluton, which agrees well with growth of a chamber with the diameter of the currently exposed pluton (He et al., 2005; He et al., 2009). 3.1 Metamorphism: Both regional and contact metamorphism can be found in Fangshan area. Characteristic mineral assemblages of regional metamorphism are: sericite+chloritoid; sericite+chloritoid+chlorite; sericite+chlorite+epidote, which indicate a regional greenschist facies metamorphism (Wang and Ma, 1989, Song, 1996; Wang et al., 2004). People reported the existence of kyanite in Nanjiao area to the NW of the Fangshan pluton (Wang, 1990) but this has not been reconfirmed by our field work yet. Contact metamorphism occurred along the margin of the Fangshan pluton and some small plutons in Nanjiao area close by. Hornfels, schists, marbles and gneisses with strong foliations and lineations are quite common within the contact metamorphic zone around the pluton (He et al., 2009). To the west of the pluton, three contact metamorphic zones are recognized: andalusite-K-feldspar, andalusite and andalusite-biotite zones with 14 corresponding metamorphic temperatures of 690-730,575-690, 450-575°C respectively (Wang and Chen, 1996). In the Southern aureole of the pluton, a steeply plunging lineation is well developed and is defined by the alignment of tremolite, andalusite, sillimanite, elongated quartz and mica assemblage (He et al., 2009). Garnet and andalusite porphyroblasts formed when the emplacement of the Fangshan pluton occurred, which caused the transposition of the older gently dipping foliation recorded by the inclusion trails in the porphyroblasts to the steeply dipping foliation wrapping around the porphyroblasts (He et al., 2009). 3.2 Structures and deformational history: Western Hills are located at the northeastern end of the NNE trending Taihang Mountains and to the south of the E-W extending Yanshan fold and thrust belt. Most regional deformation in Fangshan area is controlled by these two orientations plus the emplacement of the Fangshan pluton. The time sequence of deformational events in this area is still debatable (Yan et al., 2006; He et al., 2009; Yan et al., 2010; Wang et al., 2011). Different authors proposed different deformation history for this area and interpret similar structures differently (Table 2.1). There are five major structures around the Fangshan area, which are generally agreed upon by different authors (Fig.2.2). The geochronological sequence of these major structures that we propose is as follows: (1) E-W trending anticlines; (2) WNW vergent thrusts (Nandazhai thrust, Xiayunling-Changcao thrust, and Huangshandian thrust); (3) the bedding-parallel ductile shear zones, intrafolial to interformational recumbent folds and transposition of bedding during formation of a continuous foliation developed in the 15 pre-Mesozoic cover (Song, 1987; Song, 1996; Song et al., 1996) with a well-developed regional lineation of SE 110-130° (He et al., 2009; Yan et al., 2010; Wang et al., 2011); (4) the Beiling, Fenghuangshan, Nanguan and Taipingshan synclines around the Fangshan pluton, which are called rim synclines in He et al., 2005 and He et al.,2009; (5) NNE trending high angle normal fault to the east of the Fangshan pluton (He et al., 2009; Yan et al., 2006, 2010; Wang et al., 2011). Both Yan et al., 2006 and Wang et al., 2011 put the N-S contraction due to the collision of North and South China blocks as the first Mesozoic deformational event in Fangshan area. The E-W trending anticlines were suggested by Wang et al., 2011 to be related to this collision that happened at the beginning of Mesozoic. Yan et al., 2006, 2010 and Wang et al., 2011 agree well on the timing of the WNW vergent thrusts of 170- 150 Ma. All authors recorded the regional lineation of SE 110°-130°, but they have different interpretations. The rim synclines around Fangshan pluton that were discussed by He et al., 2005, 2009 formed during the emplacement of Fangshan pluton. All authors agree well on the timing of the high-angle normal fault in the eastern part of the Fangshan pluton which separates the NCP (North China Plain) from the Western Hills (Fig.2.2) (Yan et al., 2006; He et al., 2009; Yan et al., 2010; Wang et al., 2011). This fault strikes NNE and dips 70°-85°to the ESE. Wang et al., 2011 dated the sericite and biotite collected from the fault surface and got ages of 70-60 Ma. Of these five structures the nature and the timing of the SE 110°-130° lineation is the most debatable one. Recent 40 Ar- 39 Ar geochronology work on muscovite by He Bin (unpublished but referred to in his 2009 paper) indicated that the top to SE shearing 16 (Song and Wei, 1990; Song and Zhu, 1997; He et al., 2009) happened in early Cretaceous (128.7-150.2 Ma) and therefore immediately predates or possibly overlaps the age of the Fangshan pluton (He et al., 2009) while Wang et al., proposed 40 Ar- 39 Ar muscovite and sericite ages of 130-110 Ma for the same structure. Yan et al., 2006 and Yan et al., 2010 used this feature as the evidence of the existence of NW-SE extension and argued that the detachment fault associated with this extension together with wall rock deformation provided space for the emplacement of the Fangshan pluton: this proposed SE-vergent detachment fault was described in these two papers to happen before the WNW thrusting. In the field, this stretching lineation does not deform the Fangshan pluton, which indicates that the deformation causing the lineation happened before emplacement. This field relationship agrees well with the ages from He Bin (discussed in He et al., 2009), which predates the Fangshan pluton. The WNW vergent thrusts were overprinted by this lineation to the southwest of the pluton near Huangshandian thrust and cut by the pluton at the southern end of the Nandazhai thrust (Fig.2.2Fig.2.2) (Wang et al., 2011). The contractional features which were dated as 250-200 Ma by 40 Ar- 39 Ar method using muscovite and sericite were overprinted by the WNW vergent thrusts and the SE trending lineation to the west of the Nandazhai thrust (Fig.2.2) (Wang et al., 2011). Based on the above field evidence, the time sequence of all these events can be determined. Our new high-precision ages of the Fangshan pluton will help to better constrain the timing of these events. 17 4.0 Description of the Fangshan pluton: The exposed part of the Fangshan pluton is spherical in shape with an area of about 54 km 2 . It consists of two concentric units in map view with an outer quartz-diorite and the inner granodiorite unit. The inner unit contains two phases of coarse grained granodiorite without K-feldspar phenocrysts and porphyritic granodiorite with K-feldspar phenocrysts. The main mineral assemblages of these two units are generally the same: Q+Kf+Pl+Hb+Bio+Mt+Sp+Ap+Zr, but with different percents for each mineral (Huang et al., 1985; Yan et al., 1995). The Quartz-diorite is mostly grey, fine to medium grained with equigranular texture. It contains about 60-65% plagioclase, 10-15% quartz, about 15% hornblende, about 5% biotite and other accesssory minerals like sphene. The coarse grained granodiortie is light grey color with equigranular texture. It contains about 50% plagioclase, 15-35% K-feldspar, 15-20% quartz, 5-10% biotite and accessory minerals. The central porphyritic granodiorite is greyish white color. K-feldspar phenocrysts are very euhedral with the size increasing from 0.5 to 2 cm towards the center. The contact between the pluton and the country rock is sharp to gradational where it is exposed and dips steeply. The contact between the quartz-diorite and the granodiorite unit varies from sharp to a mingled zone with granodiorite dikes intruded into the quartz- diorite unit (Fig.2.3 photo1) but not vice versa. No sharp mappable contacts were found in granodiorite unit but instead transitions between different phases are very gradational. Inclusions are very well developed in Fangshan pluton. Both host rock xenoliths (Fig.2.3 photo 2) and magmatic enclaves can be found. Most of the xenoliths occur in the marginal area that is close to the host rocks. They have sharp corners and irregular shapes. 18 Chilled margins are developed along the profile of the xenoliths. Granitoid enclaves are distributed throughout the pluton. Their compositions are more mafic than the two major intrusive units and not homogeneous. The main mafic minerals in these enclaves are hornblende, biotite, and pyroxenes while the main felsic minerals are plagioclase, quartz, and a few k-feldspar (Yan et al., 2010). Fabrics within the pluton, including both magmatic and subsolidus, have been studied by many authors (Zhou et al., 1992; He et al., 2005; Yan et al., 2006; He et al., 2009; Yan et al., 2010; Ji et al., 2010). Measured magmatic foliation and lineation from previous studies plus our new measurements are plotted on Figure 1. Foliations are roughly margin parallel to form a typical “onion skin” pattern. All of them are steep, typically with dips greater than 70°. In the middle of the pluton, most foliations are NW-SE striking and steeply dipping which agrees well with the AMS (anisotropy of magnetic susceptibility) results (Ji et al., 2010). The magnetic foliations defined by the susceptibility ellipsoid are generally striking WNW-ESE (Ji et al., 2010)At some locations at the center of the pluton we found two steeply dipping magmatic foliations at high angles to one another.. The study of Yan et al., 2010 shows a consistent magmatic lineation plunging steeply SE, while our mapping indicated magmatic lineations are very steeply plunging and trend at different orientations along our transection (Fig.2.1). Note steep plunges of lineation in pluton center associated with constrictional fabric (L > S) and locally two foliations versus the oblate fabrics (S>L) near the margins (Fig.2.1). The aspect ratio of the dioritic enclaves was used by some authors to represent the magmatic strain in the pluton (Yan et al., 2006; Yan et al., 2010) although the use of 19 enclaves in this fashion has been challenged by Paterson et al. (2004). Since the aspect ratios increase towards the northwestern part of the pluton, Yan et al. (2010) argued that this plus the consistent plunging lineation imply the flow direction of the magma is SE- NW although mostly still vertical (Yan et al., 2010). The consistent plunging lineation was not confirmed by our field mapping and since these fabrics may record strain instead of flow directions, the above conclusion made by Yan et al., (2010) need to be carefully evaluated. Subsolidus deformation in the pluton is localized to the NW, NE and foliated dikes to the west of the pluton. Exposure of the pluton margin and host rock is missing to the south. S-C fabrics superimposed on the magmatic fabrics within this zone (Yan et al., 2006; Yan et al., 2010) with the S surface representing a reactivated magmatic foliation (He et al., 2009). Fabrics in the host rocks next to the pluton include steeply dipping, margin parallel foliation and steep plunging stretching lineation (Fig.2.3 photo3) (He et al., 2005, 2009). Kinematic markers within the thermal aureole of the pluton show strong pluton side up vertical motion and rim synclines developed well around the northwest, west and south sides of the pluton (He et al., 2005; He et al., 2009). The thinning of the host rock strata along the margin of the pluton matches well with the diameter of the pluton itself well (He et al., 2005; He et al., 2010). 20 5.0 Geochronology 5.1 Previous Geochronologic studies Published geochronologic studies include U-Pb, K-Ar and 40 Ar- 39 Ar dating on both internal plutonic units and related outside nearby magmatic bodies using various minerals. A collection of all the recently published ages plus the new ages of this study of the Fangshan pluton are listed in Table 2. Methods for U-Pb geochronology include TIMS (Thermal Ionization Mass Spectrometer), SHRIMP (Sensitive High Resolution Ion Microprobe), SIMS (Secondary Ionization Mass Spectrometer) and LA-ICP-MS (Laser- Ablation Inductively Coupled Plasma Mass Spectrometer). Except for TIMS, all the other methods use micro-beam to sputter or vaporize a volume of zircon, which allows in-situ analysis with high-spatial resolution. These micro-beam methods are rapid but the trade- off is that the precision of individual spot analysis usually is an order of magnitude larger than single grain TIMS analysis (Bowring et al., 2006). For the outer quartz-diorite unit, three U-Pb zircon ages using micro-beam methods range from 129.9±1.3 Ma to 133.6±0.8 Ma (He et al., 2009; Sun et al., 2010). One K-Ar biotite age from the same unit is of 131.1 Ma (BGMRBM, 1991). As for the inner granodiorite unit, seven U-Pb zircon ages range from 128.5±1.5 Ma to 133.8±2.1 Ma (Davis et al., 2001; Cai et al, 2005; He et al., 2009; Sun et al., 2010), which overlaps with the quartz-diorite unit within error. Four U-Pb zircon, titanite and apatite ages from the mafic enclaves and the granodiorite unit were done using micro-beam methods. These ages overlap with the zircon ages within errors as well. K-Ar and 40 Ar- 39 Ar hornblende ages from this unit range from 132.8±2.4 Ma to 136±0.5 Ma (Wang et al., 1982; Sang et al., 2006, 2007; Yan et al., 2010) with the 21 two ages of 133.3±1.5 Ma and 132.8±0.1 Ma set as the China geostandards of K-Ar and 40 Ar- 39 Ar hornblende dating respectively (Sang et al., 2007). All five available K-Ar and 40 Ar- 39 Ar hornblende ages are older than zircon crystallization age of this unit from this study. Seven K-Ar and 40 Ar- 39 Ar biotite ages range from 132.2±0.2 Ma to 145 Ma (Li et al., 1964; Wang., 1983; Sang et al., 2006) with the two ages of 132.8±1.3 Ma and 132.7±0.1 Ma set as the China geostandards of K-Ar and 40 Ar- 39 Ar biotite dating (Sang et al., 2006). All these biotite cooling ages are older than the crystallization age of the same unit from this study as well. There are other ages obtained on related rocks outside the Fangshan pluton (Table 2.2). Small quartz-diorite apophyses at Nanjiao area to the west of the pluton have LA-ICP- MS zircon U-Pb age of 134+1.0/-2.0 Ma (Zhang et al., 2008). A dioritic dike to the west of the pluton and a quartz-diorite sample near the west margin of the pluton gave zircon TIMS ages of 136±1 Ma and 135±1 Ma respectively (Wang et al., 2011). The authors of Wang et al., 2011 extract U and Pb from zircons by standard ion-exchange-column methods. From Table 2 we can see that most of the ages are results of micro-beam analyses and the errors are larger than the new data presented in this paper. A lot of the U-Pb weighted mean ages have way too large MSWD (Mean Square of Weighted Deviates) from 0.16 to 0.79 (Sun et al., 2010). Technically, the larger errors are from both the machine system errors and sample-standard bracketing measuring used by micro-beam methods (Ireland and Williams, 2003; Kosler and Sylvester, 2003). The low precision of each analysis also precludes the subtle amount of Pb loss or inheritance and the absolute age of the sample 22 is controlled to some degree by the variability of the standards used during the measuring process (Bowring et al., 2006). The large MSWD comes from the selecting of data points and the calculation of the weighted mean ages. Compared to the micro-beam analysis the high precision of TIMS analysis allows the recognition of the subtle amounts of Pb loss and the exclusion of these data points when calculating the weighted mean age of the rock. The only previous TIMS zircon age (Davis et al., 2001) has a larger error than our data as well and this might be due to the lack of special treatment of the zircons to entirely exclude the Pb loss parts. Since the field relationship between the two units of Fangshan pluton indicates the possibility of extremely close ages, high precision CA- TIMS (using thermal annealing and chemical abrasion-TIMS) analysis developed by Mattinson (2005) used in this study is the most appropriate method to apply to this pluton. K-Ar and 40 Ar- 39 Ar dating of both magmatic hornblende and biotite from both units were obtained from the Fangshan pluton and nearby host rocks by different labs in China (Li et al., 1964; Wang et al., 1982; BGMRBM, 1991; Sang et al., 2006, 2007; Yan et al., 2010). K-Ar and 40 Ar- 39 Ar methods give us cooling ages of the magmatic bodies since the saturation temperatures of the minerals of hornblende and biotite are lower than that of zircon. Theoretically, the cooling age is always younger than the zircon crystallization age of the same magmatic body. Even so the cooling ages from the previous studies are almost all older than the crystallization ages with some being as much as 4-8 Mys older than the crystallization ages (Li et al., 1964; Yan et al., 2010). This is quite a systematic problem since the samples are from the same pluton but with contradictory crystallization and cooling ages. Thus it is critically important to re-evaluate these cooling ages and 23 compare them between different labs and use the most updated calibration to recalculate them since both the hornblende and biotite separates from the granodiorite unit of the Fangshan pluton are now used as the Chinese geostandard for both K-Ar and 40 Ar- 39 Ar dating (Sang et al., 2006, 2007). 5.2 Sampling: To better constrain the age of this pluton, we collected and analyzed two samples – one from the marginal unit and one from the center. Sample FS046 is from the outer quartz- diorite unit and sample FS031 is from the center of the pluton (Fig.2.1.1). The hand sample of FS046 is dark grey in color and fine to medium grained with equigranular texture. The main minerals in this sample include plagioclase, hornblende, quartz and biotite. Plagioclase is grayish white in color, and subhedral. Quartz makes up about 15-20% of the rock and most of them are anhedral to subhedral. Sample FS031 is from the coarse- grained non-porphyritic phase of the inner granodiorite unit. Both plagioclase and k- feldspar are found in this sample and some of the k-feldspar crystals are zoned. Sample crushing and zircon selection were finished in the lab of Hebei geological survey in China with more than 1000 zircon grains obtained for each sample. Zircons were then sent to the Berkeley Geochronology Center (BGC) to be further prepared and analyzed. 5.3 Analytical Method We applied CA-TIMS method on zircons from both samples of the pluton. Errors of ID-TIMS (isotope dilution-TIMS) can be as low as within 0.1% (Mattison 2005; Mundil et al., 2004). CA-TIMS method is based on ID-TIMS method with more effective zircon 24 pretreatments to minimize or eliminate the zircon domains that have experienced open system behavior before analysis (Mattinson, 2005). The special pre-analysis treatments of CA-TIMS method consist of crystal annealing and chemical leaching. 30 euhedral zircons grains were hand picked under microscope at BGC for each sample (Fig.2.4). Some magmatic inclusions occurred in the picked zircons. These zircons were transferred into quartz container and then sent to the furnace to be heated at 800ºC-1100ºC for 48 hours. Radiation damages were completely removed for zircon domains with low to moderate original radiation damage. Then these zircons were further cleaned in hot aqua regia (HCl: HNO 3 =3:1) to get rid of any pollution from the lab and previous sample treatments.12 and 6 “clean” zircons from sample FS031 and FS046 respectively were then spiked and underwent partial dissolution in hydrofluoric acid at temperature of about 200°C for 120 hours. The high Pb loss parts within the zircons dissolved faster than the low Pb loss crystal components. Thus, a drop of zircon residue with artificial spike of 205 Pb plus 233 U is obtained for analyses. This residue has been extensively leached with lowest potential of Pb loss. Before sending the samples to the mass spectrometer we loaded the “residue drop” with a small amount of silica gel and phosphoric acid on a filament. The silica gel and the phosphoric acid help to enhance the ionization in the mass spectrometer. Then the filament is sent to the mass spectrometer to be measured. 5.4 Age calculation U-Pb geochronology has always been regarded as the most powerful technique to determine rock ages because it applies two independent decay schemes of 238 U- 206 Pb and 25 235 U- 207 Pb. These two schemes involve the same elements but are with different half-lives, which allow an effective internal check of the “closed system” issue. Before extracting best estimate age for a certain sample, we calculate the ages for both schemes separately. Then, both the equivalence and concordance of the data points will be evaluated by plotting them on a Concordia diagram and test whether the two dates for an individual zircon are the same or similar enough for us to say that there is no Pb loss or inheritance and the age is the zircon crystallization age. Ages yielding the best justifiable equivalence and concordance are used to calculate a weighted mean age for the rock (Ludwig, 1998). If both decay schemes have the same chronometric power, then the Concordia age will be more precise than any of these single ages. As for Phanerozoic samples, the 238 U- 206 Pb ratios carries most of the chronometric power, so the 235 U- 207 Pb ages are only used to check concordance of a data point (Ludwig, 1998). In terms of calculating and interpreting the zircon ages of this study, we will use the terminology from Miller et al., (2007) to distinguish between 1) autocrysts, which formed during the crystallization of the rock; 2) antecrysts, which based on their ages may have crystallized during the formation of earlier phases of the same intrusive system; and 3) xenocrysts, which are clearly inherited from the host rock or the magma source. Concordant ages possibly include ages of autocrysts, antecrysts and xenocrysts. We only calculate the weighted mean of the truly clustered and concordant 238 U- 206 Pb ages of autocrystic zircons to represent the best crystallization age of the sample. This age yields the best MSWD (Mean Square of Weighted Deviates) without arbitrarily selecting data 26 points. Concordant ages that are not quiet equivalent to the best estimated ages of the rock will be interpreted differently. 5.5 Geochronology results and interpretation The measurements and calculated 238 U- 206 Pb and 235 U- 207 Pb ages of all single zircons from the two samples were listed in Table 2.3. For sample FS031, 12 zircons were analyzed. All 12 zircons from this sample yielded concordant ages and 5 out of them clustered well around the weighted mean age of 131.02±0.26 Ma with MSWD of 1.4 (Fig.2.5). We interpret this age as the crystallization age of the granodiorite unit and these 5 zircons as autocrysts formed during the crystallization of this unit. The other 7 zircons with older ages are interpreted as antecrysts from earlier units, which we interpret to exist as unexposed units beneath the Fangshan area. These ages range from 131.96±0.30 Ma to 144.94±0.82 Ma with three of them older than 136 Ma and the other four between 132 Ma and 134 Ma (Table 3). Zircon FS031Z21 has a relatively larger error (Table 3) for both two ages because the measurement of U is more imprecise for this one analysis. There is no clear evidence to show that these older zircons are from the host rock since the host rock immediately next to the outer quartz-diorite unit is the Archean Gneiss that yielded U-Pb ages from 1800 Ma to 2500 Ma (Yan et al., 2006). Other than the Archean gneissic and mylonitic rocks, the youngest host rock which can be possible sources of xenocrysts in Fangshan pluton is the middle Carboniferous to Triassic coal-bearing metaclastic rocks to the west of the pluton. These rocks are at least 200 Ma, which is older than our oldest single zircon age of about 145 Ma. 27 Sample FS046 from the outer quartz-diorite unit yielded a weighted mean age of 131.06±0.43 Ma (MSWD=2) from 5 out of 6 zircons that have been analyzed and we interpret this age as the crystallization age of the quartz-diorite unit (Fig.2.5). 1 zircon out of the 6 gave an age of 143.2±0.86 Ma matching well with the oldest zircon age (145 Ma) from sample FS031. We interpret this zircon as an antecryst from an older unexposed plutonic body below the current pluton and probably from the same source as the oldest zircon in the granodiorite unit. There is no indication of the existence of any xenocrysts in this sample either. 6.0 Geochemistry 6.1 Previous geochemistry studies: Geochemistry studies of Fangshan Pluton have been done at different scales by many authors. Major elements analyses show that from the margin to the center SiO 2 wt% increases from intermediate to felsic (Huang et al., 1985; He at al., 1935; Wang, 1950). Trace elements and REE studies indicate the high Sr/Y ratios, which is extremely similar with the C-type adakite defined by Zhang et al., 2001, Li et al., 2001 and Ge et al., 2002. Whole rock Stable isotope and Sr, Nd, Pb isotopic studies plus isotopic studies of single minerals of zircon, titanite and apatite indicated that the magma overall is adakitic and potentially produced by remelting of the thickened lower crust (Zheng et al., 1987; Mu et al., 1988; Cai et al., 2005; Sun et al., 2010). Single mineral studies of hornblende, plagioclase, zircon, sphene and apatite from both mafic enclaves and the granitic rocks also show chemical signatures overlapping between different units, which indicate that 28 magma mixing and assimilation of host rocks are also important processes controlling the formation of the geochemical signatures of pluton (Qin et al., 2006; Sun et al., 2010). 6.2 New Geochemistry: Fifteen samples were collected for whole rock geochemistry study. Six samples from the study of Huang et al., 1985, Wang, 1950 and He et al., 1935 were added to the data set we are going to use in this paper since only these six have all major, trace, REE and isotope data. Analytical results are presented in Table 4. Major element analyses show that the SiO 2 wt% ranges from 52.92-62% in the outer unit while it ranges from 55.01-73.21% in the inner unit (Table 4a). There are obvious overlaps of SiO 2 wt% in the two main units and in the different phases of the inner unit instead of a simple trend of SiO 2 wt% decreasing from the margin to the center of the pluton. REE pattern of this study agrees well with previous geochemistry studies with strong enrichment of LREE, depletion of HREE and smooth trend in between (Fig.2.7a, Table 4b). An average of our Fangshan samples and averages of Cenozoic adakite, underplated basalt related adakite and high Si adakite were plotted together after normalizing to chondrite (Fig.2.7a). All of them fall into a similar trend with Fangshan values higher than the other three. No obvious Eu positive or negative anomalies are present. Analytical results of trace elements were also normalized to average upper continental crustal values (Fig.2.7b). Sr is highly concentrated in all samples from 496 ppm-1640 ppm with Sr/Y ranges from 58-153 (Table 4c). Incompatible HFSE (high field strength elements) of Nb and Ta are depleted compared to average upper continental crust. 29 7.0 Discussion 7.1 Temporal history of the Fangshan pluton Previous U-Pb zircon ages of the quartz-diorite unit from previous studies range from 129.9 Ma to 133.6 Ma with errors ranging from 0.8 Ma to 2.8 Ma by different methods (Table 2.2). Our age from the same unit using the youngest, clustered autocrysts is 131.06±0.43 Ma. Previous U-Pb zircon ages from the granodiorite unit range from 128.5 Ma to 133.8 Ma with errors of 0.6 Ma to 2.1 Ma (Table 2.2). These ages overlap with the ages from the quartz-diorite unit within errors. Our new age using the youngest, clustered autocrysts from the granodiorite is 131.02±0.26 Ma, which is slightly younger than the quartz-diorite unit, but within error. Compared to the previous ages, our two new ages effectively narrow the errors. This high precision is due to both effectiveness of the CA- TIMS pre-analysis sample treatments to preferentially remove parts of the zircons with Pb loss and the low analytical blank BGC applied to the measurement. These new ages indicate that the exposed part of the Fangshan pluton may young slightly from margin to core but are largely the same age within error. A particularly interesting result from both samples is the presence of the older, concordant zircon ages from antecrysts. In sample FS046, the one antecrystic age is about 144 Ma, while in sample FS031, six antecrystic ages range from 132 Ma to 145 Ma. These ages indicate that there must be sources of these older zircons somewhere along the magma generation and/or ascent path. There is evidence from previous studies that also support the existence of these old sources. Small quartz-diorite apophyses exposed in Nanjiao area to the west of Fangshan pluton have zircon U-Pb LA-ICP-MS ages of 30 134.0+1.0/-2.0 Ma and similar geochemical properties to the Fangshan pluton (Zhang et al., 2008). 20 zircons were analyzed in Zhang et al., 2008 and many of these zircons have discordant U-Pb ages, which is probably caused by the inefficient treatment of zircons to remove Pb lost domains before analyses. Among the concordant zircon ages, two of them have 238 U- 206 Pb ages of 144±3 Ma and 144±2 Ma (Zhang et al., 2008). These two ages agree very well with the oldest antecrystic ages of about 144 Ma in our samples (Fig.2.5, Table 3), so it is possible that these apophyses are exposed portions of the old sources beneath the Fangshan pluton. U-Pb zircon ages of a dioritic dike and a quartz-diorite sample near the western margin of the pluton are 136±1 Ma and 135±1 Ma (Wang et al., 2011), which also match the antecrystic ages in sample FS031 of about 134 Ma and 136 Ma (Table 3, Fig.2.5). These dikes can be originated from the old zircon sources as well. As noted earlier no known nearby host rocks have zircons young enough to act as a source of these zircons. So we think it highly likely that plutonic units with these ages reside beneath the Fangshan pluton. Although the zircon crystallization ages of the two units in the pluton are within ½ m.y. of each other, the antecrystic ages suggest that the overall magmatic system may have a growth/crystallization duration of at least 15 myrs, which is suggested for other batholithic bodies (Memeti et al., 2010). The old sources can be deeper plutonic bodies made up of multiple pulses with different ages. Later, the upwelling of the Fangshan magma then picked up some of these zircons from these older bodies and brought them up to present levels. The antecrystic zircons could be recycled more than once within the 31 magma system below and finally transported by Fangshan pluton to its emplacement site (Fig.2.8). Geophysical evidence including magnetic and gravitational anomaly investigation also show the possibility of the existence of a batholitic scale magmatic body beneath the Fangshan area (Yan et al., 2010). The evolution of the whole magmatic system below the Fangshan pluton and how the "zircon crystal cargo" was transported is illustrated by a cartoon model in Fig.2.8. 7.2 Necessity of the re-evaluation of the previous K-Ar and 40 Ar- 39 Ar ages While U-Pb zircon ages record the crystallization of the pluton, K-Ar and 40 Ar- 39 Ar ages of hornblende and biotite tell us about the cooling history of a pluton. Cooling ages are always younger than the crystallization ages of plutons since the closure temperatures for these minerals are dramatically lower than that of zircon. Many cooling ages have been reported for Fangshan pluton. Biotite and hornblende separates from the Fangshan pluton are even used as the geostandards for K-Ar and 40 Ar- 39 Ar dating in China (Sang et al., 2006, 2007). For the quartz-diorite unit, one K-Ar age is 131.1 Ma (BGMRBM, 1991) which is close to the new crystallization age of this unit, but theoretically should be at least 1 m.y. younger than this age, so it is still problematic. Other than this, all other K-Ar and 40 Ar- 39 Ar ages are significantly older than the zircon crystallization ages obtained in the present study (Table 2.2, Fig 2.6). Except for the two K-Ar studies of Li et al., 1964 and BGMRBM, 1991, detailed description of the analytical methods and methods of calculation of K-Ar and 40 Ar- 39 Ar ages can be found in all other literatures. All the ages and methods were listed in Table 2. 32 Wang (1983) first addressed the Chinese geostandards of K-Ar and 40 Ar- 39 Ar geochronology. In his study both hornblende and biotite were collected from the center granodiorite unit of the Fangshan pluton and they were treated and analyzed at the National University of Australia’s geochronology lab. This study (Wang 1983) shows that the K-Ar, 40 Ar- 39 Ar plateau and 40 Ar- 39 Ar isochron ages for both minerals agree very well, which indicates that the minerals did not experience any later disturbance after they crystallized, and so he concluded that these minerals are great geostandards for geochronology studies. The plateau ages of biotite and hornblende are 132.7±0.1 Ma (6- 16 steps) and 132.8±0.1 Ma (18-23 steps) (Wang 1983). As we all know that hornblende’s closure temperature is about 550°C while biotite’s is about 350°-310°, the cooling age of these two minerals should be different instead of being this close. Sang et al., 2006 and Sang et al., 2007 re-examined these geostandards of biotite and hornblende respectively. The measurements were carried out at the Ar isotopic laboratory of the Institute of Geology and Geophysics of Chinese Academy of Science. Seven laboratories were invited to participate in the calibrations of K and 40 Ar*of the biotite standards. K- calibration was done with flame photometry and atomic absorption while the 40 Ar* calibration were done by isotopic dilution method. 40 Ar- 39 Ar plateau age of biotite is 132.2±0.2 Ma (3-13 steps) while the K-Ar age of the sample is of 132.8±1.3 Ma (Sang et al., 2006), and the plateau age and K-Ar ages of the hornblende geostandards are 133.3±0.6 Ma (5-16 steps) and 133.3±1.5 Ma respectively (Sang et al., 2007). The most recent 40 Ar- 39 Ar geochronology work was done by Yan et al. (2010) on two hornblende samples from the pluton. This study was carried out at the Ar geochronology lab of China 33 University of Geosciences, Beijing. The two plateau ages are 134.3±1.4 Ma (6-11 steps) and 136.0±1.5 Ma (4-11 steps), while the corresponding isochron ages are 135.6±2.9 Ma and 130.5±6.8 Ma (Yan et al., 2010). The second age is this study itself is not very reliable because of the huge difference between the plateau and the isochron ages, and both of these two ages are too old compared to not only the crystallization ages we presented in this study but also other cooling ages done in other labs in China. These systematic differences between the crystallization and cooling ages for the Fangshan pluton and between cooling ages obtained by different labs is a critical problem, since the cooling ages of the biotite and hornblende are still used as the geostandards for K-Ar and 40 Ar- 39 Ar geochronology studies at different labs in China. All these studies used different instruments and different calibrations on the same minerals but with dramatically different results, it is very necessary to get the problem fixed before any further research is based on the use of these standards. It is common in all of these published papers to reach the conclusion that the cooling ages and the crystallization ages overlapped within errors and thus “agreed”. However, it is clearly not appropriate to make these conclusions since with the current precision available from modern instrumentation and lab procedures allow us to distinguish the differences between the crystallization and cooling ages of minerals with significantly different closure temperatures. 7.3 Nature of magma source of Fangshan pluton Major and trace geochemistry of this study agree well with previous studies. The geochemical overlap between different units and phases also indicates that single 34 crystallization and fractionation event cannot explain the formation of the chemical characteristics of Fangshan pluton. Magma mixing and mingling are necessary processes to form the chemical features of the current pluton. The average of our Fangshan samples falls into the same REE pattern as averages of typical adakite. The enrichment of LREE and the depletion of HREE, plus the high ratio of Sr/Y, and depletion of HFSE as Nb and Ta indicate that Fangshan pluton is very similar to the typical High Sr low Y adakite in Eastern China (Zhang et al., 2005). Sr, Nd, Pb isotopic study did by Cai et al., 2005 and stable isotope study did by Zheng et al., 1987 both support that the magma of Fangshan pluton originated from the melting of the bottom of the thickened crust. Cai et al., 2005 suggested a two-stage model for the source of the Fangshan magma. The first stage is the upwelling of the asthenosphere which caused the enriched lithospheric mantle to be melted to form basaltic magma. The basaltic magma then intruded the lower crust of the North China craton causing thickening of the crust. During the second stage, the continuing upwelling of asthenosphere melted the thickened crust to form high Sr low Y adakitic magma for Fangshan pluton. 7.4 Growth of the magma chamber below Fangshan pluton Our new high-precision ages plus field petrological and structural data of Fangshan pluton indicate a much more complicated magma chamber growth history than the simple “two pulse” model proposed by previous workers (Ma, 1989; Ma et al., 1996; Cai et al., 2005) and provide more information of the internal chamber growth processes. He et al. (2009) discussed the interaction of the pluton and the country rock during the emplacement and concluded that the Fangshan pluton is a typical example of a magmatic 35 diapir. For a typical diapir, one of the most important diagnostic features is the strong vertical movement of large batches of magma. For the host rock, this vertical magma movement will result in adjacent pluton-side-up kinematics in aureoles and potentially rim-synclines in outer aureoles as occurs around the Fangshan (He et al., 2009). Inside the rising magma chamber, the strong vertical movement may cause very steep, margin parallel foliation and near vertical lineation (Clemens et al., 1997; Miller and Paterson, 1999) as is also preserved in the Fangshan pluton. The similar ages, geochemistry, and crosscutting or shared magmatic fabrics from internal units within this pluton are all suggestive that although different magma pulses exist, they have a shared history and were rising together during final emplacement. The newly recognized antecrystic zircons plus the similar ages of some of these antecrysts with ages of nearby compositionally similar plutonic bodies indicate a more vertically extensive and complicated history of the construction of the magma system below the presently exposed Fangshan area. The antecrystic ages are interpreted to represent different parts of an evolving and crystallizing chamber(s), which during the continued ascent of the remaining magmatic portions of the system were entrained into the rising magma. 7.5 Significance for regional tectonics As introduced above, the age of the Fangshan pluton is useful in better determining of time sequence of main regional and local deformational events. Different models have been suggested in different papers as summarized in Table 2.1. 36 The deformational history of the Fangshan area in Mesozoic starts with the N-S contraction, but there is only very little relict structures of this contraction at the northern part of this area. Some authors mentioned that this structure was caused by the collision of the South and North China blocks at the beginning of Mesozoic (Yan et al., 2006; Yan et al., 2010; Wang et al., 2011). From the end of Triassic to the beginning of Jurassic, the Pacific plate started to subduct beneath Eastern China from SE towards NW, which changed the stress field of Eastern China from N-S contraction to NW-SE contraction (Wan et al., 2002). The WNW vergent thrusts in the Fangshan area are interpreted by Wang et al., 2011 to be related to this event because the contemporary WNW thrusts and volcanic acitivities in the E-W trending Yanshan tectonic belt and NE trending Taihang mountains were caused by this initial of subduction (Bartolini and Larson, 2001; Wang and Li, 2008). Then the regional ESE (110°-130°) stretching lineation occurred (He et al., 2009), which caused crustal thinning and the melting of the bottom of the crust. This regional extension is possibly caused by different tectonic mechanisms and events. There are at least three possibilities: (1) crustal thinning after crustal overthickening; (2) the roll back of the subducting plate of Pacific; (3) the closure of the Mongol-Okhostk Ocean plus the collision of Lhasa and Qiangtang blocks at ca. 130-110 Ma (proposed in Wang et al., 2011 based on 40 Ar- 39 Ar geochronology study). Because the tectonic mechanism that cause the regional extension is not the focus of this paper, we are not going to discuss that any further than this. Since the oldest antecrystic age is about 145 Ma, the crustal thinning likely began as early as the beginning of Cretaceous. From 70-60 Ma the high angle normal fault possibly caused by the collapsing of the North China Plateau separated 37 the Western Hills to the west of the fault from the North China plain to the east (Wang et al., 2011). The significance of the SE110°-130° stretching lineation is the most debated structure in this area. He et al. (2009) presented some unpublished 40 Ar- 39 Ar ages of 128.7-150.2 Ma from muscovites associated with this lineation, which indicate that the event causing this structure happened right before the emplacement of the Fangshan pluton. Wang et al., (2011) also dated biotite and sericite associated with the same feature by 40 Ar- 39 Ar method and got ages of 130-110 Ma. Based on field relationship, emplacement of Fangshan pluton postdates the SE 110-130° stretching lineation because it did not overprint the pluton at all but overprinted earlier contractional structures. Thus our new ages indicate this structure formed before 131 Ma. 8.0 Conclusions Fangshan pluton grew incrementally by at least two main pulses with ages of 131.06±0.43 Ma and 131.02±0.26 Ma respectively. Ages of antecrystic zircons are from 132 Ma to 145 Ma, which extend the evolution history of the magmatic system below the Fangshan area to about 15 myrs. Zircon crystals have been recycled within the whole magmatic plumbing system from older pulses to the younger ones. Previous K-Ar and 40 Ar- 39 Ar cooling ages have problems since they are older than the zircon crystallization ages. It is necessary to re-evaluate these cooling ages since the samples are used as geostandards for Ar-Ar labs in China. Magma of Fangshan pluton is coming from the melting of the thickened crust and rocks are typical Eastern China high Sr low Y adakite. The pluton emplaced as a typical diapir with mostly vertical movement and the magmatic 38 system below the Fangshan area is constructed by multiple pulses with different ages. Crustal thinning of the NCC caused the melting of the bottom of the thickened crust to form magmatism in this area. The oldest antecrystic zircon age tells us that this thinning could happen as early as 145 Ma. 39 Fig.2.1 Geological map of Fangshan pluton (modified after the map made by the Beijing geological survey) 40 Fig.2.2 Simplified structure map of Fangshan area (modified after He et al., 2009) 41 (a) Granodiorite dike in quartz-diorite unit (c) Steep dipping foliation in host rock near Northeastern margin of the pluton (b) Xenolith in quartz-diorite unit Fig.2.3 Field photos 42 (a) FS031 (from granodiorite unit) (b) FS046 (from quartz-diorite unit) Fig.2.4 Photos of zircons under plane-polarized light (40×) Fig.2.5 Concordia plots and weighted mean age of Fangshan samples 43 Fig.2.6 Comparison of the precision and the range of the geochronology data of Fangshan pluton 44 (a) (b) Fig.2.7 (a) Comparison of the REE pattern of Fangshan samples and other samples from literature; (b) Comparison of TE (trace element) pattern of the two units of Fangshan pluton 45 Fig.2.8 Cartoon of Fangshan pluton incremental growth model and the recycling of zircons within the whole magmatic system Table 2.1. Different deformational history models of Fangshan area 46 Table 2.2. Geochronology summary of the Fangshan pluton Mineral Ages Method 131.06±0.43 Ma [1] CA-TIMS 132.3±2.8 Ma [2] 129.9±1.3 Ma [2] 132.4±1.3 Ma [3] 133.6±0.8 Ma [2] SIMS Biotite 131.1 Ma [4] K-Ar 131.02±0.26 Ma [1] CA-TIMS 132.3±1.8 Ma [2] 133.8±2.1 Ma [2] 133.1±0.6 Ma [2] 130.1±0.8 Ma [2] 132.2±0.9 Ma [2] 130.7±1.4 Ma [5] SHRIMP 128.5±1.5 Ma [6] ID-TIMS Titanite 129.3±1.0 Ma [2] LA-ICP-MS Apatite 134±10 Ma [2] LA-ICP-MS 133.3±1.5 Ma [8] 133.0/133.3/132.2±2.4 Ma [9] 134.3±1.4 Ma [7] 136±1.5 Ma [7] 133.3±0.6 Ma [8] 132.8±0.1 Ma [9] 141 Ma, 145 Ma [13] 132.8±1.3 Ma [10] 133.1/132.6/132.3±1.2 Ma [9] 132.2±0.2 Ma [10] 132.7±0.1 Ma [9] Dioritic dike Zircon 136±1 Ma [11] Deformed diorite Zircon 135±1 Ma [11] Quartz-diorite apophyses Zircon 134.0+1.0/-2.0 Ma [12] LA-ICP-MS Reference of Table. 2: [1]This study; [2]Sun et al., 2010; [3]He et al., 2009; [4]BGMRBM, 1991; [5]Cai et al., 2005; [6]Davis et al., 2001; [7]Yan et al., 2010; [8]Sang et al., 2007; [9]Wang, 1983; [10]Sang et al., 2006; [11]Wang et al., 2011; [12]Zhang et al., 2008; [13]Li et al., 1964 Ar-Ar TIMS Units (phases) in the pluton Rocks outside of the pluton Zircon Zircon Quartz-diorite Hornblende K-Ar Granodiorite Rock Unit LA-ICP-MS LA-ICP-MS SIMS Ar-Ar Biotite K-Ar 47 Sample Nothing Easting cm.Pb (pg) Th U 207 Pb 235 U 2 σ σ σ σ %er diseq.corr. 206 Pb 238 U 2 σ %er ρ ρ ρ ρ FS031ZZ02 409478 4397768 144.94 0.82 143.08 5.05 1.3 1.03 0.1513 3.53 0.022739 0.57 .26 FS031ZZ04 409478 4397768 138.69 0.56 137.91 2.16 0.8 1.20 0.1455 1.57 0.021747 0.41 .43 FS031ZZ05 409478 4397768 136.70 0.45 138.19 2.53 0.7 0.79 0.1458 1.83 0.021432 0.33 .45 FS031.Z21 409478 4397768 134.11 5.67 134.55 5.90 1.5 0.81 0.1417 4.39 0.021022 4.21 .96 FS031ZZ01 409478 4397768 133.57 0.68 132.29 2.64 0.6 1.03 0.1392 2.00 0.020936 0.51 .41 FS031ZZ03 409478 4397768 132.86 0.53 132.42 2.77 0.5 1.00 0.1393 2.09 0.020824 0.40 .45 FS031ZZ06 409478 4397768 131.96 0.30 132.07 2.73 0.9 1.33 0.1389 2.07 0.020682 0.23 .54 FS031.Z22 409478 4397768 131.11 0.48 132.07 6.17 2.4 0.89 0.1389 4.67 0.020547 0.37 .67 FS031.Z23 409478 4397768 131.22 0.30 131.26 1.74 0.9 1.01 0.1380 1.33 0.020564 0.23 .44 FS031.Z24 409478 4397768 131.10 0.36 130.64 4.21 2.5 1.10 0.1373 3.22 0.020545 0.28 .63 FS031.Z25 409478 4397768 130.89 0.49 131.99 1.72 1.3 0.95 0.1388 1.30 0.020512 0.37 .45 FS031.Z26 409478 4397768 130.75 0.31 129.77 1.41 1.3 1.05 0.1363 1.08 0.020490 0.24 .42 FS046ZZ01 409092 4395179 130.97 0.43 129.87 4.72 0.9 0.98 0.1364 3.64 0.020524 0.33 .60 FS046ZZ02 409092 4395179 143.20 0.86 136.06 7.95 0.9 0.89 0.1434 5.85 0.022463 0.60 .49 FS046ZZ03 409092 4395179 131.83 0.62 131.51 6.44 0.7 0.87 0.1383 4.90 0.020660 0.47 .53 FS046ZZ04 409092 4395179 130.89 0.40 129.33 4.65 0.7 1.35 0.1358 3.59 0.020512 0.31 .63 FS046ZZ05 409092 4395179 130.92 0.42 129.33 3.75 0.7 1.12 0.1358 2.90 0.020516 0.32 .54 FS046ZZ06 409092 4395179 131.34 0.80 131.62 5.70 0.7 0.90 0.1384 4.33 0.020584 0.61 .46 Table 2.3 Isotopic measurements and calculated 238 U- 206 Pb and 235 U- 207 Pb ages of all zircons diseq.corr. 206 Pb* 238 U 207 Pb* 235 U 48 (a) Major elements measurements of Fangshan samples and averages of typical adakites (b) REE measurements of Fangshan samples and averages of typical adakites Table 2.4. Geochemistry data of Fangshan pluton and averages of typical types of adakite from literature Sample Unit SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 FS039 QD 52.92 1.021 18.03 8.64 0.133 4.55 8.1 4.05 2.06 0.486 FS048 GD 55.01 1.031 17.38 8.24 0.12 4.03 6.34 4.02 3.2 0.634 FS054 GD 56.47 1.004 16.38 7.18 0.126 5.35 6.44 4.17 2.42 0.456 FS037 GD 58.83 0.787 17.91 6.08 0.095 3 5.07 4.44 3.38 0.394 FS036 GD 59.22 0.824 17.3 6.42 0.104 2.99 4.8 4.31 3.62 0.416 A1 QD 59.34 0.7 16.59 5.57 0.1 2.55 5.15 3.89 3.33 0.29 3--2 QD 60.18 0.74 16.86 5.94 2.65 5.2 4.14 3.78 0.44 FS046 QD 60.570 0.687 17.82 5.09 0.088 2.57 4.7 4.42 3.74 0.319 FS044 QD 60.84 0.732 17.06 5.74 0.099 2.57 4.94 4.13 3.57 0.326 FS007 GD 60.98 0.717 17.51 5.24 0.086 2.46 4.52 4.38 3.75 0.340 A17 GD 61.56 0.68 15.61 5.76 0.12 2.8 4.58 3.38 3.67 0.33 FS020 QD 62.00 0.64 17.38 5.41 0.11 1.91 4.41 4.44 3.38 0.316 FS023 GD 62.370 0.661 17.25 4.83 0.081 2.16 4.21 4.52 3.59 0.333 3--4 GD 62.72 0.6 17.06 4.87 2.1 3.96 4.7 3.71 0.35 FS024 GD 63.62 0.657 16.59 4.66 0.077 2.13 3.94 4.35 3.66 0.316 3--12 GD 63.91 0.6 15.33 4.88 0.09 2.03 4.14 3.96 3.41 0.3 FS031 GD 65.650 0.649 16.72 3.41 0.04 1.36 2.76 4.97 4.15 0.278 3--6 GD 66.2 0.57 16.54 3.26 1.26 2.86 5.65 3.61 0.23 FS033 GD 66.26 0.535 16.26 3.54 0.054 1.5 3.17 4.57 3.86 0.253 FS026 GD 66.77 0.585 16.39 3.07 0.036 1.23 2.43 4.86 4.37 0.253 FS069 GD 73.21 0.241 14.31 1.51 0.027 0.54 1.46 4.43 4.17 0.103 CZA 63.89 0.61 17.4 4.21 0.08 2.47 5.23 4.4 1.52 0.19 UBA 64.27 0.645 17.5 3.94 0.05 1.33 4.02 5.46 2.58 0.2 HAS 64.80 0.56 16.64 0.08 2.18 4.63 5.19 1.97 0.2 Sample Unit La ppm Ce ppmPr ppm Nd ppmSm ppmE u ppm Gd ppmTb ppm Dy ppmHo ppm E r ppmTm ppmYb ppm Lu ppm FS039 QD 26.46 59.70 7.86 31.78 6.16 1.79 4.23 0.55 2.87 0.54 1.43 0.20 1.22 0.19 FS048 GD 57.57 112.74 13.46 52.05 8.85 2.25 6.02 0.73 3.71 0.67 1.63 0.22 1.26 0.20 FS054 GD 37.00 78.05 9.81 38.84 6.94 1.97 4.87 0.59 2.93 0.53 1.31 0.18 1.15 0.18 FS037 GD 36.01 77.12 9.82 39.60 7.71 2.08 5.49 0.72 3.71 0.69 1.75 0.24 1.41 0.22 FS036 GD 36.43 79.96 10.09 39.46 7.00 1.99 4.73 0.60 3.17 0.59 1.54 0.21 1.33 0.22 A1 QD 44.50 78.60 10.20 36.80 6.06 1.81 4.03 0.54 2.70 0.52 1.32 0.23 1.66 0.30 3--2 QD 32.72 65.46 7.60 26.28 5.99 1.59 4.48 0.58 3.28 0.63 1.69 0.24 1.59 0.26 FS046 QD 26.46 59.70 7.86 31.78 6.16 1.79 4.23 0.55 2.87 0.54 1.43 0.20 1.22 0.19 FS044 QD 64.82 122.31 13.57 48.39 7.99 2.04 5.51 0.71 3.75 0.73 1.85 0.27 1.70 0.26 FS007 GD 66.83 121.78 13.31 47.33 7.62 2.09 5.08 0.63 3.21 0.59 1.51 0.21 1.29 0.20 A17 GD 42.1 77.3 10 35.6 5.45 1.78 3.53 1.09 2.17 0.41 0.99 0.17 1.22 0.23 FS020 QD 51.72 97.31 11.01 40.37 7.02 1.88 4.89 0.66 3.59 0.68 1.80 0.26 1.63 0.27 FS023 GD 53.62 100.98 11.35 41.32 6.94 1.96 4.73 0.59 2.97 0.54 1.44 0.20 1.23 0.20 3--4 GD 65.4 111 13.9 47.4 7.48 2.03 4.64 0.6 2.79 0.53 1.3 0.22 1.45 0.24 FS024 GD 54.66 105.81 11.90 42.98 7.11 1.90 4.83 0.59 3.00 0.55 1.43 0.20 1.26 0.19 3--12 GD 49.79 94.81 11.62 40.57 7.65 2.09 5.5 0.7 3.44 0.64 1.63 0.22 1.34 0.2 FS031 GD 43.60 91.19 11.06 41.06 6.57 1.79 3.84 0.41 1.79 0.27 0.60 0.08 0.43 0.07 3--6 GD 67 107 13 43.1 5.96 1.71 3.37 0.36 1.41 0.22 0.49 0.09 0.45 0.09 FS033 GD 35.53 75.12 9.10 33.71 5.56 1.52 3.52 0.43 1.99 0.35 0.83 0.11 0.67 0.11 FS026 GD 41.09 83.68 9.92 36.48 5.74 1.59 3.47 0.36 1.54 0.24 0.51 0.07 0.38 0.05 FS069 GD 26.09 46.51 4.85 16.41 2.48 0.65 1.56 0.19 0.90 0.15 0.37 0.05 0.32 0.05 AVER 45.69 87.91 10.54 38.63 6.59 1.82 4.41 0.58 2.75 0.51 1.28 0.18 1.15 0.19 CZA 17.53 34.64 20.14 3.15 0.97 2.25 0.37 1.43 0.76 0.91 0.15 UBA 19.50 35.72 4.05 14.98 2.32 0.74 2.06 0.32 1.86 0.36 1.00 0.14 0.55 0.16 HAS 19.20 37.70 18.20 3.40 0.90 2.80 1.90 0.96 0.88 0.17 49 (Table 2.4 continued) Trace elements measurements of Fangshan samples and typical adakites Sample A1, 3—2, A17, 3—4, 3—12,3—6 are from Huang et al., 1985; He et al., 1936; Wang, 1950. Other samples are from this study. AVER-average of the Fangshan samples; CZA-average of Cenozoic adakite (Drummond et al., 1996); UBA- average of underplated basalt related adakite (Zhao et al., 2008; Atherton and Petford, 1993; Petford and Atherton, 1996; Muir et al., 1995); HSA-average of high SiO 2 adakite (Martin et al., 2005) QD-quartz diorite unit of Fangshan pluton; GD-granodiorite unit of Fangshan pluton Sample Unit Ni Cr Sc V Ba Rb Sr Zr Y Nb Ga Cu Zn Pb La Ce Th Nd FS039 QD 10 25 20 193 1456 39 1572 98 22 5.4 23 35 99 14 46 98 2 46 FS048 GD 21 57 16 181 2085 67 1380 198 17 7.6 22 79 118 37 55 118 4 53 FS054 GD 63 196 18 152 877 71 1250 179 14 8.3 21 22 107 13 39 76 6 38 FS037 GD 12 33 13 116 2071 66 1468 238 18 8.3 19 9 82 13 37 78 4 39 FS036 GD 12 31 10 115 2078 74 1288 268 16 8.6 20 6 98 15 36 84 4 39 A1 QD 10.66 102.2 1.02 996 25.18 1640 116 9.51 36.88 44.5 78.6 2.42 36.8 3--2 QD 3.63 2.15 10.13 1561 78.9 1113 224 10.67 53.15 32.72 65.46 10.18 26.28 FS046 QD 11 29 9 97 1975 75 1379 202 15 7.9 21 8 79 18 25 59 2 32 FS044 QD 3 17 12 113 1709 80 1211 212 19 9.5 19 9 79 20 64 122 12 47 FS007 GD 10 25 10 97 1962 70 1365 212 16 9.3 21 5 78 17 64 122 9 46 A17 GD 6.39 124.7 2.11 2420 75.56 1431 231 10.63 72.22 42.1 77.3 4.68 35.6 FS020 QD 1 2 9 83 1729 71 1091 226 19 8.1 18 7 87 20 53 102 7 42 FS023 GD 8 18 8 88 1871 72 1303 203 15 8 20 6 78 24 54 103 7 42 3--4 GD 5.33 109.2 3.21 1842 78.52 1114 199 9.95 57.22 65.4 111 9.08 47.4 FS024 GD 8 23 9 83 1672 75 1175 198 14 9.9 19 5 75 19 55 105 8 43 3--12 GD 3.58 2.71 8.75 1780 66.6 1287 380 9.64 54.92 49.79 94.81 8.23 40.57 FS031 GD 6 14 4 57 2425 68 1376 192 9 8.4 22 3 77 20 48 95 3 41 3--6 GD 3.1 113.7 5.92 4206 69.9 1429 229 6.72 110.4 67 107 4.15 43.1 FS033 GD 5 16 6 63 1511 72 1137 171 11 8.3 21 5 64 20 39 81 6 36 FS026 GD 5 12 4 51 2209 76 1251 176 8 7.7 21 5 76 23 39 84 4 36 FS069 GD 2 7 3 25 702 84 449 111 6 6.2 19 4 29 30 27 43 12 15 AVER 10 46 9 72 1864 69 1272 203 10 9 33 10 58 14 47 91 6 39 CZA 39 54 9.1 72 485 30 869 117 9.5 3.5 17.53 34.64 20.14 UBA 26.5 68.5 934 8.5 19.50 35.72 14.98 HAS 20 41 95 52 721 108 10 19.20 37.70 18.20 50 CHAPTER 3: TEMPERAL AND SPATIAL GEOCHEMICAL EVOLUTION OF MESOZOIC MAGMATISM IN THE CENTRAL SIERRA ARC, CALIFORNIA 1.0 Abstract Combined field studies, geochronology, geochemistry data sets from our Undergraduate Team Research (UTR), The Western North American Volcanic and Intrusive Rock Database (NAVDAT), graduate research projects across the central Sierra Nevada continental arc help to constrain the temporal and spatial evolution of the Mesozoic magmatism in the central Sierra Nevada batholith. 704 chemical analyses of both volcanic and plutonic rocks are included in this study. In the Soldier Lake area on the eastern margin of Tuolumne Batholith (TB), the Green Lake pluton (165 Ma), Soldier Lake granodiorite (97 Ma) and Cathedral Peak granodiorite (86 Ma) are intruded into Triassic (218-229 Ma) metavolcanic and metavolcaniclastic units. In the Saddlebag Lake pendant, Triassic pluton intruded into the Triassic metasediments along the east side of the area, and 85-95 Ma Tuolumne Batholith intruded into Triassic metvolcanic rocks and Jurassic metasedimentary rocks. In the Waugh Lake area, Cretaceous Thousand Island granodiorite/granite (93.6 Ma), Cretaceous Rush Creek granodiorite (94.5 Ma), and the Tuolumne Batholith intruded into Mesozoic metavolcanic and metasedimentary rocks. In the Cinko Lake area to the northwest of TB, the Cretaceous Harriet Lake (102 Ma) and Freemont Lake granodiorite (<95 Ma) are intruded into slightly older (102-107 Ma) metavolcanic rocks. In Jackass Lake area, the 97 Ma Jackass Lake pluton to the southwest of TB is intruded into Cretaceous metavolcanic units (98-103 Ma). In the Iron Mountain area to the southwest 51 of TB, Cretaceous plutonic rocks are intruded into Cretaceous metavolcanic units (98-106 Ma). From east to west across the main axis of the arc, magmatism becomes progressively younger, although the volumes of Triassic plutons and Jurassic volcanics are not large in the above areas. From Triassic to Cretaceous and from east to west of the main arc axis, plutonic rocks became more evolved in terms of rock types while volcanic rocks evolve from more tholeiitic to calc-alkaline. All rocks are predominantly calc-alkaline, but intermediate and more mafic plutonic rocks show tholeiitic iron enrichment. Multiple trace element lineages for Jurassic and Cretaceous plutonic rocks indicate that magma mixing is needed, in conjunction with the effects of fractionational crystallization, to account for chemical trends during magma evolution. Relative depletion of Ta, Nb and Ti to K, Ba in Sierran plutonic and volcanic rocks and existing Nd-Sr isotopic data indicate the important role of a continental crust component in the origin of Sierran magmas. The magnitude of a crustal component contributing to origin of Sierran magmas was increased for younger magmatic stages, including the late Cretaceous magmatic surge at and after 90 Ma. Plutonic and volcanic rocks show very parallel trends for major, trace elements. Nd-Sr isotope data show some spatial variation which indicates that it is highly possible that they have the same origin and the magma source of Mesozoic central Sierra did not change very much through time. 2.0 Introduction The Mesozoic Sierran magmatic arc (Fig. 3.1) is a subduction-related arc built into a complex basement of both oceanic and continental margin terranes (Bateman, 1992; 52 Saleeby 1989; Kistler et al., 1993). Our understanding of this arc has played a central role in the discussion of a number of interrelated themes that can be generally placed into two main groups: (1) the magmatic evolution of arc systems including topics such as (a) arc initiation and subsequent non-steady state tempo of arc magmatism, (b) physical and chemical connections between magma storage and volcanic eruptions, (c) the chemical evolution of the source region, the overlying crustal columns, and the magmas moving through these crustal columns, and (d) the thermal evolution of, and mass transport within the arc columns; and (2) tectonic issues such as (a) nature of basement beneath arcs, the timing and geometries of subduction, (c) whether the volcanic arc formed in marine or terrestrial environments, (d) the timing and tempo of tectonic events, which in the Sierran region include proposed events such as the pre-arc truncation of the North American margin and proposed orogenies such as the Antler, Sonoma, Morrison, Nevadan and eastern California thrust system, (e) the timing of intra-arc strike-slip faulting and interplay between faulting and magmatism (Tikoff and Teyssier, 1992; Sharp et al., 1993; Greene and Schweickert, 1995; McNulty,1995a), and (f) models linking magma emplacement, regional tectonism and downward displacement of host rocks (e.g., Saleeby, 1990; Tobisch et al., 2000). Addressing many of these issues has been hampered in the Sierras by (1) the lack of knowledge of the full extent and thus the full range of characteristics of the Mesozoic volcanic arc section and accompanying sedimentary units, since many parts of this stratigraphy have been removed by exhumation or subsequent magma emplacement and (2) by detailed studies integrating spatially and temporally linked data sets from both the 53 stratigraphic units and from the intruded plutons. In this chapter we are going to present new field studies, geochronology studies of a number of domains in central Sierra Nevada (Fig. 3.2) plus regional geochemistry study using data from different sources. All of these field study areas have sections of volcanic, sedimentary and plutonic components of the Mesozoic arc. I specifically integrate the geochemistry data from both plutonic and volcanic units in the attempt to better understand the links and difference between these two rock types and so the magmatic and tectonic evolution of this section of the arc. Appendices provide geochemical data sources and the data acquisition technique for results discussed throughout the text. The main conclusions are that (1) both the plutonic and volcanic components of this ~250 to 85 Ma arc are spatially, temporally, and geochemically linked and thus part of the same vertically connected magmatic system; (2) magmas in this arc are derived from mixing of mantle plus crustal melts and show clear evidence of fractionation and remixing during ascent. 3.0 New field studies The boxes shown in Figure 2 outline the regions that have recently been mapped in the central Sierra Nevada in which plutonic, metavolcanic, and metasedimentary elements of the Mesozoic arc are preserved. Along the eastern Sierran crest we have examined areas in the northern and central parts of the Saddlebag Lake pendant (herein called the Virginia Canyon and Saddlebag Lake regions) and in the northern Ritter Range pendant (herein called the Waugh Lake area) all of which expose fairly complete sections of the Triassic to Cretaceous volcanic arc (Fig. 3.1, 2). Farther west we have examined two 54 regions that preserve Jurassic metasedimentary and Cretaceous metavolcanic and plutonic rocks, which below we call the Cinko Lake and Jackass Lakes regions north and south of the Tuolumne Batholith, respectively (Fig. 3.2). In the Jackass Lakes region our studies focused on the Strawberry Mine and Quartz Mountain pendants and a series of small pendants in and around the Jackass Lakes pluton. Finally, we have completed some reconnaissance studies of related metavolcanic, metasedimentary, and plutonic units farther south in the central and southern Sierra Nevada. A brief summary of data sets from each of these areas is presented below. Geochemical techniques are presented below as well. The summary spreadsheet of all geochemical data that have been used in this chapter will be attached to the whole dissertation as an appendix. 3.1 Virginia Canyon area Previous work in the Virginia Canyon area includes mapping by Chestermann (1975) and Schweickert and Lahren (1991, 1993, 2006). We have focused our studies in a corridor across the Mesozoic arc section from Green Lakes (NE corner) and Virginia Lakes (SE corner) west across Virginia and Spiller canyons (Fig. 3). The western margin of the corridor consists of the ~ 86 Ma Cathedral Peak phase of the Tuolumne batholith (Fig. 3.2). In this corridor all stratigraphic units are fairly steeply dipping outside of fold hinges. The eastern edge consists of Paleozoic units (not examined in our study) overlain by a thick pile of metavolcanic (Koip sequence) and local metasedimentary units including a basal sequence of quartzites and metaconglomerates (Cooney Lake conglomerate) that are interrupted by a number of steeply dipping shear zones and locally folded (Fig. 3). If folding and faulting are assumed to only cause local displacements and 55 repetitions, then the general sequence from east to west consist of the metasediments and local thin volcanic units associated with the Cooney Lake conglomerate, a more thickly- bedded basaltic to rhyolitic (often more mafic) set of volcanic and volcaniclastic units, a bedded section dominated by dacitic to rhyolitic units, and an andesitic to rhyolitic section cored by a volcaniclastic-dominated section typically folded on a regional scale. Metavolcanic rocks in the above units range in composition from rhyolite to andesite (55 to 77 wt. % SiO 2 ) and are dominated by clastic (lapilli- to breccia-sized fragments), crystal-bearing tuffs, local flows, and volcaniclastic units. Chemical compositions are mostly similar to the plutons discussed below but also contain a distinct low-Mg, tholeiitic unit, a composition not observed in the plutons. We have obtained LA-ICP-MS ages from detrital zircons that range from 216 to 254 Ma and a single older zircon with an age of ~2 Ga in a quartzite associated with the Cooney Lake conglomerate. Schweickert and Lahren (1993, 2006) report a U-Pb zircon age of 222 Ma from a rhyolite immediately west of the Cooney Lake conglomerate and we have obtained a new LA-ICP-MS zircon age of 195 Ma from a volcaniclastic unit near the western margin of these units (Fig. 3.2) The western edge of this package of rocks is a regional, dextral oblique, transpressive ductile shear zone, herein named the Virginia Canyon shear zone, which evolved to a more localized brittle fault, herein named the Virginia Canyon brittle fault (Cao et al., 2010; Whitesides et al., 2010). Immediately west of the Virginia Canyon shear zone a package of metasedimentary rocks typically occurs consisting of cross-bedded quartzites, phyllites, calc-silicates, local marble, metaconglomerates, and rare volcaniclastic units. 56 We have obtained LA-ICP-MS ages from detrital zircons in three metasandstone samples from this package of rocks that all have minimum peaks at ~ 175 Ma and older Paleozoic and Precambrian peaks back to ~2.8 Ga. These units are likely part of the Sawmill Canyon Sequence (for definition see Schweickert and Lahren, 2006) described in more detail below in the Saddlebag Lake section. West of, and sometimes tectonically interleaved with this metasedimentary package, is a complex package of rocks that includes mixed volcanic and sedimentary units of probable Golconda affinity, and both Triassic and Cretaceous volcanic sequences (Fig. 3; see also Schweickert and Lahren; 1993, 2006). In the Golconda thrust package we have obtained LA-ICP-MS detrital zircons ages from one sample that has a minimum peak at ~305 and older lower Paleozoic and Precambrian peaks. This unit is intruded by a deformed diorite to granodiorite body for which we have determined an LA-ICP-MS zircon age of ~232 Ma. This pluton only intruded units in a single thrust package and is deformed by the bounding thrust fault (Fig. 3). The above steeply-dipping stratigraphic units are intruded by three Mesozoic plutons, which from east to west are the 165.2 ± 0.3 Ma Green Lake granodiorite, the 97.4 ± 0.4 Ma Soldier Lake granodiorite, and the 86.3 Ma Cathedral Peak granite (CA-TIMS ages from Mundil et al. 2004; Memeti et al. 2010a). The Green Lakes and Soldier Lake plutons largely consist of medium-grained granodiorite, but with some moderate textural and compositional variations, and are cut by leucogranitic, tourmaline-bearing dikes derived from the much larger Cathedral Peak intrusion. The Cathedral Peak pluton is also largely granodioritic, but with distinctive large K-feldspar phenocrysts. All 57 granodiorites contain hornblende, biotite, and sphene (titanite) and are of the high fO 2 magnetite series (Ishihara, 1977). Each pluton is compositionally distinct, but all three are high-K, calc-alkaline, and range from metaluminous to peraluminous. Portions of the Soldier Lake and Green Lake plutons have SiO 2 as low as 56 wt. %, but most of all three plutons range between 66 – 78 wt. % SiO 2 , with K 2 O exhibiting strikingly incompatible behavior unlike all other major elements that decrease with increasing silica. 3.2 Saddlebag Lake Previous work in the Saddlebag Lake area includes studies by Brook (1977), Brook et al. (1974), Keith and Seitz (1981), Kistler and Swanson (1981), and Bateman et al. (1983). More recent studies include Kistler (1993) and Schweickert and Lahren (1993, 1999, 2006). Our new mapping in this area focused on Mesozoic units exposed from just north of Saddlebag Lake to just south of Sawmill Canyon (Fig. 3.4). These units are bounded to the east by older Paleozoic units and to the west by the Tuolumne Batholith (Fig. 3.4). From east to west these units typically consist of (1) Paleozoic chert-bearing, quartzite-dominated, metasediments interpreted by Schweickert and Lahren (2006) as parts of the Roberts Mountain allochthon; (2) probable Permian units including mafic metavolcanic units with local pillows, conglomerates (called Diablo Formation by Schweickert and Lahren, 2006) and mixed metasiltstones and metasandstones (called Candelaria Formation by Schweickert and Lahren, 2006); (3) a tectonically reactivated unconformity previously examined by Brook et al. (1974); (4) the Cooney Lake conglomerate and associated metasandstone and metavolcanic units; (5) the Koip sequence, a complex pile of andesitic to rhyolitic metavolcanic units with local 58 volcaniclastic and metasedimentary beds; (6) a large, dextral-transpressive ductile shear zone, herein named the Steelhead Lake shear zone, which evolved to a more localized brittle fault, herein named the Steelhead Lake brittle fault; (7) a package of moderately to thinly-bedded metasedimentary rocks including quartzites, phyllites, calc-silicate rocks, metaconglomerates, and local marble and volcanic units (Sawmill Canyon sequence of Schweickert and Lahren, 2006) that in the northern part of this region, is increasingly intruded out by the Cathedral Peak phase of the Tuolumne Batholith along intrusive margins that locally step to the east and truncate bedding; and (8) in the southern portion of the mapped region, we find another sequence of less deformed typically dacitic to rhyolitic, clastic to phenocryst-bearing metavolcanic rocks, which are exposed west of the metasedimentary sequence and immediately along the margin of the Tuolumne Batholith. Here the batholith consists of the Kuna Crest and locally Half Dome phases of the batholith. For a detailed description of the complicated relationships between these batholithic units in this area see Paterson et al. (2008). Barth et al. (2011) report 4 SHRIMP U-Pb single zircon ages in this region, a 221 Ma age from a dioritic body near Odell Lake, and three ages from rhyolitic units in the Koip sequence just south of Sawmill Canyon that range from 232 Ma (near base of section) to 219 Ma (at top of section just east of the Steelhead Lake brittle fault; Fig. 3.4). We have obtained a series of new ages as follows (Fig. 3.4): (1) an 88.5 Ma CA-ID-TIMS, U-Pb zircon age from the Cathedral Peak phase of the Tuolumne batholith near Steelhead Lake; (2) a 221 Ma LA-ICP-MS age from a diorite body in Saddlebag Lake; (3) LA-ICP-MS zircon ages from four metavolcanic samples, two from the Koip sequence, which have 59 ages of 216 and 227 Ma and two from the western belt of metavolcanic rocks, which have ages of 95 and 113 Ma.; (4) LA-ICP-MS ages from detrital zircons in four samples from the metasedimentary package (Sawmill Canyon Sequence) just west of the Steelhead Lake brittle fault that have minimum zircon age peaks between 172 to 189 and older Paleozoic and Precambrian zircon age peaks; and (5) LA-ICP-MS ages from detrital zircons of one sample from a quartzite associated with the Cooney Lake conglomerate that has a continuous spread of zircon ages from 238 to 271 Ma and two older zircon ages around 405 Ma. Our age determinations agree with that of Barth et al (2011) for the Koip sequence and associated ~221 Ma plutons. They also match well with the ages discussed earlier from farther north in the Virginia Canyon area. These additional ages now confirm that a belt of Jurassic metasedimentary rocks with Precambrian zircons in them occurs immediately west of the Triassic volcanic sequence both here and in the Virginia Canyon area. These ages also document that both Triassic and Cretaceous volcanics occur in tectonic slices west of these metasedimentary rocks. As described in the Virginia Canyon region, stratigraphic units in the Saddlebag region generally have steeply west-dipping bedding (outside of fold hinges) and contain a steeply west-dipping mostly bedding-parallel foliation axial planar to both rare, large- scale, moderately-plunging folds and more common, small-scale folds with variable plunges in which bedding and sometimes an older mineral fabric are transposed. Mineral lineations are widespread and typically plunge steeply. Fabric intensities and associated strains measured from clastic objects are heterogeneous but increase up to >85% with shortening perpendicular to foliation and >175% extension parallel to lineation (see also 60 Albertz, 2006). The western Cretaceous metavolcanics tend to have lower strain on average and moderately- to steeply-dipping bedding. The Half Dome, Kuna Crest, and Cathedral Peak intrusives in this area are compositionally similar to the same rocks we report for other regions of the Tuolumne Batholith (Paterson et al., 2008). East of the Steelhead Lake shear zone, we have one analysis of the Triassic dioritic intrusion occupying the southeast end of Saddlebag Lake. At 58.1 wt. % silica, it is a quartz diorite but with unusually high Al 2 O 3 (19.2 wt.%), a feature shared with the Triassic metavolcanics in this same area. Otherwise, it is calc- alkaline, metaluminous, and high K. This one analysis is more mafic than the 62-77 wt. % silica range reported by Barth et al. (2011) for the Triassic Scheelite Intrusive Suite but otherwise has similarities in being both rather calcic and potassic for its level of SiO 2 . We have new geochemical data for the metavolcanic rocks, both Triassic and Cretaceous, which are similar and range from basalt (Triassic only) to rhyolite. Interestingly, the Triassic suite includes both tholeiitic (basalt to andesite) and calc- alkaline (rhyolite) members, whereas the Cretaceous volcanics (andesite to rhyolite) are all calc-alkaline. However, as a group, the metavolcanics show considerable spread in K and Na suggestive of alteration and element mobility, as seen in other metavolcanic units to the south (e.g., Hanson et al., 1993). 3.3 Waugh Lake The Ritter Range pendant (Fig. 3.1, 2) contains the most extensive and well-exposed section of Mesozoic metavolcanic arc rocks in the Sierra. Previous studies by Tobisch et al. (1977, 2000) and Fiske and Tobisch (1978, 1994) document that this pendant consists 61 of a series of fault-bounded, internally thinned tectono-stratigraphic packages of the metavolcanic sequences, within which stratigraphy has been both cut out and repeated. These stratigraphic packages contain well-preserved bedding that dip steeply and show younging to the southwest (Fiske and Tobisch, 1978; Tobisch et al., 1986, 2000). Tobisch et al. (2000) define five such tectono-stratigraphic packages, and using multigrain U-Pb zircon dating, they established that the three eastern packages range in age from Late Triassic to Jurassic (Fiske and Tobisch, 1978; Stern et al. 1981; Tobisch et al., 2000). Package #2 also has thin lenses of marble, one of which contains an Early Jurassic pelecypod Weyla, (location on Fig. 3.5; Huber and Rinehart, 1965; Fiske and Tobisch, 1978). Their tectono-stratigraphic package #4 largely consists of the Minarets Caldera complex, which unconformably overlies steeply-dipping volcanogenic rocks, yields U-Pb zircon ages of 211 ± 2 Ma and 203 ± 2 Ma along the eastern margin of the caldera and ~127 Ma and 132-144 Ma along the western margin where the western caldera margin is truncated by reverse motion on the Bench Canyon fault (Tobisch et al., 1995). Two multigrain U-Pb zircon ages obtained from this caldera complex gave ages of ~ 98 and 101 Ma (Fiske and Tobisch, 1994). Fiske and Tobisch (1978; 1994) and Lowe (1996) identified components of this caldera as follows: (1) a basal unconformity with 10-15 m relief overlain by a cobble conglomerate containing volcanic and plutonic clasts; (2) a 2.2 km thick ash-flow tuff with a basal 600 m homogenous rhyolite (average SiO 2 = 74.6) and then a weak stratigraphically upward trend from 73-66wt. % SiO 2 ; (3) an up to 2 km thick section of tuff breccias, interpreted to be a caldera collapse unit that includes cm to 1.8 km largely 62 volcanic clasts in a non-welded tuff. This unit grades upwards into an ~1660 m thick post-collapse rhyodacite with the capping 560 m welded ignimbrite consisting of dacite (average SiO 2 = 67.5). It also becomes finer grained to north, and has some local bedded units; (4) a sequence of caldera lake deposits and capping flows fed by andesitic dikes intruding earlier caldera units; and (5) the Shellenberger Lake biotite granite, interpreted to be a resurgent pluton, that has miarolitic cavities, locally preserved mixing with the andesitic dikes mentioned above, and has a Sr i of 0.7052. Lowe (1996) dated 2 zircon fractions from this pluton that gave a poorly constrained 93 Ma age and determined a two-sample, Rb-Sr isochron of 94.4 +/- 1.2 Ma. Using geochemical modeling Lowe (1996) concluded that the ignimbrite chemistry can be explained by 45-50% fractionation of plagioclase, hornblende, K-feldspar, biotite, magnetite, apatite, and zircon from an andesitic parental magma and that the Shellenbarger pluton could be either a late-stage liquid from this underlying magma chamber or formed by partial melting of the ignimbrite. The northern part of the Ritter Range pendant, herein called the Waugh Lake area (Fig. 3.2, 5), has received somewhat less attention. Here, the tectonic packages of steeply dipping metavolcanic rocks are bordered to the east by older Paleozoic rocks studied by Greene (1995) and are intruded in the north by the Tuolumne batholith (Bateman, 1992; Memeti et al., 2010a) and satellite plutons such as the Rush Creek granodiorite (Fig. 3.7; Kistler and Swanson, 1981). To the west, the northern margin of Minarets Caldera units also occur. Our new mapping has focused on this Waugh Lake area and extends from the Gem Lake area westward across the southern margin of the Tuolumne batholith and into 63 the Minarets Caldera complex (Fig. 3.5). In the Waugh Lake area the metavolcanic and local metasedimentary sequences define three large and one small, fault-bounded packages that tentatively match well with those described immediately to the south by Fiske and Tobisch (1978, 1994), and Tobisch et al., (1977, 2000). We thus use the same numerical designation of packages as described by Tobisch et al. (2000) for sake of clarity. The easternmost tectono-stratigraphic package (#1) is bordered on the east by multiply deformed Paleozoic units (Greene, 1995; Stevens and Greene, 1999) that are intruded by the Lee Vining Canyon granite, recently dated at ~220 Ma (Barth et al., 2011). The boundary between the Paleozoic and Mesozoic units is a Late Paleozoic unconformity subsequently reactivated in the Cretaceous by the ~2-3 km wide, oblique, dextral, transpressive Gem Lake shear zone (Brook et al., 1974; Greene and Schweickert, 1995) further discussed below. Metavolcanic units in package #1 are dominated by moderately to thickly-bedded andesitic to rhyolitic, both clastic air-fall and crystal-dominated flow units. Local interbeds of phyllitic metasediments and crossbedded and graded, westward younging volcaniclastic units also occur. In the eastern part of the package larger, fine- to coarse- grained, clastic metasedimentary units are exposed. A number of rhyolitic to dacitic units occur in this portion of the package. Units tend to increase in thickness and become more mafic in the central part of the package (between Gem and Waugh Lake) and here several thick clastic units with clast sizes ranging up to meter-scale are prominent. From this package #1 we have obtained three new LA-ICP-MS U-Pb zircon ages two from volcanic units (Fig. 3.5), which have ages of ~207 Ma near Gem Lake, and ~154 Ma (near western 64 edge) and one from a metasedimentary unit with minimum peak zircon ages of ~185 Ma (near eastern edge in metasediments). The former two ages plus younging indicators observed in the field indicate that package #1 is largely a westward younging package of volcanic rocks that preserves a record of volcanism over much of the Triassic and Jurassic. The eastern age raises the possibility that the mixed metasediments and metavolcanics here are tectonically displaced, probably in the Gem Lake shear zone. The boundary between the tectono-stratigraphic packages #1 and #2 is marked by a fairly discrete, ductile-brittle fault with steeply-plunging lineations. Kinematics are not well preserved, probably due to later continued contraction (see also Tobisch et al., 2000 for discussion of package bounding faults). The central tectono-stratigraphic package #2 is characterized by andesitic to rhyolitic metavolcanic units with much thinner bedding on average and more interlayered metasedimentary units, including the thin marble unit containing the fossil Weyla. Both crystal-dominated flows and clastic airfall units are common. Much of the western half of this package is intruded by plutons near which the host rock units sometimes become migmatitic. From this package we have obtained four new LA-ICP-MS U-Pb zircon ages from volcanic and metasedimentary units with ages of ~221 Ma and 193 Ma (eastern third), and ~163 Ma and ~153 Ma (central portion). LA- ICP-MS U-Pb zircon ages from a fifth sample from a leucosomal layer in the migmatized western third of this package gave an age of ~94 Ma suggesting that migmatization was associated with the nearby plutons (see below). Based on the stratigraphic position of known ages, the number of stratigraphic units above and below dated units, and the assumption that the package is not significantly internally disrupted, we infer that this 65 package records westward younging volcanism from around ~230 Ma to <130 Ma and both overlaps with and preserves somewhat younger units than package #1. To date we have only mapped into the northeastern edge of Tobisch et al.’s (2000) tectono-stratigraphic package #4. Here this package consists of about 20-50 meters of volcaniclastic units noted above overlain by rhyolitic to locally dacitic ash flow tuffs and tuff breccias. Farther southwest these give way to the thick ash-flow tuffs and megabreccias interpreted by Fiske and Tobisch (1994) and Lowe (1996) as caldera collapse breccias. Bedding in these units dip gently to moderately to the SW. We obtained two new LA-ICP-MS U-Pb zircon ages of ~97-95 Ma in a sample from the volcaniclastic unit, and ~96 Ma from a rhyolite tuff suggesting a slightly younger age for this late Cretaceous caldera complex (Fiske and Tobisch, 1994). A series of plutons intrude the above stratigraphic units. To date the only recognized Triassic pluton is the ~220 Ma Lee Vining Canyon granite (Barth et al, 2011). No Jurassic plutons are yet recognized in the mapped area although the ~161 Ma Fish Canyon pluton occurs ~8 km south of this area. A series of Cretaceous plutons intrude all three of the tectono-stratigraphic packages described above. The largest is the Tuolumne batholith, which has been recently extensively studied and dated by Memeti et al. (2010a). They reported two CA-ID-TIMS U-Pb zircon ages from the Kuna Crest, a tonalitic to largely granodioritic lobe that extends out from the main chamber down to the Waugh Lake area. These ages are 94.4±0.3 Ma from near the southwestern lobe margin and 93.6±0.4 Ma for the Waugh Lake granodiorite (Fig. 3.4). They interpreted the Waugh Lake granodiorite to have formed from magma derived from the Kuna Crest lobe that 66 intruded southeastward into the volcanic host units. We have obtained four new CA- TIMS zircon ages from (1) one sample in the lobe center, which resulted in 92.9±0.11, (2) ages of 94.7±0.17 Ma and 94.8±0.23 ages from two different units in a magmatic sheeted complex near the SW margin of the Kuna Crest lobe, and (3) a 93.0±0.82 Ma age from the Thousand Island Lake granodiorite, located just to the southeast of the Waugh Lake body (Fig. 3.4). It is interesting to note that the ages of the sheeted complex, which intrudes across the boundary of the Minarets Caldera complex, are only slightly younger than the age of this caldera complex. We also obtained LA-ICP-MS U-Pb zircon ages of ~ 89 Ma from a coarse hornblende dominated gabbro body located between the Waugh and Thousand Island Lake plutons, which we herein call the Island Pass gabbro, and an ~94 Ma age from a tonalitic to granodioritic body along the southeast margin of the Kuna Crest lobe. The Rush Creek granodiorite, called a quartz monzodiorite by Kistler and Swanson (1981), intrudes the eastern metavolcanic package and was previously interpreted by these authors to be ~100 Ma based on a Rb/Sr whole rock age. We obtained a new LA-ICP-MS zircon age of ~ 94 Ma from the central phase of this pluton (called the granite of Billy Lake by Kistler and Swanson, 1981). The Rush Creek, Waugh Lake, Thousand Island Lake, and the Kuna Crest lobe in this region are medium- to high-K, and trend from metaluminous to near or marginally peraluminous in more felsic portions. Most are also calc-alkaline but some Jurassic and Triassic volcanics are tholeiitic. However, our data is too limited to make a full appraisal of this distinction. Most notable is that Cretaceous and Jurassic volcanic rocks exhibit 67 considerable variation in K and Na, which has been attributed to hydrothermal alteration (Sorenson et al., 1998). This is more pronounced in the Jurassic section where K 2 O + Na 2 O values range by a factor of four, independent of silica. If such were primary compositions, the high values (some with K 2 O above 7 wt. %) would lead to classification as alkaline. Others low in alkalies, lead molecular ratio of Al 2 O 3 /(CaO+Na 2 O+K 2 O), A/CNK values, well above 1.1 and upwards to 1.6 which are not igneous values. However for more immobile elements, such as REE, the full range of Mesozoic volcanic rocks and Cretaceous plutons are similar with LREE enrichment and a modest negative Eu anomaly. Typical spider diagrams, normalized to MORB (not shown) are also similar, leading to the conclusion that similar processes led to the formation of these magmas regardless of post emplacement alteration. 3.4 Cinko Lake Previous work in the Cinko Lake area (Fig. 3.2, 6) includes studies by Huber et al. (1989), Wahrhaftig (2000), and Memeti et al. (2010b). Our mapping in this area examined a ~0.5 km 2 pendant of metasedimentary rocks, an adjacent belt of metavolcanic rocks, and the plutons surrounding these pendants. The metasedimentary pendant is composed of centimeter to decimeter, thin to moderately bedded, fine-grained, quartzites, metasiltstones and calcareous metasiltstones (Fig. 3.6). Dolomite and decimeter scale, fine-grained amphibolite and hornblende gneiss layers occur locally (Memeti et al., 2010b). These units display three to locally four deformation phases, the first two of which form tight to isoclinal folds and strong axial planar foliations. Memeti et al. (2010b) 68 report LA-ICP-MS ages from detrital zircons in one sample from a quartzite in the eastern margin of this pendant, which shows a minimum peak at 148 Ma, a major peak at ~171 Ma, an older peak at ~215 Ma, and a few older zircons. About 200 meters to the east of the Cinko Lake pendant a larger belt of metavolcanic rocks called the Piute Meadows pendant is exposed (Fig. 3.6). These metavolcanic rocks include beds of andesitic to rhyolitic crystal and lapilli tuffs, lithic tuffs and local flow units (Huber et al., 1989; Wahrhaftig, 2000). They are locally interlayered with siliciclastic, calcsilicate and marble layers (Fig. 3.10d), which are distinct from the well laminated and multiply deformed strata in the Cinko Lake pendant (Memeti et al., 2010b). Local interbeds of volcanoclastic and metasedimentary units with graded beds and crossbedding indicate top-to-the-west younging, but switch to top-to-the-east directions in the easternmost metavolcanic units (Foley et al., 2007). The metavolcanic rocks are more mafic in composition further to the east with andesite and basalt flows occurring within the volcanoclastic package. All of these units are now tilted to near vertical dips and are internally strained preserving a well-developed mineral foliation and lineation and local intrafolial folds. Memeti et al. (2010b) report LA-ICP-MS ages for three metavolcanic samples from the Piute Meadows pendant. These ages all fall between ~103 and 108 Ma. The Cinko Lake pendant and Piute Meadows metavolcanics are predominantly surrounded by the granodiorites of Harriet Lake and Fremont Lake (Fig. 3.6) (Huber et al., 1989). A small body of quartz diorite, called the Cinko Lake quartz diorite occurs between the metasedimentary and metavolcanic rocks. Memeti et al. (2010) report CA- 69 TIMS, U-Pb zircon ages of 101.8 ± 0.2 Ma for the Harriet Lake granodiorite and 95.2 ± 0.2 Ma for the Cinko Lake quartz diorite. These plutons typically display magmatic foliation and lineation that are statistically parallel to nearby host rock structures. The plutons range in silica from 62-69 wt. %, and although distinct in detail, are comparable in being magnetite series (high fO 2 ). The metavolcanic rocks range from 61 to 77 wt. % silica and have compositions comparable to nearby intrusions (Foley et al., 2007, Anderson et al., 2008). Both plutons and older metavolcanic rocks are calc- alkaline, medium to high-K, and are mostly metaluminous with some of the more silica- rich range samples being marginally peraluminous. A few of the metavolcanic rock samples have slightly higher A/CNK ratios (>1.05), and the higher aluminum likely reflects pre-metamorphic weathering. The plutons and metavolcanic rocks are also similar in minor and trace element abundances including P, Rb, Sr (< 800 ppm), Cr, Ni, Y, Nb, and REE, amongst others. 3.5 Jackass Lakes area Directly west of the Ritter Range pendant and south of the Tuolumne Batholith (Fig. 3.1, 2), the ~97-98 Ma Jackass Lakes pluton (JLP) and nearby plutons intrude a number of metavolcanic and locally metasedimentary pendants (McNulty et al., 1996, Nokleberg, 1981; Pignotta, 2007). Peck (1980) originally mapped this region and suggested that the JLP and associated plutons were resurgent magmatic bodies that intruded roughly coeval volcanic and subvolcanic plutonic rocks of the ca. 98–101 Ma Minarets caldera sequence. The sharp western margin of the JLP may reflect a portion of the former caldera ring fracture and the east-west striking metavolcanic and metasedimentary units in the Post 70 Peak and Strawberry Mine pendants the northern and southern boundaries of the caldera (Peck, 1980; Fiske and Tobisch, 1994, Lowe, 1996). Kistler and Peterman (1973), Kistler and Ross (1990), and Kistler (1993) provided the first systematic studies of isotopic ratios in the central Sierran region and identified approximate positions of the 87 Sr/ 86 Sr 0.704 and 0.706 lines. These authors concluded that the moderately to steeply southwest-dipping Bench Canyon shear zone, located just west of the Ritter Range (Fig. 3.2), represents a crustal scale break (their intrabatholithic break #2) across which isotopic values and basement types change. Kistler (1993) suggested that oceanic or transitional crustal sources better fit the geochemistry of plutonics and volcanics east of the shear zone and a crystalline Proterozoic lower crustal source better fit the geochemistry of plutons and volcanic units west of the shear zone. Tobisch et al. (1995) suggested that any strike slip motion on this fault occurred prior to formation of the Cretaceous volcanic sequences, and that reverse motion occurred between 90-78 m.y. Lowe (1996) used detailed whole rock geochemistry and isotopic studies, plus new geochronology, to conclude that the volcanics to the east and west of the Bench Canyon fault represent two distinct caldera complexes (Fig. 3.2), which along with their plutonic equivalents were named the Minarets and Merced Peak caldera complexes, respectively. Lowe (1996) also noted that average Sr i for the Minarets units is 0.7051 compared to the average Sr i for the Merced Peak units of 0.7064, results consistent with Kistler’s (1993) suggestion of different isotopic values across the Bench Canyon fault. Because of reverse motion on Bench Canyon, the Minarets area preserves 71 higher crustal levels and Merced Peak area lower levels of these caldera complexes, which also represent two chemically distinct systems. Lowe (1996) noted that the Merced Peak caldera complex consisted of 5 main units: (1) early leucogranite porphyries; (2) rhyolitic ignimbrite; (3) felsites interpreted as rhyolite flows; (4) post-volcanic, biotite leucogranite lenses and larger bodies such as the Post Peak granite; and (5) voluminous granodiorite and synmagmatic mafic bodies in the JLP. Lowe (1996) presented a mix of U-Pb zircon and Sr/Rb ages, all with complications and fairly large errors, as follows: (1) ~ 98-99 Ma for the Post Peak porphyries; (2) ~94-98 Ma zircon ages from the JLP; (3) ~96 Ma from two zircon fractions in the ignimbrite; and (4) ~96.6 +- 2.6 Ma Rb-Sr isochron from leucogranites such as Timber Knob and Norris Creek. Lowe also obtained whole rock geochemistry and based on this geochemistry, field relationships, and ages concluded the following: (1) the ignimbrites are caldera fill: (2) the JLP is a homogenized subvolcanic pluton; (3) the cm to m-thick bands of leucogranites and compositionally similar larger ~500 m 2 pods such as the Timber Knob and Norris Creek leucogranites have minimum melt compositions, which she attributed to being accumulated melts formed by partial melting of the caldera volcanics during intrusion of JLP magmas. Chemical modeling by Lowe (1996) suggested that all components in the Merced Peak caldera complex could have evolved by fractionation from single underlying magma chamber with an andesitic parental composition, followed by remixing of fractionates, and late remelting of volcanic units. Fractionation of plagioclase and hornblende represented 90% of the needed fractionating phases and the JLP may thus have a significant cumulate component between 7 to 41%. Enclaves in the 72 JLP approximate the needed primary andesitic composition, which suggested to Lowe (1996) that mixing of ~15-25 enclave magma and 85-75% rhyolitic magma was important during growth of the JLP. Our studies of the JLP, some of the enclosed metavolcanic pendants, and nearby metavolcanic host rocks are summarized in Pignotta et al. (2007, 2010), Yoshinobu et al. (2009) and Memeti et al (2010b). Pignotta et al. (2010) noted that the ~98 Ma JLP syn- magmatically intruded both the ~99 Ma Illilouette Creek pluton to west and the Post Peak porphyry and in turn was intruded by diorite to quartz diorite bodies, all of which are intruded to the south by 90 Ma Mt. Givens granodiorite (McNulty et al., 2000) and to north by the ~95 Ma Red Devil Lake granodiorite (Tobisch et al., 1995). A previous JLP barometric determination of 4.5 kb (Ague and Brimhall, 1988) was revised using new temperature corrected values to 2.8 to 3.1 kb and temperatures of 677-708 o C. (Coyne, 2005). Pignotta et al. (2010) noted that the dominant composition of the JLP is medium- grained, equigranular biotite, hornblende, granodiorite containing numerous enclaves and fragments of host rock, but with the overall composition ranging from granite to diorite. Mapping of the northern half of the JLP indicated that smaller, more sheet-like pulses are preserved near margins whereas fewer and larger bodies are preserved in the center. These authors suggested that there are 100s of internal recognizable magmatic pulses and that crosscutting relationships suggest a general younging to west. Evidence of mingling between pulses is widespread. These and related units exhibits SiO 2 ranging 55.7 to 74.4 wt. %. The rocks are high-K, primarily metaluminous with some crossover into the peraluminous field and straddles the calc-alkaline – tholeiitic field boundary. The more 73 mafic units, such as the Madera quartz diorite are modally monzodiorites to quartz monzodiorites. The main JLP modally overlaps with these compositions and in more felsic members includes quartz monzonite, granodiorite, and monzogranite (Pignotta et al, 2010). We have recently started to examine another pendant previously mapped by Peck (1980) just west of the Jackass Lakes pluton, called the Quartz Mountain pendant (Fig. 3.7). The pendant is entirely surrounded by Cretaceous plutons (Peck, 1980) with two plutons bordering this pendant having ages of 99 +/- 1 Ma for the Illilouette pluton and 102 Ma for the Shuteye pluton with some Proterozoic inheritance (Tobisch et al., 1995). Tobisch et al. (1995) also studied a large ductile shear zone in this area that occurs between Jurassic and Paleozoic metasedimentary rocks discussed below. This Quartz Mountain shear zone is thought to have reserve motion on steeply dipping foliation surfaces and is associated with cooling ages of ~98-94 Ma from hornblende and ~94-87 Ma from biotite. Our preliminary mapping has identified three main stratigraphic units. Southwest of the Quartz Mountain shear zone, pendants units consist of a heterogenous metavolcanic unit ranging from andesite to rhyolite and including both clastic and crystal-dominated units and a sequence of quartzites, metasiltstones, and phyllite that resemble miogeoclinal sections elsewhere in the Snow Lake block (Memeti et al., 2010b). Some of the volcanic units include fragments ranging in size to greater than several meters and show features reminiscent of units in the Merced Peak and Minarets Caldera complexes to the east. These features include internal faults, mixing of large, heterogeneous blocks in a fine- 74 grained matrix, the presence of hypabyssal intrusive units, and occurrence of widespread alteration and possible ore mineralization: their presence suggests that this pendant may preserve the western margin of the Merced Peak caldera complex or a part of another caldera complex. Northeast of the Quartz Mountain shear zone, are a fine-grained metasedimentary unit dominated by phyllites and siltstone. We have obtained three LA-ICP-MS, U-Pb zircon ages from these units, one from the quartzite-dominate unit that has detrital zircon ages all older than 1.1 Ga and peaks that match detrital zircon histograms from the Snow Lake block (Memeti et al., 2010b), a second from the phyllite that has a minimum detrital zircon peak at ~144 Ma and older Paleozoic and Precambrian zircons, and a third ~103 Ma age from a rhyolite in the volcanic unit. We interpret these ages to indicate that in this pendant preserves Ordovician miogeocline (Snow Lake block) juxtaposed with a Jurassic marine sequence, unconformably overlain by middle Cretaceous volcanics and intruded by plutonic rocks of similar age (Gelback et al., 2010). Our new analyses of metavolcanic rocks in both the Quartz Mountain pendant and pendants throughout the Jackass Lakes pluton combined with previous data from Lowe (1996) range from 51 to 78 wt. % silica and are comparable in chemistry to the Jackass Lakes plutonic units, but with more scatter presumably due to alteration, as noted for volcanic sections elsewhere in this paper. All are subalkaline and likewise high K, calc- alkaline. They also show similar REE (modest LREE enrichment, minor negative Eu anomaly) and other trace element trends. 75 4.0 Summary Regional Geochronology There are several arc-scale geochronologic datasets worth examining. These include both LA-ICP-MS U-Pb ages from detrital zircons in Sierran metasedimentary sequences, and single and multigrain TIMS and LA-ICP-MS U-Pb ages from plutons and volcanic rocks. From metasedimentary sequences in the central and southern Sierras, we have collected an unpublished database of >5000 LA-ICP-MS detrital zircon ages from ~60 samples (Paterson et al., 2009). When ages of detrital zircons from all Sierran sediments are combined, age peaks centered at ~104 Ma, ~176 Ma, and ~216 Ma, with smaller Paleozoic peaks at ~400 Ma and ~500 Ma. Precambrian peaks also occur and match well with expected North American cratonal sources. The three Mesozoic peaks match the well-known pattern of magmatic surges in the Sierra Nevada (Stern et al., 1981; Ducea, 2001; Ducea and Barton, 2007). Six hundred sixty five published U-Pb zircon ages from plutons in the central and southern Sierra, compiled by Chapman et al. (in press), show a large Cretaceous age peak centered at ~90-105 Ma, a smaller Jurassic peak centered at ~165 Ma and a Triassic peak centered at ~210-220 Ma. Sixty five U-Pb zircon ages of volcanic units from the central Sierra Nevada, including previously published ages and our new ages presented above, show a large peak centered at ~100 Ma, a smaller peak centered at ~140 Ma, another small peak at ~165 Ma, followed by a small and broader peak at ~220 Ma. These data document that equivalent timing and relative magnitudes of magmatic surges and lulls are recorded in both the volcanic and plutonic records, although there is a 76 weak pattern suggesting that a greater volume of volcanism occurring early in surges relative to plutonism. 5.0 Geochemistry data collection and processing: In order to study the regional geochemical variations through the Mesozoic in central Sierra, we collected our geochemistry data from three main accessible sources: (1) published geochemistry data from NAVDAT (The Western North American Volcanic and Intrusive Rock Database); (2) geochemistry results of Undergraduate Team Research program (UTR) and graduate research of the Earth Sciences Department of University of Southern California (USC)and other accessible data source. NAVDAT is an online database of ages, chemical and isotopic data of volcanic and plutonic rocks in western North America which are Mesozoic age or younger. The powerful map interface allows us to accurately pick our study area which in this case is the central Sierra area and the huge database makes it possible for us to investigate regional space-time geochemical patterns as well. In this study, samples from NAVDAT include 259 plutonic rocks and 33 volcanic rocks. NAVDAT’s most recent update happened in May 2011, and we updated our data after that so our data include the most updated published geochemistry in the study area. Data of different time periods are from the following references: Triassic (Anonymous, 1981; Bateman et al., 1984; Barth et al., 2011); Jurassic (Peck and Van Kooten, 1983; Bateman et al., 1984; Frost 1987; Ague and Brimhall 1988; ; John David A 1992; Cousens 1996; Ernst et al., 2003; Lackey et al., 2006); Cretaceous (Barbarin et al., 1989; Cousens 1996; Steve 1996; Truschel 1996;Ratajeski et al., 2001; Gray 2003; Kylander et al., 2005; Paterson et al., 2008). 77 Data from the UTR program include studies of the following areas around the Tuolumne Batholith in Yosemite National Park: Cinko Lake area (2006); Soldier Lake area (2007); Saddlebag Lake area (2008); Quartz Mountain area (2009); Waugh Lake area (2010). Data from graduate research projects include Tuolumne batholith (Memeti) and Jackass Lake area (Pignotta) and Lowe (1996). Major, trace elements and REE data from our research group were collected by the GeoAnalytical Laboratory in Washington State University, Pullman using XRF and MC- ICP-MS respectively. Samples as rocks were sent to the lab directly from USC. They were prepared for analysis by chipping, pulverizing, weighing with di-lithium tetraborate flux (2:1 flux:rock), fusing at 1000 °C in a muffle oven, and cooling; the bead was then reground, refused and polished on diamond laps to provide a smooth flat analysis surface. The same suite of elements is analyzed for all samples, which includes the 10 major and minor elements of most rocks, plus 19 trace elements and REE. We organized all these data in excel spread sheets and used GCDKit 2.3 (Geochemical Data Toolkit) to plot them on different diagrams. Data points were color coded with different ages of Triassic, Jurassic or Cretaceous. All the diagrams follow the same color code. 6.0 Summary Geochemistry and Isotopes The numerous prior geochemical and isotopic studies in the Sierra have concentrated on defining magma sources, the evolving magma systems, and basement terrane mapping. In the arc-systems synthesis we present here, geochemical and isotope data are reviewed with three questions in mind: (1) how are volcanic and plutonic magmatism in the arc 78 geochemically connected, either directly or indirectly?; (2) are the tempo and chemically distinguished modes of magmatism indicative of the intra-arc mechanisms controlling magmatic activity?; and (3) what is the greater relationship of tectonics to magma productivity? 6.1 Geochemistry Early geochemical studies of continental magmatic arcs include those of Lindgren (1915) and Buddington (1927). Likewise, spatial geochemical compositional variations in the Sierra Nevada arc have been studied by different authors for many years (Lindgren, 1915; Moore, 1959; Wollenberge and Smith, 1968, 1969; Bateman et al., 1970; Ague et al., 1988, Glazner, 1991; Bateman, 1992; Ducea, 2001; Kistler, 1993; Gray et al., 2008; Mementi et al., 2010; Barth et al., 2011). In order to compare Mesozoic coeval plutonic and volcanic rocks through time, we summarize regional whole-rock geochemistry in the central Sierra Nevada batholith. Available geochemical analyses come from a variety of published sources listed in Appendix and include data from NAVDAT (North American volcanic and intrusive rock database; www.navdat.org), unpublished theses such as Lowe (1996), and our new data from both undergrad and graduate research projects. Altogether, our dataset includes over 700 samples with major elements analyses, 322 samples with REE analyses and 319 samples with other trace element analyses. On plots of these data we divide analyses into plutonic and volcanic and into Triassic, Jurassic, and Cretaceous ages (Fig. 3.8-13). Whereas Triassic plutons of the central Sierras are metaluminous to peraluminous and calc-alkaline, volcanic rocks of the same age range more broadly and many are tholeiitic, 79 particularly for more mafic members, a feature shared with plutons of Jurassic age (Fig. 3.8, 9). In contrast, Cretaceous plutons and most Cretaceous volcanic rocks are strictly calc-alkaline. Although many of these Mesozoic units are metaluminous, peraluminous compositions are more prevalent in the felsic portions of Cretaceous plutons. However, we note that there are many A/CNK (molecular ratio of Al 2 O 3 to CaO+Na 2 O+K 2 O) values for Triassic and some Jurassic volcanic rocks (Fig. 3.9) that are either too low or too high for pristine igneous rocks. Much of this is due to variation in alkali abundances, particularly Na, indicating that these rocks have been altered (e.g., Hanson et al., 1993; Sorenson et al., 1998). In this region, Triassic and Cretaceous plutonic and volcanic units are mostly similar, except that for Triassic plutons, there are as yet no analyzed rocks with SiO 2 less than 60 wt. %. However, this is not the case for Triassic volcanics, which range continuously from 42-78 wt. % SiO 2 (Fig. 3.8, 9, 10, 11). In contrast, the Jurassic units tend to have slightly higher K 2 O and Na 2 O, and some Jurassic rocks are marginally alkaline. Otherwise, we see little other difference in elemental composition as a function of age. REE patterns through time are also similar with LREE N averaging near 100 and HREE N averaging near 10 (Fig. 3.12). Although magma mingling and mixing are clearly evident from field and petrologic observations, there is considerable geochemical evidence for mineral fractionation in all suites, regardless of age, including compatible element behavior for Ca, Mg, Ti, and Fe, reflective of fractionation of mafic minerals and plagioclase (Fig. 3.10). Na 2 O and K 2 O are generally seen as incompatible, but more for K 2 O. Na 2 O initially increases for mafic 80 and intermediate rocks but flattens off or decreases after about 60-65wt. % silica for all units, which is consistent with plagioclase as a fractionating phase becoming more sodic. In this regard, Al 2 O 3 increases with increasing SiO 2 for mafic rocks but decreases after about 53-57wt. % silica, consistent with the probable onset of plagioclase fractionation. Similarly, P 2 O 5 also peaks at about 55wt. % silica for all units signifying where apatite also becomes a fractionating, although accessory, phase (Fig. 3.10). Likewise, Y and most REE, particularly HREE, decrease with increasing silica indicating further accessory phase control during mineral fractionation and presumably by minerals that concentrate these elements such as zircon, sphene (titanite), allanite, and apatite. Other elements exhibiting compatible element behavior consistent with arc-wide fractional crystallization include Sr (plagioclase) and both Sc and V (magnetite). Mesozoic plutons and volcanic units of the central Sierra have less chemical variations through time than those of more inboard but comparable age located further south in the Mojave desert regions of southern California and the displaced Tujunga terrane (Barth et al., 1990; Anderson et al, 1992; Miller et al., 1992). For the latter, the Triassic units are distinctively less silicic, often alkalic or tholeiitic, with adakitic Sr (concentrations often trending above 1000 ppm) and high ratios of Sr/Y and La/Lu compared to younger Mesozoic plutons (Fig. 3.13). In the same region, Jurassic plutons are also high K, but in contrast, Cretaceous plutons are almost entirely calc-alkaline, are more siliceous, and some are peraluminous (Lackey et al., 2008). MORB-normalized spider diagrams show LILE enrichment and also certain negative anomalies typical of most arc magmas, such as for the high field strength elements Ti, Ta, 81 and Nb (Fig. 3.12). The latter is consistent with the presence of accessory rutile in source residue of these magmas. An additional negative anomaly is that of P, which is indicative of residual apatite. For the central Sierra, however, there are only two plutons having Sr levels above 1000 ppm (Fig. 3.13). Both are of Jurassic age, one being in Reno area of Nevada and another in the eastern Sierra. High Sr and high ratios of Sr/Y and La/Lu (Fig. 3.13), along with other elemental attributes, are indicative of production of melts in equilibrium with an eclogitic residue, such as magmas derived from an eclogite-bearing slab or eclogitic lower crust (Martin et al., 2005; Castillo, 2006). High Sr and high Sr/Y ratios are particularly indicative of low % melts in equilibrium with an eclogitic residue and the REE trends should be steep with La/Lu N ratios at about 100. With the two exceptions noted above, most of the central Sierran rocks have Sr between 600 to 800 ppm, which lessens in more felsic members. As indicated above, REE trends are similar with consistent LREE enrichment over HREE with minimal to no Eu anomaly and La/Lu N ratios average close to about 10 for all units, regardless of age (Fig. 3.12, 13). The lack of an Eu anomaly requires the absence or near absence of plagioclase in the residue. Melting of a source with chondritic (La/Lu ~ 1) distribution of REE will yield LREE- enriched melts because residual mafic minerals such as pyroxene and hornblende have HREE distribution coefficients versus melt that are about 10 times greater than those for LREE. For garnet, this value is close to 200, so where garnet is a significant residue phase, values for Sr and Sr/Y are high and the REE trends steepen when the percent melting is rather low, such as 15-20%. However, these relationships change with greater 82 percentages of melting. At more than 30% melting, Sr and Sr/Y lessen as does the relative abundances of LREE to HREE. Melt models have many unknowns, leading to fairly unconstrained assumptions about residue mineral proportions, relative rates of mineral melting, and source composition. That aside, the more primitive portions of these central Sierran rocks have compositions consistent with fairly high percentage melting and a residue that was mafic and likely eclogitic. 6.2 Strontium-Neodymium Arrays Initial ratios of 87 Sr/ 86 Sr (Sr i ) and 143 Nd/ 144 Nd (ƐNd) from plutonic and volcanic rocks in the Sierra Nevada (Fig. 3.14) have proven powerful for detecting the relative proportions of differently aged crust and mantle reservoirs that make up the magmas of the arc (e.g. Kistler and Peterman, 1973; DePaolo, 1981). Moreover, mapped distribution of these reservoirs, in particular the Sr i “0.706 line”, has aided mapping of the presumed boundary of western accreted terranes and North American parautochthonous crust plus the location of intrabatholithic faults between crustal fragments (Kistler, 1993). In detail, the compiled data show the general trend toward lower ƐNd and higher Sr i from west to east in the Sierra (Fig. 3.14), broadly reflecting increased input of Proterozoic mantle and crust in eastern magmas (DePaolo, 1981). When published data are plotted by age this west to east pattern in the Sierra is broadly similar throughout the Mesozoic (compare age colored fields in Fig. 3.14). Fields from previously published studies in the Sierra that locally extend away from the main trend show the heterogeneity relating to anomalies in studies of individual systems. The steep trajectory of the trend along the mantle array, which is bounded by various proposed mantle reservoirs (Zindler and Hart, 1986), 83 indicates crustal contamination of mantle reservoirs that contribute the bulk of Sierran magma sources. The “kink” and change of orientation in the array illustrated by the eastern Sierra-Mojave trend (Fig. 3.14) reflects the increased budget of crustally derived melts inboard of the Sierran arc (e.g. Miller and Barton, 1990; Wright and Wooden, 1991). Studies of migmatitic zones and plutons exposed in the middle to lower crust of the southern Sierran arc shows only thin (<100 m) zones of crustal contamination in the plutons (Lackey et al., 2008; Saleeby et al., 2008). Thus, the bulk of the ƐNd and Sr i isotopic variation in Sierran magmas reflects the melting and hybridization dynamics of sources, with crustal contamination being a relatively minor process. Our new samples, including volcanic rocks from different arc segments, fall largely on the same array defined by fields from previous studies. However, some of the volcanic rocks scatter off the main array and have low ƐNd relative to Sr i (Fig. 3.14). Moreover, they are distinct from published plutonic values (Barth et al., 2011). Our data indicate (1) that eastern Sierra plutons of Triassic to Cretaceous age having larger budgets of older lower crust and lithospheric mantle; (2) Jurassic rocks in the western Sierra, typified by the Guadalupe Complex, show the effects of minor crustal contamination causing large drops of ƐNd; and (3) that the majority of Cretaceous plutonic rocks tend to define a tight array in ƐNd-Sr i . Overall, the Triassic and Jurassic arcs appear to tap sources with greater isotopic contrast and heterogeneity than the Cretaceous. 7.0 Discussion Two questions were raised that we can address through our geochemical syntheses: (1) to what degree are the volcanic and plutonic systems chemically linked in this arc? and (2) 84 what are the major processes controlling the compositional diversity in these magmatic systems? There are certainly sampling biases in all datasets, including those in this chapter such as the paucity of isotopic data from volcanic rocks relative to plutonic and of chemistry in general from Triassic plutons. Even so the spatial and temporal overlap of flare-ups and lulls in both the plutonic and volcanic records suggest a close link between the volcanic and plutonic systems in this arc. This is supported by the similarity in whole rock geochemical data from both plutonic and volcanic units (Fig. 3.8-13) with two notable exceptions. Particularly Triassic and Jurassic volcanic rocks show a much greater scatter than their plutonic counterparts (Fig. 3.8, 9, 13), and some Triassic volcanic rocks range well into the tholeiitic field compared to their calc-alkaline plutonic counterparts. However, the greater scatter in volcanic values are evidently related to widespread K-Na metasomatism caused by interactions with Jurassic low-T seawater and to mild alkali Na- Ca alteration caused by meteoric fluids noted by Hanson et al. (1993) and Sorenson et al. (1998). It is interesting that the underlying plutons show minimal alteration (Hanson et al., 1993, Lackey et al. 2008). The comparison of four Sr-Nd isotopic values from central Sierra plutonic and volcanic units also indicates a close link since isotopic values show significant overlap and vary spatially and temporally in similar ways. Of course local deviations occur, such as in the Triassic in the eastern Sierra. Earlier we noted that comparisons of different isotopic systems in the eastern Sierra have always been a bit of an enigma and most of the exceptions we point out above also occur in this eastern domain. One possible explanation is that basement in this part of the arc varies tremendously over short 85 distances as exemplified by Sr i and ƐNd isotopic ratios discontinuities (Kistler, 1994). These basement types include Precambrian continental crust of different ages overlain by a passive margin sedimentary sequence, possible oceanic basement overlain by marine sediments such as the El Paso Terrane or Golconda terrane farther north, and the Snow Lake passive margin fragment and its uncertain basement. Thus it is likely that at the scale of our comparisons we are including units that have been generated from and passed through different lithospheric columns (see also Miller et. al., 1992). As contraction of the arc host rocks continued throughout the Mesozoic, these units would have been dramatically shortened horizontally and thinned vertically and increasingly juxtaposed. Thus during the voluminous Cretaceous magmatism, these arc magmas were generated from mantle magmas that interacted with and ascended through this partially homogenized crust and individual plutons rose through previous Triassic and Jurassic plutonic bodies, which may have played an important role in reducing isotopic heterogeneity in the Cretaceous. Our field and geochemical studies provide strong evidence that source region compositions (particularly seen in isotopic data) and both fractionation and mixing of magmas, plus limited host rock contamination all had an important role in developing the final compositional diversity of both plutonic and volcanic units in this arc. The more primitive units in the central Sierran rocks have compositions consistent with fairly high percentage melting and a residue that was mafic, verging on ultramafic, and likely eclogitic. Our spatial and temporal comparison of two different isotopic systems (Sr i , ƐNd) broadly supports earlier studies indicating that melt sources in the western portion 86 of the arc are of depleted mantle with minor input from heterogeneous, but largely oceanic crustal sources during the Jurassic and Cretaceous (no Triassic data are available). Central Sierran melt sources are also explained by a mix of depleted mantle and minor Proterozoic crustal input with the latter possibly representing Proterozoic basement (e.g., Lackey et al. 2012), perhaps beneath the passive margin Snow Lake block. Eastern sources are more equivocal but are best explained by a mix of mantle and both young (Triassic) and old (Triassic & Jurassic) or more homogenized (Cretaceous) continental crust. During ascent of magmas from source regions, fractionation of plagioclase, pyroxene, hornblende, and biotite plus accessories zircon, sphene, allanite, apatite and magnetite appear to have had a major role thus supporting the contention that large cumulate roots must have formed at depth in the Mesozoic (Ducea, 2001). Remixing of these fractionates both during ascent and in chambers is also indicated in our geochemical synthesis and directly documented by field studies (Zak et al., 2009; Paterson et al., 2010; Pignotta et al., 2010), dating of mixed zircon populations (Matzel et al., 2006; Memeti et al., 2010b) and single mineral geochemical studies (Krause et al. 2009; Memeti et al. 2009). To date, at the arc scale, we see little differences in the geochemical patterns and inferred magmatic processes in plutonic versus volcanic units and thus conclude that they are chemically linked systems. 8.0 Conclusions Combined mapping, geochronology, and geochemistry studies, when synthesized with previous datasets, indicate the following conclusions for the central Sierra Mesozoic arc: 87 (1) both the plutonic and volcanic components of this ~250 to 85 Ma arc are spatially, temporally, and geochemically linked and thus part of the same vertically connected magmatic system; (2) magmas in this arc are derived from mixing of mantle plus crustal melts and show clear evidence of fractionation and remixing during ascent. 88 Fig. 3.1. Outline of central and southern Sierra Nevada batholith (grey), location of Mesozoic metavolcanic rocks color-coded according to age, and location of proposed Mesozoic calderas. 89 Fig. 3.2. Central Sierra map showing the ~95-86 Ma Tuolumne batholith, the ~97-98 Ma Jackass Lakes pluton and the location of nearby host rock pendants. Boxes show mapped areas discussed in paper and shown in Figures 3.3, 3.4, 3.5, 3.6, and 3.7. Areas in white represent Mesozoic plutons. 90 Fig. 3.3 Virginia Canyon geologic map 91 Fig. 3.4. Saddlebag Lake geologic map 92 Fig. 3.5. Waugh Lake geologic map 93 Fig. 3.6. Cinko Lake geologic map, redrafted after Memeti et al. (2010). 94 Fig. 3.7. Preliminary Quartz Mountain geologic map 95 Fig. 3.8. Geochemical classification plots. Data sources and techniques listed in electronic Appendix: (a) A plot after Cox et al. (1979) showing Triassic, Jurassic, and Cretaceous fields defined by data from plutonic rocks, central Sierra.; (b) A plot after Le Bas et al. (1986) showing distribution of data from volcanic rocks, central Sierra; (c) AFM diagram of both plutonic (colored fields) and volcanic (colored points) rocks comparing Triassic, Jurassic, and Cretaceous magma series in the central Sierra. 96 Fig. 3.9. Shand’s alkali-aluminum classification diagram (Shand,1943) of Triassic, Jurassic, and Cretaceous plutonic and volcanic rocks in central Sierra. All values are on a molecular basis. 97 Fig. 3.10. Harker variation diagrams of both plutonic and volcanic rocks showing geochemical trends during the Cretaceous, Jurassic, and Mesozoic in the central Sierra. 98 Fig. 3.11. Trace elements patterns of plutonic and volcanic rocks for different age groups in Central Sierra with the dark grey background showing the range for all samples. All of these groups fall in the same pattern with a relatively narrow range of concentration between groups. Fig. 3.12. Chondrite-normalized REE patterns of plutonic and volcanic rocks of different age groups with the grey background showing the range for all samples. All of these age groups fall in the same pattern with different concentrations of different elements. 99 Fig. 3.13. Sr (ppm) versus SiO 2 for central Sierra Nevada plutonic (A) and volcanic (B) rocks. And Sr/Y versus La/Lu plots for central Sierra plutonic (C) and volcanic (D) units. Color-coding of data in all plots show change from Triassic (blue), Jurassic (green) to Cretaceous (red). 100 Fig. 3.14. ƐNd-Sr i plot of both published (colored fields) and new (colored circles) data and potential reservoirs (grey fields and yellow stars). 101 CHAPTER 4: LIFETIME OF AN UPPER CRUSTAL PLUTONIC- VOLCANIC PLUMBING SYSTEM: INSIGHTS FROM CA-TIMS, U-Pb ZIRCON GEOCHRONOLOGY OF INTRACALDERA TUFF AND INTRUSIONS IN SILVER CREEK CALDERA, ARIZONA, USA 1.0 Abstract Study of both plutonic and volcanic regimes in one single magmatic system is a powerful approach towards obtaining a more complete view of the long-term evolution of these systems. The recently discovered Silver Creek caldera as the source of the voluminous Peach Spring Tuff (PST) (Ferguson, 2008) presents a unique opportunity to study a field laboratory of a linked plutonic-volcanic system. This ~18.5 my, west-facing half caldera is predominantly filled with trachytic intracaldera tuff with the caldera margin intruded by several petrologically distinct hypabyssal intrusions. These include porphyritic granite with granophyric texture, felsic leucogranite, porphyritic monzonite exposed on NE side of the caldera that is zoned from more felsic to more mafic, and quartz-phyric dikes that intrude the caldera fill. In this chapter, I will present single zircon ages from 4 samples that have been analyzed using the CA-TIMS method using a pretreatment of thermal annealing and chemical leaching (Mattinson 2005), including 1 sample from intracaldera tuff and 3 samples from caldera-related intrusions. 3-D total U/Pb isochron ages from all four samples fall within a range of 18.46-18.90 Ma with uncertainties between 0.12 and 0.19 Ma, although some of them lack precision and have elevated common Pb. For example, zircon from the dated porphyritic monzonite yields an age of 18.74±0.17 Ma (MSWD=4.1) where the excess scatter may result from real age dispersion and/or 102 different compositions of the common Pb contribution. The PST had been dated at ~18.5 Ma by 40 Ar/ 39 Ar techniques (Nielson et al., 1990). In order to be compared to U/Pb ages the 40 Ar/ 39 Ar age must be adjusted for a revised age for the then used flux monitor (MMbh-1) and corrected for the now quantified systematic bias between 40 Ar/ 39 Ar and U/Pb ages (Renne et al., 2010), which results in a corrected age of 18.8 Ma. Thus, the ages for our samples match that of the PST within error. Based on current results, the age differences between the different phases of the intrusion are very small and the ages of the intrusion match within errors the age of the PST. This tight time range indicates that the super-eruption and the subsequent reactivation of the caldera by hypabyssal intrusions happened on a much shorter timescale than the evolution of large magma systems that have been described with durations of up to 10 m.y. The lack of antecrystic zircons in such a large-scale magmatic system tells us that there are either no sources of older zircons or that all the older zircons were removed from the system by one of several possible filtering mechanisms. 2.0. Introduction Large-scale magmatic plumbing systems in the crust have been intensely studied for at least the past 50 years (Buddington, 1959; Watson and Harrison, 1984; Paterson et al., 1996; Bachmann et al., 2002; Valbone et al., 2010). The lifespan of these systems and the crystal transportation and recycling within and between these systems became the topic of great interest recently (Matzel et al., 2006; Davidson et al., 2007; Miller et al., 2007; Memeti et al., 2010). Documenting a precise temporal history is critical when reconstructing the evolution of any large silicic magma system. Large silicic magma 103 systems in the upper crust, either volcanic or plutonic, generally have a prolonged lifespan. Arc volcanoes usually have an active lifetime of hundreds of thousands of years. Growth of large granitoid plutons, even if fed continuously at the same rates as the Earth’s most active volcanoes, would require on the order of 0.5-1 m.y (Lipman, 2007). And recent high precision geochronology on intrusions indicate that they can form from <0.5 to up to more than10 m.y. (Coleman et al. 2004; Matzel et al., 2006; Miller et al, 2007; Lipman, 2007; Memeti et al., 2010). Determining a crystallization age also became more challenging once it was recognized that accessory minerals like zircon had been recycled within some of these batholith-scale intrusive suites and on a whole-chamber scale (Matzel et al., 2006; Miller et al., 2007; Memeti et al., 2010). Detailed geochronological studies have been done on different calderas and outflows (Hurford and Hammerschmidt, 1985; Schmitz and Bowring, 2001; Bindeman et al., 2006). A closer examination of the zircon ages using high-precision geochronology method would be worth doing to better constrain the ages of the different regimes (plutonic and volcanic). With the high resolution of the zircon age distribution we will be able to better constrain the residence time of the magma if we can compare these zircon ages with corresponding cooling ages, and can also be used to examine if crystal recycling processes occurred. Silver Creek caldera is located at the intersection of the three states of California, Nevada and Arizona and is about 2 miles to the northwest of the town of Oatman, Arizona (Fig.4.1). It is the recently discovered eruption source of the Miocene Peach Spring Tuff (PST) based on age similarity and phenocryst assemblage of the intracaldera and outflow tuff, and the consistency with the previously predicted source area by AMS 104 (anisotropy of magnetic susceptibility) and outflow thickness studies (Hillhouse and Wells, 1991; Young and Brennan, 1974; Glazner et al., 1986). PST covers an area of about 35000 km 2 crossing five major tectonic regimes in southwestern US (Fig.4.1), so it has been recognized as an excellent regional stratigraphic marker in a broad area from Barstow, California to Kingman, Arizona. With the estimated eruption volume of more than 640 km 3 dense rock equivalent (Gusa et al., 1987; Buesch 1992), PST can definitely be classified as a superereruptive deposit (Sparks et al., 2005; Self, 2006). As the source of a supereruption, Silver Creek caldera is an ideal plutonic-volcanic system for us to apply the high-precision U-Pb geochronology study. PST outflow has been dated using 40 Ar/ 39 Ar method and the produced age is of 18.5±0.2 Ma (Nielson et al., 1990). In the caldera, there are three main rock units, the intracaldera PST, quartz-mozonitic Moss Porphyry and granitic Times Porphyry with later quartz-phyric dikes that intruded the shallow intrusions (Fig.4.2). High-precision dating of both the intracaldera PST and the intrusions will better constrain the connection between the caldera and the outflow and better picture the evolution of the magma plumbing system feeding the supereruption and the rejuvenation of the caldera. In this chapter, I am going to give an introduction of the Silver Creek caldera, and then present the new geochronology data from all three units in the caldera using CA-TIMS (chemical abrasion-thermal ionization mass spectrometer) method. I will also briefly summarize and discuss the chemical variance between the volcanic and the plutonic regimes and the horizontal chemical zonation of the ignimbrite sheet of PST. 105 3.0 Geological background The first outcrop of Peach Springs tuff was found at a location close to the town of Peach Springs, Arizona, so it was named after that. This is why in the old literature before 2008 people will see Peach Springs tuff instead of Peach Spring Tuff. To avoid duplication of rock group name and the name of the tuff, it was renamed as Peach Spring Tuff by Ferguson. As a voluminous regional stratigraphy marker with clearly exposed outcrops, PST has been studied for more than 30 years (Thorson, 1971; Young and Brennan, 1974; Glazner et al., 1986; Gusa et al., 1987; Valentine et al., 1989; Neilson et al., 1990; Hillhouse and Wells, 1991; Ferguson, 2008; Pearthree et al., 2009; Carley et al., 2009; Pamukcu et al., 2009; Carley et al., 2010; Gualda et al., 2010; Zhang et al., 2010). PST was first described by Young and Brennan (1974) in the western Colorado Plateau. Glazner et al., (1986) correlated the isolated outcrops and extended the distribution of PST to the Mojave Desert area based on field studies, phenocryst analyse, and paleomagnetic pole directions. Additional correlation evidence provided by Gusa et al., 1987’s heavy mineral suites study. PST is now recognized as a distinctive sanidine bearing Miocene ignimbrite sheet distributed across five tectonic regimes in the southwestern United States with an estimated area of about 35,000 km 2 (Glazner et al., 1986) (Fig.4.1). The five tectonic components in this broad area from west to east are: Mojave Desert; southern end of Basin and Range province; Colorado River extension corridor; Transition zone and the Colorado Plateau (Fig.1). In general, PST deposited during a time when large extensions were going on in the southwestern United States, so 106 it provides a very unique stratigraphic marker for people to reconstruct the paleotopography of this region. The eruptive source of the PST has been a puzzle for a long time until the recent discovery by Ferguson (2008) that the Silver Creek caldera may be this source. Previously others had tried different methods to predict the source of this tuff sheet. Young and Brennan (1974) predicted that the source of PST is located somewhere in or near the Black Mountains based on the trend of the outcrop thickness. Glazner et al., 1986 corroborated the assumption made by Young and Brennan (1974) and with their thickness data suggested that the source is somewhere in the Colorado River trough area, near the southern tip of Nevada. Hillhouse and Wells (1991) constrained the source of PST to the Colorado River Extensional Corridor in vicinity of the intersection of California, Nevada and Arizona (Fig.4.1) by their AMS study of the outflow fabrics. The detail mapping around the Oatman mining district reported by Thorson 1971 and Pearthree et al., 2009 both include the idea that the plutonic-volcanic complex in the Silver Creek area is a possible old caldera remnant. Ferguson (2008) carefully investigated the phenocrysts’ assemblage within the volcanic regime of this complex and found out that it has an almost identical assemblage and mineral ratio change from the bottom to the top of one cooling unit as the PST outflow. Silver Creek caldera is named after Silver Creek, which crosses the center of the caldera and is located right at the triple contact of the three states of California, Nevada and Arizona and it is roughly at the center of the currently mapped distribution of the PST (Fig.4.1). The location of the 107 Silver Creek caldera falls in the area of the possible eruptive source predicted by the previous AMS study of the PST outflow fabrics (Hillhouse and Wells, 1991) (Fig.4.1). 4.0. Description of Peach Spring Tuff and Silver Creek caldera 4.1 Peach Spring Tuff outflow The PST is exposed discontinuously all the way from Barstow, California, to the western margin of the Colorado Plateau (Fig.4.1). It has different stratigraphic setting at different places, but it consistently overlies pre-Miocene or lower Miocene rocks and underlies middle and younger rocks (Glazner et al., 1986). Road cut outcrop of outflow PST near Kingman shows the deposition of PST over early Miocene Cook Canyon tuff (Fig.4.3). Based on their own field measurements and previously published data (Young and Brennan, 1974; Buesch and Valentine, 1986; Knoll et al., 1986), Glazner et al., 1986 summarized that maximum thickness of the PST increases from 10-15 m in distal outcrops (Barstow; Peach Springs) to 65-85 m at Kingman and 130 m in the Little Piute Mountains. Young and Brennan, 1974 mentioned in their paper that the easternmost outcrop of PST reserve the deposition of a basal ash layer (distinctly bedded), averaging nearly 1 ft thick, followed by deposition of nearly 10 ft of loosely welded, nonlaminated, normally pinkish tuff which in turn is overlain by densely welded 30-60 ft thick ignimbrite. The PST can be divided into two layers: layer 1 is the basal layer related to the blast at the beginning of the eruption, and layer 2 is a massive pyroclastic flow deposit. The basal ash layer was examined in detail by Valentine et al., 1989. These layered deposits are below the main pyroclastic flow deposit over a minimum lateral distance of 70 km. In the Kingman area, basal layered deposits can be at least subdivided 108 into four layers. The first layer is about 40-80 cm thick and composed of coarse ash to fine lapilli in very thin parallel beds capped by a 1-2 cm thick layer of white fine ash. The second layer, above this fine ash layer, is a laterally discontinuous layer up to 15 cm thick. Locally, the discontinuity was caused by erosion of the overlying pyroclastic flow. The third layer in the Kingman area is generally homogeneous and is 5-35 cm thick consisting mainly of pumice and is white to tan in color. The fourth layer occurs very scarcely and consists of lenses one to a few meters long composed mostly of coarse pumice and lithic lapilli. The nature and the characteristics of the basal layer indicate that it was deposited by pyroclastic surges at the beginning of the eruption (Valentine et al, 1989). One outcrop close to Kingman area shows the basal surge below the main pyroclastic flow (Fig.4.4). The massive pyroclastic flow deposit is a voluminous, welded ignimbrite. The most distinctive feature of the tuff is the occurrence of abundant large (up to 5 mm), clear sanidine phenocrysts with blue chatoyance (blue iridescence). The phenocrysts assemblage of the tuff is composed predominantly by sanidine (70-90 vol%) and plagioclase, biotite , hornblende, opaque oxides, clinopyroxene, and sphene. Quartz phenocrysts are very rare. Phenocrysts compose 10-20 vol% of the total rock and lithic clasts can be up to 10 cm or more and are usually locally derived (Glazner et al., 1986). 4.2. Description of Silver Creek caldera Silver Creek caldera is of a half-moon shape map view with an area about 75 km 2 and is located about 2 miles to the northwest of the town of Oatman, AZ (Fig.4.2). It was named Silver Creek caldera by Ferguson (2008) as the source caldera of PST. 109 4.2.1Intracaldera Tuff The basement of the caldera is the Precambrian biotite granite that contains huge (1 to 2 inches) potassium feldspar phenocrysts and is named the Katherine Granite (Thorson, 1971). Although, this granite does not crop out within the caldera, many Katherine Granite fragments occur in the different lithologies in the caldera. Tertiary volcanic rocks overlie the Katherine granite. Then a very thick intracaldera facies tuff was identified within the caldera to have deposited on the top the Tertiary volcanic rocks (Ransome, 1923; Thorson, 1971; Ferguson, 2008; Pearthree et al., 2009). At the southern end of the Times Gulch, intracaldera tuff unconformably overlies the Precambrian basement. Above the intracaldera tuff, later bimodal rhyolite-basalt succession crops out only near and along the highway 68 (Spensor et al., 2007). The intracaldera tuff was firstly classified as the Alcyone formation by Ransome (1923) and Thorson (1971), and Thorson (1971) proposed the idea of Alcyone caldera. After reinvestigation of the phenocrysts assemblage of the tuff, Ferguson (2008) reinterpreted the tuff to be intracaldera part of the PST. In Thorson’s thesis, he provided detailed petrographic descriptions of this unit which very closely match the phenocryst assemblage of the Peach Spring Tuff outflow sheet: 20-35% feldspar with K-feldspar greater than plagioclase, and the ratio decreasing up-section from 5:1 to 3:1. Accessory phases include1-2% biotite, 2% opaque oxides, <0.5% quartz, and trace amounts of hornblende, clinopyroxene, sphene, zircon, and apatite (Young and Brennan, 1974; see also Glazner et al., 1986; Murphy et al., 2004; Spencer et al., 2007). Thin section study of Ferguson (2008) also reproduced similar results and concluded that the Alcyone 110 formation defined by Ransome (1923) and Thorson (1971) is actually part of the younger PST. One interesting phenomenon is that there is a gap where deposition of PST is lacking between the margin of the Silver Creek caldera and the closest PST outflow outcrop about 5 km to the south of the caldera (Fig.4.1). The ouflow PST and the intracaldera PST have dramatically different appearance (Fig.4.5). The intracaldera tuff is more intensely welded than the outflow, and it has a greyish color compared to the pinkish to purplish color of the outflow. This dramatic different appearance might be the reason why former workers have never related this caldera to the outflow PST for a long time. Today, the intracaldera PST is largely preserved to the west of shallow intrusions, which are interpreted as resurgent bodies that intruded the caldera fill (Fig.4.2). An intrusive contact can be observed between the tuff and the quartz-monzonite at one exposure to the north of Silver Creek (Fig.4.6 (c)). It is hard to track the contact in the field, but it can be roughly projected along the gullies between the tuff and the intrusions (Fig.4.6 (a), (b)). To the south of silver creek, local crosscutting relationship between the granite and tuff can be observed (Fig.4.6 (d)). The tuff is a grey, very well welded trachyte with potassium feldspar and plagioclase phenocrysts in a partially to completely devitrified matrix of welded shards, pumice dust and rock fragments. Sharp corners and edges of the broken phenocrysts and clasts, and embayment of phenocrysts caused by the explosive eruption can be seen in the thin sections (Fig.4.7 (a)). The clasts are poorly sorted; some phenocrysts are subhedral to euhedral, together with some rock fragments. Alteration has been moderate to intense and often obscures the optical properties of the 111 minerals to make identification extremely hard. Potassium feldspar and plagioclase have been clouded by fine sericite, and epidote. Some of the potassium feldspar still has unaltered cores. The biotite have been partially or completely altered to chlorite (Fig.4.7 (b)). 4.2.2 Intracaldera Shallow Intrusions Two plutonic bodies along the eastern margin of the caldera intruded the intracaldera PST and earlier volcanic rocks. Originally, they were named the Times Porphyry to the south of the silver creek and the Moss Porphyry to the north of the silver creek by Ransome (1923) (Fig.4.2). The Times Porphyry is a K-feldspar porphyritic granite while the Moss Porphyry is dominated by plagioclase porphyritic quartz-monzonite. Previous authors had controversial opinions about the relative ages of these two intrusive bodies. Ransome (1923) reported that the Times is younger while Thorson (1971) proposed that the Moss is younger. In the field, no clear intrusive relationships between these two bodies could be observed. They appear to grade into each other to the south of the silver creek. Only one clear contact spot between the intracaldera PST and the Moss Porphyry can be clearly observed to the north of silver creek. Our high-precision geochronology indicate that the two intrusions have identical ages within errors. In order to conveniently describe the intrusions, we still keep the names of Times and Moss in this paper, but we need to keep in mind that they may be different phases of the same intrusion. Both intrusive bodies were cut by later porphyry dikes. The Times Porphyry to the south of the silver creek is more homogeneous compared to the northern Moss Porphyry and is of granitic composition (Fig.4.2). The border of the 112 Times Porphyry is very fine-grained, pinkish color with both K-feldspar and plagioclase phenocrysts and minor amount of biotite (~5%) and even less hornblende. The border grades inward or downward into a slightly darker, coarser-grained, more conspicuously porphyritic core that has more biotite and hornblende. In thin section of the border rocks, the groundmass around each phenocrysts has K-feldspar in optical continuity with the phenocrysts but intergrown with quartz, which is an excellent example of granophyric texture (Fig.4.11 (d)). From the border to the core of Times Porphyry the SiO2% does not change much and is constantly about 74%, Al 2 O 3 about 12%, Fetotal about 1.2% and MgO about 0.3% (Thorson, 1971). Moss Porphyry is to the north of silver creek and has at least two compositionally different phases. In general, it is an intrusive mass of quartz monzonite porphyry and it occupies a rectangular area of about 2 by 4 miles (Fig.4.2). The composition changes from quartz-monzonite at the border to a monzondiorite to quartz-monzondiorite occupying the core (Pearthree et al., 2009). The quartz-monzonite phase is a purple-gray to light gray rock with plagioclase, hornblende and biotite phenocrysts in a granophyric groundmass of quartz and K-feldspar. At the center of the Moss Porphyry, a slightly more mafic phase is monzondiorite to quartz-monzodiorite. The hand samples are of gray to greenish color with plagioclase phenocrysts. In thin section, plagioclase phenocrysts are still predominant but with more hornblende phenocrysts than biotite (Fig.4.7 (d)). 4.3 Geochemistry summary Geochemical analyses have been done on both the outflow PST and intracaldera rocks (Thorson, 1971; Caley, 2010). Major elements analysis of representative rocks from the 113 Silver Creek caldera and outflow PST was summarized in Table.1. Data are from the PhD dissertation of Thorson (1971) and Master thesis of Carley (2010). I combined these data and plotted them on different geochemistry diagrams, after separating data into different units, and divided them into plutonic and volcanic rocks to make it easy to see any difference between all of them. Intracaldera intrusive rocks are from monzonite to granite in composition. The Moss Porphyry has lower SiO 2 than the Times Porphyry (Fig.4.8), which agrees well with the field observation and the thin section study. Compared to the intrusive rocks, the volcanic rocks are quite obviously separated by composition. Intracaldera PST, proximal PST and distal PST are separated into three groups and from intracaldera PST to distal PST, with units getting more felsic with distance and change from trachyte/dacite to rhyolite (Fig.4.8). Carley (2010) firstly noticed this zoning in her thesis. All the rocks are calc- alkaline series (Fig.4.9). All the different regimes range from meta-aluminous to peraluminous (Fig.4.9). On the Harker diagram (Fig.4.10), the plutonic rocks show relatively simple trends between the normalized major elements and SiO 2 content, while the volcanic rocks show some complicated trends and are still separated into three groups with almost no overlapping between each other. For some elements like K 2 O, plutonic rocks and volcanic rocks have totally different trend. In the K 2 O vs SiO 2 diagram, as the SiO 2 content increases, K 2 O within plutonic rocks slightly increase possibly due to the later crystallization of K-feldspar while the K 2 O slightly decreases from the source to the distal part of the ignimbrite sheet. The compositional zonation of plutons is usually interpreted to be caused by the following: differential diffusion of elements during the 114 solidification of the magma; crystal-liquid fractionation; mixing and mingling between different magma pulses and between the host rock and magma; different magma sources. For a pyroclastic flow like the ignimbrite sheet of PST, the magma came out of the source as one single pulse, so interaction between different pulses or between host rock and magma could not happen that broadly as in plutonic systems. Fractionation is the result of the rearrangement of the different elements of the whole chemical budget, and the main process involved in fractionation for a pyroclastic flow is the crystal liquid separation. Due to the fast horizontal travel speed of the pyroclastic flow, early-formed crystals tend to concentrated more close to the source while later crystallized minerals tend to be more accumulated at the distal part. Other than the order of crystallization, size and density of minerals can also sort them in flows. Similar process has been suggested by Civetta et al., 1997. The chemical zoning is a very interesting problem, but it is beyond the scope of this chapter. 4.4 Structure Regionally, the caldera is located at the southern tip of the northern part of the Colorado River Extension Corridor (Fig.4.1). Since Mesozoic time, this 70- to 100-km- wide region of extended crust along the eastern margin of the Basin and Range province in the southern Nevada and northwestern Arizona has played an important role during the construction of regional structures in the western Cordillera (Fig.4.1, Faulds et al., 2001). From Cretaceous to early Tertiary, this region resided directly north, east, and south of major thrusts, and at the northern margin of a broad uplifted terrane that was stripped of its Paleozoic and Mesozoic cover by erosion (Bohannon, 1983, 1984). In early Miocene, 115 the southward and northward migrating magmatic and extensional fronts caused by Basin and Range province converged toward the northern Colorado River extensional corridor (Faulds et al., 2001). This is about the same time as the eruption and the deposition of the PST and at about the same area of where the Silver Creek caldera is located. The eruption of PST happened after the main thrusts and before the large-magnitude east-west extension that began at 16.5 to 15.5 Ma. During the major extension, arrays of tilted fault blocks and associated half grabens develop and most of these blocks tilted >50° (Faulds et al. 2001). This late Miocene east-west extension was accompanied by major strike-slip faulting in the western Lake Mead area. This was evidenced by the 19 km of left-lateral offset of the 11 to 13 Ma Hamblin-Cleopatra volcano along the Lake Mead fault system (Anderson, 1973). Some of these faults are still active, as evidenced by Quaternary fault scarps in the Lake Mead and Las Vegas region (Menges and Pearthree, 1989; DePolo, 1996). This strike-slip faulting is noteworthy because some people suggested that the western half of the Silver Creek caldera is displaced about 40 km to the southwest of the current eastern half of the caldera near Oatman (personal communication with Charles Ferguson). Local structural configuration near the Silver Creek caldera is mainly controlled by two main features: the Roadside Mine down-to-west normal fault to the north of this area and an anticlinal tilted domain to the south (Pearthree et al., 2009). To the north of the silver creek, the outcrop-scale measurable foliations within the intracaldera PST dip moderately to gently to the southwest. The reliability of the measurements will be tested by the new AMS data. To the south of the silver creek, the measurable foliations within 116 the intracaldera PST consistently dip gently to the southwest (Pearthree et al., 2009) and again this will be tested with the new AMS data. 5.0 Geochronology 5.1 Previous geochronology of PST and Silver Creek caldera Since 1960s, a number of researchers have attempted geochronology work on many PST outflow unit (Damon et al., 1964; Damon et al., 1966; Dickey et al., 1981; Glazner, 1981; Howard et al., 1982; DeWitt et al., 1986; Goldfarb et al., 1986; Neilson et al., 1990). Most of these ages are K/Ar, 40 Ar/ 39 Ar sanidine or biotite ages. There was only one U/Pb zircon age done on the intracaldera intrusive rock (Table 4.2). The outflow PST ages range from 16.2 Ma to 20.5 Ma with errors ranging from 0.2 to 1.0 Ma. Prior to the correlation of the PST by Glazner et al., 1986, conventional K-Ar analyses was the only method applied on the PST related rocks (Table 4.2). All these conventional K-Ar ages have a mean value of 18.3±0.5 Ma and characterized by discordant 40 Ar/ 39 Ar age spectra. A wide range of ages is presented for most samples. The most recent 40 Ar/ 39 Ar study of the PST was done by Neilson et al., 1990 using laser fusion 40 Ar/ 39 Ar method. They used sanidine from the pumice and determined a simple mean of 18.51±0.10 Ma (1-sigma) and a weighted mean of 18.50±0.06 Ma. Using an uncertainty based on the J value and setting it as 1% due to the flux gradients of the reactor, they concluded that the best emplacement age for PST is 18.5±0.18 Ma. Based on their field observation and petrographic studies, the bulk samples of PST are contaminated by xenocrysts (regolith from the older rocks below the PST), which are at 117 least 27 Ma old (Neilson et al. 1990). These old xenocrysts might be the cause of the huge age ranges of the samples dated by convention K/Ar method previously. The only previous U/Pb zircon age of 18.5±0.5 Ma from the intracaldera intrusion does not have a clear location and the detail about the method and the properties of the analyzed minerals could not be found. In Pearthree et al., 2009 this age was mentioned, but with no detail and the literature cited was not found. Another age of the intrusion is 10.4 Ma, which is mentioned in Thorson’s dissertation with no reference, so again details about the method and the dated mineral are not clear. 5.2 Sampling In order to constrain the ages of the intracaldera PST and the intracaldera intrusions, four samples were collected from these units. One sample is from the intracaldera PST to the south of the silver creek, the three intrusive samples are from the margin of the Moss Porphyry, the center of the Moss Porphyry and the margin of the Times Porphyry. Sample SC6 is from the first Moss Mine right at the margin of the Moss Porphyry (Fig.4.2). It is a purplish color, phenocrysts rich sample. In thin section, phenocrysts are mainly euhedral K-feldspar and plagioclase with Carlsbad and albite twinning well developed (Fig.4.11a). Other phenocrysts include biotite and some opaque oxides. Quartz only occurs in the matrix and is not obviously deformed. Sample SC112a is from the center phase of the Moss Porphyry (Fig.4.2). The color of this sample is a bit darker than the margin phase sample. Both feldspar and hornblende phenocrysts can be seen plus minor amount of biotite and opaque oxides. Quartz grains are getting less and smaller. Thin section study of this phase does show that it is more mafic than the margin of this 118 intrusion (Fig.4.11b). Sample SC32 is from the intracaldera PST (Fig.4.2). The rock is greyish color and phenocryst rich. Rock chips, glass shards and broken feldspar phenocrysts are distributed in a very fine grained matrix (Fig.4.11c). Sample SC36 is from the granitic Times Porphyry and very close to the contact between the intracaldera PST and the intrusion itself (Fig.4.2). Granophyric texture is very well developed in all samples from this intrusion (Fig.4.11d). 5.3 Sample preparation All four samples were sent to a lab at the China Geological survey in Langfang, Hebei province, China. They were cut to make thin sections and then crushed with a regular jaw crusher. More than 1000 zircons were separated from each sample. These zircons were sent to the Berkeley Geochronology Center (BGC) to be further selected and treated. 5.4 Analytical method CA-TIMS method (Chemical-abrasion-TIMS) was applied to the samples in this study. Based on ID-TIMS (Isotope dilution-TIMS), CA-TIMS applies more effective zircon pretreatments to minimize and eliminate the zircon domains with Pb loss before the TIMS analysis (Matiinson, 2005). The key character of ID-TIMS method is to add an isotopic tracer to a dissolved sample to make a homogeneous mixture to be measured by the TIMS. Errors of ID-TIMS (isotope dilution-TIMS) can be as low as within 0.1% (Mattison 2005; Mundil et al., 2004) and so is the CA-TIMS method. The special pre-analysis treatments of CA-TIMS method consist of crystal annealing and chemical leaching. 30 euhedral zircons grains were hand-picked under microscope at BGC for each sample. Zircons with too many fractures, too complicated inclusions or 119 optically recognizable cores are to be avoided. In the zircons from our four samples, some magmatic inclusions and possible apatite inclusions can be found in the picked zircons (Fig.4.12). These zircons were transferred into quartz container and then sent to the furnace to be heated at 800ºC-1100ºC for 48 hours, which is called thermal annealing (Mattinson, 2001; Mattinson, 2003). Radiation damages were completely removed for zircon domains with low to moderate original radiation damage. Then these zircons were further cleaned in HNO 3 for several times and then in ultrasonically agitated hot aqua regia (HCl: HNO 3 =3:1) to get rid of any pollution from the lab and previous sample treatments. 6 “clean” zircons from each sample were then spiked and underwent partial dissolution in hydrofluoric acid at temperature of about 200°C for 120 hours. The high Pb loss domains within the zircons dissolved faster than the low Pb loss crystal components. Thus, a drop of zircon residue with artificial spike of 205 Pb plus 233 U is obtained for analyses. This residue has been extensively leached with lowest potential of Pb loss. Before sending the samples to the mass spectrometer we loaded the “residue drop” with a small amount of silica gel and phosphoric acid on a out-gassed Re filament. The silica gel and the phosphoric acid help to enhance the ionization in the mass spectrometer. Then the filament is sent to the mass spectrometer to be measured using a Daly-type ion counter. 5.5 3-D “Total Pb/U isochron” Since the daughter isotope of U-Pb decay has no pair of isotopes that have invariant ratios as Rb-Sr and Sm-Nd systems, the accuracy of isotope ratio measurements using TIMS is limited by a mass-fractionation uncertainty (Ludwig, 2001). Double or triple spiking can help to eliminate this effect (Dodson, 1970; Woodhead and Hergt, 1997; Todt 120 et al., 1996), but it needs a lot of extra work and care during the measurement. Using multicollector, sector ICP-MS with normalization to a natural thallium spike (Halliday and Rehkamper, 1998; White et al., 2000) can also largely eliminate the effect. Compared to the above ways, a more straightforward and efficient way is to use appropriate input data for the “Total Pb/U isochron” (Lugwig, 1998). This is very important for samples with relatively low 206 Pb/ 204 Pb and 207 Pb/ 204 Pb, or very young zircons, because the above mentioned uncertainty is going to play a bigger role in these samples. A significant component of the variances of the Pb*/U and Pb*/Pb* isotope ratios arises from the uncertainty in the common Pb isotope ratios. If the variances are random from sample to sample with a known means, this component can be adequately treated by standard error propagation equations (e.g., Ludwig, 1980) with results in larger error ellipses on a Concordia diagram. Age and errors for analyses with such common Pb corrections can be treated in the same way as for low common Pb samples. However, if samples have invariant common Pb, any error in the isotope ratios assigned to the common Pb will result in a consistent bias, rather than a random variation, in the calculated Pb*/U and Pb*/Pb* ratios (Ludwig, 1998). In such case, the Concordia age method is inappropriate, and we have to apply another method. Total Pb/U isochrones are usually presented by a 3-D conventional Concordia plot. The three axes of the plot are: X= 238 U/ 206 Pb; Y= 207 Pb/ 206 Pb; Z= 204 Pb/ 206 Pb. One end of the isochron anchored in the common Pb plane (YZ plane), where it must interect a geochemically reasonable position. The other end of the isochron is constrained to fall precisely on the Tera-Wasserburg Concordia curve. Thus, the age and errors of samples 121 are defined by the ellipsoids along this isochron (Fig.4.13). Our samples are pretty young with ages around 18 Ma and have a relatively high content of common Pb, so we applied 3-D Total Pb/U isochron to present the ages. In terms of interpreting the zircon ages of this study, we will use the terminology from Miller et al., (2007) to distinguish between 1) autocrysts, which formed during the crystallization of the rock; 2) antecrysts, which based on their ages may have crystallized during the formation of earlier phases of the same intrusive system; and 3) xenocrysts, which are clearly inherited from the host rock or the magma source. Concordant ages possibly include ages of autocrysts, antecrysts and xenocrysts. We will only use the ages of autocrysts to represent the best crystallization age of the sample. Concordant ages that are not quiet equivalent to the best estimated ages of the rock will be interpreted differently. 5.6 Results The 3-D Total Pb/U isochron presentations of all four samples are shown in Fig.4.13 and the original U/Pb data are listed in Table 4.3. Six or more zircons were analyzed for each sample. Sample SC36 is the relatively homogeneous Times Porphry to the south of silver creek (Fig.4.2). Six zircons gave good Concordia ages and were used to calculate the crystallization age of the sample. All of them have very well constrained error ellipses (Fig.4.13). The final age calculated is 18.90±0.13 Ma with MSWD (mean standard weighted deviation) of 1.09. Twelve zircons were used to calculate the age of sample SC 32 from the intracadera PST unit. All 12 zircons have concordant ages, but some of them have relatively large errors. The calculated age of this sample is 18.69±0.19 Ma with 122 MSWD of 3.7 (Fig.4.13). Seven zircons were used to calculate the age for sample SC 6, from the marginal phase of the Moss Porphyry (Fig.4.2). Two of these zircons have relatively larger errors. The calculated age is 18.74±0.17 Ma with MSWD of 4.1 (Fig.4.13). Sample SC112a, from the center phase of the Moss Porphyry has six zircons with Concordia ages. All of them have very small errors. The calculated age of this sample is 18.46±0.12 Ma with MSWD of 2.3 (Fig.4.13). All the four ages were presented with error ellipses of 2σ. So far, no evidence has been found within our samples of the existence of antecrystic or xenocrystic zircons. Compared to the previous K/Ar and 40 Ar/ 39 Ar studies, the four new ages have smaller errors and are better constrained (Fig.4.14). If we apply a newer correction for the 40 Ar/ 39 Ar method to the most recent outflow PST age it will be exactly the same as the intracaldera PST U/Pb age of 18.7 Ma. Some of the conventional 40 Ar/ 39 Ar ages are significantly older than the U/Pb ages, which does not make much sense since it is supposed to date the cooling age of the tuff that should be younger than the crystallization age. It does not look like that there is a systematic error with the convention K-Ar method, because even within the same sampling area, some ages are older while other ages are younger than the determined crystallization ages. 6.0 Discussion 6.1 The lifespan of the Silver Creek caldera Field evidence shows that the PST ignimbrite is one single cooling unit (Young and Brennan, 1971; Glazner et al., 1986) formed after one supereruption. Previous geochronology studies concluded that the emplacement age of PST was 18.50±0.18 Ma. 123 With new correction for 40 Ar 39 Ar method, the age of PST is about 18.7 Ma. This age is extremely close with error to the intracaldera PST U/Pb age done by this study. The three high-precision U/Pb ages of the intracaldera intrusions also overlap within errors with the outflow and intracaldera PST. The current precision still cannot tell the difference between these ages, which means that they are temporarily extremely close to each other. If we plot individual zircon 238 U/ 206 Pb ages from each sample and order them from youngest to oldest, we can see that all units of this magma system have similar lifespan (Fig.4.15). Sample SC6 from the margin of the Moss Phorphry has a crystallization history of about 1.5 myrs while sample SC112a from the more mafic phase of the same intrusion has an extremely short crystallization history of less than 0.5 myrs. Sample SC36 from Times Porphyry has the same lifespan as the marginal phase of Moss. The whole crystallization history of the intracaldera PST is about 1 myrs. The comparison of crystallization history between intracaldera intrusive and extrusive rocks shows that the former one has a longer history of about 0.5 myrs (Fig.4.16). Considering the youngest and the oldest zircon ages of this magmatic system, the whole lifespan of this system is at about 1.5 myrs (Fig.4.16 and Table 4.3). This is dramatically shorter than a lot of batholith scale magmatic system. For example, the Tuolumne batholith in the Sierra Nevada has a magmatic duration of about 10 Ma (Memeti et al., 2010), and Mt Stuart batholith has a lifetime of about 6 Ma (Matzel et al., 2007). From high-precision zircon U/Pb dating, antecryst ages of the Fangshan pluton in China indicate that the magmatic system below the exposed pluton has a duration of magmatism of about 15 Myrs (Zhang et al., in preparation). If compare Silver Creek caldera with the some of the Tertiary 124 calderas in the southern Rocky Mountains area, it also has a relatively short evolution history (Lipman 2007). Some of the southern Rocky calderas usually have lifespan between 1-5 Myrs (Lipman, 2007) and a lot of them have generated multiple ignimbrite sheets. Based on current data we have, I am still not condident to order the different units in the caldera. The oldest zircons within each sample all overlap with each other within error (Fig.4.15). In the field we can see one good outcrop of the contact between the intracaldera tuff and the Moss Porphyry to the north of the Silver Creek (Fig.4.6c). Other than this no clear contacts have been observed. 6.2 Crystal budget of this upper crustal magmatic system Of the 18 zircons dated for the intracaldera tuff so far, no xenocrysts or antecrysts have been found in the system and all 18 are interpreted to be autocrystic zircons grown during final crystallization of the melts (Fig.4.15). Similarly, some other super-eruption scale ignimbrite also lack xenocrysts or antecrysts. For example, the famous Fish Canyon Tuff from San Juan Mountains of Colorado has been chronologically studied intensely. Within a big data set, no xenocrysts or antecrysts have been found either (Schmitz and Bowring, 2001). Some workers did SHRIMP dating on some other ignimbrite sheets. They dated the core and rim of zircons and they did find some older cores which they think are inheritant zircons (Brown and Fletcher, 1999). Brown and Fletcher, 1999 concluded that some of their zircons from Whakamaru ignimbrite (New Zealand) have cores that are about 250 k.y. older than the corresponding rims. Bindeman et al., 2001 did find some xenocrystic zicons from some post-caldera lava flows that are dramatically older than the 125 starting time of super eruption in Yellowstone. So, the existence of xenocrysts and antecrysts in volcanic rocks is possible, but in Silver Creek it just does not happen based on the data we have so far. Among the 19 zircons that are from the subvolcanic plutons in the caldera, no antecrysts or xenocrysts have been found either. Susanne McDowell from Vanderbilt Univeristy did a lot of SHRIMP analyses on Silver Creek and she found several xenocrysts from the Moss Porphyry and the mafic phase of Moss. These xenocrysts are Precambrian (1.4-1.7 Ga) and this is about the same age of the basement rock of Katherine Granite in this area. No xenocrysts or antecrysts have been found (out of her 20 zircons) in the Times porphyry (Personal communication with Susanne McDowell). Quite different from many other plutonic systems that have been studied using high- precision, zircons from these subvolcanic plutons in Silver Creek clustered very well and only a few xenocrysts have been found. Zircons from other plutonic systems such as Mt Stuart (Matzel et al., 2006); Tuolumne Batholith (Memeti et al., 2010); Fangshan pluton (Zhang et al., 1 st chapter of this dissertation) all have different populations of antecrysts and xenocrysts. Antecrysts are zircons recycled from earlier magma pulses while xenocrysts are zircons that were pick up from the host rocks. The lack of antecrystic zircon crystals within these caldera systems, typically seen in subvolcanic plutons and the lack of antecrystic or xenocrystic zircons in the ignimbrite, could be caused by several possible reasons: (1) Magma accumulated in the upper crust at a very high rate, so there was no time for any older zircons to grow at all or there is no older or earlier magma pulses in the system except for the big batch of magma being 126 erupted; (2) Older zircons did form within the earlier batches of magma but all of them have a long enough time to accumulated at the bottom of the magma chamber, so when the melt-rich volatile enhanced magma evacuated from the chamber they did not carry any of the older zircons; (3) Older zircons did form and some of them were carried by the evacuated magma but due to the extremely high zircon saturatution temperature of the felsic and ready-to-erupt magma, the old zircons were totally absorbed. The first possible mechanism needs the melting rate of the crustal rocks, or the assimilation rate between the input basaltic mantle origin magma and the crustal rocks to be extremely fast. Our new U/Pb zircon ages do indicate a short-lived system of Silver Creek caldera, and the existence of xenocryst but not antecrysts within the plutons and the lack of xenocrysts or antecrysts within the ignimbrite do possibly indicate that there is no source for antecrysts at all. The second hypothesis explains the lack of older zircons within the volcanic regime very well, but problems will be met when we try to interpret the plutonic rocks. Based on the chemistry of the plutonic rocks, there must be a batch of mafic magma input that triggered the intrusions and this mafic input drag the chemistry back to be more mafic and less evolved. It is hard to explain why the plutonic rocks did not carry some older zircons sinking at the bottom of the magma chamber when the mafic input is coming from the bottom of the chamber, unless the shallow intrusion’s magma is from a totally different source as the intracaldera tuff. As for the third possible mechanism, it needs the zircon saturation temperature of the evacuated magma to be high enough to melt the older zircons. Previous research done on 127 the saturation temperature of zircons indicate that the inheritance-poor “hot” felsic magma has an average Zr saturation temperature of 837°C, and this temperature is highly possible an underestimated temperature of the initial magma since that is probably Zr unsaturated (Miller et al., 2003). Calvin Miller’s group calculated zircon saturated temperature from both outflow and intracaldera tuff. Calculated zircon saturation temperatures for high-silica rhyolite (distal ignimbrite) glass are 770°C and 780°C; bulk pumice from the same unit yields temperatures in the range of 810-830°C. Low ilica rhyolite (proximal ignimbrite) bulk pumice gives higher saturation temperatures of 880- 890°C. Trachytes within the caldera give considerably higher zircon saturation temperatures; glass from this unit yields a temperature of 920°C and bulk fiamme yield temperatures of 920°C and 930°C (Miller et al., in preparation). The above temperature is high enough to melt the inheritance zircons in the intracaldera tuff. Due to the existence of xenocrysts in the plutonic rocks, the zircon saturation temperature must not be high enough to totally melt the inheritance part at least, so it is more like that there is no source for antecrysts for the plutonic rocks. 6.3 Chemical variations between the intrusion and the tuff Rapid short-term chemical variations are well developed in the PST while the chemical signatures of the related intrusions changes simply following linear trends (Fig.4.10). In the classification diagrams (Fig.4.8), we can see that from the caldera to the distal part of the ignimbrite sheet, volcanic rocks are getting more and more evolved. This horizontal chemical variance did happen in other ignimbrite sheets as well. Compare to the horizontal variance, vertical variance is more common and easier to understand, because 128 it is usually caused by different cooling units or by the zonation within the magma chamber (Hildreth, 1981). The compositional gradients in magma chamber, saying usually felsic overlying mafic, can also explain the horizontal chemical variance from more mafic to more felsic as going away from the eruption source because we would expect that the top more felsic part will evacuate from the chamber earlier than the more mafic bottom part. One thing needs to be concerned when we use this to explain the horizontal zonation of ignimbrite sheets. During the so called “supereruption”, the melt- rich volatile enhanced part of the magma chamber should be very dynamically active, so mixing between different layers should happen very commonly. Another thing is that the pyroclastic flow is a density flow with extremely high temperature, so the flow won’t just follow a simple linear flow law. Turbulence should be very common in this type of flow, then so caused mixing between different compositions should be quite normal. There must be some other mechanisms that control the horizontal chemical variations within ignimbrite sheets, but this is beyond the discussion of the current chapter for now. In comparison to the ignimbrite sheet, the intracaldera intrusive rocks have a simpler evolve pattern. Even though the field relationships between the intrusions and the PST tells us that they are slightly younger, but they are not more evolved in terms of chemical composition. In fact, their composition overlaps that of the volcanic rocks. If the magma chamber is a relatively closed system after the formation of the caldera, the later intrusive rocks should be more evolved than the tuff, but the reality is that the intrusions still evolved from more mafic to more felsic, which indicates that there must be an mafic input that mixed with the evolved magma and triggered the resurgent of the caldera. 129 6.4 Difference between the evolution of long-lived and short-lived magmatic systems One of the fundamental differences between caldera and the plutonic systems I studied is the lifespan. The caldera forming system has an extremely short lifetime of about 1.5 m.y while many plutonic systems have lifetime >5 m.y. Another difference is that the subvolcanic plutons in the caldera have a relatively simple revolution history than the regular plutons. From Silver Creek shallow intrusions we can see that the magma did pick up zircon crystals from the host rock but not zircons from earlier magma pulses, while as mentioned before a lot of plutons are usually composed of multiple magma pulses that have different ages. To explain the above differences, one possible reason for that is the magma supply for calderas is fast but not very sustainable while that for plutons is relatively steady through time. Magma accumulated fast below a volcano but it also drained very fast during super-eruptions while magma inputs into plutons are steady and helps to keep the whole magmatic system at relatively high temperature for a long time. When magma is not totally solidified it is easier for crystal recycling to happen. This is also why crystal transportation and recycling are more usual for long-lived magmatic systems than short-lived systems. 7.0 Conclusions The newly developed high-precision U/Pb zircons ages have better constrained the ages of the intralcaldera PST and the shallow intrusions, and further strengthen the connection between the outflow PST and its source-Silver Creek caldera. The new U/Pb age of the intralcaldera PST agrees extremely well with the 40 Ar/ 39 Ar age of the outflow PST after we applied the newest correction between the U/Pb and the 40 Ar/ 39 Ar systems. 130 The whole magmatic system of Silver Creek caldera has a very short lifespan of about 1.5 m.y. The current method and its precision still can not allow us to tell the difference in terms of ages between the shallow intrusion and the intracaldera tuff. No xenocrysts or antecrysts zircon has been found within these 37 zircons we have so far, but there are xenocrysts in the subvolcanic plutons from other zircon populations. The extremely high zircon saturation temperature of the intracaldera tuff could possibly melt all the inheritance zircons. The filtering mechanism of antecrystic zircons in the subvolcanic plutons is possibly because of the lack of sources for antecrysts. The geochemical evolution of the intracaldera intrusions is pretty simple and follows a simple linear trend. The tuff has very obvious horizontal chemical variations. 131 Fig.4.1. Location of the Silver Creek caldera and the distribution of the outflow Peach Spring Tuff . 132 Fig.4.2. Simplified geological map of Silver Creek caldera with geochronology sample locations 133 Fig.4.3. Photo taken from an outcrop close to Kingman showing the deposition sequence of PST and previous tuffs 134 Fig.4.4. Photo of PST out flow showing both the pre-eruption blasts and the major eruptive deposit 135 Fig.4.5. Comparison of the intracaldera and outflow PST (a) outflow PST; (b) intracaldera PST 136 Fig.4.6. Field photos from Silver Creek caldera (a) Contact between the intracaldera PST and the Times Porphyry to the south of the Silver Creek (looking towards south) (b) Contact between the intracaldera PST and the Moss Porphyry to the north of the Silver Creek (looking towards north) (c) Intrusive contact between the Intracaldera PST and the Moss Porphyry to the north of the Silver Creek (looking toward SE) (d) Cross-cutting relationship between the granite (Times Porphyry) and the intracaldera PST (please add scale information and capitalize Silver Creek) 137 Fig.4.7. Thin section photos from units in the Silver Creek caldera (a) Thin section of sample SC 33 from the intracaldera PST. Embayment of plagioclase phenocrysts in a coarse to fine grained matrix. (b) Thin section (2.5×) of sample SC137 from the intracaldera PST to the south of the silver creek. Biotite was altered to chlorite (top part of the big biotite grain in the center of the view); (c) Thin section from intracaldera PST to the north of silver creek. Flow texture can be seen and the layers are wrapping around the plagioclase phenocrysts. (d) Thin section (2.5×) of sample SC119 from the center more mafic phase of the Moss Porphyry to the north of the silver creek. Both hornblende and biotite phenocrysts could be seen and some opaque phenocrysts (magnetite). 138 Fig.4.8. Classification of intracaldera intrusions, intracaldera PST and outflow PST (data from Thorson, 1971 and Carley, 2010). Volcanic rocks’ geochemistry change with distance from the eruption source. 139 Fig.4.9. Magma series plots of intracaldera intrusions, intracaldera PST and outflow PST (data from Thorson, 1971 and Carley, 2010). 140 Fig.4.10. Harker diagram of intracaldera intrusions, intracaldera PST and outflow PST (data from Thorson , 1971 and Carley, 2010). Major elements change with distance from the eruption source for volcanic rocks. 141 Fig.4.11. Sample thin sections (a) Sample SC 6 from the first Moss Mine. Both K-feldspar and plagioclase can be seen in this view. Quartz grains can be seen in the matrix. (b) Sample SC 112a from the center phase of the Moss Porphyry. Most of the feldspar is plagioclase and hornblende phenocrysts can be seen. (c) Sample SC 32 from the intracaldera PST to the south of silver creek. Phenocrystic plagioclase and glassy shards are with sharp corners and edges in very fine matrix. (d) Sample SC 36 from the granitic Times Porphyry. This thin section shows typical granophyric texture 142 Fig.4.12. Zircons from two analyzed samples. (40×) Fig.4.13. 3-D plots of samples ages 143 Fig.4.14. Comparison of all available ages related to PST with error bars. Our new ages are better constrained and a lot more precise than the old ages. 144 Fig.4.15. 238 U/ 206 Pb ages of individual zircons from every sample. Fig.4.16. Comparison of crystallization age time between intracaldera plutonic and volcanic rocks 145 Table 4.1 Major elements summary (data are from Thorson, 1971; Carley, 2010). Sample Unit SiO2 Al2O3 FeO MgO CaO Na2O K2O TiO2 MnO Author PST1 Intracaldera PST 65.4 16.51 2.67 0.8 1.44 4.17 6.94 0.6 0.04 PST2 Intracaldera PST 64.57 17.1 2.8 0.9 1.51 4.13 6.98 0.62 0.06 PST3 Intracaldera PST 61.59 15.99 4.88 1.92 3.95 3.49 4.36 0.96 0.07 TIMES1 TIMES PORPHYRY 75.61 11.98 0.83 0.17 0.56 3.59 5.31 0.15 0.03 TIMES2 TIMES PORPHYRY 73.09 13.4 1.57 0.37 0.87 4.26 5.5 0.32 0.06 MOSS1 MOSS PORPHYRY 59.74 15.05 5.89 3.14 4.08 3.59 4.13 1.05 0 MOSS2 MOSS PORPHYRY 63.85 15.05 4.1 2.15 3.34 3.49 4.62 0.74 0.06 MOSS3 MOSS PORPHYRY 65.83 14.88 3.63 1.6 2.91 3.85 4.67 0.7 0.06 CRW PST Intracaldera PST 66.1 17 3.26 0.81 1.21 3.49 7.33 0.57 0.06 CRW 2A Intracaldera PST 68.7 16.3 3.33 0.66 0.74 5.82 3.8 0.49 0.05 PSTG 1C Intracaldera PST 68.2 15.99 2.74 0.46 1.26 3.91 6.64 0.57 0.08 28571 PST-BF Intracaldera PST 62.9 14.87 8.35 1.5 3.89 3.82 2.73 1.22 0.15 28556 PST-P1 Proximal Outflow 69.3 15.39 2.65 1.11 1.65 2.69 6.56 0.46 0.08 WSW PST 2A Proximal Outflow 75.1 12.84 1.4 0.2 0.61 3.63 5.86 0.23 0.08 WSW PST 2B Proximal Outflow 71 14.7 1.96 0.23 0.85 4.04 6.77 0.35 0.08 WSW PST 2D Proximal Outflow 76.1 12.69 1.09 0.09 0.51 3.29 5.99 0.19 0.05 WSW PST 2F Proximal Outflow 74.8 13.35 1.27 0.13 0.6 3.45 6.17 0.21 0.04 WSW PST 2G Proximal Outflow 74.4 13.57 1.32 0.12 0.65 3.56 6.06 0.22 0.05 WSW PST 4B Proximal Outflow 69.1 16.18 1.98 0.6 1.19 3.75 6.67 0.39 0.05 WSW PST 4D Proximal Outflow 71.9 14.8 1.69 0.35 0.92 3.86 6.03 0.34 0.05 GJPST 1A Proximal Outflow 72 14.74 1.83 0.17 0.55 3.89 6.32 0.36 0.04 GJPST 1C Proximal Outflow 73.1 14.08 1.8 0.19 0.61 3.74 5.96 0.33 0.08 PT-1B-4 Distal Outflow 75.2 12.76 1.19 0.43 1.05 2.12 6.93 0.21 0.06 KPST01A Distal Outflow 75.3 12.74 1.19 0.17 1.13 2.23 6.92 0.23 0.08 KPST01B Distal Outflow 75.1 12.8 1.17 0.26 0.61 2.63 7.15 0.21 0.07 KPST01C Distal Outflow 75.4 12.24 1.09 0.35 1.15 2.61 6.82 0.19 0.07 KPST01D Distal Outflow 75.4 13.14 1.06 0.2 0.75 2.72 6.39 0.2 0.07 KPST01E Distal Outflow 75.2 12.9 1.18 0.24 1.02 2.29 6.91 0.22 0.07 Thorson, 1971 Carley, 2010 146 Table 4.2 Age summary of both outflow PST and intracaldera PST and intrusions Unpublished data are from Pernokas, M.A., Nakata, J.K., and Marvin R.F. in U.S. Geological Survey Labs Age Rock Unit Method Mineral Literature 18.9±0.13 Ma 18.74±0.17 Ma 18.46±0.12 Ma 18.69±0.19 Ma intracaldera PST 18.50±0.18 Ma PST outflow Ar/Ar sanidine Neilson et al., 1990 20.0±0.5 Ma sanidine 18.8±0.5 Ma biotite 18.3±0.6 Ma sanidine 18.1±0.6 Ma sanidine 20.0±1.0 Ma PST outflow K/Ar sanidine Glazner, 1981 18.2±0.4 Ma sanidine 18.8±0.5 Ma biotite 16.9±0.4 Ma PST outflow K/Ar sanidine Damon et al., 1966 18.3±0.6 Ma PST outflow K/Ar sanidine Damon et al., 1964 19.2±0.6 Ma sanidine 20.1±0.5 Ma biotite 16.5±0.4 Ma sanidine 18.0±0.5 Ma sanidine 20.5±0.5 Ma sanidine 16.2±0.4 Ma sanidine 16.7±0.3 Ma sanidine 17.8±0.4 Ma sanidine 17.4±0.2 Ma sanidine 18.0±0.5 Ma sanidine 18.6±0.6 Ma sanidine 17.5±0.4 Ma sanidine 18.50±0.5 Ma Intracaldera intrusion U/Pb zircon DeWitt et al., 1986 10.4 Ma Intracaldera intrusion K/Ar not clear Thorson, 1976 Howard et al., 1982 Dickey et al., 1981 PST outflow PST outflow PST outflow K/Ar K/Ar K/Ar unpublished inracaldera intrusion CA-TIMS, U/Pb zircon This study PST outflow K/Ar Goldfarb et al., 1986 147 Table 4.3 U/Pb data for all zircons Sample cm.Pb (pg) Th U 207 Pb 235 U 2σ σ σ σ %er diseq.corr . 206 Pb 238 U 2s %er ρ ρ ρ ρ diseq.corr . 206 Pb 204 Pb diseq.corr . 207 Pb 206 Pb 2σ σ σ σ %er tot.diseq.c orr. 238 U 206 Pb 2σ σ σ σ %er tot.diseq.c orr. 207 Pb 206 Pb 2σ σ σ σ %er diseq.corr . 204 Pb 206 Pb 2σ σ σ σ %er SC06.Z01 2.8 1.46 0.0203 20.57 0.002923 1.23 .89 73 0.05038 19.49 255.13 0.33 0.24919 0.17 0.01365 1.1 18.81 ± 0.23 SC06.Z03 1.8 1.96 0.0198 13.68 0.002919 1.33 .52 113 0.04917 13.04 286.22 1.46 0.17809 1.71 0.00884 1.6 18.79 ± 0.25 SC06.Z21 1.0 2.14 0.0236 47.03 0.003011 3.29 .85 40 0.05664 44.25 176.12 1.48 0.42113 0.23 0.02523 0.9 19.38 ± 0.64 SC06.Z23 0.6 1.70 0.0213 73.53 0.003021 4.31 .89 34 0.05099 69.73 147.66 0.42 0.48379 0.70 0.02974 0.7 19.45 ± 0.83 SC06.Z25 0.7 1.86 0.0435 63.71 0.003091 7.56 .92 28 0.10125 56.84 111.28 0.51 0.58111 0.45 0.03523 2.6 19.90 ± 1.50 SC06.Z24 0.8 1.66 0.0158 198.32 0.002894 9.12 .90 26 0.03929 190.15 95.03 0.31 0.61412 0.22 0.03892 0.7 18.63 ± 1.69 SC112a.Z16 0.7 1.25 0.0188 8.61 0.002864 0.57 .77 159 0.04767 8.18 308.24 0.41 0.13968 0.38 0.00629 1.3 18.43 ± 0.10 SC112a.Z15 1.3 1.21 0.0188 20.49 0.002882 1.19 .88 83 0.04722 19.45 269.46 0.48 0.22264 0.26 0.01199 2.5 18.55 ± 0.22 SC112a.Z12 1.4 1.37 0.0176 12.32 0.002779 1.31 .56 190 0.04596 11.64 324.56 1.47 0.12303 1.12 0.00526 6.5 17.89 ± 0.23 SC112a.Z11 1.4 1.35 0.0219 20.47 0.002898 1.35 .86 73 0.05469 19.32 256.75 0.54 0.25358 0.74 0.01373 2.0 18.66 ± 0.25 SC112a.Z02 1.8 1.24 0.0201 29.04 0.002885 1.82 .85 56 0.05041 27.52 231.77 0.86 0.30931 0.13 0.01778 0.4 18.57 ± 0.34 SC112a.Z14 2.2 2.05 0.0199 34.64 0.002860 2.03 .90 51 0.05026 32.83 221.46 0.29 0.33709 0.19 0.01969 0.9 18.41 ± 0.37 SC112a.Z13 2.3 1.76 0.0206 34.34 0.002876 2.09 .88 51 0.05182 32.50 220.55 0.53 0.33729 0.54 0.01964 1.3 18.51 ± 0.39 SC112a.Z01 1.8 1.41 0.0195 183.19 0.002841 11.01 1.00 102 0.04983 172.22 287.74 0.96 0.19253 0.42 0.00979 63.8 18.29 ± 2.00 SC32.Z36 1.1 2.19 0.0200 20.28 0.002950 1.22 .85 80 0.04904 19.25 259.69 0.55 0.23244 0.76 0.01257 1.9 18.99 ± 0.23 SC32.Z01 3.1 2.03 0.0192 19.88 0.002905 1.28 .84 174 0.04799 18.81 307.48 0.84 0.13182 2.30 0.00574 11.2 18.70 ± 0.24 SC32.Z14 2.3 1.50 0.0184 28.12 0.002933 1.54 .87 65 0.04543 26.79 242.74 0.59 0.27209 0.56 0.01546 1.6 18.88 ± 0.29 SC32.Z46 2.0 1.61 0.0189 26.17 0.002944 1.78 .74 65 0.04656 24.88 242.03 1.41 0.27237 0.34 0.01543 0.9 18.95 ± 0.34 SC32.Z35 0.8 1.65 0.0197 12.34 0.002907 1.95 .46 126 0.04908 11.59 293.30 2.37 0.16448 0.78 0.00791 2.7 18.71 ± 0.36 SC32.Z34 0.6 1.99 0.0138 52.68 0.002954 2.06 .87 56 0.03378 50.89 225.22 0.58 0.30114 1.24 0.01798 2.7 19.01 ± 0.39 SC32.Z02 3.2 2.16 0.0157 38.13 0.002859 2.30 .71 56 0.03979 36.54 233.59 1.95 0.30304 0.54 0.01783 1.0 18.41 ± 0.42 SC32.Z33 0.5 2.11 0.0204 36.29 0.002998 2.28 .83 53 0.04915 34.42 216.45 1.28 0.32419 0.63 0.01885 2.2 19.30 ± 0.44 SC32.Z45 0.6 2.13 0.0194 4.61 0.002976 3.40 .77 395 0.04724 2.97 320.20 4.41 0.08424 0.18 0.00253 0.5 19.16 ± 0.65 SC32.Z23 0.8 1.79 0.0278 49.22 0.003016 3.77 .86 49 0.06678 46.03 205.01 1.43 0.35904 2.70 0.02049 6.1 19.41 ± 0.73 SC32.Z12 1.9 1.49 0.0185 99.63 0.002912 5.13 .87 33 0.04582 95.22 148.75 0.93 0.49157 1.47 0.03043 2.4 18.74 ± 0.96 SC32.Z15 2.9 1.91 0.0240 77.12 0.002977 5.26 .90 31 0.05823 72.40 135.93 0.67 0.51920 0.17 0.03197 1.3 19.16 ± 1.00 SC32.Z16 2.5 1.73 0.0238 83.90 0.002957 5.68 .90 31 0.05804 78.81 131.90 0.45 0.53040 0.42 0.03275 1.6 19.03 ± 1.08 SC32.Z11 2.8 1.44 0.0190 120.09 0.002933 6.54 .90 28 0.04660 114.25 117.44 0.52 0.56151 0.17 0.03518 0.4 18.88 ± 1.23 SC32.Z13 5.6 2.04 0.0286 123.36 0.002997 9.90 .90 25 0.06860 114.56 85.99 0.80 0.63576 0.25 0.03986 0.4 19.29 ± 1.90 SC36.Z25 0.7 1.96 0.0203 14.34 0.002921 0.97 .78 98 0.05024 13.59 277.51 0.67 0.19834 0.52 0.01017 1.2 18.80 ± 0.18 SC36.Z04 2.4 1.51 0.0188 27.57 0.002939 1.55 .87 65 0.04624 26.24 242.44 0.64 0.27210 0.50 0.01542 1.7 18.92 ± 0.29 SC36.Z02 2.1 1.42 0.0080 232.58 0.002883 5.24 .86 33 0.02000 228.10 149.55 1.21 0.48193 1.54 0.03053 2.5 18.56 ± 0.97 SC36.Z05 3.1 1.92 0.0248 74.01 0.002984 5.20 .90 31 0.06001 69.36 135.91 0.66 0.51921 0.17 0.03192 1.2 19.21 ± 1.00 SC36.Z06 2.7 1.73 0.0237 84.25 0.002956 5.68 .90 31 0.05783 79.15 131.90 0.47 0.53040 0.42 0.03275 1.6 19.03 ± 1.08 SC36.Z01 3.0 12.50 0.0189 123.80 0.002902 6.69 .90 28 0.04774 117.83 118.68 0.58 0.56736 0.40 0.03555 1.0 18.68 ± 1.26 SC36.Z03 6.0 2.06 0.0294 120.59 0.002999 9.91 .90 25 0.07026 111.78 86.03 0.81 0.63597 0.25 0.03985 0.5 19.31 ± 1.91 SC36.Z21 4.9 2.67 0.0326 123.99 0.003039 11.19 .89 24 0.07712 114.10 77.62 1.45 0.65485 0.35 0.04106 0.4 19.56 ± 2.18 SC36.Z26 8.5 1.26 0.0304 133.54 0.003077 11.08 .90 24 0.07064 123.66 76.70 0.28 0.65241 0.06 0.04100 0.2 19.81 ± 2.19 isotopic ratios isotopic ratios age diseq.corr. 206 Pb* 238 U 148 CHAPTER 5: MAGNETIC FABRICS OF THE INTRACALDERA PEACH SPRING TUFF AND SHALLOW INTRUSIONS: IMPLICATIONS FOR THE REACTIVATION OF THE SILVER CREEK CALDERA, ARIZONA, USA 1.0 Abstract Magnetic fabric studies show promise when the petrological studies are not enough to provide reliable rock fabrics. Silver Creek caldera, located at the intersection of the three states of California, Nevada and Arizona, is the recently discovered source of the 18.5 Ma old regional stratigraphy marker of Peach Spring Tuff (PST) and is an ideal place to study the fabrics within both the volcanic and the plutonic regimes. The remnant eastern half caldera has three main rock units: intracaldera PST, quartz-mozonitic Moss Porphyry and granitic Times Porphyry. The two shallow intrusions intruded the intracaldera PST along the eastern margin of the caldera. 21 out of 23 samples generated good statistical AMS results. The main AMS carriers are the phenocrystic magnetite within both rock types. The average susceptibilities of the intracaldera PST range from 2.9×10 -3 SI to 1.4×10 -2 SI with a median of 7.3×10 -3 SI, which agree well with the susceptibilities of the outflow PST. For the plutonic rocks, values range from 7.7×10 -4 SI to 1.7×10 -2 SI with a median of 9.9×10 -3 SI. Degree of anisotropy (P J ) of the volcanic rocks is statistically slightly higher than that of the intrusive rocks, because they experienced both the collapse of the magma chamber roof and the emplacement of the plutons while plutons only formed their fabrics during the emplacement. But, the degrees of anisotropy of all samples are very low and within a very narrow range of 1.007 to 1.059. Magnetic ellipsoids are both prolate and oblate. The volcanic rocks developed more oblate fabrics 149 close to the contact of the two regimes. Magnetic foliations within the plutons are generally steeply dipping. Some of these foliations are parallel to the margin of the intrusions, but some are not. There is no clear pattern can be defined by the current data. Lineations within the plutons are randomly trending and moderately plunging while those within the caldera fill are steeply plunging. Based on the current magnetic fabrics, none of the three end member resurgent models fits perfectly. The closest matched model will be the “resurgent diapir” model, but there are still observations that do not fit in. Compared to the outflow PST magnetic fabrics, we found that our new data, especially the lineations within the intralcaldera PST, do not form a continuous pattern connecting well with the outflow. But, the randomly orientated intracaldera fill does indicate that the magma chamber roof collapsed to cause rock blocks randomly fall down. During the formation of the Silver Creek caldera, regional stress field is dominated by E-W extension while after the caldera formed regional stress field changed to be E-W extension plus strike-slip faulting. Current AMS data does not show the evidence of the influence from the regional stress field on the fabrics within the caldera. 2.0 Introduction Plutonic rocks more or less have widespread fabrics which are usually used as recorders of the strain due to different causes, with the causes and interpretations of these fabrics still very controversial in many cases (Zak et al., 2007; Zak et al., 2005; Paterson et al., 1998; Kenneth and Paterson, 1997; Paterson et al., 1989). Primary fabrics within the volcanic rocks formed during the deposition of different types of flows and they are usually used to infer the flow direction so as to locate the possible eruptive sources 150 (Suzuki and Ui, 1982; Hillhouse and Wells, 1991; Fisher et al., 1993; Lamarche and Froggatt, 1993). Although complications need to be considered when we try to use fabrics to infer flow patterns, accurate record of mineral fabrics is still necessary and the first step before any corelations between strain and flow can be made. A quantitative evaluation of flow-induced mineral fabrics formed during the emplacement of large ignimbrite sheets is a useful tool to accurately record fabrics especially when the strain is relatively small. Then it is possible for us to determine the eruptive sources and better understand how this fabric relates to the emplacement mechanics of ash flows (Ellwood, 1982; Incoronato et al., 1983; Hillhouse and Wells, 1991). Mineral fabric patterns in subvolcanic intrusive rocks in source calderas, potentially provide additional information about magmatic processes that occurred during caldera formation and reactivation. Because of the challenge of finding well exposed plutonic-volcanic systems, very few fabric studies of both regimes in one single magmatic plumbing system have been carried out. The Silver Creek area in western Arizona has been mapped in detail by Thorson (Thorson, 1971) and it is an ideal place to study the magmatic fabrics within both the erupted and intruded components of a caldera. Recent mapping and detailed geologic studies (Ferguson, 2008) indicate that this large pile of trachytic tuff and shallow intrusive bodies in the Silver Creek area is the eastern half of an old caldera that is the likely eruptive source of the distinctive lower Miocene Peach Spring Tuff (PST) (18.5 Ma by 40 Ar/ 39 Ar dating, Neilson et al., 1990) distributed in the Mojave desert of western Arizona, southern Nevada, and southeastern California, thus it is even more important to 151 further study the magmatic fabrics and so inferred magmatic processes within this source caldera. Due to the difficulties to measure the magmatic fabrics either in the field or by thin section study, we applied anisotropy of magnetic susceptibility (AMS) technique to define the magnetic fabric of the extrusive rocks and the shallow intrusive rocks in the caldera. AMS study has shown promise for many fabrics studies of both plutonic and volcanic rocks (Ferre et al., 1999; Pignotta and Benn, 1999; Palmer et al., 1996; Hillhouse and wells, 1991; MacDonadl and Palmer, 1991). This method principally determines the strength of the magnetization that a sample acquires when a magnetic field is applied at different orientations. The differences between different orientations then can be interpreted in terms of the net shape of the grains and the degree of their crystalline alignments which can also be interpreted in the same way as in petrographic studies (Tarling and Hrouda, 1993). The strengths of magnetization along three principal directions can be expressed by an ellipsoid similar as the one used in structural geology studies. Then we use the longest axis to represent the magnetic lineation and the plane defined by the longest and intermediate axis to represent magnetic foliation. In this paper, we will present newly collected AMS data for 23 samples (12 intrusive samples, 11 extrusive samples) along two transects in the Silver Creek caldera (Fig.5.2). We will compare the new data with the existing AMS dataset of the PST outflow (Hillhouse and Wells, 1991), and try to discuss some controversial flow orientations inferred from this previous study with consideration of the complication involved in the relationship between flow pattern and strain makers. Although the formation of caldera in 152 general has been studied for a long time and the common formation models have been accepted by most of our community (Walker, 1984; Gudmundsson, 1988; Carle, 1988; Ventura, 1994; Lipman, 2000; Roche et al., 2000; Michon et al., 2007), the reactivation of a caldera by later intrusive rocks and the magma dynamics of these later intrusions are still not well understood. After discussing several proposed reactivation end member models, we will evaluate these models in regards to the new AMS fabrics data and hope this exploratory study will lead to more research on the fabrics of plutonic-volcanic systems in the future. So far we found that: (1) Both the plutonic and volcanic rocks in the caldera have very low anisotropy of magnetic susceptibility which means that they are very limitedly deformed; (2) The intracaldera PST has similar anisotropy of magnetic susceptibility as the outflow; (3) Intracaldera eruptive rocks are in general slightly more deformed than the plutonic rocks; (4) Except for the steeply dipping foliations within the plutons, no obvious and well defined fabric patterns can be found; (5) Fabrics within the intracaldera PST did not form a continuous pattern with the outflow; (6) No structural evidence has been found to show that the fabrics have been influenced by regional stress field. 3.0 Geological setting of Peach Spring Tuff (PST) and Silver Creek caldera PST is a large Miocene ignimbrite sheet distributed across five tectonic regimes in the southwestern United States with an estimated area of about 35,000 km 2 (Valentine et al., 1989) (Fig.5.1). The five tectonic components in this broad area from west to east are: Mojave Desert; southern end of Basin and Range province; Colorado River extension corridor; Transition zone and the Colorado Plateau (Fig.5.1). This remarkable unit has 153 been studied for more than 30 years (Thorson, 1971; Young and Brennan, 1974; Glazner et al., 1986; Valentine et al., 1989; Neilson et al., 1990; Hillhouse and Wells, 1991; Ferguson, 2008; Pearthree et al., 2009; Carley et al., 2009; Pamukcu et al., 2009; Carley et al., 2010; Zhang et al., 2010). PST was firstly described by Young and Brennan (1974) in the western Colorado Plateau and then Glazner et al., (1986) correlated the isolated outcrops and extended the distribution of PST to the Mojave Desert area. Since the discovery of PST, no eruptive source has been reported for this broad ignimbrite sheet until the recent discovery of the source caldera by Ferguson (2008). The detail mapping around the Oatman, AZ mining district reported by Thorson 1971 and Pearthree et al., 2009 both include the idea that the plutonic-volcanic complex in the Silver Creek area is a possible old caldera remnant. Ferguson (2008) carefully investigated the phenocrysts’ assemblage within the volcanic regime of this complex and found out that it has an almost identical assemblage and mineral ratio change from the bottom to the top of a cooling unit in the PST outflow. Later, more detailed field mapping and geochronology further assured the connection between the Silver Creek caldera and the PST (Zhang et al., 2010; Ferguson and MacIntosh in prep.). Now this half caldera is thought by most people as the source of the PST. Silver Creek caldera is located near the triple contact of the three states of Nevada, California and Arizona and it is roughly at the center of the currently accepted distribution of the PST (Fig.5.1). In addition, it is within the area of the possible eruptive source predicted by the previous AMS study of the PST outflow fabrics (Hillhouse and Wells, 1991) (Fig.5.1). 154 4.0 Previous AMS study of PST outflow Hillhouse and Wells (1991) did AMS work on 42 different samples sites across the whole PST outflow. 30 out of 42 sites generated well-defined magnetic lineations suitable for the fabrics study. The average susceptibility of their samples is about 2×10 -3 SI, and the typical magnetic lineation is about 1.01 and foliation is about 1.02. The magnetic foliations also form an approximate radical imbrication. Based on the notion that comes from the analog between minerals in pyroclastic flows and cobbles in stream water flows, after the restoration of the major extension, strike-slip faulting and associated tectonic rotation, they concluded that the best intersection of all these magnetic lineations or the source region of PST is located near the southern tip of Nevada, in the southern Black Mountains of Arizona on the eastern side of the Colorado River extensional corridor (Fig.5.1), which includes the area of the recently discovered source, Silver Creek caldera. However, in their study, there are still several contradictory results (Fig.5.1) that are perpendicular to the expected lineation orientations, and so do the foliations at some sites. They also pointed out that these contradictories might be the results of the local interaction of the pyroclastic flows with the hills and valleys which we also think as an important influence, or the rheomorphic flow in the final stages of solidification. 5.0 Description of Silver Creek caldera Silver Creek caldera is of a half-moon shape map view with an area about 75 km 2 and is located about 2 miles to the northwest of the town of Oatman, AZ (Fig.5.2). It was named Silver Creek caldera by Ferguson (2008) as the source caldera of PST. 155 5.1 Intracaldera Tuff Very thick intracaldera facies tuff was identified within the caldera (Ransome, 1923; Thorson, 1971; Pearthree et al., 2008; Ferguson, 2008). Before the deposition of this tuff, earlier Tertiary volcanic rocks overlie the Precambrian basement of distinctive biotite granite, named the Katherine Granite containing (1 to 2 inch) potassium feldspar phenocrysts (Thorson, 1971). This granite intruded into older biotite schist, granitic gneiss and garnet gneiss (Thorson, 1971). Although the Precambrian basement does not crop out within the caldera, many Katherine Granite fragments occur in the different lithologies in the caldera. At the southern end of the Times Gulch, intracaldera tuff unconformably overlies the Precambrian basement. Above the intracaldera tuff, later bimodal rhyolite-basalt succession crops out only near and along the highway 68 (Spensor et al., 2007). The intracaldera tuff was firstly classified as the Alcyone formation by Ransome (1923) and Thorson (1971), and Thorson (1971) proposed the idea of Alcyone caldera. After reinvestigation of the phenocrysts assemblage of the tuff, Ferguson (2008) reinterpreted the tuff to be intracaldera part of the PST. In Thorson’s thesis, he provided detailed petrographic descriptions of this unit which very closely match the phenocryst assemblage of the PST outflow: 20-35% feldspar with K-feldspar greater than plagioclase, and the ratio decreasing up-section from 5:1 to 3:1. Accessory phases include1-2% biotite, 2% opaque oxides, <0.5% quartz, and trace amounts of hornblende, clinopyroxene, sphene, zircon, and apatite (Young and Brennan, 1974; see also Glazner et al., 1986; Murphy et al., 2004; Spencer et al., 2007). Thin section study of Ferguson 156 (2008) also reproduced the similar results and it made him conclude that the Alcyone formation defined by Ransome (1923) and Thorson (1971) is actually part of the younger PST. The real Alcyone formation includes mostly dacitic lava, breccia and sedimentary rocks that pre-date the PST. One interesting phenomenon is that there is a geographic gap in which deposition of PST is lacking between the margin of the Silver Creek caldera and the closest PST outflow outcrop about 5 km to the south of the caldera (Fig.5.1). Intracaldera PST is preserved to the west of the shallow intrusions and was intruded by them (Fig.5.2). Intrusive contact can be observed between the tuff and the quartz- monzonite to the north of the Silver Creek (Fig.5.3 (a)). The tuff is a grey color, very well welded trachyte with a great amount of potassium feldspar and plagioclase phenocrysts in a partially to completely devitrified matrix of welded shards, pumice dust and rock fragments. Biotite is more common than hornblende. Alteration has been moderate to intense and often obscures the optical properties of the minerals to make identification extremely hard. Potassium feldspar and plagioclase have been clouded by fine sericite, and epidote. Some of the potassium feldspar still has unaltered cores. Biotite grains have been partially or completely altered to chlorite (Fig.5.3 (b)). 5.2 Intracaldera Shallow Intrusions Two plutonic bodies along the eastern margin of the caldera intruded the intracaldera PST and earlier volcanic rocks. Originally, they were named as Times Porphyry to the south of the Silver Creek and the Moss Porphyry to the north of the Silver Creek by Ransome (1923) (Fig.5.2). The Times Porphyry is a K-feldspar porphyritic granite while the Moss Porphyry is dominated by plagioclase porphyritic quartz-monzonite. Previous 157 authors have controversial opinions about the relative ages of these two intrusive bodies. Ransome (1923) reported that the Times is younger while Thorson (1971) proposed that the Moss is younger. In the field, no clear intrusive relationships between these two bodies could be observed. They appear to grade into each other to the south of the Silver Creek. Only one contact spot between the intracaldera PST and the Moss Porphyry can be clearly observed to the north of Silver Creek. Recent high-precision geochronology data indicate that the two intrusions have identical ages within errors (Zhang et al., 2010). In order to conveniently describe the intrusions, we still keep the names of Times and Moss in this paper for now, but we need to keep in mind that they could possibly be different phases of the same intrusion. Both intrusive bodies were cut by later porphyry dikes. The Times Porphyry to the south of the Silver Creek is more homogeneous compared to the northern Moss Porphyry and is of granitic composition (Fig.5.2). The border of the Times Porphyry is very fine-grained, pinkish color with both K-feldspar and plagioclase phenocrysts and minor amount of biotite (~5%) and even less hornblende. The border grades inward into a slightly darker, coarser-grained, more conspicuously porphyritic core which has more biotite and hornblende. In thin section of the border rocks, the groundmass around each phenocrysts has K-feldspar in optical continuity with the phenocrysts but intergrown with quartz, which is an excellent example of granophyric texture (Fig.5.3 (c)). From the border to the core of Times Porphyry the SiO 2 % does not change much and is constantly about 74%, while Al 2 O 3 % is about 12%, Fe total % is about 1.2% and MgO% is about 0.3% (Thorson, 1971). 158 Moss Porphyry is to the north of Silver Creek and has at least two compositionally slightly different phases. In general, it is an intrusive mass of quartz monzonite porphyry and it occupies a rectangular area of about 2 by 4 miles (Fig.5.2). The composition changes from quartz-monzonite at the border to a monzondiorite to quartz-monzondiorite occupying core (Pearthree et al., 2009). As for the quartz-monzonite phase, it is a purple- gray to light gray rock with plagioclase, hornblende and biotite phenocrysts in a granophyric groundmass of quartz and K-feldspar. At the center of the Moss Porphyry, a slightly more mafic phase is of monzondiorite to quartz-monzodiorite composition. The hand samples are of gray to greenish color with plagioclase phenocrysts. In thin section, plagioclase phenocrysts are still predominant but with more hornblende phenocrysts than biotite (Fig.5.3 (d)). 5.3 Geochronology PST outflow has been dated using conventional K-Ar and 40 Ar- 39 Ar methods by different author since 1960s. The most recent published 40 Ar- 39 Ar age of the outflow is 18.5±0.18 Ma (Neilson et al., 1990). Not much geochronology work has been done on the intracaldera rocks. There is one U/Pb age of 18.50±0.5 Ma from the intracaldera intrusion (DeWett et al., 1986). Another age is a conventional K-Ar age which was mentioned in Thorson’s dissertation but with no clear citation and this age is about 10.4 Ma, which is way off the range of all available geochronology data about PST and Silver Creek caldera. I have done some high-precision U/Pb geochronology work on the intracaldera rocks. One age from the intracaldera tuff is 18.69±0.19 Ma, while the three ages from the intrusions are 18.9±0.13 Ma, 18.74±0.17 Ma and 18.46±0.12 Ma. So far, 159 based on these ages we can not tell the difference between the volcanic rock and the plutonic rock or between the different phases of the plutons. 5.4 Structure Regionally, the caldera is located at the southern tip of the northern part of the Colorado River Extension Corridor (Fig.5.1). Since Mesozoic time, this 70- to 100-km- wide region of extended crust along the eastern margin of the Basin and Range province in the southern Nevada and northwestern Arizona has played an important role on the construction of regional structures in the western Cordillera (Fig.5.1, Faulds et al., 2001). From Cretaceous to early Tertiary, this region resided directly north, east, and south of major thrusts, and at the northern margin of a broad uplifted terrane that was stripped of its Paleozoic and Mesozoic cover by erosion (Bohannon, 1983, 1984). In early Miocene, the southward and northward migrating magmatic and extensional fronts caused by Basin and Range province converged toward the northern Colorado River extensional corridor (Faulds et al., 2001). This is about the same time of the eruption and the deposit of the PST and at about the same area of where the Silver Creek caldera located. The eruption of PST happened after the main thrusts and before the large-magnitude east-west extension begins 16.5 to 15.5 Ma. After the major extension, arrays of tilted fault blocks and associated half grabens develop and most of these blocks tilted >50° (Faulds et al. 2001). This late Miocene east-west extension was accompanied by major strike-slip faulting in the western Lake Mead area. This was evidenced by the 19 km of left-lateral offset of the 11 to 13 Ma Hamblin-Cleopatra volcano along the Lake Mead fault system (Anderson, 1973). Some of this faults are still active, which evidenced by Quaternary 160 fault scarps in the Lake Mead and Las Vegas region (Menges and Pearthree, 1989; DePolo, 1996). This strike-slip faulting is noteworthy because some people suggested that the western half of the Silver Creek caldera was moved about 40 km to the southwest of the current half close to Oatman (personal communication). Only a large-scale left lateral strike-slip fault can accommodate this offset. Local structural configuration near the Silver Creek caldera is mainly controlled by two main features: the Roadside Mine down-to-west normal fault to the north of this area and an anticlinal tilted domain to the south (Pearthree et al., 2009). To the north of the Silver Creek, the outcrop-scale measurable foliations within the intracaldera PST dip moderately to gently to the southwest which does not really reflect the regional tilting. The reliability of the measurements will be tested by the new AMS data. To the south of the Silver Creek, the measurable foliations within the intracaldera PST consistently dip gently to the southwest (Ferguson, field report) and again this will be tested with the new AMS data. 5.5 Alteration Many gold mines, some closed and some still active, have been found in the Oatman district for the past 150 years. Gold-bearing quartz-calcite-adularia veins are fairly well distributed in this area (Ransome, 1923; Lausen, 1931). The alteration influenced the volcanic rocks before the intracaldera PST intensely, but not quite for the PST. The Moss porphyry was also intensely altered especially around the area of the First Moss mine. Such veins were also found in the southern Times Porphyry. In thin sections of the intrusions, secondary chlorite can be found quite commonly. 161 6.0 Reactivation models of Silver Creek caldera One of the most important goals of this AMS study is to use the data to constrain the magma feeding and the flow pattern causing the reactivation of the caldera. As is well known, a “caldera” is a large volcanic depression that is more or less circular, has a diameter many times larger than a single eruptive vent, and forms by roof collapsing into an underlying magma chamber (Lipman et al., 2000). In many cases, after the roof collapsed to form caldera fill, magma with less energy will feed the system and get the caldera reactivated (Orsi et al., 1996; Cole et al., 2005). In theory, resurgent magma can feed the system in different geometries, resulting in different flow patterns. Below we propose three end-member magma feeding models and the fabrics we expect to see theoretically. To make it simple for now, we suppose that the intracaldera PST does show similar fabrics in all three models, since the deposit of these intracaldera fill blocks are mainly controlled by a mechanical collapsing. In all three models, we suppose that the PST show randomly distributed lineation and the lineation formed during the deposition of the pyroclastic flow during the eruption. Please notice that the magma chamber geometries could be extremely variable underneath the whole plutonic-volcanic subsidence system, but the discussion about that is beyond this paper since we are lacking evidence to constrain 3D pluton shapes. 6.1 Ring Dikes Model Ring dikes models have been found and discussed in many case studies (Richey, 1932; Billings, 1943; Billings, 1945; Richey, 1948; Walker, 1975; Walker, 1984; Lipman, 1984; 162 Johnson et al., 2002). The word “ring dyke” was first used by Bailey (1914) to describe magmatic ring structures. Ring dikes typically develop at a subvolcanic level when the magma rise up along steep outward-dipping ring fractures. Formation of ring dikes requires the development of caldera ring-fault and associated subsidence of a central block (Roche et al., 2000). The magma pathway and the expected fabrics are show in Fig.5.4 (a). As dikes, the aspect ratio of the intrusive bodies should be large. We might or might not see detectable fabrics reserved in the dikes. If we do see them, the foliations should be parallel to the dike wall with consistent steeply ourward dipping, while the lineations should be steeply plunging. 6.2 Resurgent Diapir Model Resurgent domes into caldera fill are a largely separate process that is not linked to whether ring dikes form or not. It is actually easy to have both in reality. Resurgent domes are quite common in many calderas around the world, which forms big blobs of magma piercing the intracaldera fill. The mechanics, characteristic fabrics of magma diapirs have been documented and discussed in detail (Marsh, 1982; Paterson and Vernon, 1995; Petford, 1996; Miller and Paterson, 1999; He et al., 2009). The most characteristic feature of this mechanism is the strong vertical movement of the entire batch of magma (Fig.5.4 (b)). If magmatic fabrics formed during diapric ascent, we are expecting to see in the intrusions the margin parallel foliation and steeply plunging lineation. 6.3 Resurgent laccolith Model Other than dikes and domes, resurgent laccolith could be another possibility in Silver Creek area. Laccolith forms when the ascent magma, at some shallow level, spreads out 163 horizontally and causes the rocks above it to be domed up. Usually the overlying rocks are easily to be eroded away and to expose the underneath magmatic rocks (Fig.5.4 (c)). Again if magmatic fabrics form during laccolith formation, we expect to see in the intrusion gently to horizontally dipping magmatic foliation and radial gently plunging lineations except in the feeder. At the center of the intrusion, where the feeder dike or plume usually is, it is possible to observe some steeply plunging lineation. 7.0 Magnetic susceptibility and AMS data 7.1 Magnetic susceptibility methodology The principles and application of the magnetic susceptibility method are discussed in detail by Tarling and Hrouda (1993). Here we briefly review this method. In most rocks, the strength of the magnetization induced by a weak external magnetic field of constant strength varies with different orientations due to alignment of the magnetic minerals or their host minerals along different orientations. The ratio of strength of the measured induced magnetization over that of the external magnetic field is called susceptibility (K). Most rocks are magnetically anisotropic, so we can study the anisotropy of magnetic susceptibility (AMS) of them. The variation of susceptibility with orientation can be visualized using a susceptibility ellipsoid, which is similar to the stress or strain ellipsoid used by structural geologists. The three principal axes of the ellipsoid are represented by K 1 ≥K 2 ≥K 3 . K 1 is the magnetic lineation and K 3 is the pole to the magnetic foliation. To visualize the three axes, each of them will be given a D/I (declination/inclination) in geographical coordination system. The mean (average) susceptibility of a single sample is the average of the three principal 164 susceptibilities and is given as: K aver = (K 1 +K 2 +K 3 )/3, where K 1 , K 2 and K 3 are in SI units (Nagata, 1961; Janak, 1965). Some other parameters are commonly used by geologists to describe the degree of anisotropy and shape of the specimens. It has been suggested that the “corrected anisotropy degree” (P J ) proposed by Jelinek (1981) should be universally adopted. P J is given as: J = {2[ŋ1-ŋm) +ŋ2−ŋ +ŋ3−ŋ } where ŋ1=lnK 1 , ŋ2=lnK 2 , ŋ3=lnK 3 and ŋm= (ŋ1+ŋ2+ŋ3)/3. PJ incorporates all three principal anisotropies plus the mean susceptibility and is thus a more informative parameter. As for the shape of the anisotropy ellipsoid, lineation (L) is given as: L=K 1 /K 2 (Balsley and Buddington, 1960), and foliation (F) is given as: F=K 2 /K 3 (Stacey et al., 1960). To combine lineation and foliation, we get another parameter called shape parameter, T. T is given as: = −1 (Jelinek, 1981; Hrouda, 1982). Oblate (pancake) shape ellipsoid corresponds to 0<T≤1, while -1≤T<0 represents prolate (cigar) shape ellipsoid. 7.2 Sampling strategy In this study, we collected 23 oriented samples for AMS measurements. These 23 samples were along two transects within the caldera (Fig.5.2) with 16 samples along the northern transect and 7 along the southern one. Both transects cross both the intralcaldera PST and the shallow intrusions. By adopting this sampling strategy, we want to make sure that we will get fabrics of the tuff regime, fabrics of samples close to the contact between the tuff and the intrusions, and fabrics from the center of the intrusions. Two 165 transects better avoid the sampling bias. Each orientated sample was cut into six standard cubes with of <21 mm side with relatively constant sample volume. Each cube keeps the orientation maker of the sample it belongs to, so all the cubes will be measured in a systematic way. 7.3 Magnetic mineralogy Ferromagnetic minerals usually dominate a rock’s magnetic properties provided that the temperature remains below their Curie point. Magnetite and haematite are the most common ferromagnetic minerals owing to their high magnetic susceptibility and high magnetic anisotropy respectively. K values greater than 3×10 -4 SI suggest that the ferromagnetic minerals may make significant contributions to the magnetic susceptibility (Rochette, 1987). Paramagnetic minerals also contribute to the magnetism of rocks although their magnetic susceptibilities are low with a typical value around 5×10 -4 SI. Magnetic mineralogy of a certain type of rock is usually pretty complicated as the magnetic properties of many minerals tend to vary over short distances and change with temperature and/or pressure. The mineralogy of the intracaldera PST is very similar as the outflow PST (Ferguson, 2008). The main phenocrysts are K-feldspar and plagioclase. Accessory minerals include biotite, opaque oxides, and quartz. Other trace minerals are hornblende, clinopyroxene, sphene, zircon, and apatite (Young and Brennan, 1974; see also Glazner et al., 1986; Murphy et al., 2004; Spencer et al., 2007). In these rocks, there are about the same amount of biotite and opaque oxides (about 2%). Biotite is an important paramagnetic mineral and it usually is a host of magnetite inclusions. The median value of K from the 166 inracaldera PST is 7.3×10 -3 SI, which is a lot greater than 3×10 -4 SI, so ferromagnetic minerals are the major contributors to the average susceptibility. The PST outflow has a good amount of phenocrystic magnetite that precipitated from the magma prior to the deposition of the pyroclastic flow and it also contains submicroscopic magnetite grains as well (Hillhouse and Wells, 1991). Based on the previous magnetic mineralogy study of the outflow (Hillhouse and Wells, 1991), we suggest that, multidomain magnetite is the major carrier of AMS for the intracaldera volcanic rocks. It is hard to discern any alignment of the opaque minerals even in our thin section study, but this lack of preferred orientation is reasonable because the degree of magnetic anisotropy (P J ) of the intralcaldera PST is only about 1-5%. In the intracaldera intrusions, the main mineral assemblage is similar to the tuff, but with different textures. Main phenocrysts are K-feldspar and plagioclase. Biotite occurs both as phenocrysts and minerals in the matrix. Opaque oxides are either about the same amount as biotite or a bit less than that (about 5%). Hornblende was observed only in the more mafic phase of the Moss Porphyry to the north of Silver Creek. The main AMS carrier of the plutonic rocks are both multidomain magnetite and biotite. No preferred orientations of any of these minerals were discerned under petrographic microscope which is in agreement with the weak deformation indicated by the average degree of magnetic anisotropy of 1-3.5%. 7.4 AMS measurements and data processing Measurements of the anisotropy of induced magnetization involve the application of a weak magnetic field and measurement of the resulting induced rock magnetization in the 167 presence of this field. The AMS analyses were done using a Kappabridge KLY-4 (field strength 300 A/m, frequency 920 Hz) in the Earth Sciences Department of University of Southern California. Orientations of samples were input into the machine before each analysis, so the output data will be under geographical coordination system instead of the sample coordination system. Calculation of the average AMS followed the tensor averaging method of Jelinek (1978). Only when there are six or more cubes for one sample site, will a useful statistical result be calculated. The statistical calculation and visualizing of the AMS data were done by using the supporting program Anisoft 4.2 of the KLY-4 susceptibility bridge. 7.5 AMS results Out of the 23 sample sites in this study, 21 have ≥ 6 cubes and thus have statistical meaning using the Jelinek (1978) statistics. The average susceptibility of sample SC113a (3 cubes) and SC 125 (4 cubes) can be calculated, but other parameters do not have statistical meaning, and were not listed in Table 5.1 and 5.2. AMS results of all the other samples were listed in Table 5.1. The average susceptibilities of the intracaldera tuff range from 2.9×10 -3 SI to 1.4×10 -2 SI with a median of 7.3×10 -3 SI (with a typical error of 0.5%). For the plutonic rocks, they range from 7.7×10 -4 SI to 1.7×10 -2 SI with a median of 9.9×10 -3 SI. The vector means of the downward directions (Declination/Inclination) of the three principal axes for each samples are all of 95% confidence and have been corrected using field measurement of sample orientations and presented in geographical coordination system. The graphical presentations of all the 168 results and the confidential ellipses of each vector mean are shown in Fig. 5.5. The stereonets were done by Anisoft 4.2 program using equal-area projection. In Fig. 5.5, more than half of the samples have small error ellipses which mean the data points of all the cubes in that certain sample are very close to each other. Average shape factors are reported in Table 5.2. The average magnetic lineations (L=K 1 /K 2 ) range from 1.005 to 1.030 with a median value of 1.015 for volcanic rocks, and range from 1.004 to 1.013 with a median of 1.007 for plutonic rocks. The average magnetic foliations (F=K 2 /K 3 ) range from 1.005 to 1.037 with a median value of 1.016 for volcanic rocks and from 1.003 to 1.024 with a median of 1.004 for plutonic rocks. In order to see the difference between the volcanic and the plutonic samples, red dots represent intrusive rocks while blue dots represent volcanic rocks in all three shape factor plots (Fig.5.6). In Fig.5.6 (a), Ellipsoid shape factor T was plotted over the degree of anisotropy P J . With the same ellipsoid shape factor (T), the degree of anisotropy (P J ) of volcanic rocks is statistically slightly higher than that of the intrusive rocks by a fraction of about 1.5%, but both of them are very weakly deformed. With the same value of P J , oblate fabric develops better in intrusive rocks while prolate fabric develops better in volcanic rocks. As for intrusive rocks, the higher the degree of magnetic anisotropy the more oblate shape fabric developed. Volcanic rocks do not show obvious trend like the intrusive rocks. The degree of anisotropy for both rock types ranges from 1.007 to 1.059, which is a very narrow range, and we should keep this in mind while we interpret the data. For better visualize the shape factors, T and P J were plotted over distance of samples from the contact between the intracaldera PST and shallow intrusions, which will give us 169 an impression about how the fabrics change across the contact (Fig.5.6 (b) and (c)). In both diagrams, y axis literally represents the contact between the two rock types and the x axis represents how far the sample was collected away from the contact. Same as the map view of the caldera, to the right of the contact is intrusive rocks while to the left is volcanic rocks. The distance (D) does not represent the absolute value between the sample and the contact. It is just a scale with the farthest samples setting as close to 1 and the sample next to the contact as close to 0. All the other D values are just proportional to the farthest one based on the positions of samples on the geological map (Fig.5.2). In Fig.5.6 (b), as for the volcanic rocks, the closer it is to the contact, the more oblate fabrics developed and the linear trend is quite clear. In the plutonic regime, no obvious pattern formed. Oblate and prolate fabrics both formed at different distances from the contact. In Fig.5.6 (c), the range of P J of volcanic rocks is a bit larger than the range of that of plutonic rocks, but no obvious relationship between the distance away from the contact and the degree of anisotropy for the volcanic rocks. As for the plutonic rocks, there is an slight increase of the degree of anisotropy when it is getting close to the contacts between plutonic and volcanic rocks and between different phases of one pluton. Magnetic fabrics were also plotted on the geological map along the two transects (Fig.5.7). Within the volcanic regime, foliations are pretty steep except for one sample and they are statistically N-S and NE-SW striking except for two sites which are NW-SE striking (Fig.5.7 (c)). Lineations are randomly trending and plunging gently to pretty steeply (Fig.5.7). In the plutonic bodies, magnetic folications are pretty steep and striking 170 either roughly N-S or E-W (Fig.5.7). Magnetic lineations are plunging randomly with moderate plunges (Fig.5.7 (c)). 8.0 Discussion 8.1 Complications about the interpretation of the magnetic fabrics Mineral fabrics in both the intrusive and extrusive rocks have been used as indicators to infer the magma flow during the emplacement of intrusions and “deposition” of ignimbrite sheets (Balk, 1937; Ellwood, 1982; Abbott, 1989; Hillhouse and Wells, 1991; Philpotts and Asher, 1994; Tobisch and Cruden, 1995 etc). Although all these work made contributions to the understanding of the magma chamber processes, certain parts as the interpretations of their fabrics data skip the complicated relationship between the mineral fabrics, strain, and magma flow. With the application of the AMS technique, it is especially necessary for us to be clear about the relationship between magnetic fabrics, mineral fabrics, strain and flow before we interpret any data. Magnetic fabrics which are the results of AMS study are integrated magnetic fabrics of all magnetic minerals in an individual sample. These magnetic minerals are usually either inclusion in major rock forming minerals like hornblende, biotite, pyroxenes etc, or phenocrysts by themselves. In this case, magnetite grains are mostly occur as phenocrysts, but also occasionally occur as inclusions in biotite phenocrysts in the plutonic rocks. Properties of low-field anisotropy are affected by grain size because the magnetic susceptibility of magnetite is completely dominated by grain shape (Tarling and Hrouda, 1993). When they are as inclusions, there are more complications involved in the interpretation of the data. The first complication is that when the magnetic minerals occur 171 as inclusions, their size tends to be a lot smaller so the chances for them to be single- domain (SD) grains are a lot higher and SD grains have an inverse magnetic fabrics in contrast to the multi-domain (MD) grains (Tarling and Hrouda, 1993). MD grains have normal fabric, which means the K1 axis is parallel to the long axis of the magnetite grains. The mixing of SD and MD grains is going to give us a bulk intermediate magnetic fabrics composed of both normal and inverse fabrics, which makes neither the shape factor (L, F, T) nor the degree of anisotropy related to strain in a simple way (Ferre, 2002). This complication will definitely make the interpretation of the magnetic fabrics dramatically different in different cases. For equidimensional magnetite grains, single-domain grains are only some 0.06 to 0.08 μm in diameter (Stacey and Banerjee, 1974; Butler and Banerjee, 1975), but can be between 0.03 and 0.3 μm for grains with axial ratios (length/width) of 2:1 and more than 1 μm with ratios of 8:1. The magnetite grains in both the outflow and intracaldera PST mostly occur as phenocrysts and they are mainly of equidimensional shape (Fig.5.3 (d)). From the research did by Hillhouse and Wells (1991), evidenced by the similarity of the AMS fabric with the low-field ARM (anhysteretic remnant magnetization) fabric, they inferred that large, multi-domain grains of magnetite are the carriers of AMS. Intracaldera PST has the same mineral assemblage as the outflow, so MD magnetite is still the main AMS carrier. The intrusive rocks, although there are some inclusion magnetite grains in the biotite phenocrysts, the size of them are way bigger than 1μm, so they are still MD grains. Thus, intrusive rocks also have MD magnetite as the major AMS carrier. 172 Next complication comes from the relationship between the magnetic ellipsoids and the alignment of their host of the rock forming minerals that defines the magmatic fabrics in magmatic bodies. Many researchers are doing detail research on this. Mineral fabrics referring to a certain pattern of the alignment of minerals in the rocks include mineral foliations and lineations. However, the magnetic fabrics and the rock fabrics may not coincide. So, before interpret the AMS data we need to make sure how related they are. In our study, the main AMS contributors are the phenocrystic magnetite in both rock regimes, plus the difficulty of find preferred orientation of the main paramagnetic minerals of biotite and hornblende, to use the magnetic fabric of the phenocrystic magnetite is the best way to represent the rock fabrics so far. Then, we need to think about the relationship between the rock fabrics and the magma flow. Fabrics are representations of the strain (change of shape) experienced by the aligned minerals. Strain is the shape change between the final and the original stages, so it cannot tell us anything about the displacement paths. Flow refers to the particle displacement paths, and based on different flow types displacement paths can have different relationships with the strain ellipsoid of the minerals (Mackin, 1947; Schmeling et al., 1988; Paterson et al., 1998). This brings more complications to the interpretation of magmatic fabrics. Only after the magmatic fabrics being correctly interpreted, can a reliable relationship between the fabrics and the driving mechanisms be formed. But, this might give us a chance to reinterpret some the data from the previous AMS study of the outflow PST. There are some samples sites that give exactly opposite flow directions as the sites immediately next to them. The authors also mentioned that this might be caused 173 by the local interaction between the magma and the channels. Local topography could have played an important role in the determination of the relationship between the fabric and the flow paths. For example, if the flow was released from a paleovalley to a relatively flat and open area, the lineation might be perpendicular to the flow direction, because this channel change would cause local deceleration flow and this type of flow will cause the XY plane of the strain ellipsoid to be perpendicular to the flow path (Paterson et al., 1998). But, to get a detail study of the paleo local topography of each site is extremely hard to do. So, how practical of this type of research is still not very clear and it might be eased in the future if the techniques allow high resolution reconstruction of local topography before the eruption to be done. 8.2 Different AMS and magnetic fabrics between the intracaldera PST and the shallow intrusions AMS results show some difference between the intracaldera PST and the shallow instrusion. Firstly, the degree of anisotropy of the volcanic rock is statistically slightly higher than the intrusive rock (Fig. 5.6(a)). As we know, the collapse of the magma chamber roof due to the lack of support can cause the intracaldera tuff to break and pile over each other, so during this process, the volcanic rock more or less experienced some stress from the neighboring blocks. Then during the emplacement of the intrusions, the volcanic rock again experienced some stress from the intrusions. The fabrics of the intrusion only formed after the emplacement. If there is later regional stress, it would apply to both regimes. So, the volcanic rock experienced one more event that can cause 174 deformation than the intrusive rock. Thus, it makes sense that the degree of magnetic anisotropy of the volcanic rock is higher. Secondly, we noticed that the volcanic rock shows a quite clear trend of the change from prolate fabric to oblate fabric when it is getting close to the contact between the two regimes (Fig. 5.6 (b)). If the anisotropy ellipsoid is in prolate shape, which means the magnetic lineation is more developed than magnetic foliation and vice versa. The volcanic rocks developed more foliations when it is next to the contact, especially within 500 m away from the contact. This is very similar to the behavior of a lot country rocks immediately next to the contact between them and the plutons if their fabrics are coupled with the pluton well. The intracaldera plutonic rock behaves a bit differently. At the center of the more mafic phase of Moss Porphyry, prolate fabric formed while the next three samples within the slightly felsic phase have had oblate fabrics formed (Fig.5.7 (a) and Fig.5.6 (b)). These oblate fabrics might form because it is close to the contact between the two intrusive phases. The other plutonic samples seem to have formed both prolate and oblate fabrics. Thirdly, the degree of anisotropy of the volcanic rock does not show a pattern changing with the distance away from the contact, while the plutonic rock shows some subtle patterns (Fig.5.6 (c)). Close to the contact between the two rock types and the contact between the two intrusive the degree of anisotropy slightly increased. When the pluton emplaced at its final position within the crust, it is still a crystal mush so partially behaved like liquid or flow. So, the markers reacted more to the progressive noncoaxial flow due to the occurrence of a boundary within the flow like a contact, and it would 175 rotate towards the parallelism to the contact with increasing strain (Paterson et al., 1998). Thus, the plutonic rock is able to show the slightly change of strain when it is close to the contacts. The volcanic rock was already solidified or close to solidus when the intrusions emplaced, so even the rock close to the contact will be strained by the emplacement but degree of strain difference is not easy to show. 8.3 Magnetic fabrics and inferred resurgent models Foliations within both rock types are moderate to steep (Fig.5.7 (c)). The strike of the foliations can be divided roughly into two groups. One group of foliations strike N-S and NE-SW and another group of them strike roughly E-W. Along the northern transect, foliations within the plutonic rock do not have a constant pattern (Fig.5.7 (a)). The three foliations close to the contact between the two rock types are almost perpendicular to the contact, while some foliations that are close to the center of the pluton parallel to the contact. Along the southern transect, only three foliations were measured (Fig.5.7 (b)). One foliation is at a high angle with the contact between the two rock types, and another two are subparallel to the contact. Generally, the foliations within the plutonic rocks are very randomly distributed and do not match any of the three end member resurgent models we proposed earlier. Sampling more sites within the pluton might help to statistically better constrain the fabric pattern in the plutons if it does exist. Based on current data we have, no pattern can be seen in terms of the striking of foliations. Foliations in plutonic rocks are steeply dipping with average dipping angle of 65°. More than half of these foliations are more than 70°. The lineations within the intrusions are randomly trending and moderately plunging. 176 The lineations within the volcanic rocks especially the ones that are farther away from the contact with more prolate fabrics developed (L>F) are trending pretty randomly and plunging from very gently to steeply (Fig.5.7). Lineations within the ignimbrite should be of a radiating pattern from the conduit of the eruption, but no such convinced pattern can be found within the intracaldera PST based on our current dataset. Apparently, the tuff has been randomly deformed during the collapse of the magma chamber roof and the randomly trending and plunging lineations are caused by the random piling of ignimbrite blocks after the collapse. Intracaldera PST has relatively constant striking and steeply dipping foliations. Going back to the resurgent models (Fig.5.4), the fabrics we have found so far within the plutonic rocks do not match any of them. 8.4 Influence from regional stress field As mentioned in the description of the caldera earlier in this paper, the regional stress field in this area after the formation of the caldera and the reactivation of it changed to mainly N-S extension. No obvious features in the caldera that have been found so far that are related to this regional stress field. The earlier mentioned field measurements of the intracaldera PST foliations are not quite consistent with our new data of the magnetic foliations. Since the measurements were not done by us, so it is hard to find the detail about them. 8.5 Comparison of intraldera and outflow AMS The average susceptibilities and the degree of anisotropy are all very low, which make all the variations happen within a very narrow range. This will raise the question of how 177 reliable this data set is. Let us compare this new data with the last published data set received by Hillhouse and Wells. The main AMS parameters of the intracaldera and outflow PST were listed in Table 5.3. Both the magnetic lineation and the foliation are very similar, but the median susceptibilities are quite different. The intracaldera PST has a lot higher average susceptibility than the outflow. According to the definition of the magnetic susceptibility, it is just parameter shows how much the magnetic minerals in a unit volume of material influence the applied magnetic field. So, the higher the concentration of the AMS carrier the higher the susceptibility will be. As what we discussed earlier, the main AMS carriers for PST are the phenocrystic magnetite and the paramagnetic mineral of biotite. The concentration of the magnetite phenocrysts in the intracaldera PST is higher than that in the outflow (5% versus 2%), which must be the main reason to cause the bulk susceptibility to be different. As we know, magnetite is a pretty heavy mineral and it crystallizes early in the whole cooling process. Heavy minerals then tend to concentrate more easily in the proximal part of the ignimbrite sheet or even more in the source caldera. The intracaldera tuff is more packed than the outflow because of its greater thickness, which is another mechanism to concentrate more heavy minerals in the intralcaldera rocks. Although the heavy minerals tend to stay close to the source area and to the bottom of the tuff layer, since pyroclastic flows can sometimes travel as fast as 450 mph, they will still be transported quite far by both stratified and turbulent flows during the eruption. This is probably why the concentrations of heavy minerals in the outflow and in the intracaldera facies are that dramatically different. Even with the difference of 178 the average susceptibilities, the new data still fall in the same magnitude of 10 -3 SI as the previous data set of the outflow, which tells us that the new data set is reliable. Fabrics of the intracaldera PST were plotted in Fig.5.7. Along the two transects (Fig.5.7 (a) and (b)), the lineations plunging at all different directions. Even though we skip the complication caused by the biorientaional character of lineation and the complication of the local flows, and use the lineation as the flow pointer, we still can’t work out a constant plow pattern which is continuous from the caldera to the end of the ignimbrite sheet (Fig.5.8). This actually makes sense to us because the collapsing of the magma chamber roof during the formation of the caldera would inevitably disorder the intracaldera tuff blocks so it is definitely going to be hard to form a continuous pattern connecting with the outflow. 9.0 Conclusions AMS study results show that the intracaldera PST and the shallow intrusions have pretty low bulk magnetic susceptibility. The average susceptibility of the intracaldera tuff has a median value of 7.3×10 -3 SI while the plutonic rock has a median of 9.9×10 -3 SI. These values both fall in the same range as the average susceptibility of the outflow PST. The main AMS carriers of the intracaldera rocks are the magnetite phenocrysts and the paramagnetic biotite phenocrysts in the plutonic rocks. The degree of anisotropy is very low for both rock regimes and change within a very narrow range, but the volcanic rock has statistically slightly higher degree of anisotropy than the plutonic rocks. Both prolate and oblate anisotropy ellipsoids developed. 179 Randomly striking foliations within the plutonic rocks do not match any of the three end member resurgent models. The fabrics within the intracaldera tuff do not form a continuous pattern with the outflow PST. No evidence was found to show the influence of regional stress field on this caldera. 180 Fig.5.1 Location (left) and geological setting (right) maps of the Silver Creek Caldera 181 Fig.5.2 Silver Creek caldera geological map. 182 Fig.5.3 Field and thin section photos from Silver Creek caldera (a) Contact between the intracaldera PST and the quartz-mozonitic Moss Porphyry to the north of Silver Creek (looking NW); (b) Thin section (2.5×) of sample SC137 from the granitic Time Porphyry to the south of the Silver Creek. Biotite was altered to chlorite (top part of the big biotite grain in the center of the view); (c) Thin section (2.5×) of a sample from the granitic Times Porphyry to the south of Silver Creek showing good granophyric texture; (d) Thin section (2.5×) of sample SC119 from the center more mafic phase of the Moss Porphyry to the north of the Silver Creek. Both hornblende and biotite phenocrysts could be seen and some opaque phenocrysts (magnetite). 183 Fig.5.4 End-member caldera reactivation models and the fabrics that we expect to see in both the volcanic and plutonic regimes 184 Fig.5.5 Stereonet plots of the AMS data for each sample with confidence ellipses 185 Fig.5.6 Shape factor diagrams T-Shape factor P J -Degree of anisotropy D-Distance of the samples from the contact between the volcanic and the plutonic rocks 186 Fig.5.7 Magnetic fabrics plotted along the two transects and the stereonet plots of both lineations and foliations within both rock types 187 Fig. 5.8 Comparison of the outflow and intracaldera fabrics 188 K aver (10 -3 SI) St. Dev K1 K2 K3 K1 (D/I) Conf. Angles K2 (D/I) Conf. Angles K3 (D/I) Conf. Angles SC113b 3 5 . 1 1 0 8 5 5 5 8 - 1 1 4 . 4 5 4 5 2 5 Q-monzonite 134/70 4.10 8.73E-04 1.006 0.998 0.996 180.9/31.0 29.3/5.0 71.0/29.5 63.5/12.3 307.2/44.6 62.7/5.1 SC113c 3 5 . 1 1 0 8 5 5 5 8 - 1 1 4 . 4 5 4 5 2 5 intracaldera tuff 190/64 4.06 1.08E-03 1.006 1.001 0.993 224.4/49.9 18.4/6.5 0.4/31.2 18.6/10.0 104.9/22.5 12.0/5.9 SC114 3 5 . 1 0 9 5 3 2 4 9 - 1 1 4 . 4 5 2 4 8 2 Q-monzonite 140/71 9.26 1.26E-03 1.004 0.999 0.996 254.3/4.7 21.8/6.9 150.2/71.1 38.5/17.0 345.8/18.2 37.7/6.5 SC115 3 5 . 1 0 8 1 3 5 9 2 - 1 1 4 . 4 5 0 8 0 4 Q-monzonite 165/82 9.99 2.36E-03 1.004 1.000 0.996 263.4/12.5 21.4/11.3 19.6/63.4 26/17.6 168/23.1 27.3/13 SC117 3 5 . 1 0 6 9 3 9 9 8 - 1 1 4 . 4 4 7 5 2 8 Q-monzonite 42/21 17.40 1.11E-03 1.004 1.000 0.996 43/35.5 22.8/17.5 151.1/23.5 29.2/12.1 267.2/45.2 28.5/20.6 SC118 3 5 . 1 0 5 3 1 7 9 4 - 1 1 4 . 4 3 9 0 3 4 Q-monzonite 122/76 16.60 1.30E-03 1.011 1.002 0.987 159.7/9.4 10/4.8 34.8/73.8 9.6/6.5 251.9/13 8.2/2.9 SC119 3 5 . 1 0 4 2 2 2 8 7 - 1 1 4 . 4 3 5 8 5 4 Q-monzonite 267/60 17.90 8.64E-03 1.007 0.999 0.994 38.6/12.1 12.9/11.7 138.2/37.9 35/11 294/49.5 35.5/7.5 SC121 3 5 . 1 0 6 4 2 8 8 5 - 1 1 4 . 4 4 2 1 1 4 Q-monzonite 58/85 14.30 2.13E-03 1.012 1.006 0.982 119.8/30.6 33.5/3 26.4/5.7 33.5/5.2 286.9/58.7 5.8/1.7 SC122 3 5 . 1 0 6 9 6 8 2 3 - 1 1 4 . 4 4 5 0 2 6 Q-monzonite 306/80 13.60 8.20E-04 1.016 1.003 0.982 251.3/25.2 9.1/5.9 127.6/49.7 9.6/5 256.5/29.2 8.7/3.1 SC123 3 5 . 1 0 3 2 6 6 2 5 - 1 1 4 . 4 6 0 1 2 5 intracaldera tuff 2/49 6.36 2.43E-03 1.016 0.998 0.987 39.8/30.3 7.3/5.3 272.3/46.2 8.6/4.8 148.2/28.3 7.6/5.4 SC124 3 5 . 1 0 3 8 9 9 8 7 - 1 1 4 . 4 5 9 3 9 3 intracaldera tuff 14/44 3.91 3.20E-04 1.012 0.997 0.992 18.2/18.1 3.8/2.0 268.8/45.4 5/3.4 123.6/39 4.8/2 SC126 3 5 . 1 0 8 2 9 4 4 1 - 1 1 4 . 4 5 7 0 4 intracaldera tuff 120/22 10.70 1.19E-03 1.017 1.010 0.974 245.3/32.3 15.8/4 43.1/55.6 16.6/4 148.6/10.4 6.8/3.9 SC127 3 5 . 1 0 2 4 2 6 0 8 - 1 1 4 . 4 5 4 4 7 intracaldera tuff 68/90 13.20 4.34E-03 1.020 1.006 0.974 251/56.7 15.4/3.8 94.8/31 15.4/3.1 358.2/11 3.9/3.2 SC129 3 5 . 1 0 1 0 2 3 7 7 - 1 1 4 . 4 5 5 9 3 9 intracaldera tuff 289/40 2.93 5.71E-04 1.011 0.998 0.991 266.8/3.6 40.3/5.5 176.8/1.3 41.2/11.2 67/86.2 33.2/9.9 SC131 3 5 . 0 4 4 8 9 8 0 9 - 1 1 4 . 4 6 3 9 6 2 granite 284/28 0.77 8.88E-05 1.008 1.001 0.991 292/52.7 10.8/5 84.4/36 8.5/4 184.6/13.7 8.5/3.9 SC132 3 5 . 0 4 4 5 4 2 6 6 - 1 1 4 . 4 6 3 3 4 8 granite 284/53 0.86 1.56E-04 1.004 0.999 0.997 260.8/20.2 24.5/7 101.3/68.5 55.8/6.3 353.4/6.9 55.0/7.5 SC133 3 5 . 0 4 5 2 3 6 4 - 1 1 4 . 4 6 4 6 2 granite 313/53 5.68 7.22E-04 1.006 1.002 0.993 225.6/28.9 36.9/7.2 347/56.7 37.4/16.7 125.8/26.3 18.7/7.3 SC135 3 5 . 0 4 5 3 8 9 2 8 - 1 1 4 . 4 6 6 7 5 3 intracaldera tuff 78/64 14.20 2.84E-03 1.017 1.008 0.976 147.1/34.7 17.7/5.2 23.1/38.9 17.5/9.3 262.8/32 10.2/4.2 SC136 3 5 . 0 4 6 0 5 2 1 2 - 1 1 4 . 4 6 7 4 1 2 intracaldera tuff 324/46 11.00 8.62E-04 1.029 0.999 0.972 221.0/27.9 9.4/6.3 82.7/54.6 12.1/3.1 322.0/19.9 8.7/6.6 SC137 3 5 . 0 4 6 3 8 0 6 3 - 1 1 4 . 4 7 4 0 6 6 intracaldera tuff 255/86 6.52 5.40E-04 1.019 0.999 0.981 70.7/65.8 13.1/3.7 327.7/5.8 16.3/7.5 235.2/23.4 15.9/3.2 SC138 3 5 . 0 4 6 8 8 8 9 1 - 1 1 4 . 4 7 4 6 6 5 intracaldera tuff 92/75 8.12 2.56E-03 1.023 0.996 0.981 133.9/69.2 5.0/3.1 19.0/9.1 6.7/2.6 285.9/18.5 6.3/6.4 Table 5.1 AMS results of 21 out of 23 samples with statistical averages Sample mean Sample average Sample No Latitude Longitude Rock unit Sample orientation 189 Table 5.2 Shape factors and magnetic fabrics Table 5.3 Comparison of the major AMS results and fabrics between the intracaldera and outflow PST Outflow data are from Hillhouse and Wells, 1991. L St. Dev F St. Dev Pj St. Dev T St. Dev Lineation Foliation SC113b Q-monzonite 1.008 0.006 1.003 0.005 1.010 0.010 -0.491 0.195 180.9/31.0 37.2/45.4 SC113c intracaldera tuff 1.005 0.004 1.008 0.003 1.014 0.004 0.223 0.325 224.4/49.9 194.9/67.5 SC114 Q-monzonite 1.005 0.002 1.003 0.002 1.008 0.003 -0.212 0.412 254.3/4.7 75.8/71.8 SC115 Q-monzonite 1.004 0.003 1.004 0.003 1.008 0.005 0.070 0.442 263.4/12.5 258/66.9 SC117 Q-monzonite 1.004 0.003 1.004 0.002 1.009 0.003 -0.030 0.228 43/35.5 357.2/44.8 SC118 Q-monzonite 1.009 0.008 1.015 0.005 1.024 0.009 0.266 0.421 159.7/9.4 341.9/77 SC119 Q-monzonite 1.009 0.004 1.004 0.003 1.013 0.006 -0.322 0.211 38.6/12.1 24/40.5 SC121 Q-monzonite 1.007 0.015 1.024 0.008 1.031 0.013 0.573 0.470 119.8/30.6 16.9/31.3 SC122 Q-monzonite 1.013 0.002 1.022 0.006 1.035 0.005 0.246 0.186 251.3/25.2 346.5/60.8 SC123 intracaldera tuff 1.018 0.002 1.011 0.003 1.029 0.003 -0.232 0.165 39.8/30.3 238.2/61.7 SC124 intracaldera tuff 1.015 0.003 1.005 0.003 1.020 0.003 -0.455 0.275 18.2/18.1 213.6/51 SC126 intracaldera tuff 1.007 0.006 1.037 0.007 1.045 0.005 0.670 0.236 245.3/32.3 238.6/79.6 SC127 intracaldera tuff 1.014 0.013 1.032 0.005 1.047 0.014 0.391 0.303 251/56.7 88.2/79 SC129 intracaldera tuff 1.013 0.003 1.007 0.004 1.020 0.002 -0.310 0.197 266.8/3.6 157/3.8 SC131 granite 1.007 0.004 1.011 0.003 1.018 0.004 0.175 0.305 292/52.7 274.6/76.3 SC132 granite 1.005 0.005 1.002 0.002 1.007 0.005 -0.544 0.544 260.8/20.2 83.4/83.1 SC133 granite 1.004 0.003 1.009 0.004 1.013 0.002 0.385 0.376 225.6/28.9 215.8/63.7 SC135 intracaldera tuff 1.009 0.005 1.033 0.006 1.042 0.008 0.556 0.211 147.1/34.7 352.8/58 SC136 intracaldera tuff 1.030 0.011 1.029 0.006 1.059 0.008 -0.017 0.260 221.0/27.9 52/70.1 SC137 intracaldera tuff 1.020 0.005 1.018 0.007 1.039 0.005 -0.048 0.270 70.7/65.8 325.2/66.6 SC138 intracaldera tuff 1.028 0.003 1.014 0.003 1.042 0.003 -0.311 0.114 133.9/69.2 15.9/71.5 Sample No Rock unit Rock regime K median (10 -3 SI) Lineation (L) Foliation (F) Intracaldera PST 7.30 1.015 1.016 Outflow PST 2.00 1.010 1.020 190 CHAPTER 6: SUMMARY Upper crustal magmatic systems can be quite different based on different tectonic environments and different emplacement depths. The three field areas in this dissertation represent different magmatic systems. Fangshan pluton emplaced at a depth of about 10- 15 km and it is located at the center of the North China Craton, far away from the subduction zone along the east coast of China. Central Sierra plutons mostly emplaced at the depths of about 10-15 km as well. They all distribute along this NW-SE striking Mesozoic arc and are related to the subduction at that time. There are volcanic rocks of the same ages as the plutonic rocks and they are spatially close to each other as well. Silver Creek caldera is a much shallower magmatic system with intracaldera tuff and subvolcanic plutons. High-precision geochronological, geochemical and structural studies of the above three magmatic systems allowed us to see the similarity and difference between them to get a more comprehensive picture of magmatism in and above upper crustal level. The high-precision geochronology study of Fangshan pluton not only better constrained the ages of different units in the pluton but also exposed more hidden evolution history of this intensely studied pluton. Based on our new CA-TIMS data, Fangshan pluton grew incrementally by at least two main pulses with ages of 131.06±0.43 Ma and 131.02±0.26 Ma respectively. We also found antecryststic zircons as old as 145 Ma, which extend the evolution history of the magmatic system below Fangshan to about 15 m.y. 191 The Fangshan chapter for the first time precisely records the crystallization ages of the two mappable units of this pluton. These two new ages also bring up the problems of previous geochronology studies done on this pluton, especially the K-Ar and 40 Ar- 39 Ar ages. Careful calibration, instrumental or standards’ inspections are necessary for all the Ar-Ar dating labs that are involved in previous works on this pluton. The systematically older cooling ages than crystallizing ages is an alert to let people reevaluate whether it is appropriate to use hornblende and biotite from this pluton as the Chinese geostandards. The discovery of the antecrystic zircons again proved that large scale middle-upper crustal level magmatic systems do grow incrementally by multiple pulses. High-precision CA-TIMS method is a very powerful tool to reveal non exposed growth history of large scale magmatic systems even when many of the older magma pulses are not exposed. The recycling of zircon crystals in the Fangshan pluton is comparable to some other batholith scale systems (Miller et al., 2009; Matzel et al., 2006; Memeti et al., 2010). All of the above make this chapter of the dissertation an important contribution to not only the study of the pluton itself but also the evolution of similar scale plutonic systems. Combined field geology, geochronology, and geochemistry data sets from central Sierra magmatic rocks better constrained the temporal and spatial evolution of this Mesozoic arc. Regional geochemical study in Chapter 3 shows the spatial and temporal overlap between both the plutonic and volcanic records and it suggests a close geochemical link between them in this arc. This is supported by the similarity in both whole rock geochemical and isotopic data from both plutonic and volcanic units. Our field and geochemical studies provide strong evidence that source region compositions 192 and both fractionation and mixing of magmas, plus limited host rock contamination all played an important role in developing the final compositional diversity of both plutonic and volcanic units in this arc, but the source region did not change much for the whole Mesozoic time. Regional geochemistry studies have been done by different people even in different locations in the central Sierra arc. In chapter 3, for the first time we combined all these available data sets and divided them into different age groups to see temporal evolution of a continental arc. This work contributes to the comprehensive study of this Mesozoic arc. Moving from deeper level to shallower level magmatism, Silver Creek caldera is an ideal place to study a connected plutonic-volcanic system. From chapter 4, our newly developed high-precision U/Pb zircons ages have better constrained the ages of the intralcaldera Peach Spring Tuff (PST) and the shallow intrusions, and further strengthened the connection between the outflow PST and its source-Silver Creek caldera. The chemical-abrasion TIMS method we applied gave the intracaldera tuff an age of 18.69±0.19 Ma and the three ages of the shallow intrusions are 18.74±0.17 Ma, 18.46±0.12 Ma and 18.90±0.13 Ma. In our zircon population, there is no xenocrysts or antecrysts, but SHRIMP dating done by Susanne McDowell does show the existence of xenocrysts in one shallow intrusion. The whole magmatic system of Silver Creek caldera has a very short lifespan of about 1.5 m.y. The current method and its precision still can’t allow us to tell the difference in terms of ages between the shallow intrusion and the intracaldera tuff. 193 Silver Creek caldera attracted many geologists because it is the source of the famous Peach Spring Tuff. Our CA-TIMS geochronology study is the first high-precision U/Pb dating done on both rock regimes in this caldera. These ages definitely further proved the connection between the caldera and the outflow ignimbrite sheet. Compared to deeper level magmatic systems, zircon population in this system is relatively simple. After compare this study to some other similar studies on caldera systems, I found that all of them have a relatively simple zircon population. This is an important point because this could possibly be a fundamental difference between deeper and shallower level magmatic systems. To prove this, we definitely need more geochronology data sets from representative systems. AMS study of Silver Creek rocks in Chapter 5 quantitatively determined the rock fabrics from both rock regimes. The main AMS carriers are the phenocrystic magnetite within both rock types. The average susceptibilities of the intracaldera PST range from 2.9×10 -3 SI to 1.4×10 -2 SI with a median of 7.3×10 -3 SI, which agree well with the susceptibilities of the outflow PST. Degree of anisotropy (P J ) of the volcanic rocks is statistically slightly higher than that of the intrusive rocks, because they experienced both the collapse of the magma chamber roof and the emplacement of the plutons while plutons only formed their fabrics during the emplacement. But, the degrees of anisotropy of all samples are very low and within a very narrow range of 1.007 to 1.059. There is no clear fabrics’ pattern can be defined by the current data. Compared to the outflow PST magnetic fabrics, we found that the lineations within the intralcaldera PST do not form a continuous pattern connecting well with the outflow. But, the randomly orientated 194 intracaldera fill does indicate that the magma chamber roof collapsed to cause rock blocks randomly fall down. In addition to the efforts from previous geologists on AMS fabrics within ignimbrite sheet or plutonic rocks, we contribute a data set including both rock types within one system. The AMS fabrics within the intracaldera tuff further proved the caldera nature of this plutonic-volcanic complex in Silver Creek area. The fabrics within the plutonic rocks, although did not form any noticeable patterns, provide a good start for any future fabrics study of the subvolcanic plutons in this area, and they also allowed us to compare the difference of deformation between volcanic and plutonic rocks. We also pointed out the complication we have to consider when we try to use rock fabrics to infer any flows of magmatic systems. Going back to the questions we have about plutonic and volcanic rocks in the introduction chapter, after we combine these multiple data sets from different magmatic systems now we have a better view. But, we need to be cautious about comparing the three magmatic systems in this dissertation not only because they are of different depths and tectonic environments but also because they are at dramatically different scales. Here are some interesting discoveries I found after I put the data sets together: (1) Middle- upper crustal plutonic systems (at depths of about 15-10 km) usually have a long lifetime of >5 m.y while shallower systems have a relatively shorter lifespan, which could be as short as about 1.5 m.y or even shorter; (2) Crystal recycling within deeper magmatic systems are more often than that in shallower systems, possibly because the high zircon saturation temperature absorbed most of the inheritance and there are less magma pulses 195 within shallow intrusions to be the possible sources for older zircons; (3) Volcanic and plutonic rocks from the same magmatic system usually have a very close geochemical link to each other temporally and spatially; (4) In some cases the plutonic and the corresponding volcanic rocks are structurally well coupled where it is immediately next to the contact of these two rock types, but it is not always the case; (5) Strain within both rock types sometimes can be too low to infer any reliable flow patterns. After all, I found that magmatism is a super complicated topic and it is not reasonable to simply separate the two main magmatic rock types or simply equalize them. Parallel study of multiple representative magmatic systems and correlative study of both rocks types are definitely helpful with understanding of magmatism as a whole. 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H., and He, M.Y., 1992, Study on the mapping units of the Fangshan intrusion of Beijing, Regional Geology of China, No.2, 156-159 Zindler, A., and Hart, S., 1986, Chemical geodynamics: Annual Review of Earth and Planetary Sciences, v. 14, p. 493-571. 221 APPENDIX A: MAJOR ELEMENT DATA Symbols: JLP=Jackass Lake pluton area; TB=Tuolumne Batholith; NAVDAT=Northwestern American Volcanic Rock Data Base; Lowe=Lowe’s Thesis; Tp=Triassic plutonic rocks; Tv=Triassic volcanic rocks; Jp=Jurassic plutonic rocks; Jv=Jurassic volcanic rocks; Cp=Cretaceous plutonic rocks; Cv=Cretaceous volcanic rocks. (Appedix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 BCE-9A iron mt Cp 65.08 0.72 15.82 5.09 0.10 2.13 4.68 3.19 3.03 0.15 MR-1 iron mt Cv 51.13 0.48 14.27 10.12 0.19 9.41 11.43 1.80 0.96 0.23 HE-4 iron mt Cv 53.70 1.26 19.91 7.44 0.16 3.84 7.32 3.42 2.70 0.26 MR-7 iron mt Cv 54.56 0.66 17.79 7.48 0.15 4.03 10.39 3.18 1.31 0.46 MR-2 iron mt Cv 56.67 0.39 13.26 7.62 0.16 7.59 11.22 1.84 0.99 0.25 MN-9 iron mt Cv 58.02 0.76 17.85 6.36 0.11 3.50 8.00 2.87 2.29 0.24 YM-4 iron mt Cv 67.15 0.91 14.49 5.66 0.11 0.77 3.09 3.88 3.69 0.25 GS-3 iron mt Cv 70.46 0.36 15.35 3.02 0.07 0.76 2.53 4.21 3.11 0.12 L40B soldier lake Jp 55.98 0.85 17.90 8.03 0.22 4.03 6.32 4.05 2.41 0.21 L40A soldier lake Jp 67.48 0.41 15.89 3.87 0.08 1.46 3.70 3.57 3.41 0.14 L39 soldier lake Jp 68.03 0.39 15.74 3.76 0.08 1.36 3.71 3.61 3.19 0.13 L43 soldier lake Jp 68.12 0.38 15.70 3.64 0.08 1.32 3.62 3.48 3.53 0.13 L37 soldier lake Jp 68.62 0.38 15.45 3.62 0.07 1.31 3.36 3.39 3.68 0.12 L38 soldier lake Jp 68.80 0.36 15.50 3.51 0.07 1.27 3.37 3.42 3.57 0.12 L35 soldier lake Jp 77.98 0.22 11.69 1.75 0.04 0.42 0.95 2.41 4.49 0.05 L102 soldier lake Cp 56.82 1.04 18.42 7.19 0.22 3.39 4.80 4.96 2.88 0.30 G6B soldier lake Cp 62.60 0.75 16.21 5.03 0.14 2.94 4.80 3.93 3.38 0.22 S14 soldier lake Cp 66.71 0.57 16.08 3.69 0.07 1.52 3.53 3.92 3.73 0.19 G6A soldier lake Cp 67.03 0.56 16.09 3.61 0.08 1.49 3.43 3.90 3.63 0.19 G6C soldier lake Cp 68.31 0.38 15.71 4.20 0.15 1.21 3.37 2.59 3.95 0.14 L109 soldier lake Cp 68.89 0.47 15.28 3.20 0.07 1.29 3.00 3.66 3.99 0.15 L95 soldier lake Cp 69.18 0.45 15.25 3.11 0.07 1.26 2.93 3.68 3.92 0.14 L105 soldier lake Cp 69.48 0.45 15.10 3.05 0.07 1.19 2.81 3.55 4.15 0.14 S11 soldier lake Cp 69.57 0.43 15.14 2.97 0.07 1.18 2.76 3.71 4.02 0.14 L100 soldier lake Cp 70.80 0.37 14.77 2.59 0.07 0.95 2.45 3.66 4.22 0.11 L98 soldier lake Cp 71.88 0.32 14.53 2.22 0.06 0.78 2.18 3.55 4.38 0.09 L101B soldier lake Cp 76.98 0.05 12.73 0.41 0.02 0.07 0.52 2.76 6.44 0.01 W1B soldier lake Tv 41.32 0.59 25.65 7.04 0.27 3.56 20.96 0.30 0.14 0.17 T065 soldier lake Tv 54.77 1.02 19.58 8.07 0.23 4.88 3.95 5.23 1.98 0.28 222 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 S46 soldier lake Tv 56.26 0.82 18.98 7.13 0.16 3.55 5.64 3.90 3.27 0.28 L77 soldier lake Tv 56.45 1.02 20.63 8.02 0.12 1.40 4.70 4.76 2.52 0.38 T75A soldier lake Tv 56.54 1.05 18.52 7.31 0.23 3.41 4.77 5.01 2.87 0.31 S61 soldier lake Tv 58.80 1.22 16.79 8.74 0.19 2.19 5.24 4.66 1.62 0.55 T76 soldier lake Tv 61.18 0.72 17.55 6.44 0.15 2.46 3.69 5.32 2.23 0.25 T016 soldier lake Tv 65.44 0.57 16.75 4.03 0.14 2.03 3.09 3.14 4.61 0.21 V63 soldier lake Tv 66.16 0.47 13.51 4.49 0.42 0.09 4.38 1.29 9.06 0.13 G10 soldier lake Tv 73.62 0.19 14.29 2.27 0.08 0.73 0.75 3.02 4.98 0.07 V64 soldier lake Tv 75.85 0.16 12.89 1.26 0.03 0.22 0.99 2.99 5.50 0.11 K8 soldier lake Tv 77.51 0.05 12.58 0.28 0.03 0.02 0.46 3.12 5.93 0.01 NB27 cinko lake Cp 53.38 0.96 17.73 8.36 0.14 4.75 7.70 3.31 1.45 0.23 JT41a cinko lake Cp 63.43 0.61 16.26 4.45 0.08 2.05 4.63 3.65 2.70 0.18 JT40a cinko lake Cp 63.45 0.67 16.45 4.61 0.09 2.07 4.69 3.87 2.63 0.19 JT38 cinko lake Cp 65.49 0.55 15.67 3.83 0.07 1.69 4.08 3.59 2.99 0.16 JT37 cinko lake Cp 66.82 0.49 15.27 3.31 0.07 1.46 3.63 3.64 3.23 0.14 NB46 cinko lake Cp 67.32 0.46 15.25 3.33 0.07 1.38 3.45 3.60 3.38 0.13 BF32 cinko lake Cp 67.35 0.49 15.18 3.38 0.07 1.42 3.43 3.57 3.43 0.14 BF31 cinko lake Cp 67.41 0.49 15.27 3.29 0.07 1.48 3.46 3.56 3.36 0.13 BF29 cinko lake Cp 67.60 0.55 15.16 3.31 0.07 1.52 3.45 3.45 3.54 0.13 NB108 cinko lake Cp 56.17 0.89 19.47 6.28 0.11 2.98 7.10 3.66 1.67 0.24 HL23 cinko lake Cp 62.59 0.78 16.42 5.06 0.10 2.11 4.44 3.73 3.37 0.17 HL16b cinko lake Cp 63.00 0.81 16.64 5.02 0.09 1.89 4.25 4.09 3.21 0.20 HL09b cinko lake Cp 64.05 0.74 15.99 4.76 0.09 1.93 4.11 3.63 3.68 0.16 HL20 cinko lake Cp 64.13 0.73 16.34 4.51 0.10 1.59 3.65 3.97 3.37 0.18 HL06 cinko lake Cp 64.72 0.71 15.77 4.67 0.09 1.86 3.88 3.43 3.92 0.16 HL05b cinko lake Cp 65.19 0.69 15.59 4.57 0.08 1.85 3.67 3.37 4.09 0.14 BF08 cinko lake Cv 61.47 0.71 19.06 4.17 0.11 1.59 6.07 3.99 1.68 0.23 HL01a cinko lake Cv 62.81 0.67 17.76 4.50 0.07 1.52 3.30 3.84 3.82 0.14 BF04 cinko lake Cv 66.45 0.60 15.67 3.84 0.09 1.45 3.43 3.96 3.05 0.12 BF01 cinko lake Cv 67.40 0.55 16.02 2.82 0.06 0.87 2.59 4.39 3.98 0.15 BF26 cinko lake Cv 68.71 0.49 14.90 2.71 0.08 0.68 1.72 4.09 4.73 0.11 BF28 cinko lake Cv 68.97 0.39 15.02 2.81 0.07 1.26 3.06 3.57 3.55 0.09 BF21 cinko lake Cv 69.49 0.48 14.36 3.07 0.07 1.11 2.04 3.45 4.35 0.09 BF03 cinko lake Cv 74.48 0.14 13.55 1.10 0.02 0.31 1.64 3.15 4.61 0.04 HL03a cinko lake Cv 76.51 0.17 12.47 0.89 0.01 0.07 0.31 3.42 5.25 0.01 HL17 cinko lake Cp 53.30 1.14 18.66 8.41 0.16 4.36 8.23 3.01 1.27 0.25 BF23b cinko lake Cp 62.12 0.84 16.28 5.32 0.13 2.28 4.95 3.59 2.84 0.23 BF23c cinko lake Cp 76.31 0.15 12.22 0.85 0.02 0.07 0.41 3.49 5.13 0.01 CC01 JLP Cp 73.02 0.22 13.67 1.83 0.07 0.13 0.35 3.93 4.39 0.04 223 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 CC03 JLP Cp 67.38 0.47 15.39 3.00 0.07 0.80 2.53 3.80 3.34 0.14 CC04 JLP Cp 73.83 0.19 13.33 1.46 0.05 0.10 0.37 4.06 4.02 0.04 CC09 JLP Cp 73.02 0.22 13.43 1.48 0.06 0.09 0.51 4.08 4.19 0.03 CC11 JLP Cp 57.52 0.94 16.93 7.61 0.14 3.04 6.28 4.62 1.30 0.24 CC13 JLP Cp 55.04 1.09 16.46 8.84 0.13 3.90 6.70 2.70 2.26 0.20 CC14 JLP Cp 56.21 1.18 16.85 8.32 0.16 3.40 6.51 3.12 2.06 0.21 CC15 JLP Cp 61.30 0.60 18.80 4.78 0.07 1.04 4.50 5.02 1.77 0.12 CC16 JLP Cp 72.94 0.17 13.21 1.36 0.05 0.09 0.33 3.90 4.05 0.03 CC17 JLP Cp 70.12 0.34 14.25 2.16 0.07 0.52 1.95 3.45 3.66 0.08 CC20 JLP Cp 65.06 0.63 16.90 4.08 0.09 1.19 4.14 3.82 2.89 0.16 GJ01a JLP Cp 67.56 0.47 15.40 3.10 0.08 0.77 2.56 3.89 3.31 0.13 GJ02 JLP Cp 66.16 0.50 16.00 3.36 0.07 0.83 2.79 3.77 3.82 0.16 GJ03A JLP Cp 55.99 1.17 17.46 8.45 0.13 3.24 6.89 3.05 1.95 0.28 GJ03b JLP Cp 58.50 1.04 16.94 7.57 0.12 2.83 6.34 2.95 1.74 0.24 GJ04 JLP Cp 64.84 0.54 15.46 3.55 0.09 0.92 2.83 4.31 2.53 0.16 GJ05 JLP Cp 66.84 0.51 15.66 3.50 0.09 1.03 3.14 3.64 3.14 0.14 GJ06 JLP Cp 63.42 0.75 16.38 5.05 0.10 1.62 4.58 3.59 2.77 0.18 GJ07 JLP Cp 67.15 0.50 15.86 3.14 0.08 0.73 2.61 4.24 3.34 0.14 GP163-02 JLP Cv 69.20 0.41 14.70 2.75 0.08 0.63 1.99 3.68 3.70 0.09 GP204a JLP Cp 59.22 0.92 17.70 6.22 0.11 2.08 5.64 3.77 2.20 0.23 GP204b JLP Cp 54.14 1.09 17.20 9.23 0.14 4.00 7.31 2.55 1.81 0.24 GP204c JLP Cp 59.09 0.98 17.56 6.19 0.11 2.13 5.77 3.86 2.19 0.27 GP204d JLP Cp 66.77 0.54 15.90 3.43 0.08 0.83 2.85 4.05 3.35 0.16 GP21-02 JLP Cp 69.64 0.39 14.40 3.09 0.08 0.57 1.59 3.68 3.71 0.12 GP234 JLP Cv 64.30 0.64 16.23 4.43 0.09 1.40 4.08 3.60 2.67 0.18 GP28-02 JLP Cp 59.12 0.85 18.57 5.61 0.11 1.75 5.72 4.13 2.12 0.26 GP292 JLP Cp 55.53 1.13 17.24 8.78 0.14 3.40 6.84 3.10 2.11 0.26 GP345 JLP Cp 68.37 0.44 15.95 2.73 0.07 0.61 2.30 4.40 3.42 0.13 GP353 JLP Cp 71.17 0.17 13.67 1.58 0.05 0.29 1.27 2.61 4.41 0.04 GP385 JLP Cp 67.93 0.46 15.38 3.26 0.08 0.95 2.86 3.48 3.44 0.11 GP92-02 JLP Cp 53.48 1.39 18.21 8.93 0.12 3.50 7.46 2.80 2.01 0.34 GT105 JLP Cv 57.42 1.10 17.65 6.97 0.12 2.50 5.83 3.50 2.43 0.25 GT120 JLP Cv 73.51 0.14 12.99 1.33 0.05 0.12 0.27 3.53 4.44 0.02 GT126 JLP Cp 74.65 0.25 13.24 1.47 0.03 0.32 0.88 2.72 4.46 0.05 GT82 JLP Cv 73.85 0.09 12.44 0.84 0.02 0.03 0.10 3.56 4.04 0.01 GT92 JLP Cv 64.88 0.65 16.59 3.89 0.07 1.22 2.59 4.24 3.87 0.16 GT94 JLP Cv 69.86 0.52 14.90 2.02 0.05 0.76 2.12 3.61 3.32 0.09 J47a JLP Cp 71.91 0.23 14.08 1.58 0.05 0.17 0.54 2.86 5.69 0.03 224 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 J54 JLP Cp 67.59 0.41 15.45 2.64 0.08 0.52 1.50 4.62 3.65 0.10 J66 JLP Cv 74.54 0.18 13.17 1.37 0.04 0.26 1.01 3.09 3.63 0.03 J69 JLP Cv 69.12 0.41 14.69 2.74 0.07 0.56 2.08 3.54 3.62 0.10 J71 JLP Cp 67.62 0.51 15.58 3.40 0.09 0.85 2.63 4.47 3.06 0.13 JL01 JLP Cv 73.33 0.20 13.50 1.46 0.06 0.12 0.47 4.15 3.99 0.03 JL02 JLP Cv 74.32 0.21 12.98 1.42 0.06 0.24 0.63 3.14 4.03 0.04 JL03 JLP Cp 59.05 1.01 16.89 7.31 0.11 2.69 6.00 3.28 2.29 0.23 JL04 JLP Cp 67.71 0.45 15.64 2.87 0.08 0.68 2.23 4.23 3.35 0.12 JL05 JLP Cp 66.06 0.61 15.26 4.19 0.07 1.60 4.04 2.64 3.45 0.15 JL244 JLP Cp 74.15 0.26 12.97 1.65 0.06 0.42 0.94 3.31 4.16 0.06 JL254 JLP Cp 73.56 0.21 13.47 1.43 0.06 0.14 0.37 2.91 5.14 0.03 JL287 JLP Cp 67.67 0.44 15.57 2.86 0.08 0.61 2.21 4.49 3.33 0.12 JL288a JLP Cp 66.78 0.54 15.45 3.53 0.08 0.85 2.66 3.86 3.59 0.14 JL288b JLP Cp 56.54 1.21 17.07 7.51 0.24 2.58 5.77 4.67 1.95 0.32 JL295 JLP Cp 62.68 0.66 15.65 4.77 0.09 1.50 3.85 3.29 3.08 0.18 JL303 JLP Cv 68.87 0.39 14.72 2.69 0.07 0.51 1.86 3.82 4.04 0.09 JL304 JLP Cv 61.19 1.05 16.74 6.43 0.15 1.58 4.53 4.08 2.80 0.20 JL307 JLP Cv 76.09 0.08 12.62 0.56 0.01 0.08 0.70 2.47 4.64 0.02 JL85A JLP Cv 62.07 0.74 16.64 5.55 0.09 1.92 4.16 2.95 2.73 0.14 JL85B JLP Cp 62.60 0.71 17.94 4.34 0.10 1.40 4.95 4.28 2.19 0.21 JZ20 JLP Cp 68.23 0.52 15.00 3.26 0.09 0.81 2.42 3.83 3.45 0.14 SP107B JLP Cv 62.50 0.78 15.00 5.68 0.11 1.86 5.53 2.63 3.99 0.20 SP128 JLP Cp 59.37 0.98 17.23 6.06 0.11 2.00 5.67 3.98 2.05 0.27 SP289 JLP Cp 69.54 0.40 14.89 2.55 0.08 0.59 2.18 3.77 3.21 0.09 ZJL01 JLP Cv 67.63 0.45 15.57 3.59 0.06 0.99 4.78 3.26 1.10 0.12 ZJL04 JLP Cp 64.53 0.52 16.05 3.91 0.07 1.43 2.90 2.97 3.41 0.10 ZJL05 JLP Cv 72.02 0.31 14.70 2.38 0.07 1.26 2.08 2.15 2.65 0.07 ZJL06 JLP Cp 54.98 0.92 16.64 7.85 0.13 4.90 7.70 2.69 1.65 0.17 HD01-30 TB Cp 65.23 0.59 16.17 3.85 0.08 1.73 4.04 3.69 3.19 0.21 5 TB Cp 65.61 0.54 15.44 3.96 0.08 1.80 4.10 3.62 3.11 0.16 T-450 TB Cp 65.67 0.60 15.69 3.95 0.09 1.62 3.87 3.97 3.13 0.20 HD01-67 TB Cp 65.98 0.56 15.57 4.03 0.08 1.83 3.89 3.35 3.47 0.18 CPL-275 TB Cp 66.09 0.51 15.46 3.29 0.07 1.34 3.50 3.66 3.48 0.17 HD01-10 TB Cp 66.16 0.57 15.94 3.69 0.09 1.60 3.35 3.67 3.90 0.20 HD01-75 TB Cp 66.18 0.45 15.99 3.37 0.07 1.61 3.56 3.22 4.16 0.14 BTL 73 TB Cp 66.25 0.61 16.07 4.19 0.08 1.45 4.23 3.92 2.97 0.24 TS 26 TB Cp 66.36 0.56 16.87 3.69 0.07 1.46 4.33 4.06 3.02 0.21 TML2 TB Cp 66.38 0.55 16.14 3.78 0.08 1.55 3.95 3.74 3.50 0.20 HD01-74 TB Cp 66.40 0.57 15.31 3.55 0.07 1.64 3.43 3.03 4.19 0.15 225 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 TM 30 TB Cp 66.43 0.51 16.52 3.67 0.07 1.64 4.09 3.67 3.38 0.18 M-330-1 TB Cp 66.48 0.45 15.55 3.82 0.07 1.51 3.88 3.13 3.93 0.15 HD01-6 TB Cp 66.50 0.46 15.38 3.94 0.09 1.78 3.76 3.89 2.84 0.20 BTL 75 TB Cp 66.64 0.64 15.56 4.06 0.09 1.49 3.93 3.85 3.51 0.22 BTL 74 TB Cp 67.02 0.58 15.71 3.73 0.09 1.47 3.66 3.82 3.72 0.20 KCL-206 TB Cp 67.08 0.43 14.95 3.03 0.06 1.26 3.43 3.51 3.47 0.13 HD01-40 TB Cp 67.12 0.50 15.62 3.26 0.07 1.45 3.61 3.55 3.70 0.17 HD01-39 TB Cp 67.34 0.48 15.69 3.31 0.07 1.48 3.72 3.69 3.31 0.16 HD01-49 TB Cp 67.50 0.42 15.15 3.13 0.08 1.43 3.06 3.66 3.86 0.13 T-395 TB Cp 67.66 0.48 15.13 3.27 0.07 1.31 3.20 3.74 3.53 0.15 43 TB Cp 67.76 0.46 15.61 2.95 0.07 1.14 3.51 3.83 3.66 0.17 HD02-102 TB Cp 67.83 0.49 15.41 2.69 0.05 1.03 3.14 3.88 3.56 0.19 MP6 TB Cp 67.97 0.40 15.40 2.84 0.06 1.41 3.24 3.32 4.20 0.11 HD01-2 TB Cp 68.61 0.53 14.46 3.50 0.07 1.41 3.18 3.45 3.71 0.15 HD01-32 TB Cp 68.82 0.46 15.58 2.68 0.06 1.10 3.14 3.63 3.59 0.14 9 TB Cp 69.23 0.44 14.55 3.03 0.08 1.22 3.00 3.51 4.02 0.14 HD01-41 TB Cp 69.31 0.42 14.98 2.80 0.07 1.20 2.98 3.46 3.70 0.13 HD01-29 TB Cp 70.29 0.32 14.87 2.39 0.06 0.99 2.87 3.60 3.73 0.12 HD01-43 TB Cp 71.10 0.37 14.01 2.50 0.06 1.13 2.57 3.19 3.91 0.10 T-353 TB Cp 64.06 0.72 16.63 4.11 0.07 1.48 4.03 4.30 3.27 0.24 KCL-214 TB Cp 65.48 0.52 15.52 3.71 0.08 1.60 3.79 3.48 3.52 0.16 BTL 77 TB Cp 66.65 0.64 15.80 3.96 0.08 1.46 4.00 3.84 3.35 0.23 44 TB Cp 66.65 0.53 15.73 3.21 0.07 1.23 3.62 4.14 3.27 0.19 KCL-215 TB Cp 66.81 0.50 15.48 2.96 0.06 1.09 3.24 3.91 3.67 0.18 HD01-64 TB Cp 66.98 0.49 15.80 2.86 0.06 1.19 3.38 3.91 3.59 0.19 BTL 76 TB Cp 67.01 0.54 16.05 3.48 0.06 1.32 3.77 3.81 3.76 0.20 47 TB Cp 67.32 0.55 15.68 3.10 0.06 1.10 3.59 4.17 3.22 0.19 M-336 TB Cp 67.73 0.51 15.60 3.04 0.06 0.98 3.52 4.06 3.18 0.19 CPL-276 TB Cp 67.73 0.51 14.95 3.02 0.06 1.06 3.58 4.26 2.19 0.19 BTL 65 TB Cp 67.75 0.50 16.12 2.99 0.06 1.09 3.40 4.14 3.76 0.18 HD02-111 TB Cp 67.82 0.41 15.87 2.44 0.04 1.08 3.01 4.01 3.99 0.16 11 TB Cp 67.83 0.49 15.44 2.83 0.06 1.03 3.22 4.02 3.65 0.17 HD01-80 TB Cp 68.07 0.43 15.57 2.54 0.05 0.87 3.01 3.88 3.99 0.16 BTL 62 TB Cp 68.28 0.54 15.83 3.06 0.06 1.02 3.38 4.09 3.54 0.19 HD01-84 TB Cp 68.29 0.60 15.08 3.11 0.08 1.29 3.20 3.77 3.22 0.15 HD02-109 TB Cp 68.37 0.44 15.58 2.47 0.08 1.06 2.96 3.93 3.95 0.15 BTL 85 TB Cp 68.75 0.56 15.13 3.44 0.07 1.14 3.62 3.83 3.28 0.20 BTL 64 TB Cp 68.87 0.47 15.61 2.88 0.06 1.02 3.14 4.09 3.69 0.17 HD01-77A TB Cp 68.90 0.50 15.35 2.65 0.05 0.94 3.25 4.04 3.14 0.19 226 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 SM-5 NAVDAT (Scott et al., ) Cp 62.43 1.25 14.94 5.82 0.13 2.31 4.17 3.64 3.29 0.35 TS 33 TB Cp 65.57 0.55 16.37 3.10 0.05 1.15 3.72 4.40 3.14 0.22 HD01-82 TB Cp 66.38 0.44 16.56 2.61 0.06 0.92 3.19 4.13 3.95 0.17 HD01-58 TB Cp 66.75 0.46 16.56 2.80 0.07 1.11 3.35 4.33 3.34 0.19 49 TB Cp 67.40 0.53 15.80 2.95 0.06 1.02 3.45 4.08 3.63 0.20 BTL 79 TB Cp 67.66 0.53 16.20 3.14 0.07 0.95 3.44 4.20 3.60 0.21 TS 21 TB Cp 67.78 0.49 16.16 2.86 0.06 1.00 3.56 4.35 3.10 0.20 SM-2 NAVDAT (Scott et al., ) Cp 67.83 0.47 16.29 2.23 0.05 0.88 3.68 4.56 2.49 0.18 SM2 TB Cp 67.83 0.47 16.29 2.23 0.05 0.88 3.68 4.56 2.49 0.18 T-424 TB Cp 68.58 0.44 15.35 2.64 0.06 0.91 3.44 4.29 2.51 0.17 BTL 59 TB Cp 68.72 0.43 16.05 2.60 0.05 0.88 3.05 4.03 4.02 0.17 SM-1 NAVDAT (Scott et al., ) Cp 68.80 0.39 15.85 2.28 0.05 0.80 2.93 4.22 3.73 0.16 SM1 TB Cp 68.80 0.39 15.85 2.27 0.05 0.80 2.93 4.22 3.73 0.16 HD02-116 TB Cp 68.88 0.47 15.39 2.78 0.06 1.06 3.39 4.23 2.44 0.20 BTL 81 TB Cp 68.94 0.48 15.75 2.81 0.07 0.81 3.11 4.27 3.58 0.20 V67C soldier lake Cp 68.95 0.47 16.00 2.71 0.06 0.85 3.12 4.50 3.17 0.19 HD02-110 TB Cp 68.97 0.46 15.25 2.58 0.06 0.94 3.32 4.25 2.74 0.17 15 TB Cp 69.22 0.40 15.38 2.22 0.05 0.77 2.73 4.31 3.63 0.14 HD02-93 TB Cp 69.27 0.37 15.39 2.04 0.07 0.66 2.34 4.25 3.69 0.14 HD02-94 TB Cp 69.27 0.50 14.27 2.82 0.06 0.97 3.03 3.92 2.99 0.19 51 TB Cp 69.33 0.45 15.22 2.55 0.06 0.85 3.12 4.12 3.40 0.17 L115B soldier lake Cp 69.41 0.40 15.75 2.39 0.07 0.74 2.72 4.07 4.28 0.16 TC 3 TB Cp 69.45 0.36 15.47 2.18 0.05 0.68 2.77 4.21 3.76 0.16 BTL 36 TB Cp 69.52 0.43 15.72 2.56 0.05 0.73 2.91 4.32 3.59 0.18 26 TB Cp 69.60 0.38 15.34 2.12 0.06 0.70 2.68 4.31 3.64 0.14 HD01-81 TB Cp 69.61 0.41 15.44 2.43 0.05 0.86 3.54 4.34 2.17 0.17 L117B soldier lake Cp 69.63 0.42 15.81 2.50 0.07 0.75 2.93 4.41 3.32 0.15 13 TB Cp 69.72 0.42 15.02 2.43 0.06 0.81 2.90 4.03 3.59 0.15 17 TB Cp 69.76 0.37 15.49 2.06 0.05 0.66 2.52 4.33 3.72 0.13 BTL 55 TB Cp 69.76 0.50 15.27 2.96 0.07 0.82 3.03 4.24 3.15 0.19 BTL 68 TB Cp 69.83 0.42 15.51 2.49 0.05 0.71 2.85 4.19 3.79 0.16 BTL 82 TB Cp 70.14 0.47 15.10 2.71 0.06 0.73 2.98 4.03 3.58 0.19 L118 soldier lake Cp 70.29 0.40 15.40 2.36 0.06 0.73 2.79 4.20 3.63 0.16 TS 31 TB Cp 70.36 0.42 15.65 2.49 0.05 0.77 2.90 4.41 3.36 0.17 L120B soldier lake Cp 70.38 0.42 15.25 2.44 0.06 0.76 2.98 4.23 3.32 0.16 BTL 37 TB Cp 70.39 0.41 15.31 2.40 0.06 0.74 2.74 4.21 3.58 0.17 BTL 10 TB Cp 70.46 0.45 15.15 2.66 0.07 0.75 2.96 4.36 2.97 0.19 M-343 TB Cp 70.61 0.24 14.97 1.71 0.05 0.38 1.95 4.18 4.03 0.07 L28 soldier lake Cp 70.65 0.44 15.08 2.58 0.06 0.79 3.05 4.29 2.89 0.18 227 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 L136A soldier lake Cp 70.84 0.32 15.81 2.00 0.06 0.47 2.40 4.38 3.62 0.11 BTL 56 TB Cp 70.85 0.42 15.00 2.56 0.06 0.77 3.06 4.24 2.86 0.17 BTL 9 TB Cp 70.85 0.35 15.31 2.06 0.05 0.60 2.41 4.23 4.00 0.14 HD02-118 TB Cp 71.10 0.29 14.96 1.59 0.05 0.49 2.10 4.41 3.74 0.12 19 TB Cp 71.51 0.28 14.75 1.59 0.05 0.49 2.07 4.07 4.19 0.10 HD02-117 TB Cp 71.62 0.26 14.71 1.49 0.05 4.50 1.95 4.24 3.71 0.09 BTL 46 TB Cp 71.77 0.33 15.02 1.90 0.05 0.52 2.30 4.31 3.69 0.12 BTL 43 TB Cp 73.58 0.23 14.47 1.32 0.04 0.38 2.00 4.08 3.83 0.08 23 TB Cp 74.66 0.13 13.80 0.78 0.02 0.19 1.52 4.17 3.80 0.03 L120A soldier lake Cp 78.15 0.05 12.83 0.51 0.02 0.11 1.62 4.37 2.33 0.00 21 TB Cp 71.65 0.24 14.87 1.57 0.04 0.38 1.87 3.98 4.19 0.08 JP1 TB Cp 74.74 0.15 13.40 1.07 0.05 0.20 1.08 3.40 5.11 0.03 HD01-83 TB Cp 74.84 0.13 13.80 0.93 0.03 0.18 0.98 3.55 5.05 0.04 HD02-96 TB Cp 74.95 0.12 13.59 0.89 0.04 0.14 0.92 3.45 5.21 0.03 J1 TB Cp 75.80 0.15 14.02 1.15 0.05 0.26 1.27 3.86 4.64 0.05 2-1 SBL Tp 58.07 0.68 19.24 6.40 0.14 2.09 6.96 3.19 2.94 0.29 2-45B SBL Tv 57.38 0.94 17.25 8.99 0.17 1.60 5.51 7.46 0.43 0.26 2-68 SBL Jv 67.86 0.32 16.45 2.87 0.04 0.89 1.12 5.07 5.25 0.12 4-80-1 SBL Tv 47.66 0.94 19.27 10.56 0.56 5.98 14.00 0.74 0.09 0.20 4-16 SBL Tv 55.66 0.92 18.41 8.00 0.23 1.90 10.70 1.38 2.45 0.35 4-6-2 SBL Tv 55.84 1.08 19.66 8.86 0.31 2.08 6.01 1.14 4.64 0.38 3-118 SBL Cv 61.02 0.98 17.48 7.38 0.12 2.56 4.33 3.15 2.75 0.24 5-5 SBL Tv 71.32 0.26 15.43 2.65 0.15 1.02 3.94 1.75 3.40 0.08 3-93 SBL Tv 72.41 0.22 15.91 2.09 0.04 1.08 2.03 2.85 3.29 0.08 3-135B SBL Cv 72.43 0.32 14.83 1.85 0.05 0.53 1.64 4.28 3.98 0.09 2043h NAVDAT (anonymous) Tv 42.76 0.53 12.32 19.69 0.27 8.60 10.55 2.26 0.29 0.00 2371h NAVDAT (anonymous) Tv 42.98 2.27 12.32 17.33 0.21 10.09 10.98 2.30 0.14 0.03 2371 NAVDAT (anonymous) Tv 45.90 1.30 14.66 12.67 0.22 7.95 10.86 3.01 0.18 0.07 2043 NAVDAT (anonymous) Tv 46.41 3.11 12.27 16.04 0.26 5.94 9.18 3.20 0.19 0.24 2637h NAVDAT (anonymous) Tv 46.50 0.62 10.40 15.69 0.33 11.48 11.31 1.36 0.25 0.14 4589 NAVDAT (anonymous) Tv 46.72 0.74 15.39 10.64 0.19 7.39 12.13 1.22 1.80 0.40 2106 NAVDAT (anonymous) Tv 48.57 1.18 13.92 9.21 0.19 6.89 14.28 2.92 0.07 0.10 2371d NAVDAT (anonymous) Tv 50.02 0.43 3.50 12.07 0.30 11.85 20.54 0.48 0.01 0.03 2592 NAVDAT (anonymous) Tv 50.27 1.93 13.39 11.94 0.19 5.54 10.81 3.01 0.24 0.18 2067 NAVDAT (anonymous) Tv 50.44 1.01 16.07 10.64 0.16 4.79 9.16 3.34 0.73 0.12 2306h NAVDAT (anonymous) Tv 50.62 0.04 3.64 25.44 0.14 7.41 2.31 5.37 0.18 0.13 2155 NAVDAT (anonymous) Tv 51.00 1.01 14.85 11.56 0.17 4.41 9.22 2.44 1.18 0.27 2237 NAVDAT (anonymous) Tv 52.69 2.12 18.69 9.93 0.05 1.87 3.45 4.12 3.13 0.43 2101 NAVDAT (anonymous) Tv 62.99 0.41 17.20 4.83 0.10 2.47 5.80 3.69 1.53 0.17 228 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 10-785 NAVDAT (Barth et al., ) Tp 62.92 0.37 17.00 3.65 0.13 0.97 3.11 4.19 4.69 0.14 10-786 NAVDAT (Barth et al., ) Tp 65.11 0.32 16.91 2.77 0.10 0.67 3.25 4.00 4.74 0.12 08-696 NAVDAT (Barth et al., ) Tp 67.26 0.33 15.59 3.29 0.10 1.13 3.52 2.87 4.36 0.16 08-700 NAVDAT (Barth et al., ) Tp 68.72 0.34 15.24 3.28 0.10 1.19 3.81 3.16 3.25 0.14 08-698 NAVDAT (Barth et al., ) Tp 69.38 0.31 14.96 3.01 0.09 1.04 3.17 2.84 4.30 0.14 08-697 NAVDAT (Barth et al., ) Tp 70.13 0.32 14.50 3.03 0.10 1.03 3.07 2.56 4.46 0.14 08-701 NAVDAT (Barth et al., ) Tp 70.95 0.28 14.86 2.51 0.09 0.92 2.71 3.19 4.10 0.10 MT-1 NAVDAT (Bateman et al.,) Tp 71.46 0.33 13.62 2.87 0.11 1.01 2.87 2.79 3.71 0.12 10-803 NAVDAT (Barth et al., ) Tp 71.57 0.18 14.08 1.83 0.06 0.42 1.76 3.60 4.27 0.05 10-802 NAVDAT (Barth et al., ) Tp 71.87 0.18 14.14 1.67 0.06 0.41 1.88 3.56 4.17 0.06 08-725 NAVDAT (Barth et al., ) Tp 72.14 0.23 14.37 1.93 0.06 0.65 2.10 3.22 4.24 0.07 08-728 NAVDAT (Barth et al., ) Tp 72.38 0.23 14.39 2.19 0.08 0.72 2.52 2.95 4.18 0.08 08-755 NAVDAT (Barth et al., ) Tp 72.55 0.17 14.17 2.31 0.10 0.45 1.60 3.49 4.35 0.06 08-754 NAVDAT (Barth et al., ) Tp 72.76 0.18 14.21 1.76 0.08 0.57 1.96 3.49 3.75 0.06 08-753 NAVDAT (Barth et al., ) Tp 73.37 0.17 14.31 1.67 0.03 0.49 1.84 3.62 3.97 0.05 08-742 NAVDAT (Barth et al., ) Tp 73.78 0.17 13.98 1.73 0.04 0.49 1.64 3.37 4.39 0.05 08-707 NAVDAT (Barth et al., ) Tp 74.03 0.22 14.07 1.55 0.04 0.43 1.57 3.40 4.33 0.05 08-705 NAVDAT (Barth et al., ) Tp 74.51 0.19 13.65 1.44 0.04 0.36 1.10 3.18 4.84 0.04 08-731 NAVDAT (Barth et al., ) Tp 74.66 0.13 13.40 1.52 0.04 0.38 1.20 2.88 5.16 0.04 08-703 NAVDAT (Barth et al., ) Tp 74.93 0.18 13.47 1.50 0.06 0.42 1.44 3.32 4.19 0.06 08-729 NAVDAT (Barth et al., ) Tp 74.95 0.13 13.45 1.46 0.06 0.41 1.31 3.26 4.51 0.04 08-706 NAVDAT (Barth et al., ) Tp 76.23 0.13 12.86 1.22 0.04 0.22 1.02 3.38 4.70 0.03 08-732 NAVDAT (Barth et al., ) Tp 76.77 0.08 12.88 0.97 0.03 0.26 0.81 3.14 5.11 0.02 MG-2 NAVDAT (Bateman et al.,) Tp 79.97 0.13 10.62 0.93 0.08 0.15 0.51 3.11 3.96 0.02 08-736 NAVDAT (Barth et al., ) Tv 63.97 0.54 16.37 4.75 0.11 1.50 2.61 3.14 5.21 0.18 10-791 NAVDAT (Barth et al., ) Tv 69.68 0.21 13.57 2.08 0.11 0.72 3.13 1.95 3.58 0.07 10-792 NAVDAT (Barth et al., ) Tv 70.14 0.25 13.95 3.14 0.10 2.01 2.31 1.72 2.62 0.06 10-801 NAVDAT (Barth et al., ) Tv 70.23 0.22 13.35 2.18 0.10 0.80 3.08 1.85 3.43 0.07 09-762 NAVDAT (Barth et al., ) Tv 70.65 0.23 14.70 2.47 0.10 1.01 3.47 1.51 3.60 0.07 08-739 NAVDAT (Barth et al., ) Tv 70.67 0.26 14.87 2.56 0.10 1.39 2.18 3.06 3.34 0.09 08-751 NAVDAT (Barth et al., ) Tv 70.71 0.25 14.03 2.55 0.11 1.12 3.83 0.95 3.32 0.06 10-800 NAVDAT (Barth et al., ) Tv 70.84 0.21 15.01 2.11 0.06 0.68 1.60 4.15 3.29 0.07 09-767 NAVDAT (Barth et al., ) Tv 70.97 0.30 14.50 2.84 0.09 1.22 4.33 1.59 2.12 0.09 08-750 NAVDAT (Barth et al., ) Tv 71.66 0.23 14.42 2.52 0.09 0.89 2.43 2.22 3.55 0.07 09-763 NAVDAT (Barth et al., ) Tv 72.03 0.22 14.28 2.26 0.09 0.92 3.09 1.18 3.85 0.07 10-794 NAVDAT (Barth et al., ) Tv 72.10 0.18 13.21 1.72 0.08 0.50 2.04 2.86 3.57 0.06 08-752 NAVDAT (Barth et al., ) Tv 72.16 0.24 13.90 2.47 0.09 1.01 2.35 1.46 3.44 0.08 08-746 NAVDAT (Barth et al., ) Tv 72.48 0.19 14.40 2.01 0.08 0.67 4.26 0.19 4.40 0.06 09-766 NAVDAT (Barth et al., ) Tv 72.50 0.17 13.77 1.75 0.08 0.52 1.85 2.55 3.81 0.06 229 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 09-764 NAVDAT (Barth et al., ) Tv 72.75 0.19 13.66 1.80 0.06 0.60 1.83 2.19 3.73 0.06 09-768 NAVDAT (Barth et al., ) Tv 73.11 0.18 13.39 2.16 0.08 0.60 3.80 0.54 4.26 0.05 08-744 NAVDAT (Barth et al., ) Tv 73.71 0.20 13.61 2.06 0.10 0.65 3.50 0.06 4.51 0.05 08-749 NAVDAT (Barth et al., ) Tv 73.96 0.18 13.65 1.73 0.09 0.61 3.11 1.01 4.21 0.06 MP-351 NAVDAT (Peck and Van) Jp 73.20 0.22 13.90 1.82 0.04 0.50 1.80 3.10 4.50 0.06 SM-3 NAVDAT (Frost) Jp 39.90 2.33 14.40 17.71 0.17 7.90 13.70 1.15 0.30 0.06 CD-15 NAVDAT (Frost) Jp 40.00 2.40 12.20 16.90 0.20 12.10 10.70 1.55 0.61 0.06 CD-9 NAVDAT (Frost) Jp 40.70 0.10 17.90 11.15 0.16 17.00 9.61 0.51 0.06 0.05 CD-4 NAVDAT (Frost) Jp 40.80 0.72 18.20 12.05 0.13 11.10 13.00 0.62 0.15 0.05 CD-2 NAVDAT (Frost) Jp 40.90 0.34 9.99 15.10 0.24 22.30 8.40 0.42 0.08 0.05 CD-21 NAVDAT (Frost) Jp 41.40 0.63 20.90 9.89 0.13 10.10 12.70 0.86 0.24 0.05 TH2-17 NAVDAT (Frost) Jp 42.40 1.02 20.40 11.96 0.11 5.99 14.20 0.99 0.22 0.05 SM-10 NAVDAT (Frost) Jp 43.10 2.11 17.10 11.42 0.12 7.16 11.20 2.04 0.95 0.16 CD-11 NAVDAT (Frost) Jp 44.00 1.44 19.00 10.88 0.12 7.46 10.90 1.97 0.93 0.12 AC-8A NAVDAT (Frost) Jp 44.10 1.78 17.40 13.04 0.17 6.30 10.90 2.05 0.87 0.15 CD-17 NAVDAT (Frost) Jp 45.00 1.72 15.80 11.96 0.13 9.02 10.20 2.19 1.06 0.11 KHS-17 NAVDAT (Frost) Jp 45.00 1.27 20.50 9.98 0.12 6.10 11.20 2.16 1.05 0.13 McM-11 NAVDAT (Frost) Jp 45.00 0.36 20.90 7.14 0.11 8.36 14.30 0.97 0.31 0.05 TH223 NAVDAT (Frost) Jp 45.90 0.54 26.70 6.01 0.07 3.48 14.40 1.78 0.14 0.05 SM-8 NAVDAT (Frost) Jp 46.10 0.39 30.10 3.22 0.02 0.97 15.50 1.69 0.46 0.08 AC-21D NAVDAT (Frost) Jp 46.20 1.53 18.30 11.78 0.19 5.73 8.65 2.59 2.15 0.52 PAL-13 NAVDAT (Frost) Jp 46.48 0.91 9.87 10.08 0.17 11.94 16.90 0.95 0.18 0.04 KHS-33 NAVDAT (Frost) Jp 46.60 0.95 16.80 7.17 0.10 9.04 16.00 1.32 0.48 0.05 McM-1E NAVDAT (Frost) Jp 46.60 0.94 10.50 11.60 0.15 10.90 16.00 0.83 0.40 0.05 CD79-1c NAVDAT (Frost) Jp 47.20 0.82 24.50 7.28 0.09 2.79 11.20 2.52 0.69 0.20 AC-21A NAVDAT (Frost) Jp 47.40 1.01 21.70 9.08 0.14 3.44 9.05 3.59 1.60 0.71 KHS-19B NAVDAT (Frost) Jp 47.60 1.00 16.70 10.25 0.17 8.35 11.00 2.06 0.65 0.20 AC-23 NAVDAT (Frost) Jp 47.60 1.20 19.60 10.07 0.16 5.24 9.14 3.16 1.56 0.45 AC-27 NAVDAT (Frost) Jp 47.90 1.49 18.70 10.52 0.13 5.06 8.06 3.04 2.00 0.31 McM-15C NAVDAT (Frost) Jp 47.90 0.69 12.80 7.92 0.14 10.60 16.50 1.10 0.34 0.07 TH-D NAVDAT (Frost) Jp 48.10 0.28 24.50 4.41 0.08 4.87 14.20 1.41 0.61 0.05 McM-D NAVDAT (Frost) Jp 48.20 0.49 17.30 6.84 0.13 8.14 15.50 1.07 0.39 0.08 PAL-11 NAVDAT (Frost) Jp 48.23 0.50 15.63 5.51 0.10 8.40 17.20 1.41 0.23 0.06 McM-32 NAVDAT (Frost) Jp 48.40 0.58 10.20 7.97 0.16 13.20 16.20 0.74 0.27 0.07 McM-7A NAVDAT (Frost) Jp 48.60 0.69 11.30 8.10 0.15 11.20 16.30 1.18 0.46 0.08 McM-23 NAVDAT (Frost) Jp 48.70 0.63 16.50 6.62 0.13 8.63 14.30 1.46 0.73 0.12 KHS-19 NAVDAT (Frost) Jp 48.80 1.11 13.80 10.34 0.16 10.10 11.10 1.81 0.93 0.08 SM-9 NAVDAT (Frost) Jp 48.80 0.46 28.70 3.25 0.02 1.17 13.70 2.83 0.28 0.05 McM-19 NAVDAT (Frost) Jp 48.80 0.54 18.60 5.99 0.12 6.81 14.70 1.36 0.62 0.13 230 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 KHS-11A NAVDAT (Frost) Jp 49.20 1.08 18.30 9.98 0.17 6.01 9.87 2.82 0.50 0.36 SM-7A NAVDAT (Frost) Jp 49.40 1.22 20.60 8.22 0.13 4.78 9.88 3.08 0.38 0.29 McM-16 NAVDAT (Frost) Jp 49.40 0.57 8.41 8.27 0.16 13.60 16.20 0.82 0.36 0.08 McM-18 NAVDAT (Frost) Jp 49.50 0.62 17.70 6.54 0.13 7.70 13.70 1.51 0.50 0.17 McM-1D NAVDAT (Frost) Jp 49.70 0.61 10.60 8.24 0.16 1.50 15.50 0.97 0.57 0.11 SM-7B NAVDAT (Frost) Jp 49.80 0.94 25.70 5.11 0.05 1.44 11.50 3.56 0.50 0.14 McM-25 NAVDAT (Frost) Jp 49.80 0.70 6.99 9.08 0.18 14.10 15.40 0.97 0.42 0.12 AC-21C NAVDAT (Frost) Jp 49.90 1.42 16.90 10.07 0.14 5.65 7.43 2.63 2.26 0.31 PAL-12 NAVDAT (Frost) Jp 49.91 0.71 8.70 7.93 0.15 12.09 15.90 1.19 0.44 0.09 T-5 NAVDAT (Frost) Jp 50.00 0.68 15.00 9.89 0.21 9.27 10.70 1.65 0.72 0.10 TH2-10 NAVDAT (Frost) Jp 50.20 0.65 17.30 8.49 0.17 7.50 9.02 2.33 0.82 0.12 SM-7C NAVDAT (Frost) Jp 50.30 0.50 27.60 2.93 0.03 1.25 12.40 3.60 0.32 0.05 McM-8 NAVDAT (Frost) Jp 50.80 0.67 9.36 7.41 0.16 11.30 16.70 1.15 0.56 0.12 CD-13 NAVDAT (Frost) Jp 51.60 0.97 19.20 8.25 0.16 4.75 9.35 3.18 0.90 0.34 T-7 NAVDAT (Frost) Jp 51.60 0.58 17.10 8.23 0.17 7.70 9.84 1.90 0.85 0.11 T-10 NAVDAT (Frost) Jp 52.10 0.70 16.60 8.77 0.18 7.26 9.38 2.00 1.04 0.14 AC-29 NAVDAT (Frost) Jp 52.30 1.03 16.40 7.85 0.14 6.45 8.85 2.49 2.00 0.21 TH2-29 NAVDAT (Frost) Jp 52.40 0.92 18.80 8.69 0.17 4.15 8.71 2.50 1.29 0.38 TH2-16 NAVDAT (Frost) Jp 52.80 0.82 19.00 8.34 0.16 4.43 8.30 2.96 0.97 0.29 TH2-20 NAVDAT (Frost) Jp 53.00 0.50 7.66 8.88 0.20 12.70 12.80 0.74 0.30 0.14 KHS-12 NAVDAT (Frost) Jp 53.40 0.98 18.40 8.07 0.14 4.65 8.10 3.31 1.36 0.30 TH2-22 NAVDAT (Frost) Jp 53.50 0.76 20.10 7.12 0.13 3.88 8.93 3.09 1.17 0.25 AC-9 NAVDAT (Frost) Jp 53.60 0.85 18.60 7.72 0.16 4.24 8.38 3.02 1.46 0.25 T-3 NAVDAT (Frost) Jp 53.80 0.89 17.30 8.23 0.16 4.91 8.42 2.73 1.36 0.24 KHS-10A NAVDAT (Frost) Jp 54.50 0.94 18.90 7.48 0.13 3.73 7.68 3.46 1.84 0.33 KHS-24 NAVDAT (Frost) Jp 54.50 0.80 20.30 6.03 0.09 2.96 7.67 3.58 1.87 0.41 TH2-33 NAVDAT (Frost) Jp 55.50 0.90 19.80 2.86 0.09 2.37 9.78 3.36 3.08 0.35 TH2-27 NAVDAT (Frost) Jp 56.50 0.72 18.00 6.96 0.15 3.79 7.10 3.39 1.45 0.24 SM-19 NAVDAT (Frost) Jp 57.30 1.09 16.90 6.87 0.12 3.38 6.10 3.57 3.16 0.34 TH2-36 NAVDAT (Frost) Jp 57.60 0.72 17.50 6.40 0.14 3.27 6.71 3.06 2.38 0.22 SM-1C NAVDAT (Frost) Jp 60.30 0.51 20.40 2.99 0.04 1.50 5.94 4.74 2.38 0.17 SM-16 NAVDAT (Frost) Jp 61.60 0.67 16.30 5.21 0.10 2.45 4.93 3.40 3.69 0.30 AC-26B NAVDAT (Frost) Jp 62.30 0.70 16.70 4.76 0.04 2.94 3.94 3.92 2.63 0.33 AB-1011-69 NAVDAT (Ague) Jp 54.08 0.88 16.20 7.93 0.14 5.52 7.78 2.66 2.43 0.26 AB-1011-57 NAVDAT (Ague) Jp 67.15 0.71 15.61 3.60 0.05 1.49 3.46 4.11 2.67 0.16 AB-1011-56 NAVDAT (Ague) Jp 70.61 0.55 14.49 2.24 0.06 0.52 1.86 3.77 4.84 0.07 WM-13 NAVDAT (Ernst et al.,) Jp 45.84 1.23 12.37 11.35 0.13 15.29 10.23 0.75 1.71 0.17 WM-805 NAVDAT (Ernst et al.,) Jp 48.36 0.47 16.90 8.55 0.15 11.96 8.52 1.98 1.38 0.17 WM-409_1 NAVDAT (Ernst et al.,) Jp 51.39 1.21 16.34 8.93 0.16 5.46 7.60 3.16 2.67 0.49 231 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 WM-409_2 NAVDAT (Ernst et al.,) Jp 51.47 1.21 16.49 8.68 0.16 5.53 7.62 3.19 2.67 0.50 WM-39 NAVDAT (Ernst et al.,) Jp 53.64 0.86 10.95 7.38 0.16 10.04 12.22 1.68 1.46 0.29 WM-85 NAVDAT (Ernst et al.,) Jp 54.34 1.09 17.48 8.05 0.14 4.33 7.74 3.53 2.13 0.31 WM-757_2 NAVDAT (Ernst et al.,) Jp 54.48 1.22 16.87 7.70 0.13 3.45 6.23 3.68 2.64 0.56 WM-2 NAVDAT (Ernst et al.,) Jp 55.90 0.87 17.43 6.81 0.13 3.35 6.90 3.81 2.60 0.33 WM-280 NAVDAT (Ernst et al.,) Jp 56.07 1.55 16.56 3.73 0.04 5.63 9.69 5.36 0.18 0.67 WM-897a NAVDAT (Ernst et al.,) Jp 56.57 1.22 17.25 7.65 0.13 3.14 6.01 3.53 3.41 0.57 WM-287 NAVDAT (Ernst et al.,) Jp 57.29 0.88 16.51 7.17 0.13 4.07 6.57 3.33 3.10 0.39 WM-91 NAVDAT (Ernst et al.,) Jp 58.79 0.87 17.15 6.05 0.12 2.71 5.14 3.29 4.77 0.40 WM-820 NAVDAT (Ernst et al.,) Jp 59.32 1.08 16.21 6.43 0.09 3.61 3.67 4.25 3.93 0.40 WM-867_2 NAVDAT (Ernst et al.,) Jp 59.60 0.76 16.87 5.34 0.11 2.98 5.24 3.31 4.09 0.36 WM-867_1 NAVDAT (Ernst et al.,) Jp 59.97 0.77 16.91 5.76 0.11 2.93 5.25 3.42 4.10 0.36 WM-791 NAVDAT (Ernst et al.,) Jp 60.51 0.79 16.62 5.56 0.11 2.72 5.00 3.34 4.23 0.34 WM-792 NAVDAT (Ernst et al.,) Jp 61.56 0.76 16.73 5.34 0.10 2.71 4.85 3.28 4.26 0.33 WM-832 NAVDAT (Ernst et al.,) Jp 61.63 0.73 17.13 5.21 0.11 2.30 4.43 3.35 4.48 0.32 WM-768 NAVDAT (Ernst et al.,) Jp 62.35 0.64 16.42 5.21 0.12 2.12 4.36 3.49 4.53 0.32 WM-907 NAVDAT (Ernst et al.,) Jp 64.74 0.62 16.27 4.14 0.07 1.75 3.01 3.24 5.18 0.26 WM-724 NAVDAT (Ernst et al.,) Jp 68.24 0.45 15.68 2.97 0.07 0.90 2.24 3.69 5.39 0.17 WM-868a NAVDAT (Ernst et al.,) Jp 71.43 0.33 15.01 2.04 0.02 0.49 1.64 3.74 5.37 0.11 WM-87 NAVDAT (Ernst et al.,) Jp 73.90 0.20 13.96 1.54 0.03 0.27 1.39 2.70 5.97 0.06 WM-286b NAVDAT (Ernst et al.,) Jp 74.03 0.18 14.23 1.18 0.02 0.25 1.31 2.88 6.04 0.05 89-DJ-75 NAVDAT (John David A) Jp 55.99 1.09 15.52 6.76 0.15 5.91 6.26 4.25 3.33 0.46 89-DJ-69 NAVDAT (John David A) Jp 56.07 1.17 16.69 5.89 0.07 3.54 7.93 4.01 3.77 0.58 89-DJ-72 NAVDAT (John David A) Jp 57.37 1.09 16.52 6.71 0.12 3.99 6.17 4.32 2.90 0.48 89-DJ-64 NAVDAT (John David A) Jp 59.34 0.97 16.18 5.32 0.07 3.73 6.16 4.81 2.56 0.47 89-DJ-85 NAVDAT (John David A) Jp 59.71 0.82 16.73 2.11 0.04 3.33 8.96 3.76 4.17 0.29 89-DJ-101 NAVDAT (John David A) Jp 59.88 0.64 17.21 6.25 0.06 3.02 5.92 3.91 2.47 0.26 89-DJ-97 NAVDAT (John David A) Jp 60.55 0.73 16.29 5.47 0.09 3.86 6.16 3.83 2.42 0.36 89-DJ-70 NAVDAT (John David A) Jp 61.30 0.67 17.17 5.53 0.08 2.52 5.14 3.92 3.08 0.24 89-DJ-60 NAVDAT (John David A) Jp 61.54 0.69 16.68 5.56 0.07 2.74 5.18 3.65 3.35 0.20 89-DJ-88 NAVDAT (John David A) Jp 61.78 0.75 16.76 5.16 0.08 2.51 5.03 3.75 3.73 0.23 89-DJ-76 NAVDAT (John David A) Jp 62.07 0.79 16.88 4.33 0.05 2.04 4.80 4.57 3.86 0.31 89-DJ-100 NAVDAT (John David A) Jp 63.68 0.54 16.38 4.04 0.09 2.21 2.86 6.43 3.07 0.25 89-DJ-91 NAVDAT (John David A) Jp 64.12 0.72 16.13 1.38 0.03 2.24 7.01 3.60 4.48 0.22 89-DJ-62 NAVDAT (John David A) Jp 64.31 0.59 16.23 5.68 1.31 1.17 4.81 5.15 0.22 87-DJ-175 NAVDAT (John David A) Jp 64.51 0.65 16.28 4.74 0.07 1.95 4.13 3.43 3.90 0.14 89-DJ-105 NAVDAT (John David A) Jp 64.66 0.49 16.45 4.39 0.08 1.59 3.15 4.73 4.06 0.22 89-DJ-104 NAVDAT (John David A) Jp 64.98 0.46 17.78 3.27 1.53 2.50 5.01 4.07 0.18 89-DJ-93 NAVDAT (John David A) Jp 65.26 0.64 15.63 3.82 0.05 1.80 4.11 4.38 3.69 0.37 232 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 89-DJ-94 NAVDAT (John David A) Jp 65.31 0.74 15.46 3.83 0.05 1.90 3.92 4.34 3.72 0.38 89-DJ-67 NAVDAT (John David A) Jp 65.58 0.53 16.22 4.48 0.05 1.78 2.37 4.71 3.46 0.35 89-DJ-92 NAVDAT (John David A) Jp 65.94 0.57 15.75 2.97 0.09 1.77 4.66 3.48 4.39 0.18 89-DJ-77 NAVDAT (John David A) Jp 66.74 0.51 16.23 2.84 0.04 1.29 3.15 4.57 4.19 0.24 89-DJ-61 NAVDAT (John David A) Jp 66.94 0.59 15.42 3.14 0.04 1.53 3.65 4.03 4.20 0.25 89-DJ-102 NAVDAT (John David A) Jp 66.95 0.57 15.67 3.23 0.04 1.48 3.43 4.35 3.77 0.30 89-DJ-63 NAVDAT (John David A) Jp 67.25 0.55 15.62 3.00 0.03 1.30 3.40 4.12 4.27 0.23 89-DJ-78 NAVDAT (John David A) Jp 67.26 0.50 16.23 2.64 0.03 1.16 3.11 4.71 3.95 0.22 89-DJ-79 NAVDAT (John David A) Jp 67.86 0.53 15.62 2.95 0.03 1.30 3.40 4.46 3.44 0.21 89-DJ-103 NAVDAT (John David A) Jp 67.93 0.63 15.38 1.07 1.51 4.42 4.11 4.59 0.31 89-DJ-96 NAVDAT (John David A) Jp 67.96 0.51 15.62 2.78 0.03 1.27 3.30 4.51 3.57 0.27 89-DJ-95 NAVDAT (John David A) Jp 68.10 0.44 15.88 2.55 0.03 1.16 3.01 4.32 4.14 0.20 89-DJ-84 NAVDAT (John David A) Jp 69.70 0.36 14.77 2.65 0.03 1.26 2.80 3.27 4.81 0.15 NF4b-D NAVDAT (Babarin et al., ) Cp 48.40 1.26 19.80 8.91 0.14 4.78 9.43 3.16 1.46 0.32 NF4a-D NAVDAT (Babarin et al., ) Cp 49.60 1.71 20.10 7.84 0.10 4.22 10.00 2.62 1.40 0.44 HH5a-D NAVDAT (Babarin et al., ) Cp 51.90 1.43 18.80 7.85 0.16 4.11 7.80 3.72 1.98 0.38 CR5-A NAVDAT (Babarin et al., ) Cp 51.90 2.37 14.10 11.60 0.20 5.28 4.42 2.25 5.04 0.71 SQ12-Dx NAVDAT (Babarin et al., ) Cp 52.60 1.25 17.60 9.72 0.20 3.98 6.88 3.65 2.39 0.27 HH6a-D NAVDAT (Babarin et al., ) Cp 53.10 1.18 18.40 7.56 0.15 4.17 8.15 3.68 1.71 0.23 HH5b-D NAVDAT (Babarin et al., ) Cp 53.40 1.33 18.30 7.38 0.13 3.81 7.55 3.61 2.05 0.35 SQ12-aD NAVDAT (Babarin et al., ) Cp 53.90 1.39 14.10 11.34 0.24 4.61 6.28 2.57 2.97 0.30 HH6c-D NAVDAT (Babarin et al., ) Cp 54.30 1.12 18.10 7.27 0.11 3.93 7.71 3.34 1.77 0.25 HH6b-D NAVDAT (Babarin et al., ) Cp 54.40 1.18 17.70 7.57 0.14 4.01 7.74 3.51 1.62 0.19 SC1-D NAVDAT (Babarin et al., ) Cp 54.40 1.12 18.30 7.46 0.15 3.95 7.55 3.19 1.66 0.22 SQ12-Di NAVDAT (Babarin et al., ) Cp 54.40 1.57 13.10 11.97 0.24 4.81 5.73 2.21 3.32 0.33 CR12-1 NAVDAT (Babarin et al., ) Cp 54.60 1.03 16.50 6.92 0.35 2.57 16.30 0.94 0.14 0.33 MHb4-A NAVDAT (Babarin et al., ) Cp 54.90 1.38 13.30 10.79 0.23 5.08 4.80 2.24 3.93 0.35 DR2-S NAVDAT (Babarin et al., ) Cp 55.60 1.32 15.50 9.27 0.17 4.94 7.14 2.46 2.03 0.29 WR2-A NAVDAT (Babarin et al., ) Cp 56.00 1.36 13.40 10.17 0.21 5.03 6.40 2.02 3.14 0.28 HH5c-D NAVDAT (Babarin et al., ) Cp 56.20 1.19 17.60 6.95 0.12 3.66 7.11 3.57 1.86 0.25 CR3a-A NAVDAT (Babarin et al., ) Cp 56.60 2.05 14.20 9.36 0.16 4.42 4.02 2.48 3.42 0.55 HH2-A NAVDAT (Babarin et al., ) Cp 57.20 0.91 17.50 6.61 0.13 3.20 6.59 3.28 2.03 0.23 HH5d-D NAVDAT (Babarin et al., ) Cp 57.20 1.08 17.50 6.62 0.11 3.38 6.95 3.46 1.78 0.25 DR1-aH NAVDAT (Babarin et al., ) Cp 57.20 1.03 17.30 7.13 0.13 3.57 7.26 2.98 1.73 0.23 CR4-A NAVDAT (Babarin et al., ) Cp 57.80 1.78 14.00 8.60 0.15 3.84 4.36 2.55 3.66 0.54 HH6d-D NAVDAT (Babarin et al., ) Cp 58.40 0.98 17.40 6.42 0.13 3.11 6.59 3.70 1.62 0.21 NF5-G NAVDAT (Babarin et al., ) Cp 58.60 0.60 14.80 7.58 0.17 4.66 7.95 2.22 1.53 0.21 HH3-A NAVDAT (Babarin et al., ) Cp 59.40 0.85 17.00 6.22 0.12 2.93 6.07 3.24 1.89 0.22 WR1-H NAVDAT (Babarin et al., ) Cp 60.80 0.88 16.00 5.95 0.10 2.80 6.07 2.92 2.25 0.19 233 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 CR2a-A NAVDAT (Babarin et al., ) Cp 61.20 1.13 15.50 5.78 0.10 2.70 4.07 3.00 4.02 0.33 MHb5-A NAVDAT (Babarin et al., ) Cp 61.70 0.78 15.40 5.84 0.13 2.76 4.66 3.26 3.31 0.22 NF1-H NAVDAT (Babarin et al., ) Cp 63.60 0.53 16.80 4.31 0.07 2.04 5.13 3.43 1.88 0.11 SQ2-H NAVDAT (Babarin et al., ) Cp 65.10 0.64 15.30 4.50 0.08 1.76 4.49 2.96 3.04 0.14 CR1-H NAVDAT (Babarin et al., ) Cp 65.50 0.47 17.00 2.73 0.06 0.95 2.73 3.39 5.95 0.14 MHb3-H NAVDAT (Babarin et al., ) Cp 66.60 0.62 15.10 3.70 0.06 1.60 3.96 3.36 3.08 0.16 HH1-H NAVDAT (Babarin et al., ) Cp 66.90 0.50 15.20 3.61 0.06 1.51 3.62 2.96 3.47 0.12 MHb1-H NAVDAT (Babarin et al., ) Cp 66.90 0.57 15.40 3.51 0.06 1.55 3.78 3.26 3.60 0.16 MHb2-H NAVDAT (Babarin et al., ) Cp 67.10 0.53 15.20 3.55 0.06 1.53 3.76 3.18 3.56 0.16 RL1-H NAVDAT (Babarin et al., ) Cp 69.30 0.42 15.20 2.62 0.04 0.94 3.20 3.58 2.90 0.14 HH6e-AP NAVDAT (Babarin et al., ) Cp 72.50 0.23 14.00 1.65 0.55 2.25 2.42 4.93 0.06 YOS-113a NAVDAT (Ratajeski et al., ) Cp 53.33 1.28 18.94 8.00 0.14 4.05 8.57 2.94 1.57 0.28 YOS-109a NAVDAT (Ratajeski et al., ) Cp 54.00 1.04 17.51 7.86 0.14 5.00 9.05 2.99 1.32 0.21 YOS-18c NAVDAT (Ratajeski et al., ) Cp 55.61 1.18 17.09 7.78 0.18 4.14 7.52 3.49 1.83 0.30 YOS-206 NAVDAT (Ratajeski et al., ) Cp 56.90 0.77 17.46 4.32 0.16 8.14 6.88 2.65 2.09 0.13 YOS-104 NAVDAT (Ratajeski et al., ) Cp 57.59 0.96 17.01 6.84 0.13 4.10 7.72 2.98 1.66 0.22 YOS-105a NAVDAT (Ratajeski et al., ) Cp 57.77 0.88 17.11 6.78 0.12 4.16 7.93 2.92 1.39 0.18 YOS-193a NAVDAT (Ratajeski et al., ) Cp 61.23 0.84 16.92 5.99 0.15 2.50 5.11 4.15 2.21 0.25 YOS-18a NAVDAT (Ratajeski et al., ) Cp 68.05 0.62 15.79 3.87 0.04 1.65 4.08 3.56 1.79 0.11 YOS-67 NAVDAT (Ratajeski et al., ) Cp 69.87 0.52 15.24 3.51 0.06 0.93 3.58 3.82 1.95 0.12 YOS-180 NAVDAT (Ratajeski et al., ) Cp 72.26 0.24 14.79 1.97 0.05 0.54 1.99 3.77 4.12 0.07 YOS-1 NAVDAT (Ratajeski et al., ) Cp 73.28 0.10 14.79 1.11 0.04 0.16 1.21 3.48 5.65 0.05 YOS-113c NAVDAT (Ratajeski et al., ) Cp 74.04 0.14 14.29 1.29 0.05 0.27 1.31 3.72 4.67 0.04 YOS-94a NAVDAT (Ratajeski et al., ) Cp 75.80 0.13 13.38 1.22 0.02 0.19 1.55 3.14 4.40 0.03 YOS-210 NAVDAT (Ratajeski et al., ) Cp 76.23 0.04 13.28 0.61 0.02 0.07 1.02 3.16 5.48 0.03 S14-6 NAVDAT (Steve Macias) Cp 61.20 0.80 17.20 6.25 0.09 2.59 5.55 3.73 1.98 0.21 S52-2 NAVDAT (Steve Macias) Cp 64.00 0.64 16.30 5.37 0.09 2.19 4.56 3.51 2.73 0.16 S46-2 NAVDAT (Steve Macias) Cp 64.20 0.63 16.60 5.18 0.07 1.98 4.52 3.80 2.45 0.17 R52-9 NAVDAT (Steve Macias) Cp 64.90 0.56 15.80 4.51 0.07 1.78 4.11 3.67 2.85 0.16 S72-3 NAVDAT (Steve Macias) Cp 65.20 0.57 15.70 4.99 0.08 1.94 4.14 3.38 2.89 0.16 S10-2 NAVDAT (Steve Macias) Cp 65.40 0.57 15.60 4.46 0.07 1.40 3.99 3.80 2.67 0.16 R48-9 NAVDAT (Steve Macias) Cp 65.70 0.66 15.90 4.44 0.06 1.58 4.01 3.78 2.91 0.18 S72-4 NAVDAT (Steve Macias) Cp 66.60 0.63 15.70 4.22 0.06 1.54 3.95 3.67 3.13 0.16 S68-4 NAVDAT (Steve Macias) Cp 67.00 0.46 15.60 3.35 0.06 1.16 3.30 4.08 3.08 0.14 S50-4 NAVDAT (Steve Macias) Cp 67.60 0.44 16.00 3.38 0.05 1.01 3.39 4.24 2.91 0.16 S22-8 NAVDAT (Steve Macias) Cp 67.70 0.49 15.10 3.99 0.06 1.46 3.54 3.33 3.46 0.12 S60-4 NAVDAT (Steve Macias) Cp 67.70 0.42 16.00 3.28 0.05 1.06 3.48 4.27 2.90 0.15 S20-7 NAVDAT (Steve Macias) Cp 67.90 0.51 15.90 3.57 0.06 1.30 3.73 3.76 2.78 0.14 S28-8 NAVDAT (Steve Macias) Cp 68.00 0.44 15.20 3.90 0.07 1.38 3.29 3.47 3.35 0.12 234 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 S24-6 NAVDAT (Steve Macias) Cp 68.10 0.42 15.20 3.17 0.05 0.88 2.97 4.05 3.28 0.15 S69-6 NAVDAT (Steve Macias) Cp 68.20 0.50 15.40 3.64 0.06 1.19 3.55 3.96 2.58 0.17 S103-4 NAVDAT (Steve Macias) Cp 68.50 0.32 15.50 2.37 0.05 0.61 2.46 4.07 4.05 0.13 S48-9 NAVDAT (Steve Macias) Cp 68.50 0.36 15.20 2.88 0.06 0.65 2.64 4.33 3.22 0.14 S118-4 NAVDAT (Steve Macias) Cp 71.00 0.26 15.30 2.03 0.04 0.48 2.11 4.01 3.99 0.09 S102-4 NAVDAT (Steve Macias) Cp 71.50 0.26 14.30 2.11 0.04 0.51 1.90 4.01 3.56 0.09 FG 14 NAVDAT (Truschel) Cp 59.47 0.85 17.18 6.19 0.12 4.15 6.67 3.02 2.47 0.16 FG 23 NAVDAT (Truschel) Cp 60.25 0.89 17.70 5.94 0.10 3.48 6.21 3.72 1.69 0.16 FG 09 NAVDAT (Truschel) Cp 61.07 0.88 17.52 5.67 0.09 3.18 5.70 3.85 1.89 0.19 FG 19 NAVDAT (Truschel) Cp 61.47 0.89 16.29 5.95 0.11 3.29 6.07 3.23 2.60 0.16 FG 01 NAVDAT (Truschel) Cp 62.48 0.69 17.74 5.08 0.09 2.75 6.02 3.83 1.68 0.17 FG 06 NAVDAT (Truschel) Cp 64.46 0.64 17.01 4.21 0.07 2.63 5.14 3.96 2.17 0.14 FG 07 NAVDAT (Truschel) Cp 64.89 0.61 16.92 4.37 0.07 2.10 4.87 3.70 2.56 0.12 FG 17 NAVDAT (Truschel) Cp 65.63 0.63 16.23 4.18 0.07 2.13 4.64 3.64 2.74 0.14 FG 33 NAVDAT (Truschel) Cp 66.06 0.51 17.30 3.54 0.06 1.88 4.92 4.31 1.84 0.13 FG 22 NAVDAT (Truschel) Cp 66.24 0.54 16.47 4.19 0.09 1.82 4.60 3.67 2.55 0.12 FG 21 NAVDAT (Truschel) Cp 66.75 0.49 17.55 3.05 0.06 1.26 4.35 4.30 2.69 0.13 FG 24 NAVDAT (Truschel) Cp 67.94 0.45 16.71 3.14 0.06 1.56 4.43 4.01 1.88 0.12 FG 15 NAVDAT (Truschel) Cp 68.22 0.50 16.50 3.13 0.06 1.34 4.33 4.01 2.22 0.13 FG 26 NAVDAT (Truschel) Cp 69.15 0.42 15.98 2.93 0.06 1.52 3.86 4.16 2.37 0.10 FG 34 NAVDAT (Truschel) Cp 69.34 0.42 16.49 2.80 0.04 0.92 3.88 4.52 1.50 0.13 FG 16 NAVDAT (Truschel) Cp 69.51 0.44 15.66 2.65 0.06 1.04 3.32 3.64 3.70 0.13 FG 05 NAVDAT (Truschel) Cp 70.00 0.33 17.09 2.02 0.05 0.64 3.61 5.06 1.55 0.13 FG 32 NAVDAT (Truschel) Cp 70.32 0.32 16.95 1.98 0.04 0.78 3.62 4.99 1.61 0.12 FG 02 NAVDAT (Truschel) Cp 70.68 0.29 17.14 1.72 0.05 0.62 3.19 5.18 2.10 0.11 FG 11 NAVDAT (Truschel) Cp 70.87 0.35 15.90 1.96 0.04 0.76 2.80 4.14 3.14 0.14 FG 10 NAVDAT (Truschel) Cp 71.79 0.31 15.75 2.03 0.04 0.59 2.94 4.61 1.83 0.12 FG 04 NAVDAT (Truschel) Cp 72.02 0.30 16.45 1.80 0.03 0.54 3.43 5.12 1.33 0.10 FG 28 NAVDAT (Truschel) Cp 72.46 0.32 15.34 2.11 0.05 0.62 2.80 4.57 2.01 0.11 FG 08 NAVDAT (Truschel) Cp 72.89 0.19 15.75 1.24 0.04 0.42 2.37 4.62 2.64 0.08 FG 27 NAVDAT (Truschel) Cp 73.48 0.17 15.66 1.19 0.03 0.44 2.55 4.60 2.12 0.06 HD01-21 NAVDAT (Gray Walt) Cp 56.40 1.14 17.24 6.63 0.18 3.59 6.46 4.53 2.21 0.42 HD01-55 NAVDAT (Gray Walt) Cp 57.22 1.32 13.57 9.81 0.16 4.34 4.77 2.48 4.30 0.38 HD01-53 NAVDAT (Gray Walt) Cp 57.90 0.86 17.58 6.33 0.13 3.27 6.00 4.13 1.79 0.27 HD02-107 NAVDAT (Gray Walt) Cp 58.15 0.98 16.73 5.79 0.18 2.50 5.36 4.88 2.73 0.45 HD01-78 NAVDAT (Gray Walt) Cp 76.77 0.10 12.96 0.83 0.03 0.12 0.79 3.55 4.69 0.04 0102-10M NAVDAT (Kylander et al.,) Cp 68.03 0.45 16.77 2.62 0.08 0.71 2.93 4.51 3.61 0.16 0102-13M NAVDAT (Kylander et al.,) Cp 68.62 0.41 16.52 2.54 0.06 0.66 2.77 4.52 3.64 0.15 0102-11C NAVDAT (Kylander et al.,) Cp 69.21 0.37 15.80 2.29 0.05 0.59 2.61 4.35 3.59 0.14 235 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 0105C NAVDAT (Kylander et al.,) Cp 69.88 0.36 15.72 2.03 0.03 0.64 2.45 4.30 3.96 0.13 IP0203 NAVDAT (Kylander et al.,) Cp 73.08 0.11 14.90 1.09 0.02 0.28 0.79 4.59 4.80 0.04 D-75 WAUGH LAKE Cp 61.51 0.88 16.76 6.36 0.11 2.45 4.65 3.95 3.08 0.24 A-43 WAUGH LAKE Cp 63.78 0.80 16.64 4.77 0.26 1.82 4.21 3.35 4.16 0.21 D-121 WAUGH LAKE Cp 65.06 0.67 16.48 4.53 0.10 1.48 3.49 4.38 3.59 0.22 D-108 WAUGH LAKE Cp 69.78 0.42 15.09 2.93 0.06 0.96 2.42 3.48 4.76 0.11 D-70 WAUGH LAKE Cp 70.43 0.37 14.92 2.72 0.06 0.85 2.29 3.40 4.86 0.10 A-56 WAUGH LAKE Cp 49.96 0.73 18.35 8.61 0.14 8.43 10.28 1.85 1.53 0.11 A-58 WAUGH LAKE Cp 71.91 0.27 14.68 2.08 0.07 0.62 1.85 3.60 4.83 0.09 D-112 WAUGH LAKE Tv 56.09 0.76 19.15 7.95 0.23 4.22 4.63 3.95 2.79 0.23 C-76 WAUGH LAKE Jv 56.33 0.99 18.93 7.50 0.13 2.57 5.37 5.84 2.09 0.25 B-35 WAUGH LAKE Jv 58.02 0.71 19.60 6.54 0.04 1.31 1.24 4.65 7.61 0.28 A-106 WAUGH LAKE Cv 58.05 1.23 17.53 7.00 0.13 2.93 6.86 3.91 1.93 0.43 B-14 WAUGH LAKE Cv 59.81 1.18 17.88 6.43 0.10 1.63 4.11 4.15 4.28 0.42 C-97 WAUGH LAKE Jv 60.15 0.85 14.98 8.43 0.13 0.24 5.22 5.71 4.03 0.26 B-109 WAUGH LAKE Jv 60.71 1.06 18.86 9.64 0.12 1.67 2.22 3.02 2.63 0.07 B-15 WAUGH LAKE Cv 63.04 1.14 16.28 6.40 0.09 1.12 3.14 3.76 4.65 0.39 A-65 WAUGH LAKE Tv 63.31 0.97 18.85 5.85 0.06 0.94 2.95 5.11 1.88 0.09 34B WAUGH LAKE Jv 63.45 0.48 15.68 5.31 0.13 1.23 2.85 2.39 8.30 0.18 34A WAUGH LAKE Jv 64.82 0.40 16.74 4.52 0.15 1.81 2.05 4.28 5.06 0.17 A-67 WAUGH LAKE Jv 65.34 0.93 17.31 7.88 0.09 1.00 1.92 2.33 3.15 0.04 A-71 WAUGH LAKE Tv 65.43 0.81 15.36 6.88 0.16 2.02 5.98 0.73 2.43 0.21 B-49A WAUGH LAKE Jv 65.77 0.66 15.26 5.11 0.07 1.59 6.91 1.27 3.12 0.26 C-142 WAUGH LAKE Tv 69.20 0.48 16.45 3.64 0.07 1.18 1.96 3.11 3.86 0.06 D-115 WAUGH LAKE Tv 74.89 0.15 13.43 2.41 0.17 0.53 0.23 4.52 3.60 0.05 MC-34 Lowe Cv 74.30 0.15 13.70 1.41 0.05 0.21 0.85 4.10 4.65 0.05 MC-35 Lowe Cv 74.50 0.16 13.80 1.42 0.04 0.17 0.79 4.20 4.76 0.04 MC-37 Lowe Cv 74.90 0.13 13.60 1.36 0.05 0.18 0.76 4.19 4.53 0.04 MC-38 Lowe Cv 75.10 0.11 13.30 1.21 0.07 0.13 0.61 4.15 4.80 0.03 MC-39 Lowe Cv 75.30 0.10 13.30 1.34 0.11 0.13 0.59 4.12 4.66 0.03 MC-40 Lowe Cv 75.40 0.10 13.30 1.13 0.07 0.17 0.55 4.11 4.82 0.03 MC-41 Lowe Cv 74.60 0.18 13.40 1.50 0.08 0.19 0.80 4.38 4.34 0.06 MC-42 Lowe Cv 74.60 0.19 13.60 1.50 0.08 0.27 0.75 4.19 4.86 0.05 MC-43 Lowe Cv 74.70 0.15 13.30 1.31 0.10 0.54 1.05 3.70 5.02 0.04 MC-44 Lowe Cv 72.90 0.21 13.40 1.80 0.20 0.41 1.90 4.30 4.70 0.07 MC-46 Lowe Cv 75.10 0.13 13.60 1.28 0.06 0.17 0.93 4.13 4.60 0.04 MC-47 Lowe Cv 74.90 0.11 13.50 1.20 0.06 0.17 0.84 3.99 4.88 0.03 MC-51 Lowe Cv 71.30 0.36 14.40 2.65 0.11 0.69 2.40 4.32 3.52 0.09 MC-52 Lowe Cv 70.30 0.39 15.30 2.70 0.09 0.76 1.32 4.97 3.85 0.09 236 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 MC-53 Lowe Cv 70.00 0.43 15.50 2.75 0.08 0.72 1.38 4.96 4.03 0.10 MC-54 Lowe Cv 73.20 0.28 14.00 2.31 0.10 0.49 1.74 4.35 3.38 0.11 MC-55 Lowe Cv 73.40 0.23 13.50 2.10 0.08 0.46 1.62 5.38 2.95 0.07 MC-56 Lowe Cv 71.40 0.31 14.40 2.52 0.07 0.33 0.89 5.73 3.62 0.09 MC-57 Lowe Cv 72.40 0.26 14.10 2.03 0.07 0.45 1.36 4.31 4.47 0.07 MC-59 Lowe Cv 74.10 0.19 13.40 1.94 0.05 0.30 0.49 5.44 3.25 0.06 MC-63 Lowe Cv 69.00 0.43 15.80 2.79 0.08 0.72 1.84 4.59 4.28 0.10 MC-64 Lowe Cv 69.50 0.44 16.00 2.79 0.08 0.64 1.60 4.33 4.40 0.10 MC-67 Lowe Cv 69.70 0.43 15.50 2.97 0.09 0.81 1.79 4.14 3.98 0.11 MC-68 Lowe Cv 70.50 0.40 15.10 2.64 0.09 0.65 1.71 5.07 3.73 0.10 MC-69 Lowe Cv 71.40 0.35 14.20 2.44 0.09 0.58 1.98 4.12 4.10 0.09 MC-70 Lowe Cv 68.80 0.40 15.50 2.87 0.13 0.77 3.22 3.52 4.33 0.10 MC-71 Lowe Cv 69.00 0.39 15.60 2.60 0.06 0.75 1.79 4.84 4.51 0.10 MC-72 Lowe Cv 68.70 0.42 16.00 2.56 0.07 0.66 1.39 5.17 4.46 0.11 MC-73 Lowe Cv 70.40 0.41 15.20 2.72 0.07 0.65 1.55 4.45 4.39 0.11 MC-74 Lowe Cv 70.10 0.42 15.50 2.73 0.09 0.65 1.89 4.60 3.82 0.11 MC-75 Lowe Cv 69.60 0.41 15.70 2.90 0.08 0.74 1.77 4.30 4.28 0.10 MC-81 Lowe Cv 69.20 0.44 16.00 3.02 0.09 0.76 1.93 4.68 4.05 0.10 MC-82 Lowe Cv 70.60 0.48 15.50 3.26 0.09 1.16 2.92 2.47 3.65 0.10 MC-84 Lowe Cv 64.60 0.64 17.20 4.35 0.11 1.38 3.52 4.55 3.17 0.15 MC-85 Lowe Cv 66.80 0.58 16.40 3.56 0.11 1.01 2.21 4.37 4.63 0.13 MC-93 Lowe Cv 73.30 0.22 13.90 1.83 0.10 0.33 2.56 4.30 2.96 0.06 MC-97 Lowe Cv 73.00 0.24 14.00 2.25 0.14 0.52 0.98 4.68 3.85 0.07 MC-98 Lowe Cv 73.90 0.17 13.20 1.93 1.17 0.56 2.13 3.57 3.98 0.05 MC-99 Lowe Cv 75.00 0.16 13.10 1.65 0.11 0.50 1.08 4.15 3.89 0.05 MC-171 Lowe Cv 69.50 0.42 15.60 2.78 0.08 0.73 1.89 4.40 4.04 0.10 MC-172 Lowe Cv 69.30 0.42 16.10 2.84 0.09 0.74 2.06 4.36 3.92 0.10 MC-177 Lowe Cv 71.00 0.35 15.80 2.91 0.08 0.72 1.34 3.37 4.37 0.08 MC-178 Lowe Cv 72.20 0.35 13.60 2.68 0.10 0.74 3.55 2.79 4.00 0.09 MC-180 Lowe Cv 68.30 0.44 17.10 3.03 0.07 0.66 1.64 4.66 3.57 0.10 MC-181 Lowe Cv 70.70 0.40 15.60 2.69 0.08 0.75 2.03 4.37 3.76 0.09 MC-183 Lowe Cv 70.90 0.41 16.10 2.70 0.08 0.63 1.83 3.67 3.87 0.09 MC-187/298 Lowe Cv 68.60 0.43 16.00 3.01 0.08 0.75 1.61 4.89 4.19 0.10 MC-189 Lowe Cv 71.50 0.38 15.40 2.73 0.08 1.05 2.33 2.84 3.45 0.08 MC-226 Lowe Cv 68.20 0.46 15.80 3.39 0.08 1.33 2.27 4.34 4.11 0.10 MC-246 Lowe Cv 75.60 0.09 14.00 1.14 0.05 0.22 1.06 6.18 1.44 0.02 MC-248 Lowe Cv 75.80 0.11 13.30 1.15 0.05 0.15 0.65 4.03 4.77 0.02 MC-249/281 Lowe Cv 75.80 0.08 13.40 1.20 0.06 0.14 0.66 4.23 4.80 0.02 MC-250 Lowe Cv 76.30 0.05 13.30 0.83 0.05 0.16 0.65 4.20 4.62 0.01 237 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 MC-251 Lowe Cv 76.20 0.10 13.50 1.13 0.08 0.21 0.74 3.88 4.60 0.02 MC-252 Lowe Cv 75.80 0.10 13.30 1.29 0.12 0.15 0.44 3.25 5.66 0.02 MC-253 Lowe Cv 75.50 0.09 13.50 1.25 0.08 0.19 0.71 3.98 4.63 0.02 MC-258 Lowe Cv 75.50 0.12 13.50 1.23 0.05 0.18 0.79 4.12 4.33 0.04 MC-259 Lowe Cv 76.30 0.12 13.20 1.22 0.06 0.13 0.80 3.81 4.60 0.04 MC-260 Lowe Cv 76.30 0.05 13.40 1.11 0.09 0.21 0.61 3.62 4.72 0.02 MC-1 Lowe Cv 63.80 0.80 16.60 5.15 0.12 1.29 5.03 3.86 2.65 0.18 MC-3 Lowe Cv 75.00 0.21 13.30 1.53 0.06 0.18 0.65 4.31 4.76 0.03 MC-8 Lowe Cv 70.20 0.45 15.20 2.94 0.09 0.57 1.84 4.72 3.73 0.11 MC-13 Lowe Cv 61.80 0.86 16.00 6.27 0.20 2.90 5.38 4.28 2.10 0.22 MC-17 Lowe Cv 67.90 0.37 17.80 2.17 0.08 0.31 1.05 7.24 3.00 0.08 MC-118/278 Lowe Cv 72.80 0.25 14.60 2.17 0.06 0.27 0.72 5.06 4.22 0.04 MC-119 Lowe Cv 75.90 0.15 13.20 1.50 0.04 0.15 0.41 4.46 4.44 0.02 MC-121 Lowe Cv 74.50 0.23 13.40 1.79 0.06 0.26 0.96 4.02 4.21 0.04 MC-125 Lowe Cv 72.10 0.29 14.70 2.32 0.07 0.55 0.93 3.92 5.20 0.08 MC-126 Lowe Cv 70.40 0.42 15.10 2.87 0.08 0.73 1.99 4.52 3.93 0.10 MC-127 Lowe Cv 74.40 0.28 13.30 1.89 0.06 0.45 1.10 3.72 4.42 0.06 MC-128 Lowe Cv 73.40 0.32 14.60 1.62 0.02 0.14 1.24 4.33 4.27 0.04 MC-129 Lowe Cv 73.10 0.31 14.80 1.77 0.02 0.17 1.13 4.43 4.39 0.04 MC-132 Lowe Cv 72.70 0.36 15.10 2.22 0.08 0.36 0.93 3.46 4.54 0.07 MC-137 Lowe Cv 73.30 0.22 13.90 2.32 0.05 0.28 1.54 3.86 4.05 0.03 MC-142 Lowe Cv 74.90 0.20 13.40 1.48 0.04 0.13 0.35 4.48 4.64 0.02 MC-143 Lowe Cv 70.50 0.42 14.80 2.81 0.08 0.71 2.00 4.30 3.98 0.11 MC-144 Lowe Cv 74.20 0.20 13.90 1.60 0.05 0.16 0.47 4.53 4.70 0.02 MC-145 Lowe Cv 69.90 0.46 15.20 3.16 0.10 0.81 2.13 4.25 3.93 0.17 MC-270 Lowe Cv 72.20 0.36 14.40 2.91 0.06 0.74 2.24 3.46 3.62 0.08 MC-279 Lowe Cv 75.40 0.20 13.50 1.53 0.06 0.14 0.59 4.83 4.43 0.02 MC-283 Lowe Cv 67.10 0.65 16.20 4.71 0.08 1.13 3.49 4.56 1.74 0.17 MC-284 Lowe Cv 68.20 0.60 15.50 4.55 0.08 0.82 3.31 4.31 1.96 0.16 MC-286 Lowe Cv 76.10 0.19 13.30 1.46 0.03 0.12 0.43 4.50 4.68 0.02 MC-290 Lowe Cv 65.40 0.76 16.20 5.01 0.11 1.89 4.05 3.95 3.03 0.17 MC-292 Lowe Cv 76.40 0.17 13.20 1.36 0.05 0.12 0.46 4.47 4.59 0.01 MC-294 Lowe Cv 76.00 0.20 13.00 1.48 0.04 0.05 0.54 4.71 4.03 0.03 MC-296 Lowe Cv 75.10 0.22 13.60 1.51 0.05 0.10 0.44 4.06 5.43 0.03 MC-400 Lowe Cv 65.10 0.64 16.10 4.57 0.10 1.47 3.67 4.45 2.71 0.17 MC-402 Lowe Cv 65.00 0.69 16.60 4.94 0.11 1.54 3.90 5.28 1.34 0.19 MC-405 Lowe Cv 63.70 0.75 17.90 4.36 0.10 1.42 3.93 5.17 2.65 0.21 MC-406 Lowe Cv 64.20 0.74 17.30 4.21 0.11 1.43 3.83 4.92 2.75 0.20 MC-407 Lowe Cv 65.60 0.67 17.20 3.56 0.08 1.10 3.65 4.54 3.23 0.17 238 (Appendix A continued) Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 MC-45 Lowe Cp 73.20 0.27 14.10 2.41 0.17 0.38 0.84 3.90 4.67 0.08 MC-49 Lowe Cp 73.40 0.26 14.00 2.12 0.08 0.40 0.84 4.48 4.40 0.07 MC-104 Lowe Cp 76.00 0.10 13.10 1.68 0.07 0.11 0.41 3.74 5.13 0.01 MC-105 Lowe Cp 74.70 0.16 13.30 1.79 0.09 0.16 0.55 3.53 5.59 0.02 MC-204 Lowe Cp 75.50 0.13 13.00 1.56 0.06 0.10 0.57 3.79 5.11 0.02 MC-206 Lowe Cp 73.10 0.20 14.10 2.71 0.04 0.50 1.39 4.75 3.40 0.06 MC-207 Lowe Cp 75.10 0.15 13.20 1.69 0.08 0.12 0.49 4.03 5.14 0.02 MC-208 Lowe Cp 74.70 0.16 13.00 1.89 0.08 0.14 0.64 3.24 5.69 0.02 MC-209 Lowe Cp 75.30 0.14 13.10 1.54 0.08 0.11 0.59 3.16 5.55 0.00 MC-210 Lowe Cp 76.10 0.13 13.00 1.58 0.06 0.10 0.43 3.91 5.19 0.01 MC-211 Lowe Cp 74.30 0.18 13.30 1.87 0.09 0.16 0.63 4.08 5.05 0.03 MC-212 Lowe Cp 74.30 0.21 13.50 1.93 0.08 0.19 0.70 3.88 5.05 0.05 MC-214 Lowe Cp 75.10 0.20 13.40 1.78 0.06 0.28 0.66 4.05 4.79 0.05 MC-215 Lowe Cp 74.10 0.25 13.90 2.14 0.18 0.35 0.71 3.81 5.05 0.06 MC-222 Lowe Cp 73.70 0.23 13.50 2.00 0.12 0.32 0.89 4.20 4.55 0.06 MC-223 Lowe Cp 74.20 0.22 13.10 2.20 0.09 0.33 0.94 3.73 4.72 0.06 MC-224/299 Lowe Cp 74.60 0.25 13.50 1.70 0.11 0.32 0.61 4.05 4.63 0.06 MC-225 Lowe Cp 73.40 0.22 13.90 2.03 0.07 0.29 0.70 4.32 4.84 0.05 MC-234 Lowe Cp 73.60 0.32 13.60 1.79 0.03 0.23 0.79 3.69 5.58 0.05 MC-10 Lowe Cp 74.80 0.28 13.00 1.76 0.03 0.42 1.17 3.12 5.13 0.07 MC-15 Lowe Cp 75.00 0.31 12.80 1.82 0.03 0.45 1.11 3.25 4.98 0.07 MC-24 Lowe Cp 75.30 0.25 12.70 1.56 0.05 0.34 0.89 2.92 5.61 0.06 MC-113 Lowe Cp 73.90 0.32 13.50 2.17 0.06 0.60 1.48 3.32 4.54 0.08 MC-134 Lowe Cp 74.40 0.28 13.30 1.89 0.06 0.45 1.10 3.72 4.42 0.06 MC-138 Lowe Cp 73.60 0.33 13.90 2.15 0.07 0.60 1.43 3.96 4.15 0.08 MC-268 Lowe Cp 76.30 0.11 12.80 1.11 0.05 0.09 0.37 4.24 4.70 0.00 MC-271 Lowe Cp 76.50 0.13 12.70 1.50 0.02 0.12 0.82 3.60 4.51 0.01 MC-273 Lowe Cp 77.50 0.09 12.20 1.15 0.01 0.02 0.41 3.73 4.63 0.00 MC-274 Lowe Cp 76.10 0.15 13.10 1.47 0.03 0.14 1.01 3.63 4.48 0.02 MC-4 Lowe Cp 66.80 0.50 17.00 3.07 0.08 0.98 3.18 5.04 2.92 0.15 MC-9 Lowe Cp 63.10 0.80 17.40 5.41 0.11 1.90 4.38 4.21 2.64 0.28 MC-22 Lowe Cp 68.30 0.51 16.10 3.09 0.08 0.82 2.39 4.44 3.65 0.15 MC-117 Lowe Cp 67.40 0.52 16.20 3.40 0.08 1.05 2.95 4.50 3.31 0.12 MC-120 Lowe Cp 71.10 0.39 15.00 2.60 0.08 0.59 1.84 4.82 3.38 0.08 MC-122 Lowe Cp 66.60 0.53 16.60 3.41 0.09 1.09 3.21 4.72 3.11 0.15 MC-140 Lowe Cp 68.20 0.51 16.10 3.32 0.08 0.94 2.86 4.71 3.20 0.15 MC-272 Lowe Cp 70.00 0.49 15.10 3.31 0.09 0.99 2.55 4.17 3.48 0.13 MC-282 Lowe Cp 67.50 0.45 17.00 2.68 0.07 0.92 2.86 4.59 3.44 0.16 MC-289 Lowe Cp 66.70 0.52 16.20 3.50 0.09 1.12 2.98 4.66 3.05 0.15 239 Sample ID Data source Code SiO2 TiO2 Al2O3 FeO* MnO MgO CaO Na2O K2O P2O5 MC-295 Lowe Cp 69.90 0.46 14.80 3.14 0.08 1.03 2.69 4.15 3.21 0.12 MC-23 Lowe Cp 72.00 0.31 14.80 2.30 0.04 0.52 2.38 3.61 3.61 0.11 MC-25 Lowe Cp 75.00 0.11 13.80 0.98 0.04 0.14 1.00 3.90 4.46 0.03 MC-27 Lowe Cp 69.20 0.41 15.80 2.92 0.07 0.93 2.70 4.18 3.24 0.14 MC-28 Lowe Cp 75.10 0.15 13.30 1.03 0.04 0.22 0.83 2.90 5.87 0.04 MC-124 Lowe Cp 74.10 0.20 13.80 1.61 0.04 0.34 1.67 3.16 4.84 0.05 MC-276 Lowe Cp 71.20 0.30 15.30 2.20 0.06 0.67 2.07 3.73 4.88 0.07 MC-29 Lowe Cp 75.80 0.12 13.10 0.95 0.02 0.10 0.83 3.18 5.43 0.02 MC-111 Lowe Cp 74.80 0.22 13.60 1.70 0.06 0.16 0.54 4.50 4.50 0.03 MC-280 Lowe Cp 76.20 0.12 13.50 1.07 0.04 0.18 0.80 3.22 5.56 0.02 MC-12 Lowe Cp 60.80 1.03 16.90 6.34 0.15 2.28 5.32 4.18 2.61 0.33 MC-16 Lowe Cp 61.70 1.01 16.60 6.21 0.16 2.30 5.24 4.00 2.50 0.29 MC-115 Lowe Cp 61.00 1.04 17.00 6.11 0.15 2.04 5.02 4.75 2.49 0.35 240 APPENDIX B: REE AND TRACE ELEMENT DATA (Appendix B continued) Sample ID BCE-9A L40B L40A L39 L43 L37 L38 L35 Data Souece iron mt soldier lake soldier lake soldier lake soldier lake soldier lake soldier lake soldier lake Code Cp Jp Jp Jp Jp Jp Jp Jp La ppm 29.45 16.22 22.08 24.88 24.90 20.80 13.94 24.70 Ce ppm 54.41 39.08 39.39 43.88 43.55 37.01 26.30 43.94 Pr ppm 6.05 5.72 4.41 4.80 4.69 4.09 3.10 4.70 Nd ppm 21.26 24.23 15.67 16.62 16.33 14.42 11.65 15.97 Sm ppm 4.29 5.87 3.04 3.08 3.05 2.84 2.52 2.96 E u ppm 1.03 1.34 0.84 0.81 0.82 0.77 0.74 0.43 Gd ppm 3.79 5.24 2.57 2.56 2.45 2.42 2.14 2.45 Tb ppm 0.61 0.81 0.39 0.38 0.36 0.37 0.34 0.39 Dy ppm 3.49 4.67 2.19 2.17 2.12 2.11 2.03 2.34 Ho ppm 0.69 0.92 0.44 0.43 0.43 0.42 0.40 0.49 E r ppm 1.89 2.42 1.18 1.19 1.15 1.16 1.08 1.42 Tm ppm 0.28 0.35 0.17 0.18 0.17 0.17 0.17 0.23 Yb ppm 1.79 2.27 1.16 1.18 1.14 1.14 1.13 1.58 Lu ppm 0.30 0.35 0.19 0.20 0.19 0.19 0.18 0.27 Ba ppm 650 599 1170 961 1084 1099 1019 549 Th ppm 17.41 4.83 10.06 14.34 13.10 11.47 11.60 23.54 Nb ppm 10.04 8.61 6.16 6.27 6.05 6.11 5.85 8.46 Y ppm 18.92 24.37 11.86 11.87 11.47 11.39 10.93 13.97 Hf ppm 4.00 2.87 3.08 3.34 3.14 3.08 3.04 3.09 Ta ppm 1.11 0.57 0.60 0.64 0.65 0.68 0.64 1.18 U ppm 5.08 1.72 3.15 5.44 4.13 4.15 3.41 5.88 Pb ppm 18.63 8.25 10.27 11.51 12.23 12.03 11.67 31.44 Rb ppm 114.3 133.2 118.8 118.8 122.3 125.5 126.5 193.8 Cs ppm 5.05 5.79 4.46 4.17 4.06 4.17 4.32 15.32 Sr ppm 329 403 425 413 414 389 383 137 Sc ppm 12.5 17.4 7.2 7.0 6.9 6.8 6.5 5.4 Zr ppm 143 102 105 112 104 100 100 82 Ni ppm 5 27.00 3.00 2.00 2.00 2.00 3.00 0.00 V ppm 100 165.00 66.00 64.00 63.00 61.00 61.00 29.00 Ga ppm 17 18.00 16.00 16.00 15.00 15.00 14.00 12.00 Cu ppm 11 59.00 7.00 40.00 12.00 13.00 25.00 3.00 Zn ppm 88 104.00 37.00 36.00 39.00 34.00 33.00 21.00 241 (Appendix B continued) Sample ID L102 G6B S14 G6A G6C L109 L95 L105 Data Souece soldier lake soldier lake soldier lake soldier lake soldier lake soldier lake soldier lake soldier lake Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 29.23 29.63 32.90 34.66 28.40 32.89 30.92 29.40 Ce ppm 61.39 52.73 62.62 62.50 53.42 60.36 56.70 55.76 Pr ppm 7.15 6.01 7.11 6.87 5.80 6.72 6.32 6.27 Nd ppm 25.42 22.28 25.46 23.65 20.17 23.22 22.15 22.12 Sm ppm 4.90 4.48 4.67 4.12 3.91 4.30 4.13 4.05 E u ppm 0.96 1.14 1.10 1.06 0.97 0.95 0.94 0.91 Gd ppm 4.14 3.57 3.51 3.20 3.23 3.37 3.21 3.17 Tb ppm 0.65 0.52 0.52 0.45 0.54 0.51 0.49 0.49 Dy ppm 3.80 2.91 2.91 2.56 3.26 2.96 2.82 2.77 Ho ppm 0.78 0.55 0.57 0.50 0.69 0.57 0.56 0.56 E r ppm 2.24 1.46 1.49 1.34 2.02 1.59 1.54 1.51 Tm ppm 0.35 0.22 0.23 0.20 0.31 0.24 0.23 0.24 Yb ppm 2.40 1.37 1.44 1.32 2.06 1.60 1.54 1.53 Lu ppm 0.39 0.22 0.23 0.23 0.35 0.26 0.25 0.25 Ba ppm 592 1097 1272 1208 847 1073 1053 1033 Th ppm 7.66 10.34 15.95 18.48 11.11 22.88 23.36 18.27 Nb ppm 19.53 9.18 9.54 9.13 7.95 10.48 9.97 10.38 Y ppm 22.32 14.54 15.37 13.29 18.26 15.98 15.12 15.19 Hf ppm 4.28 3.92 4.94 4.75 3.61 4.55 4.49 4.46 Ta ppm 2.55 0.68 0.81 0.81 0.62 1.28 1.20 1.26 U ppm 16.21 4.79 4.54 5.18 3.16 7.84 9.20 8.77 Pb ppm 14.66 12.72 12.47 13.19 17.22 17.84 18.00 15.80 Rb ppm 280.0 131.2 136.2 138.1 187.4 156.0 165.4 180.4 Cs ppm 23.78 5.34 5.13 7.27 14.56 4.71 7.35 7.67 Sr ppm 335 464 517 472 124 404 394 381 Sc ppm 15.8 10.2 6.4 6.0 8.3 5.8 5.2 5.4 Zr ppm 144 132 182 169 127 156 151 149 Ni ppm 9.00 26.00 3.00 4.00 0.00 2.00 2.00 2.00 V ppm 161.00 108.00 73.00 66.00 61.00 59.00 55.00 57.00 Ga ppm 25.00 18.00 18.00 18.00 16.00 18.00 17.00 17.00 Cu ppm 20.00 9.00 3.00 3.00 9.00 4.00 5.00 1.00 Zn ppm 116.00 85.00 41.00 55.00 40.00 52.00 51.00 41.00 242 (Appendix B continued) Sample ID S11 L100 L98 B-135 B-24 B-130B HD02-119 B-130A Data Souece soldier lake soldier lake soldier lake WAUGH LAKE WAUGH LAKE WAUGH LAKE TB WAUGH LAKE Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 33.01 35.89 38.94 15.06 22.83 23.77 21.00 21.84 Ce ppm 58.66 62.14 63.82 28.65 46.85 47.37 41.40 43.62 Pr ppm 6.30 6.48 6.48 3.56 5.87 5.87 5.13 5.41 Nd ppm 21.67 21.50 21.03 14.59 23.39 23.36 21.10 21.34 Sm ppm 3.86 3.72 3.59 3.28 4.86 5.02 4.31 4.56 E u ppm 0.87 0.80 0.74 1.18 1.34 1.31 1.18 1.22 Gd ppm 3.01 2.83 2.75 3.14 4.43 4.39 3.80 3.90 Tb ppm 0.46 0.44 0.44 0.48 0.69 0.68 0.61 0.62 Dy ppm 2.61 2.47 2.57 2.81 4.04 3.96 3.39 3.60 Ho ppm 0.52 0.49 0.53 0.54 0.79 0.77 0.64 0.71 E r ppm 1.43 1.42 1.49 1.42 2.16 2.00 1.94 1.89 Tm ppm 0.22 0.22 0.24 0.19 0.31 0.27 0.29 0.28 Yb ppm 1.47 1.54 1.68 1.20 1.93 1.69 1.80 1.83 Lu ppm 0.24 0.26 0.28 0.19 0.30 0.26 0.27 0.28 Ba ppm 933 947 937 1317 736 1061 715.00 636 Th ppm 25.70 28.11 35.31 1.15 9.39 5.17 14.30 10.84 Nb ppm 10.29 10.69 11.15 3.50 6.85 7.63 7.70 7.19 Y ppm 14.60 14.04 14.86 13.80 20.64 19.30 18.00 18.77 Hf ppm 4.50 4.50 4.28 1.55 3.96 4.35 3.60 3.67 Ta ppm 1.12 1.28 1.60 0.21 0.59 0.47 0.82 0.81 U ppm 10.41 12.27 18.96 0.45 3.31 1.59 6.07 6.40 Pb ppm 19.48 20.39 25.20 10.45 11.89 14.20 12.00 15.19 Rb ppm 180.0 201.8 196.2 53.9 94.4 70.5 104.00 76.9 Cs ppm 8.23 6.39 9.96 1.22 4.54 2.31 7.00 5.44 Sr ppm 372 330 295 587 626 677 538.00 679 Sc ppm 5.2 4.3 3.5 22.9 18.4 13.5 11.7 Zr ppm 147 138 132 58 148 156 120.00 130 Ni ppm 1.00 1.00 0.00 14.00 V ppm 53.00 45.00 38.00 159.00 Ga ppm 16.00 17.00 15.00 21.00 Cu ppm 2.00 2.00 1.00 Zn ppm 53.00 47.00 41.00 93.00 243 (Appendix B continued) Sample ID HD01-48 TML1 HD01-50 HD01-35 HD02-105 FS-nonspec1 HD02-92 HD01-71 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 29.20 22.61 21.60 28.00 20.30 47.87 28.20 31.30 Ce ppm 61.20 44.30 40.70 52.10 33.00 78.78 48.70 58.10 Pr ppm 7.09 5.17 4.76 5.95 3.44 8.17 5.40 7.04 Nd ppm 28.70 20.05 19.70 23.70 13.10 29.67 20.80 28.40 Sm ppm 5.82 4.06 4.02 4.72 2.48 5.61 3.94 5.64 E u ppm 1.28 0.96 1.12 1.13 0.79 1.14 1.00 1.16 Gd ppm 5.11 3.51 3.42 3.96 2.18 4.39 3.38 4.92 Tb ppm 0.79 0.51 0.57 0.67 0.33 0.65 0.55 0.79 Dy ppm 4.40 2.95 3.08 3.62 1.77 3.55 3.09 4.26 Ho ppm 0.82 0.56 0.58 0.70 0.34 0.66 0.58 0.79 E r ppm 2.32 1.58 1.64 2.09 0.99 1.75 1.76 2.36 Tm ppm 0.35 0.23 0.26 0.33 0.14 0.25 0.27 0.36 Yb ppm 2.17 1.48 1.58 2.00 0.90 1.55 1.69 2.03 Lu ppm 0.31 0.22 0.25 0.31 0.14 0.24 0.26 0.31 Ba ppm 752.00 450.84 730.00 831.00 1178.00 827.47 714.00 854.00 Th ppm 13.30 14.36 17.70 16.10 11.30 22.57 18.80 29.50 Nb ppm 8.30 7.60 7.10 9.00 4.90 7.82 7.50 8.70 Y ppm 22.00 16.13 15.00 20.00 9.00 18.65 16.00 21.00 Hf ppm 4.40 2.10 3.60 4.20 3.90 4.69 3.70 5.00 Ta ppm 0.49 0.51 0.62 0.93 0.24 0.74 0.87 0.93 U ppm 3.14 5.47 7.38 7.28 3.35 5.73 7.23 8.71 Pb ppm 11.00 12.00 18.00 14.00 16.00 12.73 23.00 14.00 Rb ppm 110.00 136.22 104.00 137.00 100.00 110.19 131.00 154.00 Cs ppm 4.10 7.47 7.20 9.90 4.70 4.77 6.80 9.00 Sr ppm 500.00 501.80 524.00 489.00 623.00 548.53 491.00 428.00 Sc ppm Zr ppm 151.00 74.10 123.00 149.00 139.00 154.32 125.00 164.00 Ni ppm 13.00 13.32 14.00 13.00 8.00 11.00 12.00 8.00 V ppm 164.00 139.94 144.00 151.00 122.00 126.00 129.00 124.00 Ga ppm 18.00 20.13 19.00 20.00 20.00 19.00 20.00 19.00 Cu ppm 31.01 17.00 Zn ppm 116.00 85.14 97.00 110.00 83.00 84.00 78.00 95.00 244 (Appendix B continued) Sample ID M-332 HD01-72 SM3 HD01-73 Z-340 TS 27 TM 33 TM 32 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 19.10 21.30 20.20 26.80 29.85 27.80 27.46 33.38 Ce ppm 36.90 31.80 44.10 51.00 61.01 58.81 53.94 75.04 Pr ppm 4.67 3.07 5.20 5.64 7.52 6.85 5.89 9.26 Nd ppm 17.90 10.40 21.20 21.40 28.87 24.49 21.42 34.84 Sm ppm 3.70 1.79 3.70 3.71 5.93 4.36 3.95 6.52 E u ppm 0.97 0.81 1.08 1.03 1.30 1.07 0.92 1.20 Gd ppm 3.42 1.58 2.92 2.95 4.89 3.57 3.17 5.21 Tb ppm 0.51 0.25 0.52 0.45 0.73 0.52 0.45 0.75 Dy ppm 2.48 1.36 2.47 2.45 4.11 2.85 2.51 4.26 Ho ppm 0.48 0.27 0.46 0.46 0.77 0.56 0.47 0.79 E r ppm 1.53 0.80 1.25 1.36 1.95 1.62 1.30 2.24 Tm ppm 0.20 0.12 0.19 0.21 0.29 0.24 0.19 0.32 Yb ppm 1.30 0.82 1.12 1.36 1.68 1.67 1.31 2.12 Lu ppm 0.22 0.16 0.17 0.22 0.27 0.25 0.19 0.30 Ba ppm 871.60 907.00 997.70 579.00 788.26 805.72 740.89 730.74 Th ppm 15.10 4.85 13.50 13.40 24.96 23.63 22.57 22.96 Nb ppm 6.00 4.50 7.00 8.60 9.96 9.10 8.50 11.50 Y ppm 13.30 7.00 13.00 13.00 20.25 15.57 13.61 22.77 Hf ppm 4.00 4.40 4.80 4.60 4.79 2.10 2.90 3.00 Ta ppm <0.5 0.34 0.50 0.80 0.92 0.92 0.79 1.20 U ppm 8.31 4.27 4.70 5.05 9.63 17.99 5.27 7.12 Pb ppm 16.00 12.00 2.10 20.00 12.89 14.10 14.90 15.60 Rb ppm 141.00 127.00 108.80 123.00 106.82 130.40 118.74 131.67 Cs ppm 11.40 5.50 7.60 4.90 7.39 8.49 5.43 5.32 Sr ppm 575.30 523.00 680.60 484.00 566.61 502.60 583.30 549.50 Sc ppm Zr ppm 130.20 158.00 151.40 156.00 156.32 62.70 98.80 93.60 Ni ppm 10.00 8.00 4.40 7.00 6 6.77 6.10 5.56 V ppm 97.00 106.00 99.00 116.00 114 94.76 83.31 79.16 Ga ppm 17.00 20.00 20.30 22.00 18.39 18.99 18.99 Cu ppm 14.00 25.50 17 18.05 12.45 19.51 Zn ppm 60.00 93.00 51.00 97.00 86 69.06 63.66 63.62 245 (Appendix B continued) Sample ID HD01-70 HD02-114 HD02-115 HD02-106 TS 24 HD02-112 Y01-5 SM-4 Data Souece TB TB TB TB TB TB TB NAVDAT (Scott et al., ) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 15.40 26.80 27.20 22.10 27.06 24.50 23.60 25 Ce ppm 28.40 52.40 49.90 41.40 52.10 45.00 42.80 53.3 Pr ppm 3.19 6.23 5.79 5.07 6.12 5.13 4.52 6.1 Nd ppm 12.00 24.60 22.60 20.90 23.23 19.50 17.20 23.2 Sm ppm 2.52 4.54 4.10 3.81 4.41 3.34 3.07 3.9 E u ppm 0.62 1.35 1.16 1.13 0.97 0.99 0.84 1 Gd ppm 2.16 3.97 3.37 3.18 3.67 2.58 2.40 2.9 Tb ppm 0.35 0.59 0.49 0.48 0.53 0.36 0.38 0.5 Dy ppm 2.03 3.13 2.58 2.41 2.95 1.82 2.05 2.2 Ho ppm 0.39 0.59 0.47 0.45 0.55 0.34 0.39 0.4 E r ppm 1.17 1.74 1.39 1.29 1.53 0.92 1.13 1.2 Tm ppm 0.18 0.26 0.21 0.19 0.22 0.13 0.18 0.2 Yb ppm 1.12 1.60 1.23 1.07 1.44 0.82 1.13 1.2 Lu ppm 0.18 0.25 0.19 0.16 0.21 0.12 0.18 Ba ppm 738.00 790.00 959.00 1356.00 684.27 1133.00 875.00 1022 Th ppm 71.40 12.50 23.40 6.46 22.20 16.90 15.50 12.8 Nb ppm 5.60 8.90 7.60 6.20 8.00 7.00 6.10 8.4 Y ppm 10.00 17.00 12.00 12.00 14.73 9.00 13.00 12.1 Hf ppm 3.70 5.20 4.00 3.90 2.60 3.00 3.10 3.1 Ta ppm 0.48 0.92 0.82 0.41 0.68 0.67 0.73 0.9 U ppm 22.40 10.70 6.23 3.20 6.46 4.91 5.86 4.4 Pb ppm 26.00 8.00 13.00 16.00 13.10 19.00 86.00 1.6 Rb ppm 181.00 108.00 92.00 74.00 107.21 95.00 126.00 100 Cs ppm 8.30 9.70 3.50 4.60 8.35 2.10 10.10 4.3 Sr ppm 353.00 583.00 701.00 745.00 491.30 679.00 538.00 642 Sc ppm 6 Zr ppm 119.00 174.00 137.00 140.00 76.80 103.00 106.00 101 Ni ppm 8.00 7.00 6.00 9.00 6.58 4.00 8.00 2.9 V ppm 77.00 140.00 110.00 108.00 92.20 74.00 94.00 68 Ga ppm 17.00 23.00 22.00 21.00 19.19 20.00 19.00 18.4 Cu ppm 18.44 9.3 Zn ppm 80.00 99.00 89.00 92.00 73.44 81.00 218.00 51 246 (Appendix B continued) Sample ID SM4 TS-310A HD02-97 HD02-113 HD02-120 near FS64 HD01-30 T-450 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 25.00 35.20 31.20 25.00 30.60 22.47 35.10 32.96 Ce ppm 53.30 69.62 54.20 42.30 48.30 41.92 50.90 69.18 Pr ppm 6.05 8.05 5.95 4.61 5.30 4.62 5.12 8.39 Nd ppm 23.20 29.19 22.20 17.20 20.00 17.50 18.80 31.01 Sm ppm 3.90 4.93 3.66 3.07 3.39 3.56 2.98 5.82 E u ppm 1.02 1.20 1.05 0.90 0.99 0.89 0.92 1.16 Gd ppm 2.86 3.47 2.85 2.53 2.59 2.82 2.25 4.41 Tb ppm 0.46 0.45 0.40 0.37 0.38 0.42 0.32 0.62 Dy ppm 2.15 2.33 2.03 1.97 1.84 2.29 1.60 3.24 Ho ppm 0.40 0.42 0.36 0.37 0.33 0.43 0.29 0.58 E r ppm 1.19 1.07 1.07 1.13 0.98 1.12 0.84 1.51 Tm ppm 0.18 0.15 0.16 0.17 0.14 0.17 0.13 0.21 Yb ppm 1.18 0.90 0.98 1.05 0.87 1.03 0.78 1.31 Lu ppm 0.16 0.14 0.15 0.16 0.14 0.17 0.13 0.21 Ba ppm 1021.90 636.15 840.00 984.00 1044.00 828.24 1045.00 945.52 Th ppm 12.80 16.92 13.80 16.80 16.30 14.94 14.80 19.21 Nb ppm 8.40 9.80 10.40 6.20 7.60 7.84 7.40 12.99 Y ppm 12.10 11.24 11.00 11.00 8.00 12.09 9.00 15.92 Hf ppm 3.10 5.42 3.50 2.80 3.90 4.02 3.50 4.20 Ta ppm 0.90 0.75 0.94 0.69 0.71 0.80 0.69 1.29 U ppm 4.40 3.89 5.69 6.52 5.32 5.01 5.07 6.34 Pb ppm 1.60 12.63 25.00 11.00 25.00 14.26 26.00 15.42 Rb ppm 100.20 113.69 132.00 95.00 113.00 123.53 104.00 165.21 Cs ppm 4.30 6.38 15.70 4.60 4.40 8.94 5.30 11.54 Sr ppm 641.60 700.71 647.00 572.00 653.00 523.50 629.00 554.63 Sc ppm Zr ppm 101.30 195.87 128.00 91.00 142.00 129.17 130.00 140.06 Ni ppm 2.90 6 8.00 6.00 5.00 6.00 4.00 4 V ppm 68.00 96 79.00 72.00 78.00 80.00 77.00 77 Ga ppm 18.40 21.00 17.00 21.00 19.00 20.00 Cu ppm 9.30 3 9.00 4 Zn ppm 51.00 103 97.00 73.00 78.00 77.00 123.00 62 247 (Appendix B continued) Sample ID HD01-67 CPL-275 HD01-10 HD01-75 BTL 73 TS 26 TML2 HD01-74 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 37.90 31.80 44.90 28.30 32.20 30.60 61.42 27.20 Ce ppm 55.30 51.90 53.50 42.50 59.35 60.06 87.00 55.90 Pr ppm 5.33 5.56 4.91 4.19 6.46 6.87 7.89 6.30 Nd ppm 19.50 19.90 17.90 14.70 24.23 25.35 25.31 23.10 Sm ppm 3.28 3.49 2.93 2.42 4.72 4.43 3.66 4.00 E u ppm 0.89 0.95 0.85 0.76 1.15 1.09 0.93 0.99 Gd ppm 2.52 2.65 2.02 1.87 3.59 3.26 2.68 3.27 Tb ppm 0.41 0.36 0.30 0.28 0.50 0.43 0.36 0.49 Dy ppm 2.14 1.90 1.47 1.48 2.65 2.27 1.95 2.65 Ho ppm 0.39 0.35 0.26 0.28 0.49 0.41 0.37 0.51 E r ppm 1.14 0.87 0.72 0.84 1.24 1.10 1.07 1.55 Tm ppm 0.18 0.12 0.11 0.13 0.18 0.16 0.16 0.23 Yb ppm 1.14 0.79 0.73 0.81 1.14 1.04 1.12 1.49 Lu ppm 0.18 0.13 0.12 0.13 0.19 0.15 0.18 0.23 Ba ppm 894.00 892 1134.00 1228.00 823 1040.98 1023.54 918.00 Th ppm 27.40 22.81 20.10 14.50 17.83 10.60 49.18 21.90 Nb ppm 7.50 7.38 7.40 5.60 9.69 9.00 11.40 9.90 Y ppm 11.00 9.31 7.00 7.00 13.84 11.22 11.39 15.00 Hf ppm 3.50 3.48 3.70 3.10 3.65 2.30 2.20 3.30 Ta ppm 0.84 0.67 0.63 0.53 0.93 0.74 1.00 1.19 U ppm 5.97 5.36 9.75 4.54 6.02 4.49 11.14 13.60 Pb ppm 13.00 16.98 26.00 25.00 15.65 15.50 17.50 22.00 Rb ppm 120.00 113.6 158.00 130.00 101.6 86.53 119.37 149.00 Cs ppm 7.20 4.36 7.20 4.20 4.44 3.17 6.49 6.60 Sr ppm 486.00 597 565.00 530.00 570 631.10 565.90 444.00 Sc ppm Zr ppm 114.00 116 130.00 102.00 117 74.50 70.30 103.00 Ni ppm 6.00 1.11 5.00 6.00 2.54 4.11 4.45 4.00 V ppm 82.00 66.90 75.00 8.00 79.97 65.63 68.51 79.00 Ga ppm 19.00 18.70 21.00 19.00 18.6 18.88 18.82 18.00 Cu ppm 4.10 7.1 15.71 10.00 Zn ppm 86.00 64.30 164.00 81.00 67.0 60.77 65.35 81.00 248 (Appendix B continued) Sample ID TM 30 M-330-1 HD01-6 BTL 75 BTL 74 KCL-206 HD01-40 HD01-39 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 29.66 25.10 20.20 28.84 30.78 38.45 26.50 23.30 Ce ppm 57.83 43.40 31.50 49.83 53.53 59.70 47.80 43.20 Pr ppm 6.25 4.71 3.23 5.26 5.68 6.04 5.20 4.85 Nd ppm 21.36 16.70 12.40 19.82 21.28 20.65 20.00 18.30 Sm ppm 3.35 2.80 2.17 3.78 4.03 3.74 3.54 2.98 E u ppm 0.94 0.85 0.67 0.97 1.00 0.90 0.91 0.86 Gd ppm 2.43 2.63 1.74 2.86 3.01 2.88 2.66 2.35 Tb ppm 0.35 0.39 0.25 0.39 0.40 0.40 0.40 0.36 Dy ppm 1.88 1.86 1.29 2.02 2.08 2.25 2.09 1.84 Ho ppm 0.35 0.33 0.23 0.37 0.36 0.43 0.38 0.33 E r ppm 1.04 1.06 0.67 0.90 0.89 1.14 1.09 1.00 Tm ppm 0.17 0.13 0.10 0.13 0.13 0.17 0.17 0.16 Yb ppm 1.16 1.00 0.65 0.84 0.83 1.10 1.06 0.99 Lu ppm 0.19 0.16 0.11 0.13 0.14 0.18 0.17 0.17 Ba ppm 956.20 1428.50 689.00 863 908 678 975.00 824.00 Th ppm 25.99 17.10 21.80 13.57 17.48 32.24 24.80 33.30 Nb ppm 9.00 6.00 5.70 8.18 8.53 7.88 8.20 8.00 Y ppm 10.75 9.70 7.00 10.31 10.42 11.37 10.00 10.00 Hf ppm 2.90 3.00 3.60 3.11 3.14 3.29 3.60 3.50 Ta ppm 1.02 <0.5 0.58 0.76 0.74 0.96 0.96 0.92 U ppm 5.89 4.31 8.77 4.31 5.75 5.36 7.02 9.59 Pb ppm 17.50 21.00 29.00 15.98 16.38 19.38 22.00 31.00 Rb ppm 117.02 119.90 117.00 128.5 130.9 120.9 121.00 116.00 Cs ppm 4.72 5.20 5.30 5.70 5.50 3.72 7.10 6.40 Sr ppm 558.80 589.90 494.00 584 590 447 523.00 513.00 Sc ppm Zr ppm 95.90 101.30 129.00 102 101 97 123.00 112.00 Ni ppm 5.37 <5 4.00 3.68 2.31 0.00 4.00 5.00 V ppm 67.38 71.00 85.00 79.17 73.08 63.10 68.00 62.00 Ga ppm 18.20 16.00 20.00 18.6 19.8 16.40 18.00 19.00 Cu ppm 16.76 15.00 7.5 7.4 5.60 Zn ppm 57.44 51.00 165.00 68.4 75.0 46.40 90.00 114.00 249 (Appendix B continued) Sample ID HD01-49 T-395 HD02-102 MP6 HD01-2 HD01-32 HD01-41 HD01-29 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 18.70 27.10 28.70 13.40 49.20 27.90 18.30 17.00 Ce ppm 33.10 47.49 50.00 28.50 69.00 44.40 33.40 31.00 Pr ppm 3.45 5.27 5.42 3.21 6.42 4.62 3.63 3.24 Nd ppm 12.30 18.40 19.50 11.20 22.70 17.40 13.60 11.60 Sm ppm 2.22 3.28 3.32 2.20 3.65 2.87 2.34 2.15 E u ppm 0.60 0.82 0.84 0.53 0.95 0.84 0.69 0.59 Gd ppm 1.73 2.60 2.30 1.67 2.62 2.12 1.71 1.67 Tb ppm 0.25 0.38 0.29 0.25 0.41 0.32 0.26 0.25 Dy ppm 1.39 1.97 1.47 1.38 2.11 1.59 1.35 1.34 Ho ppm 0.27 0.38 0.26 0.24 0.39 0.29 0.25 0.26 E r ppm 0.76 0.94 0.69 0.74 1.13 0.83 0.71 0.75 Tm ppm 0.12 0.14 0.10 0.11 0.18 0.13 0.12 0.11 Yb ppm 0.81 0.93 0.64 0.87 1.16 0.81 0.77 0.78 Lu ppm 0.14 0.16 0.10 0.11 0.18 0.13 0.12 0.13 Ba ppm 645.00 809.73 883.00 868.60 734.00 788.00 805.00 626.00 Th ppm 23.30 28.40 17.00 16.70 30.00 16.80 13.80 21.10 Nb ppm 7.90 7.81 7.70 5.20 9.60 8.00 7.40 7.70 Y ppm 8.00 10.23 8.00 7.60 12.00 8.00 8.00 7.00 Hf ppm 3.50 3.55 3.30 3.20 3.20 3.20 3.00 3.50 Ta ppm 0.78 0.68 0.57 0.50 1.26 0.71 0.97 0.71 U ppm 10.50 8.72 3.87 4.40 9.76 4.82 15.00 10.30 Pb ppm 22.00 17.77 14.00 2.40 51.00 20.00 18.00 25.00 Rb ppm 175.00 153.11 111.00 123.40 147.00 137.00 134.00 159.00 Cs ppm 15.50 8.14 6.70 3.90 8.20 6.30 8.50 8.30 Sr ppm 363.00 471.24 630.00 488.90 428.00 485.00 441.00 372.00 Sc ppm Zr ppm 97.00 107.40 113.00 101.20 104.00 105.00 90.00 97.00 Ni ppm 0.00 4 0.00 3.30 3.00 4.00 3.00 0.00 V ppm 60.00 60 53.00 56.00 74.00 56.00 54.00 46.00 Ga ppm 18.00 18.00 16.60 18.00 19.00 18.00 16.00 Cu ppm 3 5.90 Zn ppm 82.00 58 55.00 43.00 248.00 94.00 87.00 69.00 250 (Appendix B continued) Sample ID HD01-43 T-353 KCL-214 BTL 77 KCL-215 HD01-64 BTL 76 M-336 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 25.20 36.07 25.98 29.04 29.28 26.30 40.65 31.50 Ce ppm 39.90 70.26 50.79 49.18 50.62 42.20 76.38 56.00 Pr ppm 3.95 8.09 5.92 5.16 5.59 4.53 8.34 6.30 Nd ppm 13.70 29.41 21.62 19.25 19.98 17.20 31.03 22.50 Sm ppm 2.22 5.09 4.17 3.63 3.45 2.77 5.91 3.40 E u ppm 0.63 1.28 1.01 0.93 0.90 0.79 1.37 0.87 Gd ppm 1.78 3.63 3.27 2.77 2.43 2.00 4.36 2.85 Tb ppm 0.27 0.47 0.47 0.36 0.32 0.27 0.59 0.36 Dy ppm 1.40 2.41 2.64 1.90 1.67 1.33 2.95 1.54 Ho ppm 0.28 0.42 0.49 0.35 0.29 0.24 0.54 0.28 E r ppm 0.81 1.11 1.29 0.86 0.76 0.66 1.34 0.83 Tm ppm 0.13 0.16 0.19 0.12 0.11 0.10 0.19 0.13 Yb ppm 0.85 0.95 1.20 0.80 0.68 0.63 1.21 0.70 Lu ppm 0.15 0.16 0.20 0.13 0.11 0.10 0.20 0.15 Ba ppm 596.00 1151.72 864 988 1040 1058.00 725 684.50 Th ppm 26.40 17.62 33.56 16.04 20.42 8.57 30.79 18.00 Nb ppm 7.00 9.53 8.40 7.86 7.05 6.20 11.99 8.00 Y ppm 8.00 11.52 13.17 9.76 7.89 7.00 15.13 7.90 Hf ppm 2.40 4.47 3.56 3.36 3.96 3.10 4.68 3.00 Ta ppm 0.77 0.76 0.99 0.67 0.58 0.55 1.11 <0.5 U ppm 18.80 6.71 7.52 4.78 6.60 2.78 6.84 3.84 Pb ppm 24.00 15.20 17.74 16.08 18.10 23.00 15.70 17.00 Rb ppm 168.00 106.16 125.5 126.7 129.7 108.00 95.0 116.90 Cs ppm 13.20 7.33 6.30 5.60 4.00 2.90 4.12 4.30 Sr ppm 329.00 785.00 489 626 642 676.00 630 744.90 Sc ppm Zr ppm 69.00 122 137 145 86 Ni ppm 4.00 4.70 5.09 4.62 3.47 V ppm 49.00 54.71 58.15 70.34 68.86 Ga ppm 17.00 20.0 21.5 19.5 19.1 Cu ppm 5.6 7.8 7.3 2.1 Zn ppm 80.00 66.8 66.0 64.8 58.4 251 (Appendix B continued) Sample ID CPL-276 BTL 65 HD02-111 HD01-80 BTL 62 HD01-84 HD02-109 BTL 85 Data Souece TB TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 28.26 33.50 25.50 36.20 33.16 49.90 43.10 25.36 Ce ppm 52.25 54.61 38.40 51.40 54.47 89.50 47.80 42.89 Pr ppm 5.92 5.64 4.01 5.35 5.71 10.20 4.29 4.55 Nd ppm 21.24 20.79 14.60 19.70 21.11 39.10 15.10 16.76 Sm ppm 3.56 3.82 2.33 2.97 3.82 7.08 2.33 3.09 E u ppm 0.92 0.97 0.69 0.85 0.99 1.52 0.69 0.82 Gd ppm 2.47 2.68 1.63 2.09 2.77 5.81 1.65 2.33 Tb ppm 0.33 0.35 0.22 0.29 0.36 0.96 0.24 0.30 Dy ppm 1.67 1.85 1.10 1.35 1.82 5.19 1.17 1.53 Ho ppm 0.30 0.33 0.19 0.24 0.33 1.00 0.20 0.28 E r ppm 0.77 0.84 0.57 0.69 0.82 3.08 0.61 0.71 Tm ppm 0.11 0.12 0.08 0.10 0.12 0.46 0.09 0.10 Yb ppm 0.71 0.74 0.52 0.64 0.73 2.74 0.56 0.63 Lu ppm 0.11 0.12 0.08 0.10 0.12 0.41 0.09 0.10 Ba ppm 457 949 1017.00 1127.00 1018 964.00 842.00 802 Th ppm 23.12 13.64 13.00 18.50 16.92 12.80 15.90 22.74 Nb ppm 7.38 8.25 6.00 6.90 8.66 12.10 6.80 6.73 Y ppm 8.20 9.37 7.00 6.00 9.38 28.00 6.00 7.92 Hf ppm 4.01 4.10 3.30 3.50 3.88 4.60 2.70 2.73 Ta ppm 0.58 0.68 0.47 0.56 1.59 1.25 0.51 0.58 U ppm 5.07 5.56 5.31 5.07 4.50 3.65 4.30 4.41 Pb ppm 14.31 17.59 25.00 25.00 17.59 31.00 27.00 16.34 Rb ppm 80.3 118.6 140.00 126.00 115.3 121.00 150.00 110.1 Cs ppm 3.42 4.28 4.50 2.90 4.47 7.00 7.00 4.53 Sr ppm 651 665 598.00 618.00 675 345.00 545.00 563 Sc ppm Zr ppm 106.00 132.00 113.00 88.00 113.00 102.00 155.93 133 Ni ppm 4.00 2.00 3.00 3.00 4.00 10.00 4 0.22 V ppm 61.00 54.00 51.00 45.00 49.00 53.00 78 60.30 Ga ppm 20.00 21.00 20.00 19.00 20.00 18.00 19.30 Cu ppm <5 3 3.40 Zn ppm 90.00 70.00 70.00 81.00 76.00 61.00 73 67.00 252 (Appendix B continued) Sample ID BTL 64 HD01-77A SM-5 TS 33 HD01-82 HD01-58 HD02-110 HD02-93 Data Souece TB TB NAVDAT (Scott et al., ) TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 30.36 32.50 59.5 27.78 37.50 28.30 29.70 42.20 Ce ppm 49.68 55.10 135 54.64 51.20 43.20 48.20 59.40 Pr ppm 5.10 6.12 16 6.33 5.24 4.49 5.15 6.12 Nd ppm 18.79 23.00 63.1 23.28 19.00 16.60 19.30 21.70 Sm ppm 3.42 3.56 9.9 3.80 2.83 2.48 2.93 3.04 E u ppm 0.86 0.97 2.3 0.95 0.82 0.73 0.80 0.81 Gd ppm 2.47 2.51 6.5 2.67 1.97 1.72 2.16 2.01 Tb ppm 0.32 0.34 0.9 0.34 0.27 0.24 0.28 0.27 Dy ppm 1.62 1.61 4 1.76 1.33 1.15 1.38 1.27 Ho ppm 0.29 0.28 0.7 0.31 0.24 0.21 0.24 0.23 E r ppm 0.75 0.84 2 0.85 0.69 0.62 0.70 0.70 Tm ppm 0.11 0.12 0.3 0.12 0.10 0.10 0.11 0.11 Yb ppm 0.67 0.77 1.8 0.79 0.64 0.60 0.70 0.64 Lu ppm 0.11 0.12 0.12 0.10 0.10 0.11 0.10 Ba ppm 740 697.00 445 898.99 949.00 611.00 531.00 972.00 Th ppm 17.14 17.40 26.5 9.46 8.24 20.70 18.40 17.00 Nb ppm 7.95 7.80 20.3 9.10 6.80 6.70 7.80 7.90 Y ppm 8.45 7.00 23.1 8.53 6.00 6.00 7.00 6.00 Hf ppm 3.84 3.90 7.7 3.20 3.40 3.40 4.10 3.50 Ta ppm 0.67 0.68 1.6 0.62 0.55 0.52 0.61 0.64 U ppm 6.09 4.75 5.9 3.29 4.84 3.59 7.63 3.64 Pb ppm 19.33 13.00 1.5 15.50 13.00 20.00 12.00 18.00 Rb ppm 129.6 103.00 120 99.02 145.00 116.00 106.00 164.00 Cs ppm 7.24 2.80 5.2 4.74 4.90 5.50 5.20 7.50 Sr ppm 570 629.00 591 684.60 695.00 655.00 620.00 605.00 Sc ppm 9 Zr ppm 111 128 267 114.90 112.00 125.00 132.00 120.00 Ni ppm 0.96 0.00 3.1 2.62 0.00 3.00 7.00 2.00 V ppm 77.90 61.60 125 54.57 52.00 52.00 49.00 35.00 Ga ppm 18.20 20.10 22.3 19.60 22.00 22.00 21.00 22.00 Cu ppm 7.00 3.50 5.8 3.50 Zn ppm 61.50 57.80 100 39.69 71.00 90.00 76.00 88.00 253 (Appendix B continued) Sample ID HD02-94 L115B TC 3 BTL 36 HD01-81 L117B BTL 55 BTL 68 Data Souece TB soldier lake TB TB TB soldier lake TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 35.80 28.83 30.80 53.34 25.00 33.69 38.61 30.04 Ce ppm 59.00 51.73 54.33 75.79 41.80 58.33 64.33 49.15 Pr ppm 6.26 5.71 5.84 7.29 4.57 6.26 6.68 5.07 Nd ppm 23.40 20.30 20.81 25.43 17.00 21.95 24.34 18.40 Sm ppm 3.58 3.31 3.10 4.18 2.63 3.56 4.19 3.27 E u ppm 0.95 0.85 0.78 1.01 0.76 0.91 1.00 0.83 Gd ppm 2.40 2.26 2.01 2.77 1.77 2.42 2.88 2.15 Tb ppm 0.33 0.29 0.25 0.35 0.25 0.31 0.38 0.28 Dy ppm 1.65 1.48 1.31 1.78 1.20 1.57 1.94 1.46 Ho ppm 0.30 0.28 0.23 0.32 0.21 0.29 0.34 0.27 E r ppm 0.85 0.70 0.63 0.82 0.62 0.76 0.89 0.68 Tm ppm 0.13 0.10 0.09 0.12 0.09 0.11 0.13 0.10 Yb ppm 0.79 0.65 0.62 0.77 0.59 0.73 0.84 0.63 Lu ppm 0.13 0.11 0.09 0.13 0.09 0.12 0.14 0.11 Ba ppm 471.00 1306 902.42 872 422.00 850 565 991 Th ppm 16.50 16.18 12.18 37.90 5.50 16.94 16.89 14.91 Nb ppm 8.40 7.88 7.40 9.47 6.20 8.32 10.55 7.80 Y ppm 9.00 7.53 6.52 9.40 6.00 8.25 10.08 7.51 Hf ppm 3.80 3.53 2.80 4.51 3.60 3.81 4.77 3.72 Ta ppm 0.71 0.59 0.51 0.78 0.52 0.68 2.19 0.64 U ppm 5.84 4.31 2.78 5.78 3.88 7.26 4.52 5.21 Pb ppm 13.00 18.89 16.50 16.45 17.00 14.05 16.72 17.60 Rb ppm 128.00 182.1 116.20 110.6 79.00 144.4 127.1 128.1 Cs ppm 9.50 7.38 4.25 4.04 3.30 10.91 5.21 4.63 Sr ppm 541.00 684 686.60 664 667.00 687 618 667 Sc ppm 3.3 3.3 Zr ppm 131.00 121 100.30 153 119.00 129 157 121 Ni ppm 2.00 0.00 2.17 0.68 4.00 0.00 3.76 6.04 V ppm 57.00 39.00 34.95 42.24 48.00 43.00 50.21 40.46 Ga ppm 20.00 20.00 19.29 21.5 21.00 21.00 21.3 20.4 Cu ppm 2.00 16.66 4.6 0.00 4.7 6.2 Zn ppm 74.00 62.00 48.71 59.4 71.00 49.00 63.5 58.6 254 (Appendix B continued) Sample ID BTL 82 L118 TS 31 L120B BTL 37 BTL 10 M-343 L28 Data Souece TB soldier lake TB soldier lake TB TB TB soldier lake Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 30.81 30.82 36.21 39.26 30.09 34.39 22.60 34.42 Ce ppm 51.11 53.11 63.15 61.66 50.62 57.97 39.10 60.19 Pr ppm 5.24 5.76 6.86 6.43 5.28 6.10 4.27 6.62 Nd ppm 19.22 20.30 24.24 21.98 19.21 22.02 14.50 23.07 Sm ppm 3.38 3.27 3.64 3.49 3.29 3.79 2.00 3.72 E u ppm 0.85 0.84 0.89 0.86 0.80 0.92 0.52 0.92 Gd ppm 2.32 2.20 2.37 2.32 2.18 2.52 1.59 2.53 Tb ppm 0.30 0.29 0.30 0.30 0.28 0.32 0.19 0.31 Dy ppm 1.52 1.48 1.50 1.51 1.45 1.64 0.83 1.64 Ho ppm 0.27 0.26 0.27 0.28 0.26 0.29 0.17 0.29 E r ppm 0.72 0.68 0.73 0.70 0.65 0.78 0.49 0.75 Tm ppm 0.10 0.10 0.11 0.10 0.10 0.11 0.06 0.11 Yb ppm 0.64 0.64 0.71 0.65 0.61 0.72 0.40 0.68 Lu ppm 0.11 0.11 0.11 0.11 0.10 0.12 0.09 0.11 Ba ppm 936 844 904.78 741 758 562 921.00 509 Th ppm 13.55 18.08 13.47 21.71 16.46 15.53 10.80 18.36 Nb ppm 7.80 7.35 8.60 7.68 8.22 9.13 5.00 8.23 Y ppm 7.96 7.46 7.54 7.67 7.40 8.76 4.40 8.10 Hf ppm 3.15 3.75 3.70 3.85 3.43 4.32 2.00 3.93 Ta ppm 0.63 0.58 0.59 0.62 1.95 0.74 <0.5 0.66 U ppm 3.68 6.35 3.23 4.69 5.12 4.60 3.36 3.97 Pb ppm 16.96 16.57 15.20 15.64 17.45 15.81 19.00 15.74 Rb ppm 126.2 164.0 112.08 106.4 131.1 119.2 126.60 109.0 Cs ppm 5.28 11.20 4.91 6.23 8.64 4.61 3.20 3.56 Sr ppm 636 637 663.60 685 615 630 523.10 649 Sc ppm 3.5 3.2 3.5 Zr ppm 100 125 133.70 134 112 146 79.60 134 Ni ppm 2.20 0.00 1.93 0.00 2.33 0.83 <5 0.00 V ppm 47.19 39.00 37.10 44.00 42.08 45.63 20.00 15.40 Ga ppm 20.1 19.00 20.15 20.00 19.5 20.8 16.00 15.00 Cu ppm 6.2 0.00 10.74 0.00 3.4 4.3 <5 0.00 Zn ppm 56.6 51.00 61.81 60.00 62.4 63.8 42.00 26.00 255 (Appendix B continued) Sample ID L136A BTL 56 BTL 9 HD02-118 HD02-117 BTL 46 BTL 43 JP1 Data Souece soldier lake TB TB TB TB TB TB TB Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 33.91 37.24 29.07 27.70 24.80 31.49 22.39 32.00 Ce ppm 61.66 58.75 46.08 42.40 40.70 47.39 33.60 59.80 Pr ppm 6.87 6.01 4.62 4.30 4.26 4.69 3.26 6.28 Nd ppm 24.20 21.55 16.37 14.90 14.90 16.49 11.56 21.20 Sm ppm 3.88 3.79 2.82 2.16 2.15 2.73 1.92 3.00 E u ppm 0.95 0.93 0.68 0.58 0.57 0.66 0.50 0.62 Gd ppm 2.57 2.58 1.78 1.40 1.40 1.79 1.26 1.81 Tb ppm 0.33 0.32 0.23 0.18 0.19 0.23 0.16 0.29 Dy ppm 1.70 1.69 1.19 0.91 0.96 1.15 0.85 1.42 Ho ppm 0.31 0.31 0.21 0.16 0.18 0.21 0.15 0.22 E r ppm 0.79 0.80 0.56 0.49 0.55 0.56 0.41 0.74 Tm ppm 0.11 0.12 0.08 0.08 0.09 0.08 0.06 0.13 Yb ppm 0.73 0.77 0.55 0.52 0.57 0.55 0.40 0.89 Lu ppm 0.12 0.13 0.09 0.09 0.10 0.10 0.07 0.12 Ba ppm 1486 386 854 625.00 867.00 507 601 756.00 Th ppm 8.91 27.22 14.32 14.70 10.80 23.07 16.36 16.80 Nb ppm 9.71 9.32 7.11 7.40 7.00 7.52 5.58 9.60 Y ppm 8.95 9.10 6.48 5.00 5.00 6.22 4.44 8.30 Hf ppm 4.47 4.43 3.48 3.50 3.70 3.70 2.53 3.50 Ta ppm 0.73 0.73 0.55 0.66 0.55 0.58 1.52 1.00 U ppm 2.70 8.20 3.75 3.51 2.93 6.20 4.89 3.60 Pb ppm 19.07 16.19 18.51 23.00 16.00 20.60 18.58 3.90 Rb ppm 130.9 125.0 147.3 149.00 139.00 156.0 128.5 185.20 Cs ppm 4.49 9.02 5.05 6.30 4.20 5.08 3.16 6.00 Sr ppm 718 606 597 497.00 510.00 509 482 201.10 Sc ppm 2.8 Zr ppm 161 145 117 108.00 124.00 112 78 99.90 Ni ppm 0.00 2.54 0.81 2.00 1.00 3.31 4.26 0.80 V ppm 23.00 43.21 35.80 24.00 23.00 31.87 22.96 10.00 Ga ppm 20.00 20.7 19.0 22.00 21.00 21.0 20.3 16.80 Cu ppm 4.00 3.7 5.3 5.0 3.6 3.20 Zn ppm 65.00 62.7 59.5 66.00 60.00 52.7 38.1 31.00 256 (Appendix B continued) Sample ID HD01-83 HD02-96 J1 10-785 10-786 08-696 08-700 08-698 Data Souece TB TB TB NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) Code Cp Cp Cp Tp Tp Tp Tp Tp La ppm 38.20 41.20 27.96 46.57 49.06 24.05 35.29 18.08 Ce ppm 62.40 69.70 49.89 99.53 102.64 51 66.16 38.9 Pr ppm 5.97 7.07 5.17 10.79 10.11 5.27 6.43 4.22 Nd ppm 19.20 24.50 17.47 37.92 33.01 14.44 21.02 15.15 Sm ppm 2.55 3.84 2.81 6.64 5.2 2.83 3.19 2.81 E u ppm 0.58 0.62 0.53 1.48 1.42 0.94 0.95 0.8 Gd ppm 1.60 2.70 1.95 5.94 4.9 3.08 3.33 2.69 Tb ppm 0.22 0.40 0.27 0.83 0.66 0.46 0.48 0.43 Dy ppm 1.14 2.11 1.52 4.69 3.4 1.95 2.05 1.88 Ho ppm 0.22 0.40 0.29 0.98 0.7 0.38 0.41 0.37 E r ppm 0.69 1.22 0.87 2.82 2.14 1.07 1.13 1.03 Tm ppm 0.10 0.20 0.14 Yb ppm 0.70 1.30 0.97 3.22 2.7 1.32 1.39 1.29 Lu ppm 0.12 0.21 0.16 0.47 0.41 0.21 0.22 0.21 Ba ppm 820.00 751.00 739.27 2270 2117 1128 1278 696 Th ppm 21.60 19.30 18.00 Nb ppm 6.10 12.00 9.60 15.44 19.3 19.68 16.88 19.73 Y ppm 6.00 12.00 9.31 22.25 16.69 12.2 12.67 11.92 Hf ppm 3.60 3.90 3.60 Ta ppm 0.56 1.86 0.97 U ppm 4.88 11.30 5.58 Pb ppm 25.00 33.00 27.80 Rb ppm 250.00 197.00 220.88 170 182 208 219 215 Cs ppm 9.40 5.70 7.57 1.4 4.98 Sr ppm 167.00 146.00 235.70 42 480 483 414 414 Sc ppm 1.89 4.67 Zr ppm 107.00 103.00 104.50 93 147 106 100 99 Ni ppm 0.00 0.00 N,D, 3 7 V ppm 9.00 -5.00 10.95 68 50 Ga ppm 19.00 19.00 18.72 Cu ppm 4.56 Zn ppm 43.00 45.00 36.22 42 41 40 257 (Appendix B continued) Sample ID 08-697 08-701 MT-1 10-803 10-802 08-725 08-728 08-755 Data Souece NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Bateman et al.,) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) Code Tp Tp Tp Tp Tp Tp Tp Tp La ppm 25.81 28 37.4 41.27 45.78 39.29 31.19 41.4 Ce ppm 52.92 52.11 56.4 74.37 95.08 70.56 56.4 69.1 Pr ppm 5.51 5.16 7.51 9.14 6.41 5.55 7.4 Nd ppm 18.62 16.51 17 23.79 28.46 14.66 17.74 18.48 Sm ppm 3.27 2.63 3.16 4.2 4.27 2.4 3.12 3.33 E u ppm 0.88 0.81 0.764 0.58 0.75 0.78 0.89 0.92 Gd ppm 3.13 2.93 3.84 4 3.21 3.06 4.25 Tb ppm 0.48 0.44 0.332 0.56 0.52 0.47 0.46 0.61 Dy ppm 2.17 1.89 1.8 3.14 2.64 1.93 1.98 3.56 Ho ppm 0.42 0.38 0.71 0.55 0.37 0.39 0.77 E r ppm 1.16 1.1 2.27 1.75 1.12 1.11 2.35 Tm ppm 0.239 Yb ppm 1.44 1.4 1.4 2.78 2.33 1.4 1.34 2.84 Lu ppm 0.23 0.24 0.237 0.46 0.37 0.24 0.23 0.5 Ba ppm 922 1296 1540 994 1253 1169 1467 1591 Th ppm 21 Nb ppm 22.58 20.26 19 11.47 19.45 14.16 16.9 Y ppm 13.51 12.08 23.3 13.26 11.79 12.04 24.2 Hf ppm 2.63 Ta ppm 1.2 U ppm 5.81 Pb ppm Rb ppm 119 168 135 214 199 181 155 135 Cs ppm Sr ppm 560 547 490 383 347 381 263 276 Sc ppm Zr ppm 233 190 112 103 104 109 133 135 Ni ppm V ppm Ga ppm Cu ppm Zn ppm 41 29 36 31 22 26 26 21 258 (Appendix B continued) Sample ID 08-754 08-753 08-742 08-707 08-705 08-731 08-703 08-729 Data Souece NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) Code Tp Tp Tp Tp Tp Tp Tp Tp La ppm 20.72 23.78 40.56 49.2 55.44 17.21 37.71 22.58 Ce ppm 36.42 42.61 72.48 88.26 103.82 38.98 72.03 42.96 Pr ppm 3.64 4.34 6.99 7.9 9.55 3.31 6.87 4.3 Nd ppm 7.66 11.76 19.34 22.01 28.32 9.91 19.79 12.16 Sm ppm 1.42 2.16 3.47 2.96 3.57 1.91 3.02 2.34 E u ppm 0.66 0.58 0.68 0.97 1.04 0.47 0.73 0.42 Gd ppm 2.38 2.75 3.46 3.62 4.12 2.4 3.56 2.9 Tb ppm 0.38 0.45 0.5 0.5 0.53 0.4 0.53 0.49 Dy ppm 1.66 2.26 2.21 1.93 1.85 1.81 2.37 2.63 Ho ppm 0.33 0.45 0.43 0.37 0.35 0.36 0.47 0.58 E r ppm 1 1.34 1.24 1.07 0.9 1.06 1.3 1.79 Tm ppm Yb ppm 1.24 1.66 1.46 1.26 1.08 1.33 1.45 2.12 Lu ppm 0.22 0.28 0.26 0.22 0.19 0.23 0.25 0.38 Ba ppm 1735 1554 1319 2008 2115 1148 1392 964 Th ppm Nb ppm 9.57 11.56 12.19 20.83 21.55 11.38 24.44 12.38 Y ppm 10.71 14.54 13.67 11.85 10.84 11.74 15 19.11 Hf ppm Ta ppm U ppm Pb ppm Rb ppm 192 135 160 133 135 138 111 156 Cs ppm Sr ppm 139 356 154 169 113 238 290 248 Sc ppm Zr ppm 104 164 98 95 79 97 88 171 Ni ppm V ppm Ga ppm Cu ppm Zn ppm 20 17 21 17 13 10 31 28 259 (Appendix B continued) Sample ID 08-706 08-732 NF4b-D NF4a-D HH5a-D CR5-A SQ12-Dx HH6a-D Data Souece NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) Code Tp Tp Cp Cp Cp Cp Cp Cp La ppm 21.78 20.07 15.4 17.5 21.7 96.5 26.1 23.7 Ce ppm 43.29 38.07 39.1 45.4 50.8 210 64.7 49.3 Pr ppm 4.47 3.71 4.8 5.7 3.6 24.6 9.7 2 Nd ppm 15.04 12.12 24.4 30.2 31.5 91.9 40.8 25.3 Sm ppm 3.1 2.25 5.7 6.6 4 14.3 9.9 1.8 E u ppm 0.44 0.38 1.72 1.87 2.14 3.64 1.66 1.79 Gd ppm 3.4 2.45 5.2 5.6 6 11.6 9.9 5.4 Tb ppm 0.57 0.4 Dy ppm 3.03 1.68 1.6 6.9 4.6 4 4.1 3.6 Ho ppm 0.67 0.32 0.34 1.35 0.91 0.71 0.69 0.66 E r ppm 2.19 0.89 1 3.5 2.5 1.7 1.5 1.6 Tm ppm 0.07 0.54 0.31 0.2 0.22 0.2 Yb ppm 2.42 1.12 1.23 3.25 2.3 1.48 1.35 1.45 Lu ppm 0.4 0.2 0.18 0.47 0.33 0.18 0.15 0.18 Ba ppm 527 909 1544 707 591 507 721 648 Th ppm 12.8 10.9 4.5 3.99 5.76 5.76 Nb ppm 36.41 11.41 3 7 8 7 7 5 Y ppm 23.69 10.27 12 28 21 18 17 16 Hf ppm Ta ppm U ppm 3.19 1.8 3.03 1.8 3.21 2.29 Pb ppm Rb ppm 148 187 103 653 68.8 74.1 63.8 61.3 Cs ppm Sr ppm 281 278 360 488 455 665 654 619 Sc ppm 7.5 22 18 18 16 19 Zr ppm 122 137 134 164 119 145 137 131 Ni ppm V ppm 57 130 120 180 160 180 Ga ppm Cu ppm Zn ppm 16 15 260 (Appendix B continued) Sample ID HH5b-D HH6c-D HH6b-D SC1-D CR12-1 MHb4-A DR2-S WR2-A Data Souece NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 24.5 25.7 20.9 14 30.6 64.7 31.3 23.8 Ce ppm 53.6 52.3 42.8 29.5 56.3 123 71.8 61.1 Pr ppm 0.6 1.8 1 2 6 13.6 5.2 13.2 Nd ppm 30 26.6 21.4 17.9 26.5 56.6 39.8 40 Sm ppm 1.5 1.9 1.3 1.8 5.4 10.1 6.7 9.7 E u ppm 2.11 1.65 1.51 1.49 1.75 1.69 1.64 1.52 Gd ppm 5.9 5.3 5 4.9 6.8 10.3 7.3 12.6 Tb ppm Dy ppm 3.5 4.1 3.9 3.6 3.4 4.4 5.1 4.3 Ho ppm 0.68 0.77 0.72 0.73 0.78 0.89 1.07 0.95 E r ppm 1.6 2.2 1.7 1.9 2.2 2.2 2.8 2.6 Tm ppm 0.2 0.27 0.2 0.22 0.33 0.27 0.38 0.38 Yb ppm 1.48 1.76 1.44 1.83 2.04 1.54 2.2 2.2 Lu ppm 0.19 0.26 0.35 0.25 0.3 0.2 0.32 0.31 Ba ppm 617 576 657 419 587 519 556 588 Th ppm 5 6.16 4.22 7.94 5.47 2.12 0.96 2.98 Nb ppm 5 3 6 8 3 9 6 6 Y ppm 15 19 18 17 19 17 23 21 Hf ppm 3.18 1.4 2.72 1.96 Ta ppm 0.576 0.554 0.394 0.324 U ppm 3.33 2.38 0.78 4.78 3.08 0.681 0.545 0.969 Pb ppm Rb ppm 54.9 61.8 54.4 68.8 66.5 34.3 40.6 43.9 Cs ppm 2.61 0.94 0.77 1.86 Sr ppm 595 569 637 525 276 769 620 450 Sc ppm 17 24 17 18 13.8 19 26.1 33.3 Zr ppm 123 118 128 122 95 57 104 91 Ni ppm V ppm 160 220 160 170 Ga ppm Cu ppm Zn ppm 261 (Appendix B continued) Sample ID HH5c-D CR3a-A HH2-A HH5d-D DR1-aH HH6d-D HH3-A WR1-H Data Souece NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 23.9 79 37.4 23.5 16.9 24.6 19 76 Ce ppm 48.8 192 78.3 48.3 41 47.4 40.1 144 Pr ppm 1.7 21.4 3.5 1.5 7.7 2.2 3.5 Nd ppm 24.7 82.6 38.4 24.6 26.9 22.6 24 64.7 Sm ppm 1.7 12.5 5.4 1.5 5.1 2.1 3.8 5.7 E u ppm 1.63 3.12 1.82 1.6 1.76 1.54 1.51 2.23 Gd ppm 5 10.6 8 4.9 7.1 4.8 5.6 4.8 Tb ppm Dy ppm 3.8 3.4 12.8 9.1 12.6 6.4 10.5 1.7 Ho ppm 0.68 0.74 2.46 1.79 2.65 1.33 0.35 E r ppm 1.7 1.9 6.8 5.1 7 3.2 5.5 0.9 Tm ppm 0.17 0.2 0.99 0.73 0.9 0.54 0.47 0.12 Yb ppm 1.59 1.96 6.49 4.73 6.92 3.56 3.52 0.91 Lu ppm 0.19 0.29 0.91 0.71 0.99 0.5 0.52 0.13 Ba ppm 457 755 443 316 542 290 732 1156 Th ppm 0.4 6.5 41.5 11.2 67.5 5.26 3.58 10.9 Nb ppm 5 9 22 19 25 9 14 8 Y ppm 17 22 56 40 57 26 38 14 Hf ppm 4.71 3.98 Ta ppm 1.07 0.65 U ppm 1.7 4.18 7.44 4.49 833 237 2.6 1.92 Pb ppm Rb ppm 64 125 161 156 196 50.6 124 93 Cs ppm 7.4 1.69 Sr ppm 455 330 207 276 180 471 257 572 Sc ppm 19 10 40 30 40 29 29.6 3.53 Zr ppm 109 143 266 184 304 77 185 162 Ni ppm V ppm 140 80 210 180 225 200 Ga ppm Cu ppm Zn ppm 163 56 262 (Appendix B continued) Sample ID CR2a-A MHb5-A NF1-H SQ2-H CR1-H MHb3-H HH1-H MHb1-H Data Souece NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 56.6 45.9 11.8 21.2 36.6 54.3 18.4 28.4 Ce ppm 122 86.2 25.3 45.7 57.9 93 35.9 54.5 Pr ppm 12.5 8.5 2.8 5 4.8 8.1 1 5.8 Nd ppm 52.4 39.2 13 21.9 18.4 34.1 13.9 25 Sm ppm 7.5 6.4 3.1 3.9 1.7 3.8 1.3 4.6 E u ppm 2.12 1.44 0.93 1.18 0.94 1.29 1 0.88 Gd ppm 7 7.3 3.6 4.6 3.3 5.5 2.5 4.2 Tb ppm Dy ppm 2.7 2.7 3.3 8.2 5.7 0.8 4.6 6.3 Ho ppm 0.6 0.56 0.68 1.56 1.09 0.15 0.83 1.15 E r ppm 1.7 1.4 1.7 4.1 2.9 0.4 2 2.6 Tm ppm 0.24 0.14 0.14 0.56 0.37 0.05 0.25 0.22 Yb ppm 1.52 1.49 1.81 4.06 2.86 0.38 1.87 2.48 Lu ppm 0.25 0.21 0.26 0.61 0.42 0.04 0.26 0.32 Ba ppm 764 863 732 845 630 3161 2622 1382 Th ppm 24.1 22.3 21.1 38.2 27.6 12.9 19 24 Nb ppm 10 8 7 20 12 4 14 23 Y ppm 22 21 18 38 27 12 22 30 Hf ppm 4.52 Ta ppm 1.31 U ppm 5.6 5 4.3 10.2 9.2 2.55 3.05 5.8 Pb ppm Rb ppm 130 129 126 207 142 184 120 163 Cs ppm 6.79 Sr ppm 414 425 434 262 387 484 533 390 Sc ppm 7.82 7.5 6.5 30 20 7.5 13 17 Zr ppm 136 130 129 266 184 130 161 289 Ni ppm V ppm 66 64 190 100 45 110 250 Ga ppm Cu ppm Zn ppm 57 161 263 (Appendix B continued) Sample ID MHb2-H RL1-H HH6e-AP YOS-113a YOS-109a YOS-18c YOS-206 YOS-104 Data Souece NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Babarin et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 35.2 29.4 35.8 18.14 18.79 19.06 18.68 19.8 Ce ppm 60.2 52 63.4 41.75 38.51 43.55 41.97 44 Pr ppm 3.9 5.5 4.3 5.56 4.82 5.69 5.61 Nd ppm 23 23 22.8 23.84 19.69 23.47 23.56 21.5 Sm ppm 1.6 3.9 2 5.04 4.07 4.74 4.92 4.34 E u ppm 1.05 0.82 0.9 1.4 1.25 1.45 1.36 1.23 Gd ppm 4.1 3.6 3.2 4.67 3.89 4.34 4.27 Tb ppm 0.7 0.6 0.66 0.65 0.55 Dy ppm 8.2 7.4 6.3 3.86 3.41 3.61 3.58 Ho ppm 1.5 1.36 1.36 0.76 0.68 0.71 0.69 E r ppm 3.9 3.2 4 2.02 1.81 1.84 1.89 Tm ppm 0.45 0.37 0.6 Yb ppm 3.01 3.2 4.07 0.79 0.59 1.7 1.65 0.47 Lu ppm 0.48 0.46 0.56 0.13 0.1 0.26 0.24 0.08 Ba ppm 1945 1109 66 1244.64 474.35 820.26 618.43 766.34 Th ppm 24.5 17.5 7.61 26.76 25.39 4.22 1.76 11.57 Nb ppm 25 21 6 9.39 3.17 7.47 9.36 10.3 Y ppm 33 29 34 9.23 5.09 19.97 19.75 6.6 Hf ppm Ta ppm 0.64 0.37 0.56 0.49 0.76 U ppm 4.36 9.72 4.04 3.31 4.84 1.58 1.43 2.3 Pb ppm 26.94 23.72 7.48 6 8.5 Rb ppm 141 286 3 165.44 160.13 68.95 129.26 92.27 Cs ppm 2.13 4.88 1.31 14.27 3.4 Sr ppm 395 330 275 201.34 169.76 529.83 466.19 457.25 Sc ppm 18 16 27 2.28 4.95 17.46 21.71 4.67 Zr ppm 254 312 169 162 26 79 275 197 Ni ppm 2 4.32 29.33 13.93 6.7 V ppm 220 215 260 4.53 2.5 126.65 189.62 72.66 Ga ppm 15.61 14.02 22.03 21.89 20.26 Cu ppm 0.05 10.66 18.99 7.57 Zn ppm 31.85 14.6 139.08 133.36 93.1 264 (Appendix B continued) Sample ID YOS-105a YOS-193a YOS-18a YOS-67 YOS-180 YOS-1 YOS-113c YOS-94a Data Souece NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) NAVDAT (Ratajeski et al., ) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 22 11.98 45.83 92.3 36.3 34.1 29.15 41.7 Ce ppm 43.8 30.95 80.13 157.41 62.2 63.24 52.61 64.5 Pr ppm 4.62 8.13 15.65 6.54 5.49 Nd ppm 19.6 20.93 26.3 48.47 22.6 21.54 18.1 22.7 Sm ppm 3.89 4.76 3.28 5.31 4.26 3.44 3.06 3.75 E u ppm 1.07 1.06 1.01 1.33 0.67 0.7 0.59 0.91 Gd ppm 4.36 2.16 3.11 2.4 2.34 Tb ppm 0.49 0.68 0.29 0.39 0.43 0.34 0.38 0.29 Dy ppm 3.79 1.26 1.62 1.64 2.04 Ho ppm 0.73 0.22 0.29 0.29 0.4 E r ppm 1.91 0.59 0.79 0.77 1.13 Tm ppm Yb ppm 1.6 1.24 1.4 1 1.71 0.68 1.7 1.59 Lu ppm 0.21 0.2 0.16 0.15 0.25 0.1 0.24 0.24 Ba ppm 635 1013.58 806 1970 573.28 1164.15 512 408.01 Th ppm 4.3 23.97 36.1 23.7 4.57 18.78 7.5 2.25 Nb ppm 14.01 10.88 12.15 8.24 Y ppm 18 13.34 16 10 21.51 8.82 17 19.33 Hf ppm 4.08 4.38 4.12 3.78 Ta ppm 0.55 2.07 0.73 0.35 0.8 0.56 0.89 0.52 U ppm 1.6 11.4 4.3 3 2.16 1.46 2.3 0.56 Pb ppm 27.2 8.39 9.89 5.71 Rb ppm 50 211.36 119 67 92.87 78.79 43 32.01 Cs ppm 6.66 1.45 2.01 0.78 Sr ppm 473 225.42 216 289 370.69 512.06 508 452.45 Sc ppm 21.2 2.98 2.99 1.53 12.13 4.82 20.7 26.39 Zr ppm 209 76 117 102 148 313 132 152 Ni ppm 25 2.58 9.97 4.3 27 28.17 V ppm 158 8.77 24 12 105.29 28.17 160 192.8 Ga ppm 17.77 21.37 20.02 20.49 Cu ppm 2.06 20.31 12.23 17.97 Zn ppm 34.63 118.12 73.52 113.21 265 (Appendix B continued) Sample ID YOS-210 S14-6 S52-2 S46-2 R52-9 S72-3 S10-2 R48-9 Data Souece NAVDAT (Ratajeski et al., ) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 9.47 27.23 23.16 21.52 25.86 27.22 23.26 24.62 Ce ppm 23.89 55.68 47.35 44.03 44.73 49.53 41.74 44.86 Pr ppm 2.01 6.46 5.58 5.23 4.97 5.51 4.66 5.05 Nd ppm 6.82 24.88 20.59 19.9 18.46 20.7 17.7 19.46 Sm ppm 1.33 4.43 3.8 3.42 3.25 3.63 3.13 3.44 E u ppm 0.5 1.15 0.95 0.91 0.87 0.87 0.82 0.93 Gd ppm 1 3.76 3.25 2.72 2.75 3.16 2.5 2.76 Tb ppm 0.16 0.51 0.47 0.35 0.36 0.44 0.32 0.34 Dy ppm 0.83 2.71 2.64 1.78 1.89 2.49 1.58 1.69 Ho ppm 0.16 0.5 0.52 0.33 0.35 0.49 0.28 0.3 E r ppm 0.49 1.31 1.43 0.88 0.92 1.36 0.76 0.77 Tm ppm 0.19 0.22 0.12 0.13 0.2 0.1 0.11 Yb ppm 1.78 1.15 1.36 0.75 0.82 1.3 0.64 0.65 Lu ppm 0.26 0.17 0.2 0.11 0.13 0.2 0.1 0.1 Ba ppm 621.1 790.89 753.54 909.11 856.38 791 823.87 827.63 Th ppm 1.86 11.35 11.2 8.25 17.81 16.46 11.84 12.1 Nb ppm 9.35 10.84 10.2 9.67 8.96 10.43 7.93 9.26 Y ppm 21.11 Hf ppm Ta ppm 0.62 U ppm 1 2.4 2.91 2.9 3.97 4.38 4.1 3.57 Pb ppm 7.09 Rb ppm 51.16 83.2 85.8 69.3 101 94.2 105 104 Cs ppm 0.9 Sr ppm 588.27 614 528 641 563 562 451 543 Sc ppm 25.3 Zr ppm 149 143 132 150 123 124 146 105 Ni ppm 16.25 8.79 4.9 7.66 4.82 5.98 7.05 5.4 V ppm 199.45 Ga ppm 23.39 Cu ppm 31.18 15.03 9.73 15.68 11.5 11.66 13.17 11.66 Zn ppm 127.38 74.18 56.34 79.53 67.27 65.13 63.05 65.6 266 (Appendix B continued) Sample ID S72-4 S68-4 S50-4 S22-8 S20-7 S28-8 S24-6 S69-6 Data Souece NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 22.39 18.82 25.56 22.13 25.99 19.2 28.27 26.6 Ce ppm 41.06 33.69 47.21 46.05 49.38 32.28 48.4 45.05 Pr ppm 4.67 3.78 5.21 5.25 5.56 3.48 5.3 4.95 Nd ppm 17.95 13.82 18.69 19.43 20.37 12.9 19.25 18.78 Sm ppm 3.17 2.42 3.12 3.34 3.31 2.29 3.13 3.05 E u ppm 0.85 0.65 0.78 0.83 0.84 0.62 0.75 0.76 Gd ppm 2.58 1.87 2.39 2.78 2.59 1.9 2.45 2.45 Tb ppm 0.33 0.23 0.29 0.38 0.32 0.25 0.3 0.3 Dy ppm 1.59 1.12 1.44 2.05 1.62 1.29 1.49 1.47 Ho ppm 0.29 0.2 0.27 0.39 0.3 0.24 0.28 0.27 E r ppm 0.74 0.52 0.75 1.08 0.79 0.64 0.77 0.71 Tm ppm 0.1 0.07 0.11 0.16 0.11 0.09 0.11 0.1 Yb ppm 0.65 0.46 0.7 1.04 0.71 0.58 0.73 0.65 Lu ppm 0.1 0.07 0.1 0.16 0.11 0.09 0.11 0.1 Ba ppm 649.35 736.99 704.5 784.41 904.73 679.81 675.56 497.89 Th ppm 12.76 10.72 13.42 15.25 10.82 23.08 7.76 14.91 Nb ppm 8.72 6.93 8.43 10.75 10.1 8.68 9.68 8.53 Y ppm Hf ppm Ta ppm U ppm 3.96 6.41 3.72 4.64 4.53 3.66 5.4 4.05 Pb ppm Rb ppm 107 131 92.1 118 115 117 132 149 Cs ppm Sr ppm 517 431 504 426 557 614 507 566 Sc ppm Zr ppm 133 112 117 108 106 105 122 120 Ni ppm 8.28 5.73 5.13 5.36 4.96 4.67 2.59 2.61 V ppm Ga ppm Cu ppm 17.42 11.84 8.72 11.02 10.45 9.26 10.41 8.64 Zn ppm 90.07 54.16 63 57.95 75.02 66.91 56.4 45.42 267 (Appendix B continued) Sample ID S103-4 S48-9 S118-4 S102-4 FG 14 FG 23 FG 09 FG 19 Data Souece NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Steve Macias) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 32.28 29.29 24.09 25.84 16.92 11.42 17.47 24.1 Ce ppm 51.88 49.62 42.31 44.39 39.02 26.16 34.39 48 Pr ppm 5.57 5.28 4.6 4.84 5.04 3.73 4.11 5.68 Nd ppm 19.86 18.39 16.43 16.29 21.49 17.53 16.94 23.07 Sm ppm 3.1 2.95 2.67 2.61 5.54 4.94 3.86 5.56 E u ppm 0.73 0.71 0.63 0.58 1.11 1.18 1.14 1.19 Gd ppm 2.25 2.26 1.9 1.96 4.74 4.23 3.09 4.86 Tb ppm 0.27 0.27 0.23 0.25 0.86 0.71 0.49 0.87 Dy ppm 1.33 1.34 1.13 1.25 5 4.14 2.73 5.24 Ho ppm 0.24 0.25 0.21 0.24 1.01 0.8 0.51 1.04 E r ppm 0.67 0.68 0.6 0.7 2.89 2.13 1.36 2.93 Tm ppm 0.1 0.1 0.09 0.11 0.39 0.28 0.17 0.41 Yb ppm 0.66 0.68 0.59 0.75 2.39 1.65 1.07 2.6 Lu ppm 0.1 0.1 0.09 0.12 0.37 0.26 0.17 0.4 Ba ppm 1133.98 675.77 1149.69 670.25 667 737 665 671 Th ppm 14.89 18.92 18.95 17.85 12.21 0.66 3.09 8.95 Nb ppm 9.36 9.41 8.67 9.69 7.77 6.44 5.87 11.7 Y ppm 28.92 19.9 14.62 28.84 Hf ppm 4.75 3.79 2.91 5.3 Ta ppm 0.58 0.33 0.36 0.81 U ppm 4.82 2.7 3.47 6.2 3.09 0.36 0.7 3.1 Pb ppm 8.19 5.18 6.31 10.69 Rb ppm 101 162 166 141 76.8 39.7 39.1 101.7 Cs ppm 3.27 1.26 1.71 5.09 Sr ppm 578 408 500 570 404 427 544 334 Sc ppm 21 33 14 13 Zr ppm 122 113 103 133 218 161 132 195 Ni ppm 3.3 3.86 2.31 4.09 13 2 3 13 V ppm 160 141 116 140 Ga ppm 20 24 22 19 Cu ppm 9.64 11 3.97 6.61 21 11 17 Zn ppm 63.88 58.41 38.86 71.02 78 90 91 71 268 (Appendix B continued) Sample ID FG 01 FG 06 FG 07 FG 17 FG 33 FG 22 FG 21 FG 24 Data Souece NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 8.83 11.92 5.2 18.14 5.14 18.41 36.18 4.75 Ce ppm 21.41 22.86 12.38 33.23 10.93 32.9 64.7 9.38 Pr ppm 3.17 2.71 1.92 3.61 1.67 3.56 6.89 1.27 Nd ppm 14.63 11.28 9.6 13.98 8.44 13.99 24.48 5.87 Sm ppm 4.31 3.08 3.2 3.11 2.72 3.29 4.28 1.87 E u ppm 1.11 0.95 0.95 0.92 1 0.9 1.09 0.82 Gd ppm 4.05 2.84 3.06 2.62 2.64 2.68 2.59 1.92 Tb ppm 0.73 0.49 0.56 0.44 0.45 0.45 0.37 0.34 Dy ppm 4.27 2.98 3.45 2.66 2.65 2.61 1.87 2.03 Ho ppm 0.87 0.61 0.68 0.55 0.53 0.52 0.31 0.39 E r ppm 2.4 1.66 1.92 1.5 1.43 1.39 0.77 1.05 Tm ppm 0.34 0.22 0.26 0.22 0.2 0.19 0.11 0.15 Yb ppm 2.17 1.41 1.67 1.42 1.21 1.25 0.65 0.95 Lu ppm 0.35 0.22 0.27 0.24 0.19 0.21 0.1 0.14 Ba ppm 629 575 714 938 532 640 898 565 Th ppm 0.76 2.38 1.65 7.06 0.52 9.29 8.61 1.13 Nb ppm 5.83 6.58 5.28 7.11 4.63 7.58 7.64 6.17 Y ppm 25.36 16.38 18.91 15.21 14.69 14.09 9.23 10.46 Hf ppm 4.25 3.58 3.82 3.59 3.17 3.26 2.58 2.7 Ta ppm 0.35 0.46 0.43 0.65 0.3 0.76 0.74 0.77 U ppm 0.63 0.92 3.82 2.39 0.7 3.14 1.75 1.72 Pb ppm 6.55 9.42 10.3 10.24 6.85 14.05 12.92 7.67 Rb ppm 49.8 62.4 65.2 72.9 46.7 90.6 62.4 55 Cs ppm 2.34 3.31 2.51 1.98 1.58 6.31 2.47 2.52 Sr ppm 400 366 315 385 400 377 516 318 Sc ppm 17 16 19 11 8 17 8 28 Zr ppm 152 146 126 135 131 122 123 98 Ni ppm 8 11 10 6 4 4 4 4 V ppm 112 78 96 90 66 74 47 56 Ga ppm 19 20 21 19 21 19 24 22 Cu ppm 11 13 9 3 Zn ppm 76 58 61 50 62 63 66 65 269 (Appendix B continued) Sample ID FG 15 FG 26 FG 34 FG 16 FG 05 FG 32 FG 02 FG 11 Data Souece NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 12.02 7.91 15.37 24.85 14.88 16.68 12.05 14.59 Ce ppm 25.86 15.97 30.17 45.29 28.98 32.83 23.28 29.52 Pr ppm 3.41 1.99 3.76 4.93 3.46 3.88 2.84 3.54 Nd ppm 14.73 8.42 15.82 18.68 13.79 15.61 11.81 14.63 Sm ppm 3.62 2.33 3.56 3.68 3.01 3.16 2.83 3.42 E u ppm 1.06 0.82 1.08 1.02 0.9 0.92 0.8 0.79 Gd ppm 2.8 2.09 2.76 2.67 1.94 2.11 2.18 2.44 Tb ppm 0.41 0.36 0.39 0.39 0.26 0.29 0.34 0.38 Dy ppm 2.11 2.01 1.98 2.02 1.26 1.38 1.75 1.97 Ho ppm 0.38 0.38 0.34 0.38 0.21 0.24 0.3 0.36 E r ppm 0.96 1.03 0.83 0.95 0.51 0.56 0.76 0.91 Tm ppm 0.13 0.14 0.11 0.13 0.06 0.08 0.11 0.12 Yb ppm 0.75 0.89 0.64 0.8 0.4 0.42 0.67 0.72 Lu ppm 0.12 0.14 0.1 0.12 0.06 0.07 0.1 0.12 Ba ppm 892 566 679 1403 604 444 522 1309 Th ppm 4.19 2.66 1.94 5.7 2.3 2.76 2.53 2.56 Nb ppm 8.55 5.08 5.19 8.9 3.3 4.12 5.84 5.08 Y ppm 11.06 9.76 9.65 10.58 6.27 6.9 9.76 10.69 Hf ppm 3.07 2.62 3.37 2.9 2.88 2.75 2.74 3.29 Ta ppm 0.83 0.54 0.3 0.94 0.21 0.33 0.44 0.28 U ppm 1.73 1.62 0.46 2.99 1.14 1.07 1.63 0.55 Pb ppm 12.69 10.86 6.4 16.49 10.07 9.72 12.49 12.68 Rb ppm 60.4 42.5 31.5 80.4 43.4 47.1 64.7 58.6 Cs ppm 2.75 2.2 1.21 2.38 1.96 1.89 3.01 1.12 Sr ppm 529 328 466 505 543 523 474 430 Sc ppm 4 27 5 2 7 6 6 3 Zr ppm 120 90 137 118 119 111 104 117 Ni ppm 4 6 1 6 2 5 8 5 V ppm 53 57 25 49 22 24 23 2 Ga ppm 23 18 21 18 19 23 23 20 Cu ppm 12 1 Zn ppm 67 50 69 45 65 63 69 58 270 (Appendix B continued) Sample ID FG 10 FG 04 FG 28 FG 08 FG 27 HD01-21 HD01-55 HD01-53 Data Souece NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Truschel) NAVDAT (Gray Walt) NAVDAT (Gray Walt) NAVDAT (Gray Walt) Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 17.31 15.73 21.93 14.56 12.49 45.5 41.9 24.3 Ce ppm 33.35 30.61 39.9 28.53 23.44 79.1 83.6 45.2 Pr ppm 3.95 3.67 4.39 3.32 2.68 8.78 10.1 4.94 Nd ppm 15.9 15.01 16.64 13.39 10.38 34 45.2 19 Sm ppm 3.38 3.29 3.24 3.06 2.17 5.98 7.67 3.44 E u ppm 0.86 0.96 0.83 0.74 0.71 1.73 1.14 0.938 Gd ppm 2.31 2.13 2.25 2.09 1.46 4.53 6.27 2.89 Tb ppm 0.33 0.27 0.31 0.29 0.21 0.63 0.92 0.43 Dy ppm 1.61 1.25 1.59 1.41 1.13 3.07 4.81 2.31 Ho ppm 0.27 0.19 0.29 0.24 0.2 0.56 0.85 0.43 E r ppm 0.65 0.43 0.72 0.55 0.56 1.49 2.71 1.2 Tm ppm 0.09 0.05 0.1 0.07 0.08 0.217 0.4 0.178 Yb ppm 0.52 0.33 0.66 0.42 0.5 1.34 2.4 1.13 Lu ppm 0.09 0.04 0.11 0.06 0.08 0.208 0.337 0.179 Ba ppm 742 556 600 654 653 336 1306 315 Th ppm 2.83 2.92 5.67 3.1 2.72 16.9 22.4 7.41 Nb ppm 4.78 3.47 6.58 4 4.33 10.6 15.9 7.9 Y ppm 7.72 5.65 8.6 6.96 6.01 14 23 12 Hf ppm 3.02 2.89 3.47 2.22 2.3 4.3 8.2 3 Ta ppm 0.27 0.17 0.72 0.29 0.45 0.75 1.47 0.65 U ppm 0.66 0.68 2.66 1.85 1.67 8.37 7.56 3.74 Pb ppm 8.68 11.67 10.46 13.61 9.56 42 13 7 Rb ppm 37.9 32 67.5 62.9 55 104 162 103 Cs ppm 0.88 0.94 3.17 2.06 1.55 5.3 5.4 5.1 Sr ppm 414 527 363 362 371 502 409 548 Sc ppm 8 6 2 2 1 13.8 18 12.7 Zr ppm 134 113 126 83 86 152 272 112 Ni ppm 4 10 6 7 8 20 26 8 V ppm 12 22 13 5 9 162 232 143 Ga ppm 21 21 20 20 19 24 22 23 Cu ppm 5 1 Zn ppm 64 63 60 55 46 136 139 223 271 (Appendix B continued) Sample ID HD02-107 0102-10M 0102-13M 0102-11C 0105C IP0203 D-75 A-43 Data Souece NAVDAT (Gray Walt) NAVDAT (Kylander et al.,) NAVDAT (Kylander et al.,) NAVDAT (Kylander et al.,) NAVDAT (Kylander et al.,) NAVDAT (Kylander et al.,) WAUGH LAKE WAUGH LAKE Code Cp Cp Cp Cp Cp Cp Cp Cp La ppm 62.3 39.49 38.03 34.42 31.04 25.41 32.79 34.51 Ce ppm 113 68.36 66.42 58.05 52.46 42.97 63.96 67.87 Pr ppm 12.1 7.11 6.88 5.97 5.43 4.41 7.61 8.12 Nd ppm 44 25.74 24.91 21.56 19.46 15.12 28.53 30.49 Sm ppm 6.51 4.41 4.3 3.67 3.28 3.08 5.94 6.29 E u ppm 1.73 1.1 1.1 0.9 0.9 0.5 1.38 1.37 Gd ppm 4.81 3 2.8 2.4 2.2 2.4 5.07 5.48 Tb ppm 0.61 0.37 0.36 0.3 0.27 0.41 0.80 0.86 Dy ppm 3 1.9 1.9 1.6 1.4 2.4 4.72 4.98 Ho ppm 0.55 0.33 0.34 0.27 0.24 0.49 0.91 0.95 E r ppm 1.6 0.84 0.83 0.69 0.62 1.4 2.38 2.52 Tm ppm 0.234 0.1 0.1 0.1 0.09 0.2 0.34 0.37 Yb ppm 1.52 0.75 0.73 0.63 0.57 1.5 2.14 2.33 Lu ppm 0.243 0.1 0.1 0.1 0.09 0.2 0.34 0.36 Ba ppm 225 1450 1350 918 843 453 956 924 Th ppm 13.9 8 10 16 17 13 12.55 15.25 Nb ppm 15.9 10 10 8.4 9.4 11 10.71 12.52 Y ppm 16 9 9 9 7 16 23.93 25.27 Hf ppm 5.3 5.19 4.9 4.61 4.28 3.52 5.58 6.69 Ta ppm 1.29 0.74 0.74 0.74 0.72 0.75 0.83 0.98 U ppm 24.7 1.7 2.34 4.13 3.63 1.81 3.94 4.85 Pb ppm 23 12 13 15 13 11 10.03 24.07 Rb ppm 123 140 122 123 110 174 130.3 152.3 Cs ppm 5.6 2.6 1.7 1.7 1.2 1.4 6.23 5.68 Sr ppm 570 659 652 597 591 106 414 289 Sc ppm 19.8 3 4 3 3 1 12.0 10.7 Zr ppm 170 207 203 172 153 111 215 256 Ni ppm 7 3 4 5 6 8 V ppm 114 42 35 35 33 3 Ga ppm 27 21 22 20 21 15 Cu ppm 3 6 4 1 2 Zn ppm 113 66 58 59 33 15 272 (Appendix B continued) Sample ID D-121 D-108 D-70 A-56 A-58 MR-1 HE-4 MR-7 Data Souece WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE iron mt iron mt iron mt Code Cp Cp Cp Cp Cp Cv Cv Cv La ppm 36.88 33.80 40.01 10.15 32.86 18.68 23.95 27.15 Ce ppm 71.33 63.05 71.05 20.61 59.37 35.60 49.01 53.80 Pr ppm 8.41 6.88 7.64 2.67 6.35 4.49 6.16 7.10 Nd ppm 31.72 24.26 25.75 11.02 21.36 18.68 24.69 29.38 Sm ppm 6.49 4.80 4.63 2.59 4.22 4.14 5.28 6.56 E u ppm 1.49 0.89 0.83 0.83 0.63 1.36 1.51 2.00 Gd ppm 5.52 3.91 3.68 2.41 3.68 3.69 4.80 5.66 Tb ppm 0.87 0.63 0.58 0.36 0.65 0.53 0.74 0.81 Dy ppm 5.14 3.75 3.39 2.17 4.22 2.98 4.37 4.24 Ho ppm 0.99 0.73 0.66 0.42 0.90 0.57 0.86 0.79 E r ppm 2.62 2.03 1.83 1.12 2.75 1.55 2.21 1.97 Tm ppm 0.38 0.31 0.27 0.15 0.48 0.23 0.31 0.28 Yb ppm 2.38 2.08 1.81 0.96 3.43 1.46 1.91 1.74 Lu ppm 0.37 0.33 0.30 0.14 0.58 0.23 0.30 0.28 Ba ppm 1164 1006 1037 352 794 338 957 356 Th ppm 14.39 31.83 32.85 2.22 27.90 2.82 4.83 4.44 Nb ppm 12.86 12.36 10.73 3.42 20.62 2.06 9.75 4.23 Y ppm 26.52 20.44 18.36 10.87 27.29 14.82 21.24 20.63 Hf ppm 6.04 5.75 5.49 1.56 4.60 1.18 3.96 2.98 Ta ppm 0.98 1.51 1.34 0.26 3.03 0.09 0.62 0.26 U ppm 3.82 14.34 14.07 0.90 6.79 0.86 1.30 1.94 Pb ppm 14.28 15.25 15.91 4.10 22.18 4.02 13.31 5.83 Rb ppm 128.3 216.0 210.5 81.2 226.8 22.8 81.7 31.8 Cs ppm 4.01 6.91 6.59 15.10 3.37 0.94 10.68 0.71 Sr ppm 345 242 238 782 261 398 452 896 Sc ppm 10.2 5.9 5.2 20.8 4.1 50.7 25.1 22.5 Zr ppm 237 203 196 52 139 43 153 121 Ni ppm 87 21 22 V ppm 353 190 255 Ga ppm 13 21 17 Cu ppm 124 1 109 Zn ppm 77 117 79 273 (Appendix B continued) Sample ID MR-2 MN-9 YM-4 GS-3 W1B T065 S46 L77 Data Souece iron mt iron mt iron mt iron mt soldier lake soldier lake soldier lake soldier lake Code Cv Cv Cv Cv Tv Tv Tv Tv La ppm 17.95 17.20 36.52 26.04 51.59 20.38 26.20 28.43 Ce ppm 34.59 35.23 72.78 54.35 85.73 43.38 51.85 60.59 Pr ppm 4.38 4.57 10.61 6.07 8.85 5.70 6.41 7.90 Nd ppm 18.17 18.61 43.32 21.90 29.52 23.74 25.70 32.63 Sm ppm 3.98 4.51 9.76 4.29 5.27 5.56 5.54 7.41 E u ppm 1.17 1.55 2.27 0.93 1.18 1.54 1.66 1.96 Gd ppm 3.56 4.47 9.06 3.66 4.35 5.26 5.01 6.49 Tb ppm 0.50 0.72 1.48 0.62 0.69 0.85 0.77 1.01 Dy ppm 2.73 4.31 8.86 3.74 4.09 5.25 4.55 5.95 Ho ppm 0.51 0.88 1.82 0.77 0.85 1.08 0.92 1.19 E r ppm 1.38 2.35 4.78 2.11 2.44 2.91 2.47 3.30 Tm ppm 0.20 0.35 0.72 0.33 0.38 0.43 0.36 0.47 Yb ppm 1.25 2.28 4.41 2.16 2.61 2.66 2.26 2.94 Lu ppm 0.20 0.36 0.72 0.35 0.45 0.42 0.36 0.46 Ba ppm 318 487 1507 974 70 979 1510 1627 Th ppm 2.58 4.47 11.00 10.50 29.84 5.62 5.34 7.87 Nb ppm 2.21 6.52 18.63 11.22 13.04 6.79 7.49 7.91 Y ppm 13.46 22.86 46.10 20.40 23.19 26.71 24.10 29.77 Hf ppm 1.35 2.75 9.66 4.65 5.19 2.85 2.72 3.29 Ta ppm 0.10 0.53 1.17 0.95 1.37 0.43 0.46 0.49 U ppm 0.87 1.40 3.44 2.86 9.67 2.40 1.77 2.35 Pb ppm 4.68 5.24 9.06 15.96 21.91 8.81 18.22 11.49 Rb ppm 24.1 120.9 64.0 87.9 5.6 66.9 134.8 99.4 Cs ppm 0.59 14.19 0.99 2.93 0.32 12.18 15.34 5.35 Sr ppm 398 521 321 280 505 441 954 369 Sc ppm 34.9 19.7 16.1 6.1 13.0 29.2 22.6 18.4 Zr ppm 54 100 384 167 174 96 98 108 Ni ppm 68 5 2 2 24.00 6.00 3.00 0.00 V ppm 281 154 21 30 131.00 291.00 190.00 185.00 Ga ppm 13 17 19 18 23.00 19.00 18.00 18.00 Cu ppm 71 4 4 4 2.00 60.00 5 1.00 Zn ppm 62 60 49 68 72.00 230.00 94.00 49.00 274 (Appendix B continued) Sample ID T75A S61 T76 T016 V63 G10 08-736 10-791 Data Souece soldier lake soldier lake soldier lake soldier lake soldier lake soldier lake NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) Code Tv Tv Tv Tv Tv Tv Tv Tv La ppm 29.12 45.43 30.52 34.23 21.26 26.20 40.68 28.21 Ce ppm 60.79 94.87 58.41 61.91 36.70 44.51 97.45 55.76 Pr ppm 6.94 12.10 6.93 7.19 4.08 4.55 11.05 5.51 Nd ppm 24.42 49.31 26.22 26.43 15.08 14.62 34.3 17.92 Sm ppm 4.66 10.81 5.42 5.47 3.20 2.57 7.26 2.94 E u ppm 0.95 2.41 1.35 1.24 0.89 0.61 1.54 0.83 Gd ppm 3.90 9.56 4.58 4.61 2.93 1.94 7.04 2.74 Tb ppm 0.62 1.46 0.71 0.71 0.48 0.31 0.99 0.39 Dy ppm 3.73 8.80 4.19 4.32 2.94 1.88 5.83 2.15 Ho ppm 0.76 1.80 0.84 0.89 0.58 0.40 1.19 0.45 E r ppm 2.12 4.83 2.32 2.48 1.58 1.18 3.31 1.42 Tm ppm 0.34 0.70 0.35 0.37 0.24 0.20 Yb ppm 2.34 4.35 2.25 2.44 1.53 1.41 3.09 1.35 Lu ppm 0.40 0.68 0.36 0.39 0.25 0.25 0.47 0.23 Ba ppm 581 1038 1774 1806 1994 1470 2227 1891 Th ppm 7.24 14.03 12.31 15.12 8.77 13.55 Nb ppm 19.35 14.15 8.97 10.23 5.37 7.54 19.69 9.95 Y ppm 21.49 45.07 21.93 23.18 15.73 11.38 33.33 11.47 Hf ppm 4.27 5.63 3.68 4.42 2.97 2.73 Ta ppm 2.22 0.85 0.63 0.74 0.46 0.79 U ppm 11.67 4.72 3.87 5.01 4.44 3.15 Pb ppm 14.43 10.88 13.35 6.84 26.27 7.64 Rb ppm 284.5 66.7 39.6 218.6 246.3 157.1 207 97 Cs ppm 23.62 4.96 2.19 10.39 4.64 5.81 Sr ppm 332 342 529 294 68 181 360 301 Sc ppm 15.9 26.2 18.3 10.8 12.1 3.0 Zr ppm 148 191 126 159 102 91 256 111 Ni ppm 11.00 0.00 4.00 0.00 0.00 0.00 V ppm 165.00 102.00 176.00 90.00 97.00 15.00 Ga ppm 24.00 21.00 17.00 18.00 12.00 15.00 Cu ppm 24.00 11.00 16.00 6.00 9.00 0.00 Zn ppm 122.00 123.00 75.00 80.00 23.00 26.00 61 41 275 (Appendix B continued) Sample ID 10-792 10-801 09-762 08-739 08-751 10-800 09-767 08-750 Data Souece NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) Code Tv Tv Tv Tv Tv Tv Tv Tv La ppm 26.59 30.05 34.45 25.35 28.01 37.68 32.74 32.26 Ce ppm 56.74 59.37 55.35 45.66 47.02 73.08 53.44 55.25 Pr ppm 5.27 5.86 5.53 4.61 4.66 7.04 5.35 5.47 Nd ppm 16.77 18.75 18.14 11.49 12.42 22.29 18.13 14.74 Sm ppm 2.89 3.07 3.01 1.96 2.12 3.46 3.13 2.4 E u ppm 0.89 0.82 0.74 0.83 0.7 1.1 0.75 0.88 Gd ppm 2.82 2.85 2.86 2.81 3.03 3.38 3.06 3.35 Tb ppm 0.41 0.4 0.39 0.44 0.45 0.45 0.44 0.5 Dy ppm 2.24 2.13 2.18 1.9 1.82 2.39 2.52 2 Ho ppm 0.47 0.44 0.45 0.38 0.38 0.5 0.53 0.4 E r ppm 1.47 1.4 1.36 1.12 1.17 1.55 1.6 1.26 Tm ppm Yb ppm 1.24 1.3 1.8 1.3 1.29 1.47 1.38 1.35 Lu ppm 0.21 0.22 0.31 0.23 0.22 0.25 0.23 0.23 Ba ppm 733 703 858 681 1944 1583 1417 1213 Th ppm Nb ppm 10.58 10.29 9.2 10.6 11.47 11.17 10.34 11.06 Y ppm 11.39 11.73 16.4 11.8 11.53 13.38 12.55 12.92 Hf ppm Ta ppm U ppm Pb ppm Rb ppm 200 199 90 188 171 150 140 149 Cs ppm Sr ppm 83 118 183 141 292 288 292 184 Sc ppm Zr ppm 106 99 101 91 89 100 90 96 Ni ppm V ppm Ga ppm Cu ppm Zn ppm 25 24 35 25 22 33 38 39 276 (Appendix B continued) Sample ID 09-763 10-794 08-752 08-746 09-766 09-764 09-768 08-744 Data Souece NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) NAVDAT (Barth et al., ) Code Tv Tv Tv Tv Tv Tv Tv Tv La ppm 32.11 30.84 27 29.46 36.91 34.66 31.01 31.63 Ce ppm 50.96 60.73 46.15 49.79 57.14 54.3 48 52.72 Pr ppm 5.11 5.97 4.57 4.74 5.59 5.34 4.76 4.97 Nd ppm 17.04 18.84 13.11 12.99 18.07 17.88 15.38 12.3 Sm ppm 2.96 3.01 2.2 2.01 2.83 2.97 2.53 1.87 E u ppm 0.73 0.86 0.7 0.6 0.71 0.72 0.66 0.57 Gd ppm 2.71 2.93 2.97 2.91 2.74 2.97 2.4 3.02 Tb ppm 0.37 0.41 0.44 0.43 0.36 0.39 0.34 0.44 Dy ppm 2.07 2.2 1.85 1.64 2.02 2.19 1.83 1.62 Ho ppm 0.44 0.46 0.38 0.34 0.43 0.48 0.38 0.33 E r ppm 1.34 1.41 1.21 1.08 1.29 1.43 1.14 1.02 Tm ppm Yb ppm 1.65 1.56 1.59 1.59 1.79 1.77 1.81 1.96 Lu ppm 0.29 0.28 0.31 0.29 0.28 0.29 0.29 0.33 Ba ppm 1602 1727 1986 2031 2539 1867 2527 2593 Th ppm Nb ppm 11.41 11.27 12.4 11.97 7.61 8.41 8.09 9.14 Y ppm 14.07 13.35 14.75 12.97 10.73 10.69 10.59 11.41 Hf ppm Ta ppm U ppm Pb ppm Rb ppm 171 171 148 186 160 109 138 117 Cs ppm Sr ppm 265 217 410 381 292 281 389 282 Sc ppm Zr ppm 97 104 91 95 99 101 89 109 Ni ppm V ppm Ga ppm Cu ppm Zn ppm 45 41 31 39 29 53 22 25 277 (Appendix B continued) Sample ID 08-749 D-112 C-76 B-35 A-106 B-14 C-97 B-109 Data Souece NAVDAT (Barth et al., ) WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE Code Tv Tv Jv Jv Cv Cv Jv Jv La ppm 30.81 18.45 18.49 17.74 31.66 42.57 15.45 61.15 Ce ppm 51.33 35.89 37.49 34.56 65.20 84.64 32.13 114.60 Pr ppm 4.93 4.37 4.91 4.27 8.18 10.21 3.98 14.93 Nd ppm 13.59 17.57 20.35 17.26 32.82 40.07 16.62 59.66 Sm ppm 2.1 3.78 4.95 3.97 7.13 8.45 3.83 12.83 E u ppm 0.71 1.21 1.44 1.26 1.96 1.89 1.07 2.45 Gd ppm 3.04 3.56 5.14 3.81 6.57 7.70 3.85 11.54 Tb ppm 0.44 0.56 0.84 0.62 1.00 1.17 0.59 1.75 Dy ppm 1.7 3.50 5.37 3.83 5.99 6.81 3.57 9.95 Ho ppm 0.34 0.73 1.10 0.82 1.19 1.34 0.71 1.92 E r ppm 1.1 1.97 3.05 2.22 3.04 3.53 1.89 5.06 Tm ppm 0.29 0.44 0.32 0.43 0.50 0.27 0.72 Yb ppm 1.63 1.84 2.75 2.07 2.63 3.12 1.68 4.48 Lu ppm 0.27 0.30 0.44 0.33 0.41 0.49 0.27 0.71 Ba ppm 1980 957 826 2140 756 1530 529 323 Th ppm 3.36 3.37 5.30 8.15 15.48 2.82 5.29 Nb ppm 7.41 5.49 5.53 5.28 10.88 15.23 4.81 7.87 Y ppm 10.14 18.69 28.16 20.85 30.16 34.90 18.06 44.96 Hf ppm 2.69 3.58 2.60 5.45 7.96 2.64 4.70 Ta ppm 0.35 0.36 0.41 0.73 1.13 0.30 0.56 U ppm 1.09 1.15 2.10 3.00 5.53 1.45 1.68 Pb ppm 26.09 7.45 20.12 16.17 30.79 9.45 37.82 Rb ppm 150 109.2 44.3 257.6 57.5 143.1 96.2 93.9 Cs ppm 13.41 2.58 8.60 4.46 9.84 3.38 5.28 Sr ppm 228 500 694 450 472 349 142 237 Sc ppm 18.0 21.5 18.4 18.5 15.6 21.5 25.6 Zr ppm 98 101 128 93 212 305 98 171 Ni ppm V ppm Ga ppm Cu ppm Zn ppm 24 278 Sample ID B-15 A-65 34B 34A A-67 A-71 B-49A C-142 Data Souece WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE WAUGH LAKE Code Cv Tv Jv Jv Jv Tv Jv Tv La ppm 36.72 33.11 21.06 24.48 23.56 25.08 23.62 26.43 Ce ppm 73.85 65.13 39.12 44.26 46.62 48.25 43.66 59.71 Pr ppm 9.10 7.47 4.56 5.03 5.49 5.89 5.34 6.46 Nd ppm 36.05 29.22 16.92 18.09 21.21 23.21 20.67 24.16 Sm ppm 7.68 6.48 3.54 3.62 4.73 4.89 4.38 4.96 E u ppm 1.63 1.85 0.95 0.97 1.34 1.38 1.22 1.19 Gd ppm 6.84 6.29 3.07 3.06 4.95 4.52 4.04 4.52 Tb ppm 1.06 1.08 0.49 0.49 0.94 0.73 0.61 0.74 Dy ppm 6.05 6.58 2.98 2.82 6.34 4.37 3.59 4.64 Ho ppm 1.19 1.37 0.58 0.57 1.35 0.89 0.71 0.97 E r ppm 3.06 3.84 1.60 1.58 3.89 2.35 1.90 2.76 Tm ppm 0.44 0.59 0.24 0.24 0.59 0.34 0.27 0.42 Yb ppm 2.79 3.80 1.52 1.61 3.75 2.19 1.70 2.81 Lu ppm 0.42 0.60 0.25 0.25 0.60 0.34 0.27 0.45 Ba ppm 1388 736 2276 1325 524 1278 867 2543 Th ppm 12.68 5.62 6.39 7.55 7.46 7.90 6.63 9.34 Nb ppm 13.36 8.50 6.49 6.63 9.29 10.28 6.51 12.16 Y ppm 30.62 33.18 15.31 15.67 37.63 23.39 19.30 26.83 Hf ppm 6.63 4.80 2.75 3.15 5.38 3.49 3.88 4.73 Ta ppm 1.00 0.59 0.48 0.52 0.64 0.78 0.48 0.96 U ppm 4.43 2.74 2.10 2.65 1.93 2.98 1.46 2.27 Pb ppm 24.90 16.89 9.22 3.58 7.94 10.90 16.89 18.92 Rb ppm 161.3 89.1 287.6 222.7 108.9 103.9 125.0 88.8 Cs ppm 8.28 5.28 5.41 6.59 5.49 8.69 21.94 6.01 Sr ppm 291 382 103 292 184 106 152 390 Sc ppm 15.3 23.3 11.0 7.8 22.1 15.3 14.0 10.2 Zr ppm 257 176 102 121 199 132 145 161 Ni ppm V ppm Ga ppm Cu ppm Zn ppm

Abstract (if available)

Abstract Magmatism is the most important process to form crust in Earth’s history. Both volcanic and plutonic rocks are major components of Earth’s current crust and their geochronologic, geochemical and structural features provide key information for rock sequence, source reservoirs, tectonic environments and emplacement mechanisms of igneous rocks. In order to better picture the igneous rocks as a whole I picked three upper crustal magmatic systems in different tectonic environments to study. Fangshan pluton is an intraplate pluton that emplaced at the depth of about 10-15

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University of Southern California Dissertations and Theses

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Asset Metadata

Creator Zhang, Tao (author)

Core Title Evolution of upper crustal magmatic plumbing systems: comparisons of geochronological, petrological, geochemical and structural records in the Cretaceous Fangshan pluton, Beijing, China, the Meso...

School College of Letters, Arts and Sciences

Degree Doctor of Philosophy

Degree Program Geological Sciences

Publication Date 05/04/2012

Defense Date 03/28/2012

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag AMS study,geochemistry,magma,OAI-PMH Harvest,plutonic-volcanic connection,U/Pb geochronology

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Paterson, Scott (committee chair), Lund, Steven P. (committee member), McCann, Edwin (committee member)

Creator Email taohsu@me.com,taozhang@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-29203

Unique identifier UC11289022

Identifier usctheses-c3-29203 (legacy record id)

Legacy Identifier etd-ZhangTao-751.pdf

Dmrecord 29203

Document Type Dissertation

Rights Zhang, Tao

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA