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Stratigraphy and sedimentology of the Drummond Mine Limestone, Starhope Creek, Idaho

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Stratigraphy and sedimentology of the Drummond Mine Limestone, Starhope Creek, Idaho

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Content STRATIGRAPHY AND SEDIMENTOLOGY OF THE DRUMMOND MINE LIMESTONE, STARHOPE CREEK, by Darlene A. Condra A Thesis Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE (Geological Sciences) IDAHO January 19 80 UMI Number: EP58673 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI EP58673 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346 UNIVERSITY OF SOUTHERN CALIFORNIA THE GRADUATE SCHOOL UNIVER SITY PARK LOS ANGELES. C A LIFO R N IA 9 0 0 0 7 G & )&0 C7 ^ This thesis, written by Darlene A. Condra under the direction of h.§.¥...Thesis Com m ittee, and approved by a ll its members, has been pre sented to and accepted by the D ean of The Graduate School, in p a rtial fu lfillm en t of the requirements fo r the degree of Master of Science Dean THESIS CO M M ITTEE Chairman ACKNOWLEDGMENTS Principal credit for suggesting this thesis goes to Dr. Tor H. Nilsen of the U.S. Geological Survey. He provided an introduction to the field area and reviewed this manuscript. Dr. Robert H. Osborne offered invaluable guidance and constructive criticism in the field and labo ratory and also reviewed the manuscript. Dr. Gregory A. Davis reviewed the manuscript and offered helpful sugges tions. I wish to thank Diane Nelson for her help in the field and many discussions concerning the Drummond Mine Limestone. The work was greatly facilitated by Wayne Hall and John Batchelder (U.S. Geological Survey) who provided logistical and geological support in the field. Dr. Charles Sandberg (U.S. Geological Survey) and Dr. Rick Miller (California State University, San Diego) looked at sample separates to determine if conodonts were present. Dr. J. Lawford Anderson offered assistance with mineral identification and usage of the X-ray diffractometer. Drafting and photographic reproduction was supplied by Texaco Inc., Los Angeles. This project could not have been completed without the direction and support of Dr. Christopher P. Buckley; he reviewed field work, laboratory methods, numerical analyses and this manuscript. The project was partially funded by the Branch of Western Environmental Geology, U.S. Geological Survey, as part of ongoing geological studies in the western United States. The Department of Geological Sciences, University of Southern California, was cooperative in providing equipment and employment. TABLE OF CONTENTS Page ACKNOWLEDGMENTS...................................... ii LIST OF ILLUSTRATIONS................................ vii LIST OF TABLES....................................... ix ABSTRACT............................................. X I. INTRODUCTION................................... 1 General Statement.............. 1 Previous Work................................ 5 Nomenclature............................... 5 Paleogeographic Models..................... 9 Statement of Intent.......................... 14 Geographic Setting........................... 15 II. FIELD WORK.............. 20 Techniques and Definitions................... 20 Field Observations........................... 24 Primary Sedimentary Structures............. 24 Lithology and Grain Size................... 31 Fossils and Bioturbation................... 34 Diagenesis and Metamorphism................ 34 Beds and Interval Thickness................ 37 III. LABORATORY ANALYSIS............................ 44 Lithology.................................... 44 General Statement.......................... 44 Rock Type I................................ 44 iv Page Rock Type II.............................. 47 Rock Type III.............................. 51 Rock Type IV.............................. 51 Diagenesis and Metamorphism.................. 54 General Statement.......................... 54 Diagenetic History......................... 55 Metamorphism............................... 59 Grain Orientation............................ 61 Particle Size Analysis....................... 64 Insoluble Residue............................ 68 Conodont Analysis.......... 72 IV. FACIES ANALYSIS................................ 74 General Statement. . ......................... 74 Facies D..................................... 75 Description................................ 75 Interpretation............................. 84 Facies G..................................... 87 Description................................ 87 Interpretation............................. 88 Facies E..................................... 91 Description................................ 91 Interpretation............................. 92 Facies C..................................... 93 Description................................ 93 v Page Interpretation............................. 9 3 Facies B..................................... 93 Description................................ 9 3 Interpretation............................. 94 V. STATISTICAL ANALYSIS........................... 96 Turbidite Facies............................. 96 Regression Analysis........................ 96 Interpretation............................. 97 Stratal Thickness............................ 98 Regression Analysis........................ 98 Population Distribution.................... 101 VI. INTERPRETATION................................. 104 Drummond Mine Limestone...................... 104 General Statement.......................... 104 Sedimentological Model..................... 105 Modern and Ancient Analogs................... Ill Modern Analogs............................. Ill Ancient Analogs............................ 113 Conclusions.................................. 115 REFERENCES........................................... 120 APPENDIX A. GREEN LAKE LIMESTONE MEMBER, MULDOON CANYON FORMATION...................... 126 APPENDIX B. FIELD DATA.............................. 132 Drummond Mine Limestone............... 133 Green Lake Limestone, Muldoon Canyon Formation........................... 178 vi LIST OF ILLUSTRATIONS Figure Page 1. Index map showing location of the study area in Pioneer Mountains, south-central Idaho........ 3 2. Lithofacies map of Lower Mississippian and lower most Upper Mississippian rocks (partly restored)..................................... 6 3. Summary of stratigraphic nomenclature used in south-central Idaho.................. 10 4. Geologic map of the study area.................. 16 5. Schematic comparison of a typical Bouma sequence and sequences of primary sedimentary structures commonly observed............................. 26 6. Graph showing the percentage of each type of bedding sequence averaged within each 10 m. of stratigraphic section......................... 28 7. Rose diagram of paleocurrent data and a listing of the data................................... 32 8. Outcrop photographs of the Drummond Mine Limestone..................................... 35 9. Stratigraphic log illustrating changes in stratal thickness of beds, Td and Tc intervals through time..................................... 39 10. Logarithmic-normal population distribution histo grams of bed and Bouma interval (Tb, Tc, Td) thickness, percent frequency vs. stratal thickness..................................... 41 11. Field photographs and photomicrographs of turbi- dite facies D lithotypes I and II............. 45 12. Field photographs and photomicrographs of litho types III and IV.............................. 52 13. Photomicrographs of diagenetic and metamorphic features ................................. 57 14. Rose diagrams of grain orientation data derived from thin sections of Tb, Tc and Td intervals.. 62 Figure Page 15. Histograms and cumulative curves constructed from grain size analysis with the Zeiss TGZ3 Particle Size Analyzer....................... 66 16. Explanation of symbols used in the stratigraphic column....................................... 76 17. Composite stratigraphic column of the Drummond Mine Limestone as measured at Starhope Creek.. 78 18. Stratigraphic log of average percent turbidite facies per 10 m of section................... 81 19. Logarithmic - normal population distribution cumulative curves of stratal thickness........ 85 20. Summary of a submarine fan depositional system and relationship of the Copper Basin Group to that system.................................. 106 viii LIST OF TABLES Table Page 1. Petrographic modal analysis of lithotypes I, III and IV.................................... 48 2. Petrographic modal analysis of lithotype II..... 49 3. Weight percent insoluble residue data........... 70 4. Regression analysis of stratal thickness data.... 99 ix ABSTRACT The Drummond Mine Limestone of the Copper Basin Group is a sequence of mixed carbonate and clastic sediments deposited in an outer fan-basin plain submarine fan envi ronment in the Antler Foreland Basin of south-central Idaho. Terrigenous elastics (quartz and chert) were derived from the Antler Highland, mixed with micrite and deposited by turbidity currents in deeper water on the outer fan. Turbidite deposition is characterized by the occurrence facies B, C and D, whereas periods of non-turbidite deposition are marked by accumulation of facies G pelagites and hemipelagites. Sedimentation trends indicate a statis tically significant increase in turbidite activity and a decrease in stratal thicknesses through time. This repre sents progradation of the fan system as the Drummond Mine Limestone grades into the overlying terrigenous, turbiditic Scorpion Mountain Formation. Tectonic activity in the Antler Highlands continued and caused further progradation of the fan systems, as seen in the coarsening and thickening upward sequences in the remainder of the Copper Basin Group. x I. INTRODUCTION General Statement Paleozoic sedimentary rocks in Western North America are exposed in a relatively linear trend from southern California through Nevada and Idaho into Canada. These rocks crop out most extensively, and have been studied most intensely, in Nevada. Paleozoic paleogeographic model-building is based on the recognition of fault- displaced sedimentary depositional facies. Roberts and others (19 58) published a comprehensive study and paleo geographic model of Paleozoic sedimentary rocks in Nevada. They identified an eastern (carbonate) and western (silicic- lastic) age-equivalent facies accumulating west of the cratonal carbonate platform. In Late Devonian-Early Mississippian time the Antler orogenic highland began to influence sedimentologic patterns, resulting in an assem blage transitional between eastern and western facies (Poole, 1974). Thrust-faulting related to the Antler Orogeny and (possibly) to later orogenies such as the Permo- Triassic Sonoman Orogeny and Mesozoic Sevier Orogeny, 1 juxtaposed different sedimentary facies. Basin and range inormal faulting further displaced Paleozoic rocks. In I Idaho, the Mesozoic Idaho Batholith occupies a position on-trend with outcrops related to the Antler Highland in Nevada, possible remnants of the highland, Pre-Mississip- j pian siliceous elastics, are found as windows near the exposed margins of the batholith. South-central Idaho also has been affected by extensive Tertiary volcanism, Tertiary normal faulting and Paleozoic and Mesozoic thrust-faulting. Devonian and younger Paleozoic rocks of the tran sitional and carbonate assemblages crop out east of the Idaho Batholith and north of the Snake River Plain. The Mississippian Copper Basin Group is a thick (6,000 m) sequence of Antler Flysch rocks which crop out in the Pioneer Mountains of south-central Idaho (Fig. 1). Micro fossil biostratigraphy (Shunick, 1974) has established that the Copper Basin Group spans the range of Mississippian time. As such, it provides an example of the sedimentology of the Antler foreland basin in the Mississippian of central Idaho. The Copper Basin Group, as described by Pauli and others (1972), is composed of six formations. These are, in ascending order: the Little Copper Formation, thin-to medium-bedded argillite and sandstone; the Drummond Mine Limestone, thin-to-medium bedded silty micrite, argillite and sandstone; the Scorpion Mountain Formation, medium-to thick-bedded quartzarenite and quartz pebble conglomerate; 2 Figure 1 Index map showing location of study area in the Pioneer Mountains, south-central Idaho. 3 2 0 M IL E S / Montana Idaho 20 3 0 KM. Challis 93 r~~ Stanley / A i t : \ 93j i -----U Mackay 22 Sun Valley 'Arco. 26 93 20 Alt. . 93, 68 [B u tte _Coun_ty] 1 Blaine County C A N A D A 100 M IL E S 3 0 C D 5 0 100 KM. M O N T A N A Id a h o . C D - o . X \ ^ I D A H O ____ Utah iv e r N evada the Muldoon Canyon Formation, medium-to-thick-bedded quartzarenite, quartz pebble conglomerate and minor thin- to-medium-bedded silty micrite (Green Lake Limestone); the Brockie Lake Conglomerate; and the Iron Bog Creek Formation, quartzarenite and conglomerate. Several generalized trends are apparent in the Copper Basin Group: 1) grain size becomes coarser up-section; 2) bed thickness increases upsection; 3) bedded carbonate is restricted to the Drum mond Mine Limestone and the Green Lake Limestone of the Muldoon Canyon Formation; 4) bedded conglomerate is found only in the upper part of the Copper Basin Group (Pauli & others, 1972). Reconstruction of Mississippian lithofacies maps indicates the proximity of the Pioneer Mountains to the tectonically active Antler Highland and the carbonate cratonic platform (Figure 2). Generally, sedimentologic characteristics of the Copper Basin Group reflect the proximity of an emerging orogenic provenance. The purpose of this thesis is to analyze the mixed siliciclastics and carbonates of the Drummond Mine Limestone and determine its sedimentologic significance. Previous Work Nomenclature Geologic investigation of the Pioneer Mountains between 1930 and 1958 were conducted by Lindgren (1900), 5 Figure 2: Lithofacies map of lower Mississippian and lowermost Upper Mississippian rocks (partly restored). From Poole and Sandberg (1977). 6 EXPLANATION CRATONC PLATFORM CARBONATE BOCKS 'S3 UncMont, in pan flotanwciad Mostly ootonvttrad Iknaatona FORELAND BASIN ROCKS Mostly craton-dartvad daooaita~ Umsstons, phoscnsoc ahala. aatstona, ana sandstona. with minor rsworkad ftyscn sadknants Aritsr narh ad flyaeh Osoosrt*- Mmtoarria, aatstona. aandstons, and contAomsme, with suCordlnats ANTLER OROOENIC BELT AND INNER-ARC BASIN ROCKS Umsstons and dotamltizad I (AUTOCHTHONOUS) Mudstona. aatstona. chart, volcanic rocks, mnor Bmaatona, aanoatona. and eongtomaraia (AU.OCHTHONOUS) % V/ Erosionoi lim it T K r v t t ^ i v i f , t M t t i om »»p«r p lot* S ♦ t ► * • — S M p F»a 1 1, prrp w9 indicetpp ipt«pf SCALE SO '0 0 ISO 2 0 0 m i l e s 100 2 0 0 KILOMETERS CO NIC P R O J E C T IO N O Umpleby and others (1930), Ross (1934) and Bostwick (1955). Regional stratigraphic nomenclature was found to be inade quate as more detailed work was completed in the Pioneer Mountains. Thomasson (1959) described a thick assemblage of siliciclastic strata in the central Pioneer Mountains, which he informally named the Muldoon formation. The forma tion was subdivided into four members which are, in ascen ding order, the Copper Creek, Garfield, Iron Mine, and Wildhorse. In 1960, Ross published a short paper to note the presence of a thick siliciclastic sequence, "not previ ously recognized anywhere else in Idaho", which crops out in the Mackay quadrangle. Ross (1962) named this Early Mississippian to Early Permian sequence the Copper Basin Formation, and designated the type section in upper Star- hope Creek, Pioneer Mountains. The Copper Basin Formation was thought to interfinger with, and contain lithic equi valents to, the Milligen, Wood River, and White Knob Forma tions (Ross, 1962; Wolbrink, 1970). It is in part approx imately equivalent to the informal Garfield limestone member of the Muldoon Formation. Ross (19 62) also intro duced the name White Knob Limestone for carbonate and sili ciclastic strata in south-cnetral Idaho formerly mapped as the Brazer Limestone. U.S. Geological Survey geologic quadrangle maps, using the stratigraphic nomenclature proposed by Ross, were published in 1968 (Nelson and Ross). Wolbrink (19 70) mapped the Drummond Mine Limestone as a distal tongue of the bioclastic White Knob Limestone. Bollman (1971) distinguished the Drummond Mine Limestone from the White Knob Limestone; the Drummond Mine Limestone lacks large fossils and chert pods, is in stratigraphic continuity with the overlying Scorpion Mountain Formation, and is older than the White Knob Limestone. Pauli and others (19 72) formally raised the Copper Basin Formation to group status and divided it into six formations. Skipp and Hall (1975) restricted the Copper Basin Formation of Ross to Mississippian age on the basis of conodont, foraminiferal and ammonoid data. Sandberg (1975) established a Devonian age for the Milligen Formation in the type section. Conse quently, Pauli and Gruber (1977) renamed the strata assigned to the Milligen in the Copper Basin Group, the Little Copper Formation, which is Early (?) Mississippian in age. In addition, the following authors have made recent contributions to understanding the geology of this area: Nelson (1979), Nilsen (1977), Larsen (1974), Rothwell (1973) and Grover (1971). Figure 3 illustrates the sequence of nomenclatural changes outlined above. Paleogeographic Models Roberts and others (1958) established a model and nomenclature for northeastern Nevada which is still used to described Paleozoic sedimentary rocks throughout the Antler foreland basin trend. The basin of deposition was 9 Figure 3: Summary of Stratigraphic nomenclature used in south- central Idaho. Compiled from Pauli and others (1972), Pauli and Gruber (1977), and Nilsen (1977). 10 M ISSISSIPPIAN PENNSYLVANIAN PERMIAN SYSTEM Lower Upper Lower Middle Upper Lower Middle Upper SERIES K inderhook- ian O sagean M eram ecian C hesteran SERIES < o C D 3 O o CL ' 3 3 0 O D c 1 “ O C / 5 3 3 T D C L S C D td O C T to X " v: 3 “ C D “ C O Q C O m T_ O Ui O < « Q C D if — O C D CL « < l ! , Muldoon Form ation i Copper Creek r~ cd \ 3 § / =• q \a> / 3 — i \ / C D Z t ' . \ / C / 5 C D Y O C l 3 C D * W ildhorse O o C L 5 < C D Wood River Fm W hite Knob Lim estone H 3^ o 3 o C / 5 C O o 3 CD < _ n C O 3) o w C / 5 CD C T > no 3= "0 < o o O “5 o L L C D * “ C D C D 3 0 3 v: < C D 2 -5 3 C / 5 (0 _ o I =r £ a g (O C D 3 CD f? m q o 3 3 C D 3 C D C D C / 5 O ^ 3 3 C D o CT co e- C T ) — ® 8 C O 3 < J ) Q P c o QD t / > CT " 3 O CT OP Copper Basin Group (O C D 3 "0 _ o c o E L - > i — no Copper Basin Group Wood River Fm. G lide M tn. P la te Copper Basin PI at e r- ° n C — q " ° - ■ “ % - * ■ c d o D ru m m o n d M in e L im e s to n e c <2 c "j4 W h ite K nob L s . O _ o C O C D -vl "• C T ) C D C O $ o C D 3 m Copper Basin Group r r s a C D ?» c 3 o o 3 TD TD C D r 3 CL o®J--' 3 3 "Oo <o o O I cr a > *E -> l “0 a “ 0 c o — 3 " — C D S P C D C D 2 c 3 CT C / 5 C D — i o C D 3 * 3 Q 3 o CO o CO o C L o C L 3- l e C Fm. m 3 "0 C D o ;*■ 3 C D m >< 3C 3 O CO Q c 3 3 3 3 “* ■ C O " 0 a c c 3 ■T C D TD 3 Q o TD O O M o C D — t 3 C D O Q . C O C O 5" S’ T D T D T > "O C O s o C P w 2 2 C D C O aS ’ 5- < o • O C D C O * c 3 -► O 3 - CT C D “1 2 3 b Copper Basin Fm ( of Ross, 1962) z -V _■ o C / 5 3 C D C D O 3 C D C D 3 3 < o - s i 2 -5 a -> l 3 C / 5 divided into an eastern, miogeosynclinal carbonate assem blage, a transitional assemblage, and a western, eugeo- synclinal siliceous assemblage. Ross (1960, 1962) suggested that the strata assigned to the Copper Basin Formation formed the northwestern portion of a "geosyn clinal lobe" present in southeastern Idaho and extending south into Nevada. An eastern source area for the Copper Basin sediment was implied. Pauli and others (1972) published a detailed discussion of the stratigraphy of the Copper Basin Group, but did not include comments on the provenance, mode of deposition or paleogeographic setting. Poole (1974) suggested that strata assigned to the siliciclastic and transitional assemblage were derived from the Antler Highland to the west, whereas the carbonate assemblage was derived from the cratonal platform to the east. The Antler Highland was composed of pre-Mississip- pian eugeosynclinal strata thrust into a structurally high, subaerial position (Poole, 1974). The Drummond Mine Lime stone of the Copper Basin Group was identified as a turbidite-interturbidite accumulation of carbonate in a basin floor depositional environment with an eastern source (Thomasson, 1959 and Poole, 1974). A structural study of the Fish Creek reservoir by Skipp and Hall (1975) involved the recognition of a thrust sheet of the Copper Basin Group, which included the Drum mond Mine Limestone. They concluded that the entire 12 Copper Basin Group was derived from the Antler Highland and deposited by turbidity currents adjacent to the conti nental margin. Subsequently, the Copper Basin Group was thrust at least 16 km east where it now overlies miogeo- synclinal rocks of the eastern assemblage. Sandberg (1975) also suggested a western source for the Drummond Mine Lime stone as a result of study of the McGowan Creek Formation which may be a thinner, eastern facies of the Drummond Mine Limestone. Ross (1960), Wolbrink (1970), Poole (1974), Bissell (1974), Sando (1976), Rose (1976) and Nilsen (1977) suggest an eastern source area for the sediment assigned to the Drummond Mine Limestone. The carbonate cratonic platform is an obvious source area. Nilsen (1977) recognized the terrigenous clastic component in the Drummond Mine Lime stone and suggested an interfingering of siliciclastics derived from the west with carbonate derived form the east. A paleogeographic model for the Copper Basin Group must satisfy the requirements of a predominantly medium-to- coarse-grained terrigenous clastic sequence with a thick formation of carbonate in its lower part. Many previous workers have based their models on two basic assumptions: 1) that the Drummond Mine Limestone is 100% carbonate, and 2) that carbonate was derived from the east and silici clastics from the west. 13 Statement of Intent The Copper Basin Group was chosen for study because its age, lithologic composition, primary sedimentary struc tures, and location indicate that it was deposited east of the Antler Highland in the Antler foreland basin during the Early Mississippian (Stewart and Poole, 1974; Poole, 1974; Poole and Stewart, 1977; Nilsen, 1977). Although the Copper Basin Group has been incorporated into regional discussions of Paleozoic Cordilleran tectonics and sedimen tation, very little has been published concerning the specific sedimentologic characteristics of individual forma tions within the Copper Basin Group. The Drummond Mine Limestone is anomalous in the Copper Basin Group because it is primarily a calcisiltite interbedded with micrite, limey argillite and argillite. All other formations, with certain exceptions, are composed of terrigenous elastics with little or no carbonate content. The exception is the 85 m thick Green Lake Limestone of the Muldoon Canyon Formation. The Green Lake Limestone is discussed in Appendix A. It is a premise of this thesis that a detailed stratigraphic analysis of the Drummond Mine Limestone will provide information necessary for the interpretation of the Copper Basin Group, the Antler foreland trough depositional environment, and the mode of deposition of fine-grained 14 mixed carbonate and clastic sediments. Stratigraphic analysis is divided into four stages: 1) field work, 2) laboratory analysis, 3) statistical analysis, and 4) interpretation and modeling. Field work involved observation and collection of data concerning the extent and physical characteristics of outcrops, bedding thickness and type, primary sedimentary structures and lithologic composition and relationships between and among bedding units. Statistical analysis was applied to bed thickness, bed frequency and primary sedimentary structures in an effort to more completely characterize the formation. The purpose of the stratigraphic analysis is to provide a useful data base from which models may be proposed to explain the modes of deposition, the paleogeography and to relate modern and ancient sedimentary analogs to the Drum mond Mine Limestone. Geographic Setting The Drummond Mine Limestone crops out in a linear pattern through the central portion of the Pioneer Mountains (Fig. 4). The Pioneer Mountains are the highest range (3,200 m) of a sequence of northwest-trending ranges in south-central Idaho. To the west is the relatively lower, but still spectacular Sawtooth Range. Sun Valley, Ketchum and Hailey, the closest towns are located in the 15 Figure 4 Geologic map of the study area. Modified from Wolbrink (1970) and Dover and others (19 76). 16 intervening Wood River Valley. East of the Pioneer Mountains, a series of valleys and ranges continues to the Continental Divide and includes the White Knob, Lost River, Lemhi, Beaverhead, Tendoy, and Bitteroot Ranges. Elevation decreases abruptly to the south where the Snake River Plain begins. The Copper Basin is a triangular-shaped inter- montane basin located between the Pioneer Mountains and the White Knob Mountains. Starhope Creek drains north into Copper Basin from a U-shaped glacial valley. Extensive glaciation in the Pioneer Mountains combined with subse quent stream erosion is responsible for the excellent exposures of unweathered bedrock in the study area. Head ward erosion of Starhope Creek has modified the lower two- thirds of the valley. Glacial features of Starhope Valley include arretes, cirques, hanging valleys, lateral moraines and the outwash plain of the Copper Basin. Slopes are steep, and in places, covered with scree. Snow blankets the Pioneer Mountains from October until mid-June, and may be a detriment to mapping as early as August and September. o o Summer daytime temperatures range from 20 to 25 C, and at O night drop to as low as 5 C. Rainfall is frequent, commonly from late afternoon thunderstorms during July and August. Vegetation is alpine to subalpine, consisting of sage, sumac, aspen, grasses, wildflowers and clusters of conifers in the lower valley areas. Free-flowing streams, creeks and springs are found throughout the area. 18 The Pioneer Mountains traverse Blaine and Custer Counties, south-central Idaho. Sections studied along Starhope Creek are in the Challis National Forest, Blaine County. Copper Basin and Starhope Creek are accessible via dirt roads from Sun Valley, Mackay and Arco. A reconnaissance study, begun in July, 1977, deter mined where the best exposures of the Drummond Mine Lime stone are along Starhope Creek. This area is one rigde north of the type section measured and described by Pauli and others (1972). The remainder of July and August were spent measuring sections, documenting stratigraphic infor mation, lithology, primary sedimentary structures, fossils and weathering characteristics were noted for each bed. 19 II. FIELD WORK Techniques and Definitions The Drummond Mine Limestone was examined over approxi mately five square miles along Starhope and Little Copper Creeks. The geologic map by Dover and others (19 76) was refined during the course of field work (Fig. 4). Unpub lished U.S. Geological Survey advance sheet of the Mackay 3NW (scale 1:24,000) topographic map was used as a base map. A reconnaissance survey indicated the usual method of measuring a stratigraphic section would not be an adequate approach to study the Drummond Mine Limestone. In the Drummond Mine Limestone significant sedimentological and stratigraphic data occurs on a small, but measurable scale delimited using the Jacob's staff and Abney level method. Within each Jacob's staff interval more detailed measure ments were taken concerning bed thickness (measured with a centimeter scale), primary and secondary sedimentary struc tures, color, lithology and grain size. A short-hand notation was developed to described these features. Time and outcrop exposure precluded measurement of the entire 20 formation with the centimeter rule. The thickness of a Bouma division was measured directly. Bed thickness was derived by adding the divisional thickness values within each bed. Approximately 1800 individual measurements on Bouma divisions and beds were taken. Color was determined by comparison with a U.S. Geological Survey color chart. Appendix B is a compilation of the field data. It is necessary to clearly define the terminology used in measuring the stratigraphic section. A "bed" is a sedi mentation unit, deposited by a single flow mechanism at a particular time and place. Primary sedimentary structures within a sedimentation unit relate to a common genetic history. The occurrence of a sequence of primary struc tures within beds prompted use of a modified version of Bouma's (1962) turbidite divisions, Ta, Tb, Tc, Td and Te. Field use of the Bouma divisions was based strictly on characteristics observable in the field, such as primary sedimentary structures, color, lithology, and bedding contacts. Field use of the Bouma sequence does not imply that Bouma's hydraulic interpretation is applicable to the Drummond Mine Limestone. Every effort was made to be consistent in classification of beds. For example, all cross-laminated and convoluted or contorted strata were assigned to the Tc division. In the field it was not possible to distinguish between a Te which was part .of the bed and a Tf (Hesse, 1975) which was deposited as a 21 pelagite, therefore, a separate bed. That distinction requires interpretation and analysis beyond the scope of the field situation; the Tf division was not used in field classification. All parallel-laminated to massive, dark gray to black, thin-bedded strata were designated Te inter vals. Notes in the comments section of the stratigraphic log (Appendix B) clarify the relationships between sets of strata. Limitations on the field techniques reflect the physical characteristics of the formation and the qualita tive interpretation of the stratigraphy. Although outcrop exposure is generally excellent, portions of the formation are covered by talus or vegetation. The covered portion was measured only with a Jacob's staff, or a bed was followed until a well-exposed out crop was found. Addi tional error may be introduced in the misidentification or nor-recognition of Bouma divisions and beds. The fine grained and monotonous character of the bedding sometimes created problems in field identification of a single bed versus a division within a bed. Although every attempt was made to separate observation from interpretation during data collection, some interpretive assumptions are unavoid able in categorization of strata. The Drummond Mine Limestone was measured in three sections: Section 4 (219 m) begins at the base of the formation; Section 5 (92 m) and 6 (247 m) cover the middle 22 and upper portions of the formation (Fig. 4). A bed at the top of Section 5 was followed along strike to the outcrop where Section 6 begins. The top of the formation is in the cirque at the head of Starhope Creek and is covered by talus and a possible rock glacier. The contact between the overlying Scorpion Mountain Formation and the Drummond Mine Limestone is identifiable within about 15 m (stratigra- phically). The formation is poorly exposed between the top of Section 4 and the base of Section 5: this portion was not measured with Jacob's staff or centimeter rule. Sec tions 4, 5 and 6 represent a stratigraphic composite (558 m), which is less than the total thickness of the Drummond Mine Limestone. In the opinion of this author, the sections measured adequately represent the stratigraphy of the formation, and an accurate sedimentologic analysis of the formation is possible based on the data collected. A total of 5 8 oriented hand samples were collected from the Starhope Creek locality of the Drummond Mine Lime stone. Representative samples were taken from each major lithotype, where significant lithologic changes occurred, and to document small-scale sedimentary structures. Appendix B includes location and field description of each sample. 23 Field Observations Primary Sedimentary Structures Sedimentologic analysis of bedding in the Drummond Mine Limestone is based on the sequence of primary sedi mentary structures and bedding contacts as observed in the field. Sedimentary structures noted include the following: parallel laminations; convolute or contorted laminations; low-angle, small-scale ripple lamination; graded bedding; rip-up clasts; load structures; flame structures; massive bedding; flat bedding; flaser-type bedding; channel cut and fill; scouring; erosional, sharp and gradational basal contacts within and between beds; and bed thickness ranging from lamina through very thick beds (greater than 1 m). Bed thickness is classified according to Reineck and Singh (19 76). It is important to note the apparent absence of some sedimentary structures: sole marks such as flutes; tool marks such as grooves, prod, bounce, brush, skip and roll marks; ball and pillow structures, inverse grading, high-angle cross stratification, and dish structures. However, the Drummond Mine Limestone commonly does not weather out along bedding surfaces; the most favorable condition for observation of sole marks and bedding surface features. Certain sequences of primary sedimentary structures 24 recur throughout the formation. Figure 5 presents a sche matic comparison of the typical Bouma sequence and the sequences most commonly observed in the Drummond Mine Lime stone. Although the complete Bouma sequence is relatively rare, it does occur in beds with an erosional, scoured or cut, basal boundary. Base-cut-out Bouma sequences predom inate; Ta, Tb and/or Tc intervals are absent. The Tcde sequence occurs frequently throughout the formation. This is illustrated in a graph of the percent of type bed sequences averaged within each 10 m of stratigraphic sec tion (Fig. 6). It may be seen from Figure 6 that the base-cut-out sequence Tde is most common throughout the formation. Sequences which do not fit the typical Bouma sequence are shown in Figure 5. Figure 5 is the mixed Tc-e sequence of flaser-type bedding which occurs toward the top of the formation. The mixed Tc-e sequence appears to be small cross-laminated ripples embedded in a finer-grained pelitic material. The finer-grained sediment has faint to distinct parallel laminations, and may represent Tb, Td, Te or Tf intervals. In the field, some beds were designated Tde sequences even though they contained structures, such as thin wavy laminae, not mentioned in Bouma's scheme. As in Figures 5d and e, the sedimentary structures are either thin cross-laminae or slightly contorted lamina of a coarser grain size. Differential weathering causes the anomalous lamina to appear as yellow-gray stringers against 25 Figure 5: Schematic comparison of a typical Bouma sequence and sequences of primary sedi mentary structures most commonly observed in the Drummond Mine Limestone. Diagrams are drawn from thin sections of samples, as indicated. 26 A parallel laminations to thin bedding parallel laminations cross laminations parallel laminations massive or graded Idealized Bouma Sequence B eor f pelagite silty argillite pelitic parallel laminations silty sand deformed current laminations silty sand current ripple laminations silty sand parallel laminations e silty argillite sample 4 -8 sample 4 -2 3 B b,dore cBe parallel laminations flaser - type current ripples parallel laminations sample 5 - 8 sample 5 - 7 parallel laminations parallel laminations with deformed parallel laminations current ripples pelitic parallel laminations small current ripple parallel laminations deformed current laminations 27 Figure 6: Graph showing the percentage of each type of bedding sequence averaged within each 10 m. of stratigraphic section. The frequency of Td and Tde beds remains about the same, whereas Tcde and Tee units increase in frequency up-section. 28 SECTION 4 SECTION 5 SECTION 6 Tee Td, Tde Tcde (Meters) ■not measured in detail 200 150 1 0 0 50 'not measured in detail 100 sificified 200 150 100 50 100 50 50 100 Bouma sequences* % frequency of occurrence the pale gray background. Interval Te was identified as the black to gray-black pelitic interval overlying or underlying any other division. Te intervals commonly exhibit a regular variation in color which may represent bedding. A thick (greater than 20 cm) accumulation of this type was called bedded argillite and measured as a single unit. Bedded argillite occurs most frequently in Sections 4 and 5. Several bedding types which do not follow the Bouma sequence were observed throughout the formation. Massive gray limestone (mgl) is an unusual lithology which occurs almost exclusively in Section 4. Mgl is distinguished from Td intervals by lithology, thickness (from 20 cm to 100 + cm), primary structures and weathering characteristics. Lithology and thickness will be discussed in more detail later. Primary sedimentary structures include massive bedding, and minor, very faint, parallel or slightly undulatory laminations and sharp bed boundaries. Some mgl has a basal thin (1-2 cm) cross-laminated interval. Bedded white and gray limestone noted in Sections 5 and 6 appear to be silicified, thickly-laminated or thinly-bedded litho- logic couplets. No other sedimentary structures are present. Rarely, bedded quartzarenite appears in the forma tion, as a graded medium to thick bed with sharp, planar, to slightly concave, basal contacts. Paleocurrent data were collected in the field wherever 30 possible. In addition, oriented hand samples were taken and cross-bedding measured from cut surfaces. The data used to construct the rose diagram in Figure 7 is from small-scale cross-laminated Tc intervals. Data were corrected for tectonic tilt by the method outlined in Ragan (1973). Division of the data into 30° classes (after Pettijohn and Potter, 1977) results in a strongly bimodal distribution; 80% of the data indicates paleocurrent flows west-northwest and east-southeast. However, the rose diagram was constructed from only 17 data points and small- scale cross-laminations may be the result of low volume traction currents at some angle to the major depositional slope. Thin, fine-grained pulses of sediment could be diverted by irregular bottom topography or bottom currents. Lithology and Grain Size From a distance, the Drummond Mine Limestone appears to be an accumulation of beds in shades of medium to light gray with a few interspersed black to dark gray beds (Fig. 8). There appears to be a field relationship between color, lithology and Bouma interval. The Ta, Tb, Tc and Td inter vals are always calcareous and weather as light to medium gray. Te, as designated in the field, grades from calcar eous (gray) to non-calcareous (dark gray to black). Bedding is disrupted where calcite veins have developed parallel to stratification. A physical description of rock samples 31 Figure 7: Rose diagram of paleocurrent data and a listing of the data. Bimodal distribution of the data indicates west-northwest and east-southeast directions of transport. 32 PALEOCURRENT DATA N * 17 3 0 ° c/asses Sample master #______bedding 2 5W55E 2 5W55E 5-7 17W44E 5-8 9W55E 5-/7 17W44E 5-7 17W44E 4-2 2 1E40E 4-23 5W40E 4-23 5W40E 3 20W64E 3 12W67E 3 53W45W 3 21W42W 5 8W54E 6 3W60E Recon. 12W77E Recon. NS 3 8E cross- paleo- laminae current o 9W3 5E 275 30W35E 275 4 3W67E 105 5W85E 100 60W15W 106 4 3W2OW 106 8W20W 90 40W20E 275 40W17E 276 3 8W62E 288 27W7 7E 101 20W57W 324 20W70W 292 48W64E 98 44W46E 276 18W3 3E 282 3E47E 90 33 collected is presented in Appendix B. Grain size is so fine throughout the formation that a quantitative field evaluation is not possible for most strata. Grain size is primarily in the coarse silt to fine sand range; rarely, medium to coarse sand is present. On a fresh surface individual grains are difficult to discern from carbonate matrix. Normally graded to medium sand is visible in Ta and some Tb intervals. Grain size studies were conducted in the laboratory. Fossils and Bioturbation Biotal evidence is sparse in the Drummond Mine Lime stone. Fossils were found only in small channelized beds in middle to upper portion of the formation exposed in Sections *5 and 6 (Fig. 8C). Invariably, these small chan nels contain a collection of pelmatozoan debris foramini- fera, sponge spicules, bryozoans (?) and mollusk fragments. The allochem content represents about half of the channel fill; quartz, carbonate and chert clasts of similar size and shape comprise the rest of the material. Grain size grades from medium to fine sand; differential weathering enhances grain visibility. Bioturbation was not observed in the formation. Diagenesis and Metamorphism Field observation of diagenetic and metamorphic 34 Figure 8: Outcrop photographs of the Drummond Mine Limestone. (A) Outcrop character of thin bedding at the head of Starhope Creek, section 6, turbidite facies D and G. (b) Typical outcrop of Tde or Tdef bedding sequences. Note lateral continuity of beds and bed thickness. Jacob's staff is 1.5 m in length, the upper end is divided into 1 cm segments. (c) Sandy silty micrite with bioclastic flaser-type structures. This is an unusually thick, sand bed of turbidite facies E. (D) Two beds of massive gray limestone (mgl) seperated by a thinner Tde bed (Tde). The lower bed is is capped by a thin argillite layer, Te or Tf. The base of the upper bed shows small-scale low angle cross-laminae. 35 features is limited by the fine-grained character and the quartz and calcium carbonate composition of the rocks (Winkler, 1974). The most obvious diagenetic feature is the highly indurated character of the formation. Compaction during the process of lithification may have reduced the total formation thickness. Zones of white and gray "lime stone", mentioned previously, appear to be silicified. These units have bedding characteristics typical of the limestone, but are now siliceous. Silicification also occurs in some banded argillite accumulations. Silicified zones are rare, and usually occur in Section 5. Veined, calcite-injected zones cause a local thickening of the stratigraphic section and disrupt primary sedimentary structures. Bedding and sequence measurements were not taken from bedding altered by silicification or calciti- zation because of the uncertainty of identification of sedimentary sequences. In a very few Td beds a broad S- shaped reorientation of very thin lamina was noted. This always occurred near small-scale, megascopic folds. Bed and Interval Thickness Bedding in the Drummond Mine Limestone is laterally continuous and appears monotonously regular in thickness (Fig. 8). Even thin beds may be traced as much as 30 m or more. Thickness does not vary significantly along the length of the bed. A stratigraphic log of stratal 37 thickness, averaged over 10 m of section, versus position in the measured section, was constructed from the field data (Fig. 9). The log illustrates changes through time in total bed, Td and Tc thickness. Ta and Tb intervals were not plotted because of the paucity of data for these intervals. The Te interval was not included because it was recognized that the field designation of Te probably includes both Te and Tf intervals. Bed, Td and Tc values reflect a distinctive bed thinning from Section 4 through Section 6. It is apparent that most of the thickness of a bed is derived from the Td interval. There is more varia tion in the bed and Td log than in the Tc data. Averaged over 10 m, bed thickness ranges from 9 cm to 83 cm, Td thickness from 7 cm to 69 cm, and Tc thickness from 0.5 cm to 12 cm. As suggested by King (19 71), anomalously large bed thickness values were not used in the analysis. Histograms were constructed to show strata thickness, population distributions (Fig. 10). Sturges's Rule (King, 1971), for normal and log normal population distributions, was used to determine cell boundaries of the histograms. Bed thickness measurements, N = 16 41, do not include the five anomalously high values, silicified beds, argillite beds or white gray limestone. These bed types comprise a very small portion of the formation. The large number of strata measured should provide an adequate data base for the purposes of this study. The Td histogram was 38 Figure 9: Stratigraphic log illustrating changes in stratal thickness of beds, Td and Tc intervals, through time. The bed thick ness curve is very similar to the Td thickness curve and Tc thickness remains almost constant through time. 39 200- 0 20 40 60 80 TOTAL BED THICKNESS (cm) i 20 40 60 8 Tc,Td THICKNESS (cm) Figure 10: Logarithmic-normal population distri bution histograms of bed and Bouma interval (Tb, Tc, Td) thickness, percent frequency vs. stratal thickness. N is the number of thickness values used to construct the histogram and g is disper sion of the data. Arrows indicate mean thickness for each set of data. 41 % Frequency LOG NORMAL DISTRIBUTION 40 - 30 - 20 - 10 - 0 1.8 3.3 5.9 10.7 19.3 35 40-| 30- 20 10 - 1 . 3 1 . 7 2.3 3.0 4.0 5.2 6.9 9 . 1 0 120 Tb N = 5 4 ^ = 5.6 g = 3 .3 / Tc N = 332 7 - 2.4 g =1.8 Td N = 1410 7 = 6.2 g =2.76 40 H 30 - 20 - 0 1 . 5 2.2 33 5.0 7.6 1 1 . 4 1 7 . 3 26.1 39.4 59.5 90 © Bed 40 H 1641 13.48 3 ./ 30 - 20 - 0 .93 1 . 2 32 6.0 1 1 . 2 20.9 38.9 72.4 134.9 2512 467.7 S trata Thickness (cm) 42 constructed from 1410 thickness measurements ranging from 0.5 cm to 90 cm. Six anomalously thick beds were not used. The Tc thickness histogram was made from 332 measurements ranging from 0.5 cm to 12 cm. All the Tc intervals measured were used in construction of the histogram. Tb intervals range from 1 cm to 150 cm thick; however, 54 out of 56 intervals are less than or equal to 35 cm in thickness. Histogram data is discussed in greater detail in the section on Statistical Analysis. 43 III. LABORATORY ANALYSIS Lithology General Statement Petrographic analysis of sedimentary rocks of the Drummond Mine Limestone is based on point count data collected from 40 Bouma intervals in 23 thin sections. The sedimentary rocks may be divided into four basic lithotypes based on the presence, absence and/or abundance of micrite, argillaceous micrite, allochems, terrigeneous clasts and argillaceous material. The samples are classified using Folk's (1974) scheme for impure chemical limestone and a sandstone classification by Pettijohn and others (1973). Rock Type I Massive gray limestone (mgl) is exclusively composed of rock type I, argillaceous spicular micrite (Fig. 11). This lithotype consists of micrite and microspar with or 44 Figure 11: Field photographs and photomicrographs of turbidite facies D lithotypes I and II. Scale is 15 cm long. (A) Massive gray limestone with parallel laminae, silty brown-weathering laminae (a) and cross cutting calcite veinlet (b). (B) Photo micrograph of massive gray limestone showing micrite-microspar-pseudospar matrix with sponge spicules (a) and pelma- tozoan fragment (b) (plane light). (C) Field photograph of a Tbcde bed com posed of graded sandy-silty micrite (scale is 15 cm long). (D) Photomicrograph of lithotype II showing silt- and sand-size monocrystalline quartz (a) chert (b) carbo nate (c) and feldspar (d) clasts. Matrix is composed of micrite and the authigenic minerals microspar, quartz, diopside, feldspar, tremolite and pyrite (cross polarized light). Photomicrograph scale bars are 1.0 mm. 45 46 without sponge spicules and argillaceous components. Micro spar is usually less than 10% and is probably a neomorphic diagenetic phenomenon. The argillite is distributed throughout the rock as a fine-grained material that imparts a dark color to the rock. Calcareous sponge spicules, up to 7% of the rock, are aligned parallel to stratification. Thin, slightly deformed, brown-weathering laminae noted in the field are layers with a higher concentration of authi- gneic quartz and calcite (Fig. 8d). Authigenic quartz occurs as very finely crystalline material in the micritic matrix. Td intervals thicker than about 20 cm are usually rock type I. A tabulation of petrographic data from five type I thin sections is given in Table 1. Rock Type II Rock type II, quartzitic calcisiltite, is the common lithology throughout the Drummond Mine Limestone. Although variations occur, it is usually composed of silt- to fine sand-size quartz clasts in a matrix of argillaceous micrite and microspar (Fig. 11). Other clasts noted include chert, mudstone, siltstone, quartzite, polycrystalline carbonate, micritic intraclasts and allochems. Petrographic modal analysis of the rock type II samples examined are presented in Table 2. A limited variety of allochems occur: sponge spicules, pelmatozoan fragments, foraminifera and mollusks. Pelmatozoans, foraminifera and mollusks have rounded, 47 Rock Type III Rock Type I Rock Type IV 4 Samples 5 Samples S Samples Table 1. Petrographic mortal analysis of lithotypes I, III and IV. Note. o u ( 1 ) P (U P o id e u ■p a H -1 .q < u xi i d <U 3 (U u < l lN <U «r| p o u & in O U < td04 < u o Classif i ca tion Mdm 6 17 / 0.6 35 45 /2 /p quartz wacke 4-14 33 12 53 / .6/6.4 / 4q quartz wacke 4-20 35 / 0.2 0.2 0.4 47 16 /I / l.lq quartz wacke 5-1 4 1 5 4 7 9 16 14 0.6 t/t / t 2 2q quartz wacke Tb 6-5A 54 15 1 20 / 1/ / 8 2 quartz wacke Tb 6-5B 60 8 0.6 19 10 / quartz wacke Tc 6-5B 55 4 2 23 0.6 0.6 • 3/ / 15 quartz wacke 6-12 42 t 23 22 0 t/ 7d 6q quartz wacke Mean 42. 1 8.8 1.9 6.1 3.3 0.5 29. 5 18. 1 0.6 .6/3.7 8.3 3.2 Min 17 t 0 0 0 0 16 0 1 0/0 0 0 Max 60 15 4 12 9 0.5 53 45 1/6.4 15 6 KSamples 8 5 4 2 3 1 8 6 3/2 3 5 4-6 4-8 4-21 2-9 6-4 / 44 84 / / ' / 38 2 / 0.5 /// /5 2/ / s 6R ts trt argillaceous spicular micrite argillaceous spicular micrite argillaceous spicular micrite micri te finely crystalline micrite rUpper 4-5 1 68 8 10 n micritic argillite Lower 4-5 3 3 59 7 24 / 4 micritic argillite Te 4-17 8 9 60 10 / 4 9 ts micri tic arq illi te Te V 11 / / / / /■ /// micritic argillite t - trace , d = diopside, q = quartzite, p = prehnite, s = sponge spicules 00 Table, 2. Petroyraphio modal analysis of l i thotype 1.1 r a - I I - p r a r a 0 1 N C tn p p» e 0 +j H e, p p .d Hi p E r a r a p r a o r a p Xi r a < —i •H < / > o o o u S3 p r a P. in o P o ‘rt S 3 P t t i a, m o n p Q J U ) A. r a m x c • H h .q p ra P -M A id a) 0 0 2 >. X ■P H U P d > .p xi r a u S 3 Si ra p p ra ra ■ p p 'd N p 11 -H < i » c p c P +» o p r a • r 1 r a• ri o ra ts tA e p r a p r a P r a tn c* o r t 3 A3 Ai o • H & f i \ 3 o r a g P r a a ) - i J C d H U ) E r a .C o o in -P r a c +j o r a A § . ^ «J Classification •H p (Po1k) Mdm 2 21 1 0 43 5 0 48 4 17 8 0.2/0 . 2 -H 0 0 0 0 4-2 8 2 46 14 60 8 11 sandy micrite 4-7 11 1 2 21 2 9 13 63 7 3 14 t sandy finely crystalline microspari te 4-15 26 1 33 6 40 30 1 t 3 silty- sandy finely crystalline mi.crosparite 4-16 21 2 1 9 2 3 6 38 4 20 11 sandy finely crysta11ine microspari te Ta 4-17 4 10 33 9 14 23 2 8 22 silty finely crystalline calcarenitic intra-microspari te l)[j| i : 4-18 8 12 13 38 8 59 7 0 4 l/t 12 si 1 ty finely crystalline calcareni tic in tra-microsparite I.owe i 4-18 1 10 18 43 10 71 4 0 4 /t 14 silty finely crystalline calcarenitic i ntra-microspar ite Uppe l 4-22 23 3 27 35 4 66 5 1/ sandy finely crystalline calcareni tic mi.crosparite Lower 4-22 25 7 24 31 16 71 11 4/ sandy finely crystalline calcarenitic microsparite Te 4-23 27 0 7 46 25 71 0 7 2/ si lty finely crystalline fine to medium calcarenitic micrite Tc 4-23 13 7 29 10 49 7 2/ 4 silty fi nely crystalline fine to medium calcarenitic micrite Te 4-23 4 1 76 9 85 - 5 0.3/ 5 si lty fi nely crystalline argillitic micrite l'c 2-7 23 3 3 35 22 57 13 1 /0. 6 sandy finely crystalline fine to medium calcarenitic sparite Tc 2-7 15 4 7 42 16 58 12 • 3 /l.6 sandy finely crystalline fine to medium calcarenitic sparite Tc 2-7 21 1 2 4 8 16 0 2 64 8 2 sandy finely crystalline fine to medium calcarenitic sparite T'd 2-7 18 1 11 42 15 57 9 3 /2. 4 silty finely crystalline fine to medium calcarenitic micrite Td 2-8 2 8 28 50 2 80 1 7.6 coarse calcilutite biomicrosparite 'J'c 2-9 18 0 .6 1 60 9 70 9.4 2 silty finely crystalline ■i'c 5-2 13 0.6 13 21 45 2 6 8 7 0.3 t sandy finely crystalline calcarenitic biosparite Tb 6-7 26 8 2 9 15 2 26 12 13 10 4 sandy finely crystalline spari te ‘ i‘e 6-9 25 0.3 6 45 1 46 0. 3 7 11 /0. 3 3 3 sandy finely crystalline very fine to fine calcarenitic microsparite Td 6-9 14 1 7 66 2 68 3 6 /0. 3 silty finely crystalline very fine to fine calcarenitic microsparite 6-9 20 3 3 16 20 9 45 16 11 silty finely crystalline very fine to fine calcarenitic microsparite Mean 16 . 6 2.8 6 .2 31.2 22.7 6. 8 57.6 11.8 9.6 4.6 1.5/0.9 7.2 10. 4 3 7.6 Mi 11 1 0 0 1 1 0 23 0 0 0 0/0 0 0 0 0 Ma x 26 10 33 66 60 16 85 13 30 11 4/1. 6 14 14 3 22 ( f Samples 24 13 23 2 4 24 12 24 9 19 16 7/6 2 4 2 5 abraded edges, and are often broken. Some originally calcareous allochems have been replaced by chert. Silt- to sand-size quartz may comprise from 3% to 4 3% of the rock. Quartz clasts are angular to subrounded, monocrystalline, common plutonic quartz (Folk, 19 76) with slight to moderate undulosity. Angularity of grains is strongly related to grain size: silt is angular to subangular, whereas, fine to medium sand is subrounded to subangular. Well rounded and rounded grains occur only in Ta intervals with grain sizes of medium to coarse sand. Micrite-microspar matrix is ubiquitous in rock type II. The matrix also exhibites a fine mixture of authigenic minerals: quartz, calcite, diopside, pyrite and hematite. In some of the finer grained laminae it is difficult to distinguish fine to medium silt- size quartz clasts form finely crystalline authigenic quartz. Some type II samples also have a significant percentage of argillaceous intraclasts; probably rip-up clasts from Te or Tf intervals. Although generally not visible in hand sample, argillaceous intraclasts may constitute from 1% to 24% of a thin section. Intraclasts are elongate and often are aligned in stringers parallel to laminations. Rock type II was observed in Ta, Tb, Tc and Td Bouma divisions. Cross-laminations and other current-formed primary sedimentary structures commonly occur in this lithotype. 50 Rock Type III The third rock type, silty to non-silty siliceous to limey argillite or argillaceous micrite is common in the Te, Tf and banded argillite units (Fig. 12). In the field, this rock type appears in association with Tc and/or Td divisions as black to very dark gray, very thin- to thin- bedded strata. On a fresh surface, the dark gray layers react to dilute cold HCl, whereas, black layers do not react. In thin section gray beds are argillaceous micrite, and black beds are micritic argillite. The argillaceous material is finely disseminated throughout the micrite. Lithotype III is distinguished from type I by the lack of sponge spicules and an increase in the argillaceous micrite. Field and laboratory study indicates that Te directly above Td layers are usually argillaceous micrite. The Tf inter vals overlying Te intervals are usually micritic argillite. Table 2 presents petrographic data from four thin sections of rock type III. Rock Type IV Rock type IV, quartz wacke (Pettijohn and others, 19 73) is characterized by an abundance of detrital monocrystalline quartz (43% average), common occurrence of detrital chert and minor contribution of carbonate clasts, micrite, micro spar and pseudospar (Table 2). Finely crystalline cherty 51 Figure 12: Field photographs and photomicrographs of lithotypes III and IV. (A) Photomicrograph of laminated silty argillite (upper) and silty argillaceous micrite (lower). Silt- size clasts are monocrystalline quartz (a), which are sometimes indistinguishable from authigenic quartz (b) (plane light). (B) Photomicrograph of lithotype II cut into very-fine grained non-silty argillite. Small-scale flame and scour features are visible at bed contact (cross-polarized light) . ( C ) . Field photograph of lithotype IV, a graded, sandy quartz wacke. Scale is divided into centimeters. This Ta unit is cut into the underlying Te argillite and contains ripup clasts similar to the under lying bed ( . a ) . (D) Photomicrograph of lithotype IV quartz wacke (cross-polarized light). The quartz wacke is composed of poorly sorted well-rounded to subangular monocrystalline quartz (a) and chert (b) in a matrix of micrite argillite and finely crystalline prehnite, diopside, epidote, tremolite and hematite. Scale bars are 0.5 mm on photomicrographs. 52 53 matrix occurs in all samples examined petrographically. In Pettijohn and others (1973) sandstone classification gray- wacke is appended to the name if more than 10% detrital matrix is present. The original detrital matrix was probably a mixture of clayey, siliceous and calcareous material. Petrographically the matrix consists of chert, argillite, and low to medium grade metamorpnic minerals. Prehnite, diopside, epidote, talc and tremolite occur as fine crystals disseminated throughout the matrix. Mono- crystalline quartz, polycrystalline quartz and chert are grouped under the quartz pole (Pettijohn and others, 1973) . Chert clasts occur in all samples, from 0.3% to 15% of the rock. Polycrystalline quartz clasts occur in five of the samples and appear to be quartzite clasts. Authigenic quartz was noted in all samples in the form of pore-filling cement and quartz overgrowths on detritial grains. Vein- filling calcite was noted in three samples. Allochems occurred in only four samples. Diagenesis and Metamorphism General Statement Petrographic analysis confirmed suspected diagenetic and metamorphic alterations in the Drummond Mine Limestone. Diagenetic features include the following: replacement or recrystallization of authigenic quartz, calcite and 54 plagioclase (minor); chertification of calcareous allo chems; calcification of siliceous clasts; calcite infilling of fractures; and formation of authigenic iron minerals j | (Fig. 13). Metamorphism postdates all except the frac ture filling. Diopside, talc, tremolite, epidote, prehnite, pumpellyte and chlinochlore were identified in thin sec tions or by X-ray diffraction. Only rock type III appears to lack evidence of metamorphism. All other lithotypes contain a mixture of primary, diagenetic and metamorphic minerals. Although the boundary between diagenesis and metamorphism is gradational, the occurrence of an amphi- bolite grade paragenesis (diaopside, quartz and calcite) indicates a metasedimentary classification for the Drum mond Mine Limestone (Winkler, 1974). Diagenetic History Recrystallization, dissolution, replacement and cementation (minor) have occurred in the diagenetic history of the Drummond Mine Limestone. In type II silty to sandy micrite some micrite is recrystallized to microspar and pseudospar (Fig. 13a). Recrystallization of micrite is incomplete; over half remains in its original state. Silicification occurred as a result of dissolution, replacement and/or precipitation of silica in the form of microcrystalline or crystalline quartz (Fig. 13a). Chert usually occurs as a patchy replacement of micritic matrix. 55 Figure 13: Photomicrographs of diagenetic and metamorphic features (A) Recrystallization of micrite to microspar and pseudospar, calcite veining in quartz clasts and calcification of chert clast (a) (plane light). (B) Chert replacement of micritic matrix, syntazial silica cement (a), sutured and concave-convex grain boundaries (b), authigenic calcite rhombs encroach on quartz (c) (plane light). (C) Photomicrograph of a finely crystalline quartz wacke (plane light). The matrix is composed of micrite, microspar, quartz, prehnite, diopside and tremolite. Calcite crystals are benning to degrade the edges of the quartz grains (a). (D) Radio- larian (a) chert clast partially replaced by calcite rhombs (b) with spotty replacement by quartz (c) (plane light). (E) Finely crystalline microsparite composed of microspar, pseudospar, micrite, diopside, microcrystalline chert, hematite, pyrite, epidote, tremolite and talc. Grains are elongate parallel to bedding. Recrystallized micrite, lithotype I (plane light). (F) Quartz arenite showing sutured and concave-convex grain boundaries, syntaxial quartz, blebs of authigenic quartz (a), chert grains (b), and cherty matrix (cross polarized light). All scale bars are 1.0 mm. 57 The degree of silicification is variable, from less than 5% to over 80% of the rock sample. Chert replacement of calcitic allochems also occurs. Precipitation of syntaxial silica on quartz grains also is relatively common; epitaxial cement is less common (Fig. 13a). Silicifi- cation is favored by relatively low pH, low temperature and pore waters supersaturated with silica (Berner, 1971; Blatt and others, 1972). Authigenic feldspars usually pre-date tectonism, and require a high concentration of dissolved silica, moderately elevated temperatures and a high ratio of sodium or potassium ions to hydrogen ions (Berner, 1971). Muscovite requires similar conditions, with the addition of abundant aluminum ions. The third stage in the diagenetic history is characterized by calci fication of detrital chert clasts, dissolution of quartz and replacement or precipitation of calcite as cement. The process of calcification of detrital chert is illu strated in Figure 13b. It involves almost simultaneous dissolution of chert and precipition of calcite. This occurs only in fossiliferous calcarenite (rock type II), for example, samples 4-17 and 5-10. Syntaxial or epitaxial calcite precipitated on detrital clasts is uncommon. Precipitation of calcite indicates conditions of high pH, higher temperatures and supersaturation of pore waters with respect to calcium carbonate. Three diagenetic accessory minerals, hematite, pyrite and magnetite, formed 58 by replacement. Pyrite is almost ubiquitous in the thin sections examined, hematite is common, and magnetite is uncommon. Pyrite and hematite occur as euhedral crystals, blotches, and in disseminated patches. Magnetite was identified in X-ray diffraction analysis of insoluble residues from samples 4-5 and 5-5. Many thin sections exhibit a dark coloration to a basically micritic matrix which may be due to some combination of diagenetic iron minerals and quartz. The abundance of pyrite indicates an ample source of iron compounds and dissolved sulfate (Berner, 1971). These conditions are characteristics that are typical of fine-grained marine sediments high in organics (Berner, 1971). Barker and Bissell (1978) report similar results from analysis of the Great Blue Limestone of Utah. A late stage diagenetic feature present in some samples is a system of fractures infilled with calcite. Metamorphism Siliceous limestone of the Drummond Mine Limestone is not ideal for use in identifying metamorphic grade. The mineral assemblage of quartz + calcite may persist through medium grade metamorphism (Winkler, 1974). Several minerals (quartz, feldspars, muscovite) may form under diagenetic or metamorphic conditions. The most common metamorphic mineral paragenesis in the Drummond Mine Limestone is diopside and quartz (Fig. 13). Diopside 59 was identified in about half of the Tc and Td interval samples. In all samples it represents less than 10 percent of the total modal analysis. Usually, diopside occurs dispersed among the silicified micrite matrix as indi vidual very fine to fine crystals. Other metamorphic minerals identified in the petrographic analysis include: epidote, prehnite, and talc (very low grade metamorphic minerals); muscovite (diagenetic or very low grade meta morphic mineral)? and tremolite (very low grade metamorphic mineral). The presence of diopside, magnetite, tremolite, muscovite and quartz were also confirmed in the X-ray analysis of selected insoluble residues. X-ray diffraction of insoluble residues also permitted the identification of pumpellyite (a very low grade metamorphic mineral) and chlinochlore (a diagenetic or very low grade metamorphic mineral). Other metamorphic minerals characteristic of medium grade metamorphism probably did not form because of the essentially stable configuration of siliceous lime stone (Winkler, 1974). Occurrence of diopside suggests that the Drummond Mine Limestone was heated to about 50 0 c and/or buried to a depth of 20 to 25 km. The essentially undisturbed character of bedding and preservation of small- scale primary sedimentary sturctures does not suggest great depth of burial. The necessary heating could have occurred by circulation of metasomatic fluids during emplacement of the Mesozoic Idaho Batholith. 60 Grain Orientation A pilot study of grain orientation was undertaken to substantiate the paleocurrent data. Seven hand samples were chosen based on the following criteria: detrital grain size of at least coarse silt; presence of current- derived primary structures, such as parallel laminations and/or cross-laminations; and known orientation in the field. Selected samples are from Tb, Tc and Td intervals. Thin sections were cut parallel to bedding and the north arrow scribed on the thin section. A petrographic micro scope was used to measure the orientation of the long axis, in degrees from north, of at least 300 detrital grains per thin section. Only detrital quartz, carbonate or rip- up clasts with apparent length to width ratios of approxi mately 2:1 were measured. This method of analysis is described by Onions and Middleton, 19 68; Colburn, 19 68; and Spotts, 1964. Using Sturges's Rule (King, 1971), orientation measurements were grouped into nine cells of o O 20 each, from 0° to 179. Figure 14 shows rose diagrams of the grouped data for each thin section as well as the combined data for all thin sections. Mean, variance and standard deviation were calculated for each sample and for the combined data. Mean values range from 66° to 99°, the average is 82°. Mean and mode coincide in the fifth cell 61 Figure 14: Rose diagrams of grain orientation data derived from thin sections of Tb, Tc and Td intervals. N is the number of grain orientation measurements used to construct each rose diagram. The Tc intervals and one Td interval show a unimodal distribution (but not in the same direction). The other samples show a bimodal distribution of the data. Rose diagram of combined data indicates a strong east-west component with some northwest-southeast influence. 4-l5(Td) N-300 6 - 7 (Tc) 6 - 9 ( T d ) N-300 4 - 7 ( T c ) N-306 6-l2(Ta ) 4-16 (Tc) N =300 4-18 (Tb) Combined Data N= 2/08 63 o ° between 80 and 99 . Values for standard deviation range from 14° (sample 6-9) to 39° (in sample 4-15), and the average is 28°. Cells 4,5 and 6 (between 60° and 119°) account for 44 percent of the data. Grain orientation data indicates a current direction approximately east-west. Comparison of the grain orientation and paleocurrent rose diagrams suggests a slight correlation between the two. The mode of the paleocurrent data overlaps the mode and mean of the grain orientation data. Several considerations serve to place limitations on this data. The primary limitation is the possibility of grain reorientation during diagenesis and metamorphism of the rock. Relatively high variance values suggest that substantial post-depositional grain reorientation has not occurred. The fine sand grain size may respond more readily to variations in the current and come to rest at some angle to the main current and current direction may vary through the depth of the turbidity current (Colburn, 1968; Onions and Middleton, 1968). Particle Size Analysis A pilot study of quartz grain size was conducted using a Zeiss TGZ3 Particle Size Analyzer. The purpose of the study was to measure textural differences in various Bouma intervals. Four thin sections were analyzed: 5-10 64 and 5-11 from Ta intervals; 4-18 from a Tb interval; and 4-22 from a Tc interval. Photographic prints, enlarged from 7 to 8.3 times, were made from thin sections. Quartz grains were measured wherever they intersected the grid superimposed on the photograph. The greatest accuracy for construction of a cumulative cuve is obtained by counting at least 1000 grains per sample. Grain size is measured by adjusting the light spot to the size of the grain, results are tabulated on a bank of 48 telephone counters. The Particle Size Analyzer may be adjusted for grain size range (standard or reduced), cell width (linear or expo nential) and for calculation of cumulative or distribution curves. Reduced size range, and exponential settings were used in the present study to obtain data suitable for the cumulative curve. The exponential setting provides greater accuracy when the particles are small (Boggs, 1967). Actual particle size is determined by dividing the interval limits (cell boundary values) by the magnification of the photograph. Histograms and cumulative curves were constructed from the data (Fig. 15). Median, graphic mean, inclusive graphic skewness, and inclusive graphic standard deviation were calculated using equations developed by Folk (1968). Samples 4-18 (Tb) and 4-22 (Tc) have primary modes in the fine sand range; secondary mode is very fine sand in 4-18 and fine sand in 4-22. The Ta divisions have primary and 65 Figure 15: Histograms and cumulative curves con^ structed from grain size analysis with the Zeiss TGZ3 Particle Size Analyzer. 66 100% •0 ■ 0 > TO » - < -I 3 s 3 U SO - SO - D fins GRAIN SIZE (i C 1 0 0% •0 u > • 0 < _J 3 s TO •0 3 O SO 40 SO SO •and vary fin * fin * m m ! ,0,ld GRAIN SIZE (mm) 6 0 . 1 •s . 3 A . 5 . 4 n o n * vary fins msdism sand | eoarss M ad s ilt fins •and 1 sand GRAIN S IZ E (mm) D 100% •0 ■ 0 TO • 0 5 0 40 SO s o . 1 5 . 0 5 . 1 0 cootm I ssry fin * silt | sand GRAIN S IZ E (mm) 67 ^ secondary modes in the very fine sand size. More than 50 percent of 5-11 is very fine sand. Graphic mean and median values are in the fine sand range for all samples. Ta samples are moderately to moderately well sorted; Tb and Td samples are well sorted. Skewness values range from near symmetrical, 0.03, to strongly coarse-skewed, -0.88. The five statistical parameters discussed above are consistent with conclusions regarding the medium of depo sition, source material and environment of deposition based on primary sedimentary structures, Bouma sequences and bedding characteristics. Several factors appear to support a single-source hypothesis for the quartz clasts: 1) lack of polymodality; 2) well-sorted to moderately sorted size distribution; 3) relatively close agreement between mode, mean and inclusive graphic mean; and 4) coarse-skewed samples. Insoluble Residue Insoluble residue analysis of 50 samples was conducted to determine the following: 1) if there is a difference in weigh percent insoluble residue between Bouma divisions; and 2) if there is change in percent insolubles between lower, middle and upper parts of the Drummond Mine Lime stone, among the various Bouma divisions. Two methods were used in preparation of rock samples for insoluble 68 residue analysis. Twenty-five rock samples were crushed, powdered in a ball mill, and 10 gm of material was acidized with 10 percent HCl solution for 24 hours, using the method described in Evans and others (1977) . Eight residue samples were analyzed for composition on the Norelco X-ray Diffractometer. A second set of rock samples was analyzed for weight percent insoluble residue with a slightly different procedure. Each sample was crushed in a small jaw crusher, approximately 10 gm weighed out, then the chips were acidized in a 10 percent HCl solution for 24 hours. The rest of the procedure was the same. Seven samples analyzed as powders also were run through as rock chips to test reproducibility of results. Table 3 presents the insoluble residue weight percentages. Comparison of rock chip and powder insoluble residue results indicates a moderate compatibility between the two procedures. In five out the six cases the difference is less than 8.2%; and three cases have a difference of less than 2.0%. Therefore, powder and rock chip insoluble residue values will be used interchangeably in the following discussion. Sample 4-4 is anaomalous in this test: it is a gray lime stone, probably a Td interval. In this sample 33.7 percent more carbonate dissolved when the rock was powdered. Apparently the carbonate is bound up with clay or quartz so that less is dissovled from rock chips than from powder. Values of weight percent insoluble residue reveal 69 Table 3. Weight percent insoluble residue data. Sample I Ta Sample 1 Tb Sample 1 Tc Sample # Td Sample # Te 4-7 59.6 4-18 45.9 5-8. 79.4 4-10 60.9 *4-17 64.4 5-10 88.6 6-5A 93.3 6-2 35.5 5-9 2 3.6 *5-10 93.8 5-5 41.2 4-16 69.6 5-12 58.0 *11 70.1 5-11 43.3 4-22 52.3 4-22 35.3 * 5 68.0 5-6 38.3 5-8 82.7 4-4 41.2 4-17 44.2 4-23 61.6 6-9 f 86 .9 *5-6 37.1 6-7 85.9 4-15 74.5 *6-10 34.8 6-5D . 92.7 6-9c 84.7 *6-7 81.5 5-6f 23.8 *4-23 59.9 5-7c 34.1 *6-14 87.6 *6-10 38.6 *6-9f 78.7 *4-15 72.7 *4-4 27.5 * 5 48.3 Average^ wf- _ % ~ 48.4 69 .6 70.1 54.8 74.1 f = fine, c = coarse *data derived from powered rock samples X-Ray Diffraction Analysis Lithotype Sample # Sample Type Minerals banded *4-8 32.0 *4-5 87.5 *4-6 27.7 *5-1 94.3 *4-11 36.4 *4-12 76.3 III 4-5 ins,. res. quartz, hyalophane, muscovite, magnetite II 5-5 ins . res. quartz, tremolite, diopside, magnetite I 4-6 ins . res. quartz, muscovite, pumpellyite, chlinochlore III 4-17 ins . res. quartz II 5-5 wh . rk. quartz, calcite I 4-6 wh . rk. quartz, calcite, mica II 6 wh . rk. quartz, calcite, diopside ins. res. = insoluble residue wh. rk. = whole rock 32.0 86.0 O some trends among Bouma divisions, beds not assigned to a Drummond Mine Limestone (Table 3). All Bouma divisions exhibit a wide range in values: the greatest difference is in Tc intervals, which range from 23.6 to 87.6 percent and average 54.8 percent. Bouma divisions Tb, Tc and Te have residue values close to 70 percent. Ta and Td both average near 50 percent. However, the percentages are not sufficiently different to distinguish between and among Bouma divisions based solely on insoluble residue content. Two stratal units which do not fit the Bouma classifi cation have distinctive insoluble residue percentages. Insoluble residue values in massive gray limestone range from 27.7 to 36.4 percent and average 32.0 percent. This is considerably lower than any of the other values. The low insoluble residue values of mgl reflect its dirty (clayey) micritic composition, as confirmed petrographi- cally. Banded argillite insoluble residue values range from 76.3 percent to 94.3 percent and average 86.0 percent. These values are higher than the Te intervals analyzed, and reflect the mixing of calcareous and siliceous argil lite during the insoluble residue analysis. Grouped values, Ta through Te, show little difference between lower, middle and upper parts of the Drummond Mine Limestone. The data suggests the following conclusions: 1) up-section increase in carbonate content in Ta units; 2) up-section decrease in carbonate content in Tc and Td 71 units; 3) Te remained about the same throughout the stratigraphic sections; and 4) insufficient Tb data precludes evaluation of vertical changes. Conodont Analysis Pauli and others (1972) described a Late Mississippian age to the Drummond Mine Limestone. Subsequently, Shunick (19 74) analyzed 16 samples (1 kg each) of the Drummond Mine and determined a Late Kinderhookian age for this formation. Six of Shunick's samples yielded conodonts: two from Wildhore Canyon, probably not an outcrop of Drum mond Mine Limestone; two samples from Copper Creek, the type locality of the Drummond Mine Limestone; and two samples from the Fish Creek reservoir area. All samples contain representatives of the genus Siphonodella; and most fit the descriptions of Siphonodella isostricha (Copper) , j3. obsoleta, and £3. cooperi (Shunick, 1974) . Polygnathus communis (Branson and Mehl) also is common in the Drummond Mine Limestone samples (Shunick, 1974). Four samples collected by the author from the Starhope Creek area were prepared for conodont separation and sent to Dr. Charles Sandberg, U.S. Geological Survey, for analysis. No conodont elements were found in any of the samples. The four samples choosen for conodont analysis were coarsest-grained, 500 gm samples collected. In conclusion, 72 although conodonts occur in the Drummond Mine Limestone, they are not common. As established by Shunick's work, a Late Kinderhookian age for the Drummond Mine Limestone is accepted. 73 IV. FACIES ANALYSIS General Statement Recently, the concept of facies analysis has been applied to ancient and recent turbidite basins by Walker (1970), Mutti and Ricci Lucchi (1972), Walker and Mutti (1972), Nilsen (1977), Normark (1978), and Nelson and others (1978). Mutti and Ricci Lucchi (1972) define "facies", as used in turbidite facies analysis, as follows: Facies, or better, lithofacies, are used herein to indicate a group of strata, or less commonly a single stratum, with a well-defined litho- logy, stratification, sedimentary structures, and texture. An association of facies is the combination of two or more facies in a broader spatial arrangement. Turbidite facies analysis to the Drummond Mine Limestone is suggested by the common occurrence of sedimentary struc tures in sequences typical of turbidites. The Mutti and Ricci Lucchi turbidite facies classification is applicable to all of the clastic sediments deposited within a basin. Although this scheme is referred to as a "turbidite" facies classification, it does not mean that all lithofacies were deposited by turbidity currents, sensu stricto. "Turbidite 74 facies" and "turbidite basin" are used to indicate basins in which most of the accumulated sediment was deposited by turbidity currents or by some other density underflow mechanism. Mutti and Ricci Lucchi (19 72) describe five turbidite and two non-turbidite facies. Only their facies B, C, D, E and G were identified in The Drummond Mine Lime stone. Figure 16 is a composite stratigraphic column of the Drummond Mine Limestone compiled from field data and facies analysis. Figure 17 is an explanation of symbols used in the stratigraphic column. In the following discus sion each trubidite facies identified in the Drummond Mine Limestone will be described and an environmental inter pretation suggested. Facies D Description Pelitic-arenaceous facies D, consists of laterally continuous bedding units composed of lithologic couplets with base-cut-out Bouma sequences (Mutti and Ricci Lucchi, 1972). The lithologic couplet is pelite and fine to very fine sand and coarse silt with a sand-to-shale ratio of 1:2 to 1:9. Most beds are composed of Tcde sequences; Ta and Tb intervals were not deposited. Mutti and Ricci Lucchi (19 72) attribute deposition to slow, dilute turbi dity currents in which the coarse fraction is a low-flow 75 Figure 16: Explanation of symbols used in the stratigraphic column. 76 Explanation For Stratigraphic Columns > CD O _J o X h- i 'r —r rr- ir: > C O X LU < X b => is/V/VA/N L lI O I d Q X k j j H C O C O vv •v to <1 ® o o 15VRAT Argillite Sandstone Limestone Limestone with cl ostites Limestone with thin, irregular sandy layers Argillaceous limestone Calcareous mudstone S tlicified rocks Tertiary intrusives Lam ination ^fcfih sandstone argillite limestone indistinguishable lithology distinct .fa in t Cross - stratificatio n Convolute lam ination Flaser bedding Massive bedding F la t bedding Graded bedding Rip - up clasts Load & flam e structures Transitional Abrupt Erosional Deformed COMPLETE TURBIDITE SEQUENCE (Boum a,l962) T a - e P elitic P aralle l lamination d Current rip p le or convolute lam ination P arallel lam ination b Graded or massive a 77 Figure 17: Composite stratigraphic column of the Drummond Mine Limestone as measured at Starhope Creek. Left side of the column illustrates lithology and the right side illustrates primary sedimentary structures. Detailed sections are 10 m thick, Bouma sequences and turbidite facies classifi cation of the detailed segments are listed at the right. 78 (meters) DETAILED SECTIONS BOUMA FACIES SEQUENCES CLASSIF ICATION 79 regime traction deposit and the fine fraction settles from the suspended portion of the turbidity current. Examples of facies D turbidites are well-developed in the following areas: 1) Monte Antola Formation, Late Cretaceous, Apennines, Italy (Mutti and Ricci Lucchi, 19 72; Martini and others, 1978); Pico Formation, Pliocene, Santa Paula Creek, California (Crowell and others, 1966); 3) Cloridorme Form ation, Ordovician, Gaspe, Quebec (Walker and Mutti, 1973). Facies D is the most abundant lithofacies throughout the Drummond Mine Limestone (Fig. 16 and 18). Assignment of strata to facies D is based on occurrence of the following: 1) base-cut-out Bouma sequences; 2) continuity of strata; 3) lithologic couplets; 4) parallel laminations; 5) cross-laminations. Lithologic couplets, within and between beds, include silty limestone (Tb, Tc, Td inter vals) , calcareous argillite (Td and Te intervals), and siliceous argillite (Te intervals). Grain size is graded normally from sand to clay within intervals. Most Tc and Td divisions examined have a modal grain size in the coarse silt to fine sand range. When Tc and Td intervals occur in sequence, Tc is coarser (fine to very fine sand) than Td (coarse silt to fine sand). Petrographic analysis indi cates that normal grain size grading may occur over a narrow range, for example, grading from 0.04 mm to 0.10 mm versus grading from 0.06 mm to 0.15 mm. The various types of laminations observed are usually defined by a change in 80 Figure 18: Stratigraphic log of average percent turbidite facies per 10 m of section. Construction of this log is based on detailed measurements made in the three sections studied. Linear regression analysis of facies substantiates trends of decreasing facies G frequency and increasing facies E frequency up-section. 81 SECTION 4 SECTION 5 SECTION 6 % TURBIDITE FACIES (meters) 200 150 100 50 100 50 200 150 100 50 FACIES REGRESSION ANALYSIS D G E slope 0.62 -0.41 0.34 correlation coefficient 0.07 -0.28 0.61 certainty 80% 99 - 99.9% 9 9 % TORBIDITE FACIES V not measured = j B I H C 82 the density of a particular grain size. This was illu strated in the section on lothology. The sequence of primary sedimentary structures sommonly observed include parallel-, wavy-, and small-scale cross-laminations. Facies D is composed of strata of various field classi fications. Base-cut-out Bouma sequences include Tbcde, Tcde, and Tde strata composed of lithotypes II and III. Spicular, micritic, massive gray limestones (type I) is also classified as facies D. Evidence in support of this assignment for mgl includes: 1) occurrence of a thin Tc layer at the base of some mgl; 2) parallel alignment of sponge spicules; 3) mgl is always overlain by Te or Tf units; 4) laterally extensive; 5) occurrence interbedded with normal facies D strata; and 6) similarity between lithology of mgl and lithology of thinner, solitary Td strata. Mgl is essentially a fine-grained, lithologic variation of the typical Tcde silty micrite common to facies D. Solitary Td strata, sometimes overlain by Te, also are included in facies D. Petrographic analysis showed these solitary Td layers to be very similar to mgl. Both have sponge spicules, abundant micrite and microspar, little or no clastic quartz, and finely-desseminated clay. These beds were counted like Td because thickness and primary sedimentary structures are identical, and they occur interspersed with Tcde and Tde sequences. 83 Interpretation All facies D units (except Tf, as noted previously) were transported by, and deposited from, turbidity currents. The coarsest fraction, fine- to medium-sand, was deposited from tractive flows that formed parallel-laminations, convolute-laminations, scours, load structures, flames, grain-size grading and cross-laminations. The relative paucity of erosional structures indicates a "slow" rate of turbulent tractive flow (Middleton and Hampton, 1973). Climbing ripples (Fig. 11 and Fig. 19a) are not common, but suggest the rapid deposition of large quantities of sedi ment (Reineck and Singh, 1976). The finer grain-size fraction was transported by turbulent suspension and depo sited by settling (Mutti and Ricci Lucchi, 1972; Middleton and Hampton, 19 73). Primary sedimentary structures formed in this manner include parallel-laminations, gradational contacts between strata, and grain-size grading. Facies D strata in the Drummond Mine Limestone were deposited from low-density turbidity currents composed of a coarser- grained tractive portion and a finer-grained suspended portion. Massive gray limestone (mgl) is an unusual lithotype in facies D. Mgl may represent carbonate pelagite which has been resedimented by a dilute turbidity current or a nepheloid layer, from an accumulation site above the CCD. 84 Figure 19: Logarithmic - normal population distri bution cumulative curves of stratal thick ness. N is the number of measurements used and g is the geometric dispersion of the data. Bed thickness Tb and Tc thick ness produce a straight line, indicating a logarithmic-normal population distribu tion. The Td cumulative frequency line is curved, suggesting that the population is not logarithmically distributed. 85 CUMULATIVE % FREQUENCY BED THICKNESS Tb THICKNESS -99.9 N : 54 7 - 5.62 ■0 . 0 1 0.1 3.0 20 1 . 0 05 99.9 N - 1641 7 - 13.48c m o - 0 . 1 3.0 20 10 05 Tc THICKNESS Td THICKNESS ■99.9 N - 1410 7 - 5. x€.7 3 ^ m l =276 ' 1 .5 1 • 0. 01 3.0 20 0.5 99.9 L4 0.01 1.0 05 0.1 2 . 0 © (cm ) THICKNESS ® 86 This would account for the paucity of clastic constituent in, and preservation of, the carbonate in mgl. This litho facies is rare above the basal 120 m of section 4, and may have been diluted by the increasing volumes of silic- iclastic sediment. This is clearly illustrated in Fig. 18. D. Nelson (19 79) used a similar approach to study the Drummond Mine Limestone near its type locality at the head of Little Copper Creek (Fig. 4). Nelson concluded that only base-cut-out Bouma sequences Tbcde and Tcde are facies D strata. All field-identified Tde intervals and "micritic limestone and argillite not associated with sandstone" were assigned to facies E by Nelson. Nelson calls these strata hemipelagites because of a reported scarcity of primary structures and random orientation of sponge spicules. As described in this report, my findings contradict this aspect of Nelson's work. Facies G Description Pelagite and hemipelagite of facies G also a common lithofacies (Fig. 16 and 18). Mutti and Ricci Lucchi (1972) use Kuenen's (1950) definition of hemipelagite, as a sediment composed of terrigeneous pelitic material with variable percentages of silt, fine sand, mica and/or carbo nate. Beds described in the field as solitary Td 87 calcareous siltite or silty micrite are probably hemi- pelagites. Petrographic analysis confirms the presence of terrigenous clastic silt and sand in a clayey micrite matrix. Facies G also includes pelagite, a deep-sea sedi ment of inorganic clay or organic ooze, without terrigenous components, deposited by settling through the water column. Strata identified as white limestone, gray limestone, silicified and banded argillite, may be pelagite. True pelagite is very difficult to identify positively in the field, and it is probably more correct to refer to these strata as pelite. The banded argillite alternates from slightly calcareous laminae (hemipelagite ?) to non-cal- careous laminae (pelagite, hemipelagite). Both types of lamina are representative of facies G and have similar modes of deposition and depositional environments. Facies G occurs throughout the formation. It is most abundant in the lower half, and decreases significantly in the upper third of the formation (Fig. 18). Primary sedimentary structures observed in the pelite of facies G include parallel and wavy-laminations, grading, and very thin- to thin-bedding. All facies G units are in the clay to silt size range. Interpretation Sequences, as much as six meters thick, of thin-bedded, banded argillite occur throughout the Drummond Mine 88 Limestone. Two hypotheses may be suggested to explain the origin and mode of deposition of these rocks. The alter nating lithologies may represent a cyclic variation in: 1) the position of the calcium carbonate compensation depth (CCD); or 2) saturation of calcium carbonate in the water column. The calcareous fraction of pelagites dissolves as it settles through the water column below the CCD. A deeper CCD, due to a change in seawater temperature, pH, eH or seawater composition, would result in accumulation of sedi ment enriched in calcium carbonate. Pelagic sedimentation proceeds at a very slow rate; therefore, a great thickness could only accumulate in an area with little turbidite deposition for a given time. An alternate hypothesis is indicated from research done by Hesse (1975) on modern and ancient fine-grained sediment. Hesse suggests that fine-grained turbidites may be distin guished from non-turbidites by calcium carbonate content. When the bottom is below the CCD, pelagites will accumulate with a calcium carbonate content. The relatively rapid emplacement of a turbidite precludes dissolution of the carbonate fraction. If this model is correct, each light- colored bed in the sequence is turbiditic, whereas each dark-colored bed is pelagic (non-turbiditic). Petrographic examination of sample 4-5, a banded argillite, confirms that the light bed contains more carbonate and parallel laminations than the dark beds. Analysis of a composite 89 sample including both bed types, yields 8 7.5 percent insoluble residue, primarily siliceous argillite. If the light-colored beds are turdiditic, they originate along slopes of pelagic sediment above the CCD. Terrigenous elastics were not observed in these strata. The mode of deposition used in this model is that of a very dilute turbidity current reworking bottom sediment with the tail of either a turbidity current, nepheloid layer, or contou- rite (Middleton and Hampton, 19 73; Hesse, 19 75). Evidence to unequivocably determine the exact mode of deposition is lacking. Two models have been presented to explain the occur rence of thinly interbedded calcareous argillite and argil lite. Available evidence tends to support deposition of hemipelagite by dilute turbidity current or nepheloid layers. The basin of deposition was the site of active turbidite accumulation at this time; the argillite are interbedded with thick packages of facies D strata. The hemipelagite could represent the "last gasp" of turbidity currents within the basin. A very thick sequence of facies G might indicate a shift in the focus of turbidite activity to another area. Lithology, grain size, primary sedimen tary structures and the probable mode of deposition, suggest that banded argillite may be assigned to facies G. 90 Facies E Description Pelitic arenaceous facies E, is assigned to strata composed of Tee units (Fig. 8c). These strata are best described as flaser-type structures with silty to sandy cross-laminated ripples, Tc intervals, isolated in argil- litic or micritic Te intervals. Contacts between Tc and Te intervals are usually distinct, and the external form of the ripple is often preserved. The ripples are 1 to 5 cm high, 2 to 10 cm long and occur in a string continuous over a meter or more. Facies E is rare in Section 4, uncommon in Section 5 and common in Section 6. (Fig. 16 and 18). Lithology and grain size of the cross-laminated portion of this facies, are the same as Tc units found in the Bouma sequences of facies D and C. The Te portion of this facies is pelitic sediment of rock type III, either argillite or calcareous argillite. Calcareous argillite is more common. Primary sedimentary structures observed in the field and in thin section are shown in Figures 5 and 19. Cross-, convo lute-, and wavy-laminae are typical of the Tc layers. Parallel- and wavy-laminae are found in the pelite. Contacts between the two lithologies are abrupt, planar or non-planar. Some lower boundary contacts are marked by small load, flame, or slump structures. 91 Interpretation Facies E is an unusual but relatively common unit in the Drummond Mine Limestone. The flaser-type bedding is a combination of current-deposited "coarse" material surrounded by pelagic (?) finer-grained sediment. Two flow regimes operated during deposition of this facies. Facies E is composed of more than one sedimentation unit. The pelitic Te intervals may be the tail end of a turbidite, a normal pelagite or a hemipelagite deposited by a dilute flow. Silty micrite in the cross-laminated Tc layers of facies E is identical to that found in turbidite beds and is considered to be turbiditic. The overlying Te interval may be a separate bed or it may be part of the flow which deposited the Tc unit. Nelson and others (1978) suggest that facies E repre sents turbidites which overflowed channels and were depo sited in interchannel areas which normally receive pelagic sedimentation during accumulation of the Drummond Mine Limestone. Occurrence of facies E indicates the proximity of channelized areas and the shifting of sediment lobes on the outer fan region. 92 Facies C Description Facies C is composed of the classic complete turbidite sequences Tabcde, as described by Bouma (19 62) and many others. This facies is rare, but it occurs in the middle part of the Drummond Mine Limestone (Figs. 16 and 18). Primary sedimentary structures, lithology, grain size and bed thicknesses in facies C are similar to those found in facies D. Coarser-grained sediment is found in the Ta divisions which are micritic quartz wackes (lithotype IV). Interpretation Facies C units are the result of deposition by turbid ity currents. The complete sequence of regimes is visible, from higher velocity dense flow (Ta intervals) to a slower, more dilute flow (Td and Te intervals). Enough sediment was available and the turbidity current moved at a rate sufficient for formation of the classical turbidity current-formed primary sedimentary structures. Facies B Description Arenaceous facies B is rare in the Drummond Mine 93 [Limestone (Figs. 16 and 18). It occurs in Section 4, the j I |upper part of Section 5 and in the uppermost 10 m of |Section 6. Beds labeled "fine black sand," "black quartz- j | I jite," "white quartzite" and (solitary) Ta intervals, in j | i the field are assigned to Facies B. These strata occur within the usual stratigraphic sequence of facies D and G. "Black quartzite," as in sample 4-14, is a matrix-supported chert arenite (Folk, 1974) or quartz-wacke (Pettijohn and others, 1974). In the clastic portion of these beds, grain size ranges from coarse silt to medium sand. "White quartz ite1 1 is silica-cemented quartz arenite, and is rare in facies B. Both quartzites are included in lithotype IV and the petrographic analysis is given in Table 1. Soli tary Ta beds are lithologically a combination of rock type II (silty to sandy micrite) and rock type IV (quartz-wacke). Ta beds were identified by their erosional curved basal boundaries and grain size grading. These strata are included in facies B because they occur isolated within the normal sequence of thin- to medium-bedded facies D and G. Interpretation Facies B is anomalous in lithology, primary sedimentary structures and bed thickness characteristics. The abun dance of clast types and paucity of carbonate matrix suggests a local source different from the one supplying 94 type I and II sediments. Thick, graded beds with imbri cated fine- to coarse-sand grains indicate the availability of abundant siliciclastic sediment and deposition by dense turbidity current flow. The source of facies B sediment was an intermittent contributor to the outer fan environ ment. This source may have become a major contributor to the basin during the accumulation of sediment assigned to the overlying Scorpion Mountain Formation. 95 V. STATISTICAL ANALYSIS Turbidite Facies Regression Analysis The percentage of turbidite facies, averaged for each 10 meters of stratigraphic section, was calculated for each section measured. Figure 18 is a graphic presentation of the data and a summary of the regression analysis values. Assignment of bedding sequences to a turbidite facies already has been presented. The percent facies strati graphic log in Figure 18 is a graphic illustration of the predominance of facies D throughout the Drummond Mine Lime stone. Least-squares linear-regression analysis of percent facies D versus startigraphic position results in a posi tive slope of 0.62, correlation coefficient of 0.07 and goodness of fit of less than 80 percent. Statistically and geologically, this indicates an insignificant increase in the percentage of facies D strata upsection in the Drum mond Mine Limestone. Facies G illustrates a linear regres sion with a negative slope, -0.41. The decrease in frequency of facies G is statistically significant with a 96 99 percent degree of certainty. Facies E, flaser-type sedimentary structures, has a linear regression slope of 0.34, correlation coefficient of 0.61 and the goodness of fit is 99 percent. The data demonstrates a signigicant increased frequency of occurrence of strata assigned to facies E. Interpretation Several hypotheses are possible to explain the geologi cal significance of facies frequency data. Turbiditic facies D is the primary component of the Drummond Mine Limestone; the relative frequency of deposition of litho- type II-turbidite sediment did not change significantly during the time interval studied. Facies D represents the sedimentologic consistency factor for the formation. Other facies reflect subtle sedimentologic changes through time. Less pelagic-hemipelagic sediment was introduced to the basin; and more of facies E strata was being deposited in the upper part of the Drummond Mine Limestone (Section 6). Facies probably represents a migration of channel-levee systems or an infilling of channels resulting in more overb'ank deposits. Turbidite deposition (inclusive of facies D, E, C, and B) occurs more frequently upsection and effectively limites the influence of facies G strata. The trend of facies frequency data is a reflection of an increase in the rate of turbidite deposition. 97 Stratal Thickness Regression Analysis Least-squares linear regression analysis of bed and interval thickness versus stratigraphic position was performed to establish a statistical criterion to describe changes observed through time as represented by the strati graphic sequence. Thickness values used are average thick ness of beds or intervals per 10 meters of section (Fig. 6). The results are summarized in Table 4. The slope of the Td interval linear regression line is -0.64; the steeper negative slope indicates a more pronounced thinning of Td strata higher in the section. Goodness of fit is 99 percent. Total bed thickness values yield a steeper line with a slope of -0.94, correlation coefficient is -0.80 and 99.9 percent goodness of fit between stratal thickness and stratigraphic position. The Ta, Tb and other bed units were not tested because of the relatively small amount of thickness data available. Least squares linear regression analysis of Tc thickness data resulted in a correlation coefficient, -0.28, and goodness of fit of 99 to 95 percent. The Tc data set was further tested against geometric and exponential regression models to determine if a higher correlation coefficient was obtainable. Coefficient of correlation for geometric regression was -0.28 with a 90 98 Table 4. Regression analysis of stratal thickness data. Linear Geometric Exponential beds Td Tc Tc Tc slope -0.94 -0.64 -0.05 -0.16 -0.02 y-intercept 52.13 35.84 4.66 5.43 5.08 correlation coefficient -0.80 -0.69 -0.28 -0.29 -0.48 goodness of fit 99.9% 99.9% 95-99% 90-95% 99-99 X 25.45 18.46 3.43 a 19.14 14.45 2.56 a2 366 208 6.5 x = stratigraphic position y = unit of thickness VO VO to 9 5 percent goodness of fit; which is the same as for linear regression. Exponential regression is a more accu rate description of Tc thickness data; a correlation coef ficient of -0.48 was obtained with a 99 percent certainity of correlation. The exponential component of Tc thickness may reflect a source or depositional mode difference between Td and bed thicknesses. Decrease in bed thicknesses through time suggests the following possibilities: 1) decreased sediment supply, because either sediment was not available or available sediment was diverted from the depo-site; 2) a change in the source area(s); 3) change in the mechanism of depo sition; or 4) some combination of these factors. The mechanism of deposition probably did not change substant ially through time because the primary sedimentary struc tures observed are consistent throughout this part of the Drummond Mine Limestone. Negative correlation between stratigarphic position and Tc thickness suggests several factors remained essentially constant through time: 1) the mechanism(s) of deposition of sediment; 2) position of the depo-site relative to the local source area; 3) the sedi ment supply which resulted in formation of Tc strata. Enough sediment was available to the depositional system throughout time for a relatively consistent thickness of Tc to the deposited. 100 Population Distribution The thickness data collected presents an opportunity to determine population distribution characteristics of fine-grained, predominately thin-bedded turbidites. The method of data collection allows for comparison between bed thicknesses: and the Tb, Tc, and Td interval thicknesses. All the data were treated in the same way: 1) using Sturges1 Rule (King, 1971), data were grouped for normal and log normal distributions; 2) normal and log normal histograms were constructed; 3) cumulative probability curves were plotted for the normal and log normal options; 4) estimates for population parameters were computed; and 5) results were interpreted. Figures 9 and 10 and Table 6 summarize this data. Several generalizations about the thickness data are possible. Tc, Tb and bed thickness values most likely are drawn from a log normal population. Thickness data for Td intervals apparently do not fit either normal or log normal population distributions. All four data sets may reflect mixed population distributions. Tb Bouma interval thickness measurements, N=54, were analyzed as a normal and log normal population distribution. These data range from 1.0 to 35 cm, the mean is 9.9 cm and the standard deviation is 9.2. Plotted as a normal histo gram, the data is positively skewed, with 50 percent of the data in the first cell (<_ 5. 7 cm) . The normal probablility 101 curve is a concave upward line with a tail in the first cell. A tail indicates that the population distribution is not purely normal (King, 1971). The log normal histo gram of the Tb data resembles a uniform distribution, i.e., each class has approximately equal percentages of data. The log normal-probability curve is very slightly convex upward with a tail in the last class (values greater than 83 percent). Tb interval strata thickness data does not strictly fit normal or log normal population distributions. Statistical analysis of Tc strata thickness data is drawn from 332 measurements from throughout the Drummond Mine Limestone. The data ranges from 0.5 to 12 cm. The mode is in the third class with 29.3 percent of the data, the mean is 3.1 cm, and the standard deviation is 2.2. Plotting the data on log normal cumulative probability paper results in a straight line, with a tail in the last class. Tc interval thickness data may be considered log normal; but there is some suggestion of another population distribution altering the curves in the thicker strata. Field measurement of Td strata resulted in 1410 values from which histograms and cumulative probability curves were constructed. The range of values used in 0.5 cm to 90 cm; anomalously thick strata, less than 1% of the population, was disregarded (King, 1971). A normal histo gram of Td is very strongly positively skewed; over 50 percent of the data is in the first class, 0 - 9 cm. A 102 normal probability curve of Td is concave upward as is the log normal probability curve (Fig. 19). Population distri bution of Td interval thickness does not appear to be either normal or log normal distribution. Bed thickness data, N = 1641, has a form similar to the Td histograms and curves. Concave-upward shape of the normal probability curve is derived from 30 percent of the data; 70 percent of the data falls in the first class (0 - 19 cm). Log normal distribution probability plot is a straight line between 10 and 99 percent. Values less than about 5 percent form a dog-leg in the curve; repre sentative of a mixed population or poor control on the tails of the distribution. In summary, Tb, Tc and bed stratal thickness measure ments may have been drawn from log normal parent population; however, none of the strata are perfectly log normal. All of the sampled populations contain some indication of population mixing. Apparent population mixing may be the result of: 1) sampling bias; 2) inadequate sample size; 3) operator error in field measurements; 4) the reflection of a geological phenomena which influenced the accumulation of sediment in the basin. The unusual form of the Td data may be an indication of mixed populations, truncated populations, operation of several different depositional modes or operator error. 103 VI. INTERPRETATION Drummond Mine Limestone General Statement Stratigraphic-sedimentological analysis of the Kinder- hookian Drummond Mine Limestone has yielded information concerning the filling of the Antler Foreland Basin in south-central Idaho. The Drummond Mine Limestone is an accumulation of fine-grained turbidites composed of four basic lithotypes: micrite, silty micrite, argillite and quartz wacke. Each lithotype represents a particular combi nation of geological conditions: sediment source, sediment availability, mode of transportation, mode of deposition, and depositional environment. Post-depositional changes in each lithotype is somewhat variable throughout the forma tion, but indicates amphibolite grade metamorphism. Inte gration of field, laboratory, statistical and facies analyses suggests a geological model for the Drummond Mine Limestone and the Copper Basin Group. The strata assigned to the Drummond Mine Limestone were derived from land areas marginal to the Antler Foreland Basin and from within the 104 basin. Sediment was deposited by turbidity currents, of various forms, in several sub-environments of an outer submarine fan system. Figure 20 summarizes the submarine fan depositional system and the position of the Drummond Mine Limestone and the Copper Basin Group in that system. The Copper Basin Group is a coarsening upward series of formations, which are part of the submarine fan system filling the Antler Foreland Basin during the Mississippian. Sedimentological Model The association of thin-bedded D, G and E facies suggests the Drummond Mine Limestone was deposited on the outer fan or basin plain of a submarine fan system. The basal part of the formation (Section 4) was a relatively active part of the outer fan. The area was receiving poorly sorted, coarser grained, thicker, micritic quartz-wacke (lithotype IV) interbedded with thin-bedded base-cut-out turbidites, sandy to silty micrite (lithotype II), and thick, spicular micrite (lithotype I). These strata are interbedded with Tf interval argillite (III) representative of the normal, pelagic background sedimentation. Turbiditic strata have an upper layer of Te interval calcareous argil lite (III) which is gradational between the turbidite and the pelagite. Calcareous argillite represents the fine grained tail of the turbidity current which originated above the calcium carbonate compensation depth (CCD) 105 Figure 20: Summary of a submarine fan depositional system and relationship of the Copper Basin Group to that system. (Modified from Mutti and Ricci Lucchi, 19 72). 106 pm i . «u> i a 2 - ° - Q . o = > o o £ 3 2 8 to w«o at . % > » O * Q C O Jam c I l ow CO CO §<5 i E < B * *• 2 » * » Q _i — I DEPOSITIONAL ENVIRONMENT Fan Delta Shallow 8 Marginal Marine Starved Basin (non turbiditic) Middle Fan Basin Plain 8 Lobe Fringe Middle 8 Inner Fan Outer Fan,Outer Lobe Outer Fan, Basin Plain Basin Plain C F Slope IC Inner Fan v Middle Fan Outer Fan SL IL IL SL plain THIN-BEDDED FACIES TC Interchannel 8 Levee CMB Channel Mouth Bar IL Interlobe BS Basin Plain Facies’ C,D,E,G THICK-BEDDED FACIES CF Channel Fill CMB Channel Mouth Bar SL Outer Lobe Facies : A,B,C,0,F (Middleton and Hampton, 1973; Hesse, 1975). This arrange ment of calcareous turbidite, calcareous argillite and argillite is typical of basins with sedimentation below the CCD (Hesse, 1975). Spicular micrite (mgl) is pelagic carbo nate originally accumulated above the CCD; later redepo sited by dilute turbidity currents below the CCD and preserved by burial beneath pelagic argillite or facies D turbidites. Both lithotypes I and II decrease significantly up-section, which indicates either a change in depositional patterns or source area sediment supply. Stratigraphic relationships in Sections 5 and 6 reflect the outer fan depositional environment with an abundance of facies D, G and E. The influx of flaser-type strata (facies E) is indicative of overbank deposits, infilling of shallow channel and inter-channel, interlobe areas on the outer fan. Rippled sandy to silty micrite is directly overlain by argillite. Velocity of transport was fast enough to carry sandy micrite over the levee and form cross laminated ripples. Deposition of fine-grained sediment did not deform the small-scale ripples. An increase in the frequency of strata assigned to facies E suggests a possible progradation of the fan system through time. Channels were being filled and the turbidite flows began to accumulate in inter-channel regions. Thick accumulations of thinly interbedded siliceous and calcareous mud (lithotype III), as much as six meters 108 jof thick interbedded strata were deposited in areas of non- I ! I turbidite deposition. Color differences in the argillite may be due to seasonal or longer-term variations in temper- j ature, salinity, microfauna and microflora populations and availability of suspended sediment. Facies D turbidites overlay these thick accumulations of lithotype III strata. Linear-regression analysis of strata thickness confirms significant thinning of strata up-section. Stratal thin ning could be the result of: 1) a decreased sediment supply from the source terranes; 2) lower velocity turbidity currents containing less sediment; 3) accumulation in a different subenvironment on the outer fan; or 4) decreased sedimentation rate. The thinning of strata assigned to the Drummond Mine Limestone probably reflects a decline in availability of mixed carbonate and terrigenous clastic sediment. Changes in primary sedimentary structures, facies associations, and stratal thickness are not great enough to consider assignment of the upper sections to some other depositional environment. Thin-bedded facies D turbidites constitute the bulk of the Drummond Mine Limestone. These strata could have been deposited anywhere in the outer fan environment. Lenti cular bedding, presence of laterally continuous beds and lack of channeling indicates the associated turbidity currents were able to spread out over the fan. Nelson and others (1978) report thin-bedded turbidites fill wide 109 shallow channels in the Holocene of Astoria Fan. If i I jpresent, such channels are not readily apparent in the j j j Drummond Mine Limestone. The source terrane for sandy- j I silty micrite in facies D supplied subangular to well- rounded terrigenous clasts of consistent lithology. These clasts are well sorted by both size and shape. Possible source terranes existed on both the west, the emerging Antler Highland, and the east, the craton, Primary sedi mentary structures provided little information bearing on the question of source terrane. Petrographic analysis revealed the occurrence of rounded chert clasts, some with evidence of radiolarians (discussed previously). A litera ture review of pre-Mississippian formations in the area indicates that chert occurs as a secondary feature in the Carey Dolomite (to the east) (Skipp and Sandberg, 1975) and as a sedimentary facies in the Trail Creek and Phi Kappa Formations (Poole and Sandberg, 1978). Both the Trail Creek and Phi Kappa Formations were included in the Antler orogenic landmass (Poole and Sandberg, 1978). This evidence suggests that terrigenous elastics in the Drummond Mine Limestone most likely were derived from the Antler Highland, mixed with micrite in "shallow" water, then transported and deposited by turbidity currents below the CCD, In summary, stratigraphic analysis of the Drummond Mine Limestone yields a picture of sedimentation in the outer fan facies of a submarine fan system. At least 110 three turbiditic lithotypes are superimposed on the normal siliceous-pelitic background sedimentation of the outer fan. Each of the three lithotypes represents slightly different depositional history. The relative availability of micrite declined and the input of terrigenous elastics increased initiating the deposition of strata assigned to the Scor pion Mountain Formation. The remainder of the Copper Basin Group reflects an abundant supply of elastics and the coarsening upward sequences common in a prograding subma rine fan-fan delta depositional system. Modern and Ancient Analogs Modern Analogs Modern analogs to the Drummond Mine Limestone are easily recognized in the voluminous literature on turbidite sedimentation. Piper (1978) recently summarized data on thin-bedded turbiditic mud and silt, and estimates that over 60 percent of the fine-grained sediment deposited in the sea environment is turbiditic. Piper's descriptions of turbiditic silt is quite similar to those found in the Drum mond Mine Limestone. Nelson and others (1978) studied Holo- cene and Pleistocene fan systems and emphasize recognition of depositional environment from sequences and associations of fine-grained, thin-bedded sediment. Their research substantiates a change in the distribution pattern of thin- ill |bedded turbidites through Pleistocene and Holocene time. j j I I ; ! In the late Pleistocene, canyon-fan valley systems received! j j J thick, coarse-grained sediment, non-channelized area (inter-) ! | channel, inter-lobe, levee crest) received thin-bedded turbidites (overbank deposits). Holocene high sea level has restricted the distribution of coarse sediment. Thin- bedded turbidites are found in the channels, whereas inter channel areas receive hemipelagites. These relationships are analogous to the Drummond Mine Limestone, which may represent a time of decreased terrigenous sediment supply, followed by increased supply resulting from renewed orogenic activity in the Antler Highland. A modern example of calcareous turbidite accumulation is provided by Davies (1972). The abyssal plain north of the Campeche Shelf in the Gulf of Mexico is currently receiving thin- to thick-bedded (2-120 cm) calcareous turbi dites. Calcareous turbidites are well-sorted, cross laminate calcarenite or calcisiltite. The strata exhibit Bouma-type sequences, but some divisions may be repeated within the vertical sequence of a single bed. Basal contacts are gradational with the succeeding calcilutites. Calcilutites occur only at the tops of beds and are a 1:1 mixture of micrite and siliceous pelagite. Siliceous pela- gite is the "normal Gulf suspensate" and overlies the calci- lutite. Davies recovered cores containing Campeche Shelf- derived carbonate turbidites from an area of 161,000 square 112 km; with an associated straight-line travel path of a much as 500 km. Ancient Analogs Possible ancient analogs to the Drummond Mine Limestone are found in the literature about the geology of Europe. The Upper Cretaceous Monte Antola Flysch of the northern Apennines was deposited in a turbidite basin adjacent to the active orogenic Apenninic highland (Hesse, 1975; Martini and others, 197 8). Monte Antola Flysch is char acterized by facies D and G strata which are composed of five lithotypes: sandstone, calcareous sandstone, calcare ous marlstone, marlstone and shale (Scholle, 1971; Mutti and Ricci Lucchi, 1972; Hesse, 1975; Martini and others 19 78). Descriptions of the Monte Antola Flysch appear similar to the four lithotypes described from the Drummond Mine Limestone. Scholle (1971) and Hesse (1975) indicate the depositional environment of the Monte Antola Flysch as an outer fan-basin plain, deposited in a carbonate turbi dite basin, below the CCD. Martini and others (1978) conducted a statistical analysis of the formation which included Markov chain analysis of lithology and Fourier power spectral analysis of bed thickness. As a result, the Monte Antola Flysch was divided into four members which are lateral facies in the outer fan-basin plain environment. This study is an instructive example of the integrated 113 approach necessary for a sedimentologic analysis of mono tonous, thin-bedded turbidite sequences. The Mississippian was a time of carbonate deposition in various parts of the Antler Foreland Basin. Published descriptions indicate a similarity in age, depositional environment, lithology and primary sedimentary structures among Mississippian-age carbonates in the Antler Foreland Basin. The lower part of the Kinderhookian McGowan Creek Formation crops out in the Lost River, Lemhi and Beaverhead Ranges of south-eastern Idaho and consists of interbedded fine- to coarse-grained limestone turbidites and argillite (Sandberg, 1975; Nilsen, 1977). Nilsen (1977) assigned these strata to turbidite faces C and Sandberg (19 75) consi dered them to be facies equivalent to the fine-grained lime stone turbidites of the Drummond Mine Limestone. The Lodge- pole Limestone (Madison Group) of southwestern Montanan is a lower Mississippian biohermal and bioclastic limestone (Sandberg, 1975) and is probably a more shallow water facies than the Drummond Mine Limestone. The Kinderhookian Camp Creek sequence crops out in the Independence Range, Nevada. It is a turbidite composed of bioclastic calcarenite, calcisiltite and calcilutite (Smith and Ketner, 19 68; Ketner, 1970). Lower and middle portions of the Tripon Pass Limestone are turbiditic calcisiltite, calcarenite and calcirudite which crop out in the Windermere Hills and southern Snake Mountains, Nevada (Oversby, 1973). Other 114 |formations which may be turbidite-deposited carbonates ! | associated with those previously mentioned include the Webb | Formation, Pinon Range, Nevada (Ketner, 1970; Oversby, 1973) and the lower part of the Joana Limestone, eastern Great Basin (Langenheim, 1960; Smith and Ketner, 1968; and Oversby 1973). Conclusions The Kinderhookian Drummond Mine Limestone of the Copper Basin Group crops out in the Pioneer Mountains of south-central Idaho. A composite stratigraphic sequence of three sections was measured along Starhope Creek in Blaine County. The purpose of this study is to evaluate the stratigraphic and sedimentologic significance of a thin- bedded, fine-grained, mixed carbonate and siliciclastic turbidite sequence. Sequences of primary sedimentary struc tures commonly found in turbidites were identified in the Drummond Mine Limestone. Assignment of strata to a parti cular Bouma division is based soley on the sets of primary sedimentary structures present. As used in this study, a bed is a sedimentation unit deposited from a single hydro- dynamic flow. Small-scale measurements (+1800) concerning bed thickness, Bouma interval thickness and occurrence, bedding plane characteristics, lithology, color, and the presence/absence of primary sedimentary features were 115 compiled into a coded stratigraphic log. Subsequent analysis of field data identified sedimentation trends from turbidite facies analysis and statistical analysis of turbidite facies and stratal thickness. Laboratory analysis of 58 hand samples included studies of petrography, grain size, grain orientation, insoluble residue analysis and conodonts. The Drummond Mine Limestone is divided into four lithotypes based on the presence, absence and/or abundance of micrite and argillaceous material. Lithotype I, argil laceous spicular micrite, is found in medium- to thick-beds near the base of the section. Lithotype II, quartzitic calcisiltite is composed of silt-to sand-size quartz and other clasts in a matrix of argillaceous micrite, microspar and finely crystalline metamorphic minerals. Other clasts noted include chert, quartzite, mudstone, siltstone, allo- chems and rip-up intraclasts. Intervals Tb, Tc and Td are usually composed of type II, the most abundant lithotype. Lithotype III, silty to non-silty, siliceous to limey argillite, or argillaceous micrite, is common in the Te intervals, Tf intervals and banded argillite. Fine to coarse silt clasts are monocrystalline quartz. Authigenic finely crystalline quartz also occur. Limey argillite was probably deposited as calcareous mudstone from the tail of a turbidity current. Siliceous argillite may represent the normal pelagite deposited in a basin below the CCD. 116 Lithotype III occurs throughout the formation in associ ation with bedded Bouma intervals. Lithotype IV, quartz wacke, is distinguished by an abundance of sand-size detrital quartz and chert in a finely crystalline cherty matrix. Amphibolite-grade metamorphic minerals, prehnite, diopside, epidote, talc and tremolite are disseminated throughout the matrix. Quartz wacke occurs in graded medium- to thick-bedded Ta intervals in the lower and upper parts of the Starhope Creek section. Turbidite facies analysis of the Drummond Mine Lime stone illustrates a decrease in frequency of occurrence of the pelagite-hemipelagite facies G with time. Facies E, flaser-type units, demonstrate an up-section increase in frequency. The frequency of facies D, base-cut-out Bouma sequences, remains about the same throughout the strati graphic section. The basic sedimentologic sequence (Facies D) shows little change with time. However, turbidite activity increases in section 5 and 6, as shown by an increase in the frequency of facies E. Facies G is masked by increased turbidite sedimentation. This pattern of sedi mentation through time may reflect the progradation of the outer fan-basin plain system. Primary sedimentary structures indicative of paleo- current direction were noted in the 1-12 cm thick Tc intervals. Paleocurrent direction is bimodal, west-north west and east-southeast, based on 17 cross-laminated Tc 117 units. This paleodirection is also supported by grain orientation measurements, +300 per thin section, on 7 samples. Clasts of radiolarian chert noted in sandy micrite samples were probably derived from the Antler highland to the west and indicate a western source terrane for the Drummond Mine Limestone. Paleodirectional data compiled by others for the rest of the Copper Basin Group indicates a western source terrane. Insoluble residue analysis of 50 samples indicates that massive gray limestone (lithotype I) has the lowest values, average 32%, and Te-Tf intervals (lithotype III) have the highest values, average 8 6%. Intervals Tb, Tc and Td are all lithotype II, therefore have similar weight percent insoluble residue values, which average about 70%. No statistically significant differences were noted between the lower, middle or upper parts of the stratigraphic section. Statistical analysis of stratal thickness and frequency used to determine the type of population distribution, significant thickness and frequency changes through time. Over 18 00 stratal thickness measurements were made during the course of the field study. Bed thickness, N=1636, ranges between 9 and 83 cm, the average is 18 cm. Linear regression analysis confirms a significant up-section thin ning trend in beds and Td intervals. Bed thickness, Tc and Tb intervals appear to be log normal population distri 118 butions. Interval Td thickness values, N=1374, average 19 cm and range between 7 and 69 cm. Td interval popu lation distribution is neither normal or log normal. Linear regression analysis indicates an insignificant decrease in Td interval frequency with time. The Tc interval data is drawn from 332 samples between 0.5 and 12 cm in thickness. Regression analysis shows a slight thinning of Tc intervals, and an increase in frequency with time. Only 54 intervals, 1 to 35 cm thick, were used in the thickness analysis; and the thickness is log normally distributed. This interval is rare, but usually found in the upper part of the strati graphic section. Base-cut-out Boumas sequences in the Drummond Mine Limestone most frequently consist of Tcde or Tde beds. Although structural complexities necessitate a careful approach to stratigraphic relationships, it is recommended that detailed stratigraphic and petrographic studies be conducted to determine sedimentologic trends throughout the Copper Basin Group. Further study of the Drummond Mine Limestone and similar rock units would lead to a better understanding of mixed carbonate-clastic systems. 119 REFERENCES Berner, R. A., 1971, Principles of chemical sedimentology: McGraw-Hill, New York, New York, 24 0 pp. Bissell, H. J., and Barker, H. K., 1977, Deep-water lime stones of the Great Blue Formation (Mississippian) in the eastern part of the Cordilleran miogeosyncline in Utah, in Cook, H. E., and Enos, P. (eds.), Deep-water carbonate environments: Soc. Econ. Paleontologists and Mineralogists Spec. Publ. 25, p. 221-247. Bissell, H. J., 1974, Tectonic control of late Paleozoic and early Mesozoic sedimentation near the hingeline of the Cordilleran miogeosynclinal belt, in Dickinson, W. R. , (ed.), Tectonics and sedimentation: Soc. Econ. Paleontologists and Mineralogists Spec. Publ. 22, p. 83-97. Blatt, H., Middleton, G., and Murray, R., 1972, Origin of sedimentary rocks: Prentice-Hall Inc., Englewood Cliffs, New Jersey, 634 p. Boggs, S., Jr., 1967, Measurement of roundness and spheri city parameters using an electronic particle size analyzer: Jour. Sedimentary Petrology, v. 37, p. 908-913. Bollman, D. D., 1971, Geology of east part of Mackay 3 SE and west part of Mackay 4 SE quadrangles, Blaine, Butte, and Custer Counties, Idaho: Unpubl. M.S. thesis, Wisconsin Univ., Milwaukee, 115 p. Bouma, A. H., 1962, Sedimentology of some flysch deposits: Elsevier Publishing Company, New York, 16 8 p. Colburn, I. P., 1968, Grain fabrics in turbidite sandstone beds and their relationship to sole mark trends on the same beds: Jour. Sedimentary Petrology, v. 38, p. 146-158. Crowell, J. C., Hope, R. A., Kahle, J. E., Ovenshine, A. T., and Sams, R. H., 1966, Deep-water sedimentary struc tures, Pliocene Pico Formation, Santa Paula Creek, Ventura Basin, California: Cal. Div. Mines Geol., Spec. Rept. 89, 40 p. 120 Davies, D. K., 1968, Carbonate turbidites, Gulf of Mexico: Jour. Sedimentary Petrology, v. 38, p. 1100-1109. Dover, J. H., Hall, W. E. , Hobbs, S. W., Tschanz, C. M., Batchelder, J. N., and Simons, F. S., 1976, Geologic map of the Pioneer Mountains region, Blaine and Custer Counties, Idaho: U.S. Geol. Survey open file rept. 76-75, scale 1:62,500. Evans, I., Kendall, C. G. St. C., Butler, J. C., 1977, Genesis of Liassic shallow and deep water rhythms, Central High Atlas Mountains, Morocco: Jour. Sedi mentary Petrology, v. 47, p. 120-128. Folk, R. L., 1974, Petrology of sedimentary rocks: Hemp hill's Austin, Texas, 170 p. Grover, R. L., Jr., 1971, Upper Paleozoic limestone units in the Pioneer Mountains, south-central Idaho: unpbl. Univ. of Wisconsin M.S. Thesis. Hesse, R., 1975, Turbiditic and non-turbiditic mudstone of Cretaceous flysch sections of the east Alps and other basins: sedimentology, v. 20, p. 387-416. Ketner, K. B., 1970, Limestone turbidite of Kinderhookian age and its tectonic significance, Elko County, Nevada, in. Geological Survey Res. 1970: U.S. Geol. Prof. Paper 700-D, p. D18-D22. King, J. R., 1971, Probability charts for decision making: Industrial Press, Inc. , N.Y., N.Y., 290 p. Kuenen, P. H. , 1950, Turbidity currents of high density: 18th Internatl. Geol. Congress, London, Repts., pt. 8, p. 44-52. Langenheim, R., L., Jr., 1960, Early and Middle Mississip pian stratigraphy of the Ely area, in Geology of east-central Nevada: Intermtn. Assoc. Petroleum Geologists 11th Field Conference Guidebook, p. 72-80. Larsen, T. A., 1974, Geology of TIN and T2N - R22E, R23E and R24E, Blaine and Butte Counties, South-Central Idaho: unpubl. Univ. of Wisconsin M.S. Thesis. Mansfield, G. R., 1927, Geography, geology, and mineral resources of part of southeastern Idaho,: U.S. Geol. Survey Prof. Paper 152, 453 p. 121 Martini, I. P., Sagri, M., and Doveton, J. H. , 1978, Lithologic transition and bed thickness periodicities in turbidite successions of the Antola Formation, Northern Appennines, Italy: Sedimentology, v. 25, p. 605-623. Middleton, G. V. , and Hampton, M. A., 1973, Sediment gravity flows: mechanics of flow and deposition, iri Middleton, G. V. , and Bouma, A. H. (eds.), Turbidites and deep water sedimentation: Short Course Notes, Pacific Sec., Soc. Econ. Paleontologists and Mineral ogists, p. 1-3 8. Mutti, E., and Ricci Lucchi, F., 1972, Le torbiditi dell' Appennino settentrionale: introduzione all1 analisi di facies: Memorie della Societa Geologica Italiana, 1972, p. 161-199. Translation by Nilsen, T. H., 1978, Turbidites of the northern Apennines: introduction to facies analysis: International Geology Review, v. 20, no. 2, p. 125-166. Nelson, D. M., 1979, The Drummond Mine Limestone: Mississi ppian basin plain carbonate turbidites and hemipelag- ites in the Pioneer Mountains, Blaine County, south- central Idaho: unpubl. Univ. So. California M.S. Thesis. Nelson, W. H., and Ross, C» P., 1968, Geology of the Alder Creek mining district, Custer County, Idaho: U.S. Geol. Survey Bull. 1252-A, p. A1-A30. Nelson, W. H., Normark, W. R., Bouma, A. H., and Carlson, P. R., 1978, Thinn-bedded trubidites in modern submarine canyons and fans, in Stanley, D. J., and Kelling, G. (eds.), Sedimentation in submarine canyons, fans, and trenches: Dowden, Hutchinson and Ross, Inc., Stroudsburg, Penn., p. 177-189. Nilsen, T. H., 1977, Paleogeography of Mississippian turbidites in south-central Idaho, in Stewart, J. H., Stevens, C. H., and Fritsche, A. E. (eds.), Paleozoic paleogeography of the western United States: Soc. Econ. Paleontologists and Mineralogists, Pacific Sec., Pacific Coast Paleogeography Symposium 1, p. 275-299. Normark, W. R., 1978, Fan valleys, channels, and deposi- tional lobes on modern submarine fans -- characters for recognition of sandy turbidite environments: Am. Assoc. Petroleum Geologists, v. 62, p. 912-931. 122 Onions, D. and Middleton, G. V., 1968, Dimensional grain orientations of Ordovician turbidite graywackes: Jour. Sedimentary Petrology, v. 38, p. 164-174. Oversby, B., 1973, New Mississippian formation in north eastern Nevada and its possible significance: Am, Assoc. Petroleum Geologists Bull., v. 57, p. 1779-1783. Pauli, R. A., and Gruber, D. P., 1977, Little Copper Forma tion: new name for lowest formation of the Mississip pian Copper Basin Group, Pioneer Mountains, south- central Idaho: Amer. Assoc. Petroleum Geologists Bull. v. 61, no. 2, p. 256-262. Pauli, R. A., Wolbrink, M. A., Volkmann, R. G., and Grover, R. L., 1972, Stratigraphy of the Copper Basin Group, Pioneer Mountains, south-central Idaho: Amer. Assoc. Petroleum Geologists Bull., v. 56, no. 8, p. 1370-1401. Pettijohn, R. J., Potter, P. E., and Siever, R., 1972, Sand and sandstone: Springer-Verlag, New York, 618 p. Piper, D. J. W., 1978, Turbidite muds and silts on deepsea fans and abyssal plains, iri Stanley, D. J., and Kelling, G. (eds.), Sedimentation in submarine canyons, fans, and trenches: Dowden, Hutchinson and Ross, Inc., Stroudsburg, Penn., p. 163-176. Poole, F. G., 1974, Flysch deposits of the Antler foreland basin, western United States, in Dickinson, W. R. (ed.), Tectonics and sedimentation: Soc. Econ. Paleontolo gists and Mineralogists Spec. Publ. 22, p. 58-82. Poole, F. G., and Sandberg, C. A., 1977, Mississippian paleogeography and tectonics of the western United States, in Stewart, J. H., Stevens, C. H., and Fritsche, A. E. (eds.), Paleozoic paleogeography of the western United States: Soc. Econ. Paleontolo gists and Mineralogists, Pacific Sec., Pacific Coast Paleogeography Symposium 1, p. 67-85. Ragan, D. M., 1973, Structural geology, an introduction to geometrical techniques: John Wiley and Sons, New York, 220 p. Reineck, H. E., and Singh, I. B., 1975, Depositional sedi mentary environments: Springer-Verlag, New York, 439 p. Roberts, R. J., Hotz, P. E., Gilluly, J., and Ferguson, H. G., 1958, Paleozoic rocks of north-central Nevada: Am. Assoc. Petroleum Geologists Bull., v. 42, p. 123 Rose, P. R., 1976, Mississippian carbonate shelf margins, western United States: U.S. Geol. Survey Jour. Res., v. 4, no. 4, p. 449-466. Ross, C. P., 1934, Correlation and interpretation of Paleo zoic stratigraphy in south-central Idaho: Geol. Soc. America Bull. v. 45, p. 937-1000. Ross, C. P., 1962, Upper Paleozoic rocks in central Idaho: Amer. Assoc. Petroleum Geologists Bull., v. 46, no. 3, p. 384-387. Rothwell, B. G., 1973, Geology of the Mackay 2 SW and parts of the Harry Canyon (Hailey 1 NE), Mackay 3 NW, and Standhope Peak (Hailey 1 SE) quadrangles, Custer County Idaho: unpubl. Univ. of Wisconsin M.S. Thesis. Sandberg, C. A., 1975, McGowan Creek Formation, new name for lower Mississippian flysch sequence in east-central Idaho: U.S. Geol. Survey Bull. 1405-E, 11 p. Sando, W. J., 1967, Mississippian depositional provinces in the northern Cordilleran regions: U.S. Geol. Survey Prof. Paper 575-D, p. D29-D38. Sando, W. J., Dutro, J. J. T., Sandberg, C. A., and Mamet, B. L., 1976, Revision of Mississippian stratigraphy, eastern Idaho and northeastern Utah: U.S. Geol. Survey Jour. Res., v. 4, no. 4, p. 467-479. Scholle, P. A., 1971, Sedimentology of fine-grained deep water carbonate turbidites, Monte Antola flysch (Upper Cretaceous) Northern Apennines: Geol. Soc. America Bull., v. 82, p. 629-658. Shunick, T. W., 1974, Conodont biostratigraphy of some middle and upper paleozoic limestones, central Idaho: Unpubl. Univ. of Wisconsin, Milwaukee, M.S. Thesis. Skipp, B. A. L., 1974, Copper Basin allochthon in central Idaho: U.S. Geol. Survey Prof. Paper 900, p. 34-35. Skipp, B. A. L., and Hall, W. E., 1975, Structure and Paleozoic stratigraphy of a complex of thrust plates in the Fish Creek Reservoir area: U.S. Geol. Survey Jour. Res., v. 3, no. 6, p. 671-689. Smith, J. F., Jr., and Ketner, K. B., 1968, Devonian and Mississippian rocks and the date of the Roberts Mountains thrust in the Carlin-Pinon Range area, Nevada: U.S. Geol. Survey Bull. 1251-1, p. 11-118. 124 Stewart, J. H. and Poole, F. G. , 1974, Lower Paleozoic and uppermost Precambrian Cordilleran miogeocline, Great Basin, western United States, in Dickinson, W. R. (ed.), Tectonics and sedimentation: Soc. Econ. Paleontolo gists and Mineralogists Spec. Pub. 22, p. 28-57. Thomasson, M. R., 1959, Late Paleozoic stratigraphy and paleotectonics of central and eastern Idaho: Unpubl. Univ. of Wisconsin, Madison, Ph.D. Thesis, 288 p. Umpleby, J. B., Westgate, L. G., and Ross, C. P., 1930, Geology and ore deposits of the Wood River region, Idaho: U.S. Geol. Survey Bull. 814, 250 p. Walker, R. G., 1967, Turbidite sedimentary structures and their relationship to proximal and distal depositional environments: Jour. Sedimentary Petrology, v. 37, p. 25-43. Walker, R. G., and Mutti, E., 1973, Turbidite facies and facies associations, in Middleton, G. V., and Bouma, A. H. (eds.), Turbidites and deep water sedimentation: Short Course Notes, Pacific Sec., Soc. Econ. Paleonto logists and Mineralogists, p. 119-158. Winkler, H. G. F., 1976, Petrogenesis of metamorphic rocks: Springer-Verlag, New York, 334 p. Wolbrink, M. A., 1970, Geology of the Mackay 3NW quadrangle, Custer and Blaine Counties, Idaho: Univ. of Wisconsin, Milwaukee, M.S. Thesis, 108 p. 125 APPENDIX A. GREEN LAKE LIMESTONE MEMBER, MULDOON CANYON FORMATION The Green Lake Limestone of the Muldoon Canyon Forma tion was studied at the type locality below Green Lake in the Pioneer Mountains. The purpose of this study is to determine if a significant genetic relationship exists between the Green Lake Limestone and the Drummond Mine Limestone. Nilsen (1977) suggested the Green Lake Limestone is a tectonically displaced distal facies of the Drummond Limestone. Stratigraphic and sedimentologic analyses of the Green Lake Limestone was identical to that used to study the Drummond Mine Limestone. Bed and Bouma interval thickness measurements taken in the lower, middle and upper parts of the unit comprise approximately 12% of its 87 m thickness. The lower contact is sharp, and the upper contact gradational, between the Green Lake Limestone and the Muldoon Canyon Formation. Lateral outcrop extent of the Green Lake Limestone is limited by faulting. Sample GL-4 is similar to GL1-6: it is a normally graded, spicular silty biomicrite (type II) overlain by a micrite (type I). 126 An erosional, non-planar contact seperates the two rock types. Rock type II in this thin section contains detrital quartz, detrital carbonate, sponge spicules, a recrystal lized mollusc fragment (?), pelmattozoan fragment, in a micrite-microspar matrix. The Green Lake Limestone consists of 87 meters of lithologic couplets, limestone and argillite beds. Compo sition of rock types varies from silty biomicrite, micrite argillite, to micritic argillite. Detailed bed thickness measurements were taken following the method and criteria used for the Drummond Mine Limestone. A limited number of measurements (273) were made because of problems with poor outcrop exposure and a limited time frame. The data is tabulated in Appendix B. The carbonate fraction may be subdivided based on the occurrence of certain primary sedimentary structures. As mentioned previously, Bouma1s classification of beds is used only in a descriptive sense; the genetic model is not implied. Te intervals range in thickness from 0.1 - 20 cm, mean is 1.66 cm, standard devi ation is 2.35. Linear regression analysis of stratigraphic position (x) vs. interval thickness (y) results in a nega tive slope of -0.022 and correlation coefficient of -0.102. Goodness of fit is 80% to 90%. Carbonate strata include Ta (N = 2), Tb (5), Tc (7), and Td (128) intervals. The Td divisions range from 0.7 to 45 cm thick, average is 5.32 cm, standard deviation is 6.68. Linear regression analysis of 127 Td data yielded an almost flat, negative slope, -0.004. Correlation coefficient value of -0.021 is a goodness of fit less than 80%. These strata are commonly marked by faint to prominent parallel laminations. Laminations and very thin "beds" within Td divisions reflect local accumulations of coarser silt. Wavy-laminations, erosional contacts, flame structures, load structures, and rip up clasts may also occur in these divisions. All Tc intervals measured were 1 - 2 m thick, average is 1.3 cm. Tc may have any of the primary structures mentioned previously; but, they must have cross- or convolute-laminations. It is apparent from this data that Tc divisions are rare in this unit. The same is true for Tb and Ta divisions. Only 5 Tb intervals were measured, range is 1 to 9 cm mean is 3.0 cm; the Ta1s measure 1 cm and 5 cm. Total bed thickness data was also analysed using linear regression: slope = -0.009, corre lation coefficient = 0.045. The low correlation coeffi cient value indicates less than 80% certainty of a corre lation between bed thickness and stratigraphic position. Bed thickness was also investigated for periodicity with a computerized fast fourier transform (FFT) program. Mean and trend is removed from the data before calculation of FFT. The character of the plot suggests that periodicity is not present in the data. Lithologic similarity between the Green Lake and Drummond Mine Limestones was confirmed by petrographic 128 analysis of four out of twelve samples collected. Rock types I, II and III, as previously described, predominate throughout the section. Rock type I, micrite with or without sponge spicules, appears to be more prevalent in this unit than in the Drummond Mine Limestone. Thin sections GL1-6 and 1-8 amalgamated very thin beds of micrite. The "bed" contacts in GL1-8 are non-planar and (possibly) erosional. Two thin sections of sample GL-3; are composed of silty micrite (rock type II) interbedded with micritic argillite and argillite (rock type III). Type II is medium to fine quartz and chert silt with cherti- fied allochams. The allochem is tentatively identified as a small (0.15 x 0.5 mm) solitary coral. Sample GL-3B consists of laminated, graded, silty micritic argillite. Very thin brown-weathering laminae are siltier and thicker than the other laminae. Contacts between units are non- planar and erosional with scours, flames, and rip-up clasts (in one lamina). Pauli and others (1972) considered the Green Lake Limestone to be a member of the Lower Pennsylvanian Muldoon Canyon Formation. Shunick (1974) recovered conodonts from two rock samples which have been identified as poorly preserved specimens of Polygnathus communis (Branson and Mehl); these are biostratigraphic indicators of late Upper Devonian to late Mississippian (Chesteran) time. Samples collected by the author yielded one poorly preserved 129 specimen of Hindeodella sp. Hindeodella sp. occurs through out the Paleozoic era and is not biostratigraphically signi ficant. These results suggest several possible conclusions about the Green Lake Limestone. The paleoenvironment was not conducive to the accumulation of conodonts. Post- depositional environment was unfavorable to preservation of conodonts. Green Lake Limestone is older than the Muldoon Canyon Formation, and should not be assigned member status of that formation. The Muldoon Canyon Formation is older than previously indicated, and the limestone is an integral part of the formation. The conodonts are forms reworked from an older formation, therefore not age-diagnostic for these rocks. In light of the common occurrence of these conodont forms in older formations in the area (Shunick, 1974) and the poor condition of preservation, it seems probable that these are reworked specimens. As such, they do not resolve questions about the relationship between Muldoon Canyon Formation, the Green Lake Limestone and the Drummond Mine Limestone. Nilsen (19 77) has suggested that the Green Lake Limestone is a thin distal facies of the Drummond Mine Limestone, subsequently displaced by movement along the Muldoon Canyon Thrust. Several lines of evidence support a positive correlation between the Green Lake and Drummond Mine Limestones. (1) Petrographic analysis confirms lith- ologic similarities, both units are primarily composed of 130 lithotypes II and III. Similarities are present in grain size, clast composition, matrix composition and fine sand in the Green Lake Limestone. (2) Primary and secondary sedimentary structures are equivalent in these units. The Green Lake Limestone has fewer cross-laminated beds, bedding is thinner, syn-sedimentary deformation is more common and the bedding does not maintain lateral continuity as well as the Drummond Mine Limestone. Turbidite facies analysis of the Green Lake Limestone places it in facies G, basin plain or outer far depositional environment. (3) Conodonts found in the Green Lake Limestone are similar to those found in the Drummond Mine Limestone, but are not time- stratigraphically diagnostic. In conclusion, the sedimen- tologic evidence suggests a strong similarity between these two units in depositional process, depositional environment, sedimentary source material and subsequent geologic history. However, there is no conclusive evidence to indicate a facies relationship between the Green Lake Limestone and Drummond Mine Limestone. 131 APPENDIX B. FIELD DATA 132 Drummond Mine Limestone 133 r o i —! Lith./Samples i N H H + ) 5 > - r l D1 £ c n ro | 1 \ • • ^ m • i I M £ £ £ \ \ • • • • • • • • • • N N Do Do i —1 O'1 i —1 Do N Do -P -P P Vi tJ> H S' P -p P D 1 D 1 id id £ id £ id D1 id S ' Total Thickness w in in in o o o CN ro o CO 1 —1CN 00 o r- O CN 00 o CM in CO ro o o 00 10 r- O CM o o o in MO CM ro ro in O 00 in CN ro i —I c —1CN ro CN 10 00 in m c —1ro i —1 CM 10 CO 10 r- 00 in in in CO ro i £ iro O 1 —1 c —1 c —1 c —1 in in i —100 c —1in 00 c —1 in CN i —1 CM ro 00 CM o in o ro 00 i —ICM O CM i —I 00 CM ro m i —I i —1ro iH 'd £ C D u Q p C D a > o < u o H o u Eh a U U C D H S 3 • W D1 a ) CO i d f r j w PQ C D O i d § H g S 3 W O < 0 < 10 £ PQ PQ m n i o iH CN o cm ro H CM in ro CN 00 LD 00 in o o o ro cm ro in i n 1 0 in in ro o ro 'd1 ^ ro oo in ro ro o ro O 1 0 M O 1 0 Strat. Interval H CM ro 'I'lOCDhOOOOHCMfO^incOhCDtDOHrMfO'l'IfliflhOOOOHCMrO^incOhCOtDOHCM HHHHHHHHHHCN(N(NCMCMCM(N(N(N(Mrorororororororororo^^^ cn r + H P j r + Bouma Sequence (cm) H D £ A B C D E 43 2 55 16 44 32 4 45 28 2 46 2 5 47 14 20 48 49 150 i 2.0 m unmeas. (covered) 150 ;51 28 3 |52 12 4 53 23 3 '54 6 29 1 155 10 18 1 ] 56 38 3 ;57 6 2 158 10 1 59 60 28 60 8 7 |61 1 5 1 162 | 63 2 64 7 4 65 42 66 30 |67 10 50 40 168 13 55 69 28 40 70 250 3 !71 10 1 72 13 4 1 73 61 10 74 3 1 175 23 9 76 8 80 1 77 50 20 !78 10 6 79 50 30 ! 8 0 9 53 1.5 m unmeas. (covered) 81 10 146 20 82 10 83 f H - f t p * c n J M f D cn mgl. qtz. wk. arg. mgl. qtz. wk. mgl. 4-7 mgl./6-8 135 i - 3 0 rt P > i - 3 & H - O 3 C D cn cn 73 36 30 7 34 150 150 85 31 16 26 36 29 41 8 11 88 15 7 210 2 11 42 30 100 68 68 253 11 17 71 4 32 89 70 16 80 62 176 10 525 < D CO Lith./Samples r - " ' d < c n i H r o o Total Thickness n r o v o ^ w O ( M ( 7 i I s o • i —i CN h i i —i i —1 u i 1 i d \ \ < 1 ) • • • • • • • • • • i —ih > i —ii —i h > h > h > i —i h > i —1 ■H h i u ■H h > u u u h > S - ) T ) £ i d W £ i d i d i d £ i d £ i no O o o O o r - "o i n0 0CN O o o o o r oo o < X i00 o O i no i ni —iO o 0 0o o O i n< £ > 0 00 0< X ii ni —i r oi ni ni —1 o i no 0 0CN 1 —1o r - " CN i —io r - "v hr oo i no i —1 i —i ■ d *i —i i —I i —1 CN r o CN 1 —1< X i CN r o i —1i —i 1 —1 i n c no o 0 0CN CN o r o o i ni —lO 0 0i no r o CN CN < £ ir oi —iCN i n< X i CN o r o< £ i i —l 1 —1 o i n o O i no O CN O o o o o < X i i n o o o i nO r - " r oi n < X i CN < X iCN h i i n r oV i h1 —1 r - " i —i i nV i hr o i —I 'P * 0 K _ ^ h N O 1 - 1 a ) o u o in o oo g ° “ -1 h1 w a ) f d co cq aj i d ^ § 3 o C g P Q r - " o ^ in VD 00 (Ti OHtNm^invDhOOffiOHtNM^inDhCDOIOHtNM^inmhCDOIOHtNrO'jLn 000000000000 0 1 0 1 ( H O l ( J l O l 0 1 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 H H H H H H H H H H O J ( N ( N N ( N t N | Strat. Interval ■ —i > —i • —i ■ —i i —i < —1<—i < —i < —i < —1<—i < —1<—i < —1<—1<—1<—1<—1<—i < —i < —i < —1<—1<—!■—ii—i cn r+ H P J rt H £3 r+ CD H - rt J3* cn * 0 M C D ( / ) 126 5 2 7 127 9 3 12 128 2 1 3 129 45 45 90 130 7 65 72 131 160 134 10 1 11 133 14 2 16 134 18 1 19 135 25 1 26 136 22 25 47 137 9 1 10 138 15 2 17 139 50 70 120 140 15 15 141 150 142 10 143 100 144 80 145 30 5 35 146 10 0.8 m unmeas. (covered) 2 12 147 20 70 90 148 9 20 29 149 73 10 83 150 7 14 21 151 84 2 86 152 38 4 42 153 20 5 25 154 26 10 36 155 12 4 16 156 15 6 21 157 8 8 16 158 3 1 4 159 46 18 64 160 10 4 14 161 45 11 56 162 400 163 26 26 164 70 2.5 m unmeas. (uncovered) 30 100 165 30 30 166 2 77 30 109 arg. mgl, arg, mgl, arg, m g l . / 4 - 1 3 137 c n rt r+ Bouma Sequence (cm) i - 3 J3* H - O * 3 f l > t o t o F H- r+ J3* cn M C D t o 2.0 m unmeas. (uncovered) 167 8 1 9 168 10 18 28 169 12 1 13 170 1 1 2 171 9 1 10 172 6 20 26 173 10 4 14 174 50 70 120 175 20 3 23 176 10 30 40 177 25 1 26 178 33 60 93 179 23 23 180 150 150 181 100 182 183 60 184 55 185 55 12 67 186 55 40 95 187 3 30 33 188 6 32 38 189 18 16 34 190 8 3 11 191 8 .3 8.3 192 1 16 45 62 193 9 4 13 194 16 3 19 195 8 27 35 196 19 1 20 197 15 35 50 198 10 5 15 199 20 20 200 200 200 201 100 202 50 10 60 203 8 8 204 200 205 .5 .5 206 9 .5 9.5 207 50 16 66 208 20 8 28 qtz. wk./4 sill. 4-15 arg. & Is. arg. qtz. wk. arg. 4-16 mgl. -14 138 m rt n p j r+ H £ 3 r+ CD n < pj Bouma Sequence (cm) D E h3 o r+ P) H - O * * 3 CD c n C O f H- r+ t J 4 t o ► 0 H ( D C O 209 210 211 212 8 40 1 300 10 41 213 15 2 17 214 215 216 35 3 160 6 38 217 10 18 28 218 1 1 2 219 3.5 1 4 220 78 3 81 221 10 25 35 222 8 200 3 283 223 25 6 31 224 225 35 20 200 55 226 5 2 7 227 60 20 80 228 45 20 65 229 20 16 36 230 16 8 24 231 5 1 6 232 70 10 80 233 75 15 90 234 235 6 150 25 10 25 166 236 22 3 25 237 5 12 17 238 3 50 3 66 239 10 7 17 240 40 6 46 241 15 3 18 242 40 10 50 243 30 7 37 244 4 65 69 245 1.5 m unmeas. (covered) 55 4 59 246 65 7 72 247 85 6 91 248 75 10 85 249 250 35 35 5 4-17 mgl. arg. mgl. arg. mgl. mgl. 4-18 Tee. 139 w ft n ft Bouma Sequence (cm) o » Hi t r * O H- ft ft H H i U i 3* e H - f + A B C D E Q tg ( D w < * * i r * 3 ( D (0 01 01 01 251 25 13 38 252 40 40 253 9 9 254 12 15 27 255 9 1 10 256 3 1 4 257 9 8 17 258 60 8 68 259 11 11 260 60 261 5 8 6 19 262 25 12 37 263 2 25 2 29 264 5 2 7 265 5 12 17 266 5 3 55 5 68 267 85 6 91 268 60 269 40 270 35 .5 35.5 271 17 17 272 3 75 10 88 273 18 18 274 16 16 275 20 5 45 70 276 56 277 32 278 6 17 2 25 279 10 2 12 280 32 18 50 281 1 100 101 282 35 283 2 46 10 58 284 11 10 21 285 9 5 14 286 8 30 4 42 287 9 7 16 288 23 11 34 289 22 14 36 290 28 10 38 291 8 .5 8.5 292 4 mgl. mgl. 4-19 qtzt./4-20 arg. arg, 140 w n | h r+ 0 h - £ r+ r+ P f U t r rt ( _ i . Bonma Sequence (cm) \ h t r p t » H- S £ A B C D E O >3 5 3 f l > < ( D W p w H* C O 1.2 m unmeas. (covered) 293 12 4 16 294 16 4 20 295 7 3 10 296 8 10 24 6 48 297 2 2 4 298 3 24 4 31 299 1 70 32 103 300 10 5 35 14 64 301 10 10 302 42 303 20 1 21 304 1.5 1 2.5 305 5 25 1 31 306 2 3 5 307 3 12 15 308 24 14 18 309 10 1 11 310 12 3 23 1 39 311 6 1 7 312 5 2 7 313 1 18 8 27 314 30 30 315 6 60 — — 12 78 316 12 4 16 317 14 7 21 318 4 30 — — 10 44 319 15 6 21 320 13 6 19 321 32 1 33 322 1 1 2 323 14 4 18 324 17 4 21 325 18 6 24 326 6 2 8 327 4 2 6 328 1 1 2 329 19 11 30 330 16 1 17 331 9 12 13 34 332 10 7 17 333 18 5 24 10 57 4-21 sil. Tee. arg. 141 cn r + h & > V Bouma Sequence (cm) H g A B C D E < & > ( - ■ 334 11 9 335 8 6 336 8 15 337 5 13 338 2 16 14 339 21 4 340 65 8 341 9 6 342 9 5 343 11 25 344 7 8 345 9 19 346 4 1 347 7 1 348 7 13 349 350 15 10 7 351 2 37 352 8 22 353 7 24 354 355 356 3 15 30 15 2 357 6 1 358 11 1 22 3 359 10 3 360 4 3 361 9 5 12 362 1 4 363 15 1 19 6 364 1 14 13 365 4 16 0.7 m unmeas. (uncovered) 366 12 1 367 1 24 10 368 11 6 369 8 25 370 15 6 371 22 1 372 14 2 373 10 3 2 0.9 m unmeas. (uncovered) I - " - J = O * 0 W H 3 O (D cn m in 20 14 23 18 32 25 73 Tee. 17 14 36 15 28 5 8 20 22 10 39 30 31.5 4-22 33 30 2 7 37 13 7 26 5 Tee. 41 28 21 13 35 17 33 21 23 16 15 142 cn r+ f u r+ H 3 r+ C D < S D t —1 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 Bouma Sequence (cm) 28 ^ 3 F O H - f l - f + j u y i - 3 cn h | D E & * 2 , r 1 3 C D C D C D C D C D 72 arg, 15 20 sil. 11 3 14 13 9 22 8 3 11 6 2 8 10 14 24 2 16 3 21 10 12 22 20 3 23 40 1 41 4 1 5 2.5 1 3.5 8 1 9 3 5 2 10 2 6 4 40 3 11 4.5 18.5 35 16 51 5 9 1 17 33 1 34 3 2 5 15 4 19 4.5 2 6.5 12 2.5 14.5 26 1 27 22 4.5 26.5 4 8 12 5 2 5 12 13 3 16 25 11 36 11 1 12 4 2 6 4 55 59 3 16 2.5 25.5 10 2 12 12 3 15 24 10 34 10 7 30 47 4 8 12 2.0 m unmeas. (covered) 25 1 26 143 U i rt n ( U rt f O H - rt rt f u tr H Bouma Sequence (cm) h i cn o " A B C D E ** h* h 3 n > 2 n > m 2 m p c o H 3 rt C D 415 3 5 8 416 11 2 13 417 4 1 5 418 20 4 24 419 13 2 15 420 5 1 6 421 17 1 18 422 14 6 20 423 2.5 2 4.5 424 2 .5 2.5 425 7 2 9 426 427 17 428 13 1 14 17 14 429 7 3 10 430 11 4 15 431 14 1 15 432 2 1 3 433 8 3 11 434 4 2 6 435 1 .5 1.5 436 3 17 20 437 5 15 3 23 438 13 8 21 439 4 2 6 440 3 2 5 441 8 3 11 442 13 5 18 443 17 1 5 444 3 2 11 445 1 8 2 11 446 12 6 18 447 2 1 3 448 2.5 1 3.5 449 2 2 4 450 17 1 18 451 13 2 15 452 6 26 3 35 453 18 2 20 454 11 6 17 455 7 1 8 Tee, qtz. wk. sil. arg, gy. Is. & Is. 144 cn rt i i P J r+ H 3 r+ < t > 3 P J t - 1 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 Bouma Sequence (cm) A B C D E 3 30 1 6 7 22 .5 3 12 5 3 4 1.5 1 11 1 11 4 6 1 1 1 8 7 30 5 20 2 3 2 30+ break in stratigraphic section begin Section 5 \ c n H H 0 0 1 Tee./4-23 end Sect. 4 sil. bd. arg. Is. sil. Is. sil. Is. sil. sill. sil. Is. sil. Is. sil. Is. Is. Is. sil. Is. sil. Is. sil. Is. sil. Is. 145 ^ 3 O r+ P J H 3 * H - O * 3 f l > 0 1 0 1 34 13 22.5 20 2.5 12 15 7 2 15 35 22 5 30+ 70 4.5 14 11 100 10 680 120 8 3 4 3 18 3 4 3 17 5 14 10 18 8 20 5 m t - 3 t- 1 rt- 0 H - H f t r t pu pu tr r t H* • Bouma Sequence \ H p § rt A B C D E o *0 ( D * * P* P D O < n > w pu Ui H W 496 40 sil, 497 12 Is. 498 30 sil, 499 7 Is. 500 20 sil. 501 8 Is. 502 12 sil, 503 18 Is. 504 6 sil, 505 5 Is. 506 10 sil, 507 8 Is. 508 3.5 sil, 509 6 Is. 510 29 sil, 511 4 1 5 512 4 5 9 513 4.5 9 13.5 514 1.5 1 2.5 515 3 2 5 516 16 8 24 517 2.5 1 3.5 518 3 5 6 14 519 14 1 15 520 2 1 3 521 14 6 20 522 7 1.5 8.5 523 10 6 16 524 24 10 34 525 4 8 12 256 16 3 19 527 2 3 5 528 4 3.5 7.5 529 6 10 16 530 2 3 5 531 3 8 11 532 4 8.5 12.5 533 15 4 19 534 3 3 6 535 1 3 4 536 23 2 25 537 3.5 1.5 5 146 U 1 rt p i rt 8 rt p) H 3 < D Bouma Sequence A B C (cm) D E 3 H- 0 ** 3 3 P > H ( D 0 ) 0 1 538 6 3.5 9.5 539 6 3 9 540 5 1 6 541 4 7 11 542 5 12 17 543 5 10 15 544 3 4 7 |545 9 2 11 546 4 2 6 547 6 .5 6.5 548 1 1.5 1 3.5 ,549 17 3 20 550 2 2 2 6 12 551 11 4 15 552 6 6 12 553 2.5 1 3.5 554 1 2 3 555 6 8 18 556 6 4.5 10.5 557 4 10 14 558 5 21 16 42 559 40 52 92 560 4 3 7 561 3.5 7 10.5 562 3 1 4 563 2 1 3 564 3 1 4 565 5 9 14 566 6 12 18 567 14 5 19 568 33 28 61 569 13 8 21 570 5 5 10 571 23 10 33 572 4 2 6 573 8 13 21 574 2 8 10 575 3 2 6 3 14 576 10 1 11 577 3 .5 3.5 578 2 10 4.5 16.5 579 38 8 46 f H - e l s ' \ cn i —1 ( D 0 ) 147 U i ft t u c + 3 c + ( D 2 H Bouma Sequence A E h3 o rt t u H f 3 * H * 0 X ? 3 ( D 0 1 0 1 IT1 H * ft 3* 0 1 ► 0 H f l > 3 580 10 2 12 581 5.5 10 15.5 582 4 12 4 20 583 3 5 8 Tee. 584 7 3 10 585 2 1 3 586 3 2 2 1 8 587 34 3 37 588 36 20 56 589 8 8 17 590 7 6 13 591 9 4 13 592 4 11 15 593 1 5 1. 7 594 5 4 9 595 3 11 14 596 6 13 19 7.5 m unmeas. (covered) 597 9 4 13 598 3 2.5 5.5 599 17 4 21 600 15 4 19 601 40 12 62 602 250 sill. 603 20 sil. arg. 604 6 Is. 605 10 sil. 606 17 Is. 607 52 sil. 608 12 Is. 609 6 sil. 610 15 Is. 611 25 sil. 612 5 Is. 613 4 sil. 614 6 Is. 615 11 sil. 615 6 Is. 617 30 sil. 618 9 Is. 619 6 sil. 620 6 1 7 14 8 tn h3 t- 1 r+ O H - 2 f f S r+ ( u c n h c o 621 4 1 5 622 8 3 11 623 7 12 19 624 18 625 7 7 626 50 627 8 1 9 628 4 629 14 630 6.5 2 8.5 631 3 1 4 632 2 3 1 6 633 7 40 9 56 634 2.5 1 3.5 635 1.5 1 2.5 636 2 9 11 637 10 4 14 638 42 8 50 639 9 15 24 640 8.5 2 10.5 641 3 9 12 642 2 13 15 643 4 10 8 644 2 .5 2.5 645 1 1 2 646 2 1 3 647 1 1 2 648 2 12 7 21 649 in • in 14 13 32.5 650 4 3 7 651 2 7 9 652 28 2 30 653 25 7 32 654 2 7 9 655 3 1.5 4.5 656 3 3 6 657 1 1.5 2.5 658 1 2 3 659 2 2.5 4.5 660 8 2 10 661 2.5 .5 3 662 10 14 24 \ Bouma Sequence (cm) yj h p . | J a b c d e & % 3 C D C D w sil, sil, Is. sil, Tee, Tee, Tc. arg. arg. 149 CO r+ H i ( U r+ H 3 f t ( D 3 0 > i —1 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 Sequence (cm) h3 & H- B C D E O W 3 ( D W W 8 6.5 14.5 2 7 15 24 11 •5 11.5 3 4 7 4 9 13 16 3 3 6 28 5 10 15 6 6.5 12.5 11 4.5 15.5 2 1 3 3 1 9 12 24 1 1.5 1.5 4 1 1.5 2.5 1 1 2 2.5 1 3.5 3 5 8 25 2 27 3 1 4 4 8 12 .5 2 2.5 .5 1 1.5 15 3 18 1 6 7 5 1 6 1 •5 1.5 1 5.5 9 15.5 2 9 2 13 9 2 11 1 1 2 7 16 23 7 8 15 6.5 4 10.5 50 4 3.5 7.5 4.5 4.5 12 17 12 41 1 2 3 7.5 1 8.5 2 4 2 8 1 1 2 1 1 2 1 1 2 h3 f O H - rt rt 3* c o T S H ( D W Tee, Tee. Tee. Tee. sill. 150 cn rt t u rt H 3 ft C D 3 M 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 Bouma Sequence (cm) £3 A B C D E H- O ** 3 C D c n c n 1 6 4 11 3 1 4 2 2 4 5 3 8 2 2 4 1 10.5 11.5 1 30 5 36 5 2.5 7.5 2.5 1 3.5 6 2 8 11 13 24 12 13 25 12 3 15 5 4 9 4 4 8 2 6 8 2.5 7 9.5 6 10 16 4 1 5 2 2.5 4.5 33 1.5 8 42.5 3 5 8 6 1 7 36 3 39 10 2 12 4 1 5 2 2 4 23 2 4 29 7 3.5 10.5 2.5 2 4.5 2.5 1 5.5 9 9 2 11 5 3 8 2.5 3 1.5 7 7 14 21 m unmeas. (covered) 10 9 19 4 7 11 2 3 2.5 7.5 3 3 6 18 1 19 2 6 8 ^ 1 3 O H - rt- f t 0 ) 3 * cn > 3 C D c n 5-7 T e e . T e e . 151 CO ft H P J f + H 3 f + C D H < ! P J H 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 Bouma Sequence (cm) 9 e s s t - J . 1 - 3 CO •3* g A B C D E q ^ H 3 C D C D C O cn w 10 6 16 4 8 12 54 54 13 sil. 3 Is. 15 sil. 7 Is. 5 sil. 7 Is. 9 sil. 15 Is. 2 sil. 5 Is. 16 sil. 10 Is. 54 sil. 10 Is. 11 sil. 7 Is. 40 sil. 9 Is. 5 10 33 48 16 Is. 30 sil. 6 Is. 5 sil. 5 Is. 4 sil. 4 Is. 2 sil. 4 Is. 300 sill. 4.0 m unmeas. Covered) 5 8 13 Tee. 0.5 0.5 0.5 1.5 1 0.5 1.5 6 5.5 11.5 4.5 1 5.5 10 2 12 4 2 6 7.5 12 9 28.5 5-8 2 4 1 7 152 t o rt H P > rt H 3 rt ( D H H 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 i - 3 tH O H * rt rt P i 3 * Bouma Sequence (cm) \ 3* & H - B c D E o * 0 ( D c n w 1.5 0.3 1.8 3 5 8 4 5 9 4 2 6 3 30 2 35 4 2 6 3 5 11 2 6 3 11 13 10 23 8 10 18 2 1 3 12 1 13 5 1 6 3 2 4 9 7.5 2 9.5 3 3 6 3 2 5 27 0.5 27.5 2 6 8 2 2 4 7 10 17 3 2 5 5 2 7 2 4 6 3 1.5 4.5 1 19 3 23 2 0.5 2.5 2 9 5 16 5 17 22 7 2 9 30 1 31 7 9 16 2 3 4 5 4 9 5 14 3.5 1 4.5 4 3 7 8 3 11 2.5 1 3.5 2 0.5 2.5 2 0.5 2.5 6 1.5 7.5 37 16 53 t o f l > W Tee, Tee, Tee, Tee, Tee, Tee, 153 Ui r+ ■ I P J r+ H 3 r+ C D < P J H 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 t —1 Bouma Sequence (cm) ^ • - 3 I t* O H - r f c + p j & cn 3 * H - 3 A B C D E g. fl 3 C D C D W W W 13 10 23 11 19 30 12.5 m unmeas. (uncovered) 9 11 20 4 5 9 1 2.5 3.5 1 3 4 Tee. 5 4.5 9.5 3 3.5 6.5 12 1 13 6.5 2.5 9 2.5 1 3.5 6 3 1 10 9 1 10 12 4 16 12 3 15 4 4 2.5 10.5 6 19 25 2.5 2 4.5 2 9 2 13 25 arg. 15 1 16 2 1 3 20 2 22 6 8 14 Tee. 2 3 5 Tee. 10 7 17 35 3 38 30 6 36 19 10 29 7 7 14 2 2 4 4 1 5 6 1 7 14 14 5-3 34 34 66 sill 32 8 6 14 3 1 4 2 0.5 2.5 3 0.5 3.5 154 co rt t { PJ rt H 3 rt < PJ 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 h3 t - * O H - rt rt P J 3 * Bouma Sequence (cm) ^ 3* A B C D E c o H- o ►d f t * i - * 3 ( D ( D W W W 10 10 5 4 3 12 10 12 3 25 5 1 6 2 4 6 Tee. 7 1.5 8.5 4 4 27 sil. 7 Is. 14 sil. 5 7 12 3.5 5 2 10.5 4.5 2 6.5 3 1 4 47 3 50 5-10 2 5 7 Tee. 3 7 10 Tee. 4 0.5 4.5 4 4 2 6.5 2 18.5 2 6.5 12.5 Tee. 11 100 100 qtz. wk./5-ll 1 2 3 1 1 2 13 7 20 30 30 qtz. 6 6 7 1 8 5 1 6 13 13 qtz. wk. 4 4 10 3 13 3 2 6 11 4.5 1.5 6 1.5 1 2.5 27 27 qtz. wk. 4 4 20 20 qtz. wk. 6 6 13 35 3 7 8 66 20 2 22 9 6 15 155 H 3 r+ ( D n { U Bouma Sequence (cm) ■ - 3 o f t p j 1 - 3 H - 0 * < D 0 1 0 1 t r 1 H * \ U 1 ► c M C D 0 1 913 12 9 15 914 3 4 7 915 35 35 916 5 5 917 16 1 17 918 3 1 4 919 2 1 3 920 3 1 4 921 14 11 25 922 32 923 5 4 9 924 6 1 7 925 18 18 926 15 15 927 12 18 30 928 5 1 6 929 10 1 11 930 2.0 m unmeas. 2 3 4.5 9 931 3 55 25 83 932 9 3 4 2 18 933 6 9 15 934 1 6 2 9 935 22 13 35 936 4 1 5 937 6 9 4 19 938 11 8 6 2 27 939 9 13 22 940 19 17 36 941 3 9 12 942 3 3 1 7 943 5 0.5 5 944 2 3 5 10 945 14 3 17 946 8 1 9 947 1 30 8 39 948 2 2 9 13 949 3 20 23 950 20 18 38 951 3 7 10 20 952 3 6 3 12 953 300 300 sil, Tee. sil. arg. 156 cn rt tu rt H 3 rt f l > H < 0 ) M 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 Bouma Sequence (cm) A B C D 20 1.2 m unmeas. (covered) 12 30 3 6 5 33 5 24 10 20 19 10 4 4 ■ - 9 0 H- rt rt f u U 1 —1 • i - 9 cn ST & H- O •b ** i —1 0 (D (D c n c n c n begin Sect. 6 25 Is. 30 sil. arg 21 ^ S - } 6 - l 9 Is. 15 sil. 12 Is. 63 sil. 13 Is. 11 sil. 7 Is. 30 sil. 10 Is. 36 sil. 22 50 sil. 47 4 8 11 37 10 sil. 9 sil. 90 sil. 23 Is. 45 sil. 7 Is. 15 sil. 12 48 Is. 12 Is. 7.5 sil* 15 Is. 19 sil. 18 Is. 12 sil. 25 16 34 25 15 11 E 2 5 1 2 6 4 7 1 6 14 6 5 3 157 cn rt H P J rt H 3 rt f D 3 p j M 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 i-3 F O H - rt rt f D t J * Bouma Sequence (cm) 1 - 1 \ i-3 cn E J * | ♦ 0 I — ' ( D w D E H - O ** 3 C D W W 6.5 1 7.5 10 2 12 37 15 52 17 1 1 2 2.5 1 3.5 22 1 1 8 15 23 4 8 19 4 11 15 35 41 40 2 42 40 1 41 32 3 35 7 1 8 5 1 6 20 2 22 14 6 21 12 1 16 5 12 17 2 1 3 9 2 11 3 3 6 12 13 25 9 25 2 27 9 4 15 2 4 7 19 19 38 Is. I s . 6-2 Is. 17 Is. 23 Is. & ch. 21 Is. 14 Is. 23 Is. & ch. 24 Is. 27 sil. 25 Is. 36 sil. 10 1 11 2 4 Tee. 5 2 7 15 15 158 cn r+ 3 f u r+ H 3 r+ CD 3 H 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 ■-3 F o H- r+ f+ p j f j * / X ng cn Bouma Sequence (cm) tr g o t s J A B C D E 3 n > fD W cn cn 20 Is. 15 sil, 7 Is. 10 sil, 16 Is. 30 m unmeas. (mostly silicified 6-3 6-4 18 18 qtz. 72 72 qtz 18 4 1 7 13 1 14 3 1 5 7.5 1 8.5 3 1 4 72 14 3 1 4 4.5 1 5.5 2 3 5 2 6 8 3 3 6 21 1 22 10 2 19 4 2 6 29 3 31 6 23 31 9 10 27 30 8 1 9 4 3 7 3 1 4 3 1 4 6 1 7 15 1 16 15 4 19 30 2 32 4 1 5 15 15 1.5 16.5 2 1 3 1 2 4 2 3 5 2 1 3 sil, sil w k . wk. 159 C£ H P rt O h- H r+ r+ f u j u t r ’ c + m \ t o H c n 6-5 Bouma Sequence (cm) h - 3 H tr 3 H- ff A B C D E o IV 3 < 1 C D c u c n M c n 1079 3 1 4 1080 5 14 3 22 1081 9 6 15 1082 20 1 21 1083 11 3 14 1084 2 3 5 1085 1 4 1.5 6.5 1086 11 0.5 11.5 1087 1 2 2 5 1088 9 4 13 1089 24 24 1090 7 7 3 17 1091 2 2 4 1092 2 0.5 2.5 1093 1.5 1.5 3 1094 3 8 11 1095 7 3 8 4 22 1096 5 4 3 12 1097 12 1 13 1098 7 1 8 1099 12 2.5 14.5 1100 8 0.5 8.5 1101 7 5 4 16 1102 26 3 29 1103 6 2 8 1104 14 0.5 14.5 1105 7 5 2.5 14.5 1106 7 1 8 1107 9 7 16 1108 4 9 14 27 1109 4 1 5 1110 4 0.5 4.5 1111 5 1 6 1112 5 4 9 1113 10 1 11 1114 8 1 9 1115 5 2 7 1116 2 4 3 9 1117 5 1118 4 0.5 4.5 1119 2 3 2 7 1120 10 2 12 Tee, Tee, 160 Ui r+ H P > f t H a r+ C D H ► — 1 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 Bouma A 8.25 m Sequence (cm) Hi 0 ft p > ► —1 Hi t - * H- ft p* m B C D E H- o ** 3 C D c n c n H ► —1 C D c n 4 0.5 4.5 11 3 14 7 2.5 9.5 2 1.5 3.5 45 Tee. Tee. 11 5 16 5 5 4 14 150 Tee./6 unmeas. (same 25 as above) 25 4 2 10 16 18 1 19 22 Tee. 2 25 10 37 3 1.5 4.5 6 1 7 2 9 11 5.5 6 11.5 23 5 28 in 4 15 2 25.5 6 1 7 2.5 5 7.5 8 3 11 10 10 7 Tee. 15 6 21 25 0.5 25.5 3 6 9 Tee. 7 4 11 4 4 8 3 2 5 2 1 3 9 3 12 4 4 8 90 10 mgl. Tee. 12 2 14 25 1.5 26.5 4.5 4.5 2.5 7 3.5 6 7 6.5 32 8 46.5 161 CO r + * & r + H 3 r + C D < & M 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 ► 9 t * O H - r+ r+ i U 3 * Bouma Sequence (cm) ^ 3.0 m unmeas. CO o A B C D E §• £ C D cn cn cn 11 Tee, 14 3 17 4 5 9 Tee, 12 9 21 13 2 15 8 3 11 13 3 5 21 75 mgl, 5 Tee, 13 4 17 9 2 11 10 5 15 3 2 3 8 13 1.5 14.5 30 1 31 20 20 10 Tee, 35 2 37 15 2 17 3 2 3 8 22 1 23 15 0.5 15.5 52 0.5 52.5 2 1 3 2 1.5 3.5 22 2 24 7.5 0.5 8 10 2 12 7.5 2 9.5 14 2 19 16 1 17 7 7 4 Tee, 21 1 22 7 1 8 11 2 13 8 2 10 3 0.5 3.5 11 0.5 11.5 2.5 4.5 Tee, 19 0.5 19.5 162 cn rt- H f u rt- H P r+ C D H < £ U I - 1 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 • - 3 IH O p . 1 —1 Bouma Sequence (cm) ^ ^ 6 m unmeas. 12 O ' H - D E o ** 3 C D W C O 5 0.5 5.5 2 19 21 7 26 26 15 5 5 9.5 15.5 2 1.5 3.5 16 1 17 12 1 13 10 3.5 13.5 3 1.5 4.5 4 0.5 4.5 50 1 51 2 0.5 2.5 2 1 9 4.5 2 6.5 11 11 2.5 1 3 14 1 15 3 1 4 16 8 24 4 4 8 1 1 1 2 3 14 1 27 8 2 2 9 1 10 2 4 12 1 13 4 1 5 12 2 14 15 3 18 16 2 18 7 1 8 1 1 2 7 1 8 20 0.5 20.5 Tee, arg. Tee. Tee. Tee. Tee 163 cn n- £ U n- H 3 n- C D h { < £ U I - 1 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 « - 3 t r 1 O H - < + n- s » ^ i — 1 • Bouma Sequence (cm) \ h § A B C D E g. ^ 3 C D C D W w w 2.5 1 3.5 3 2 5 55 12 12 9 2.5 0.5 3 4 8 12 4 1 5 25 1 26 19 5 24 34 0.5 34.5 8 1 9 7 0.5 7.5 6 2 8 11 1 12 21 0.5 21.5 2 0.5 2.5 18 1 19 7 0.5 7.5 4 1 5 2 3 5 3 1.5 4.5 2 2 4 5 0.5 5.5 8 2.5 10.5 13 0.5 13.5 8 0.5 8.5 12.5 0.5 13 2 3 5 7 1 8 4 7 15 34 1 35 2 2 4 7 7 3.5 3.5 38 1 39 23 1 24 4 1 5 2 0.5 2.5 18 3 21 23 0.5 23.5 5 0.5 5.5 qtz. wk. Tee. Tee. Tee. Tee. Tee. Tee. 164 Ui r+ H P r+ H P r+ ( D H < P M 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 H t r * 0 h- r+ n- p j p r Bouma Sequence (cm) hi cn H * J j O ^ A B C D E # H P ( D f D W W CO Tee, 1.5 0.5 2 7 3 10 2 3 5 29 2 31 10 3 13 1 4 2 7 8 5 13 1 4 2 7 8 5 13 10 0. 5 10.5 4 3 7 16 0.5 16.5 3 0.5 3.5 2 0.5 2.5 6 2 2 0.5 10.5 20 0.5 20.5 13 0.5 13.5 28 0.5 28.5 unmeas. 1 1 2 3 1 4 10 1 11 12 1.5 13.5 2 3 5 4 3 7 34 1 35 13 1 14 10 2 12 5 4 6 15 2 1 3 10 1 11 10 1 11 30 4 34 21 1 22 24 1.5 25.5 6 2 8 6.5 1 7.5 32 2 34 12 6 18 1 3 1 5 35 35 3 7 10 Tee, Tee, Tee. Tee, 165 CO r+ p) ft H 3 ft ( D < P) M 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 i-3 IT1 O H - ft <+ p) Bouma Sequence (cm) i - g cn o " ^ A B C D E * m 3 ( D (D CO CO C O Tee, 7.5 m unmeas. 6 6 12 13 1.5 14.5 15 3 18 9 2.5 11.5 14 1 15 11 11 5 3 8 2 3 5 25 1 26 3 7 4 14 9 5 14 30 2 32 4 2 6 3 2 5 2 4 8 10 5 15 27 9 36 14 14 25 3.5 1 4.5 15 1 16 2 4 6 8 1 9 9 1 10 2 1 3 4 1 5 3 4 4 11 2 4.5 6.5 7 0.5 7.5 18 0.5 18.5 10 0.5 10.5 4 8 12 7 1 8 2 5 7 2 3 5 2 2 4 9 3 12 2 8 4 14 6 1 7 7 2 9 6 1 7 Tee, arg, Tee. Tee. Tee Tee, 166 cn rt * ( u rt H 3 ft fD < ( U M 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 Bouma Sequence (cm) H tr* o H - rt ft ( U J J * H t -3 cn H § A B C D E o' ? v I— 3 ( t > (D CO cn cn 7.5m unmeas. 3.0 m unmeas. 9 1 10 2 4 6 5 5 8 18 30 3 33 4 1 5 4 3 7 3 2.5 5.5 13 7 20 9 5 14 8 0.5 8.5 11 1 12 11 0.5 11.5 1 32 1 34 6 0.5 6.5 7 0.5 7.5 2 6 0.5 8.5 10 0.5 10.5 2 6 0.5 10.5 3 2 0.2 5.2 45 1 46 5 10 4 19 2 4 0.5 6.5 10 0.5 10.5 1 7 6 14 6 7 13 26 4 30 16 2 18 12 1 13 30 1 31 14 14 7 5 1 6 1 1 2 5 1 6 25 0.5 25.5 3 1 4 2.5 0.5 3 1.5 4 0.5 6 7 2 9 1 2.5 1 4.5 Tee, Tee, Tee, Tee, Tee. 167 U i rt 3 r+ H 3 rt ( D H < p o t — 1 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1 - 3 t r 1 O H - rt r+ pu tr t — 1 Bouma Sequence (cm) K) cn h - % „ o 'n A B C D E ** h 3 f l > fl> cn cn cn 35 9.5 m unmeas. 5 0.5 5.5 10 1 11 6 1 7 15 4 19 1 5 0.5 6.5 2 0.5 2.5 7 1 8 4 5 5 14 90 Tcde/6-8 12 Tee. 2 2 4 Tee. 20 12 32 Tcde. 3 3 6 Tee. 2 2 4 Tee. 4 2 6 4 1 5 1 1 2 39 2 1 3 36 6 42 7 4 11 2 3 5 Tee. 14 3 17 10 3 13 5 3 8 Tee. 2 1 3 Tee. 1 2 3 Tee. 13 2.5 15.5 2 9 11 Tee. 7 1 8 9 1 10 2.5 5 7.5 Tcde. 10 1 11 1 2.5 3.5 as. 14 2 16 7 7 2 3 5 Tee. 34 3 37 15 2 17 100 mgl. 0.5 0.5 4 3 7 168 cn r + p ) r + H 3 ft C D < J 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 Bouma Sequence (cm) o H - r+ r+ p ) D - * ■ - 3 cn •3* g A B C D E o *0 X l - * 3 C D C D cn cn cn 3.5 4.5 4.5 m unmeas. 3 6.5 Tee. 4 2 2 22 1 23 2 4 Tee. 2 6 Tee. 4 2 6 6 12 Tee. 20 5 25 2.5 2 9 2 4 5 Tee. 18 2 20 21 1 22 4 2 6 33 1 34 18 2 20 5 10 Tee. 9 9 2 4 Tee. 4 6 Tee. 13 1 14 8 1 9 12 1 13 13 7 20 8 11 Tee. 12 1.5 14.5 8 4.5 12.5 3 4 7 5 7 Tee. 2.5 4 4 2 2 4 2 0.5 2.5 12 12 Tee. 37 1 38 4 0.5 4.5 6 4 10 Tcde 11 5 16 2 3 Tee. 3 5 Tee. 12 1 13 169 cn r + H i p j r + H 3 ft C D < f U H 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 Sequence B C (cm) D E Total Thickness Lith./Samples 11 1 12 6.5 6.5 2 3 5 Tee, 5 0.5 5.5 2 2 6 sil, 5 0.5 5.5 1 1 2 13 2 13 5 2 sil, 2 2 4 10 2 12 2 4 5 11 3 4 7 Tee 1 3 4 Tee 5 1 6 11 4 15 3 2 5 Tee 2 1 3 Tee 13 1 14 4.5 0.5 5 1 0.5 1.5 8 3 11 1 23 1 25 3 1 4 4 1 5 2 6 5 13 2 2 4 3 1 4 2 3 5 7 1 8 15 1 16 3 3 6 Tee 6 1.5 7.5 2 4 6 Tee 8 3 11 16 16 9 Tee 7 1 8 3 1.5 4.5 9.5 3 12.5 170 c n r t rt H 3 r t ( D H J D 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 Bouma Sequence (cin) O H - ff S * 1 - 1 \ cn p i A B C D E g, £ 3 ( D ( D C Q W W 6 4.5 m unmeas. 24 3 27 2 5 1 2 3 2 0.5 2.5 5 1.5 6.5 9 2 11 3 1 4 10 10 8 10 1 11 3 1 4 8 3 11 12 2 14 2 4 14 1 15 11 11 3 1 1 10 2 12 2 0.5 2.5 4 1 6 5 0.5 5.5 5 3 8 3 0.5 3.5 2 0.5 2.5 1 5 6 15 2 17 13 5 18 20 8 34 25 1 26 8 1 9 3 2 5 45 1 46 8 0.5 8.5 3 0.5 3.5 3 0.5 3.5 5 1 6 5 2 7 4 3 7 4 1 5 1 1 2 14 3 17 Tee. Tee. Tee. Tcde 6-8 171 Ui r+ P J r+ H 3 n - ( D 3 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 I t1 O H - n - n - P J 3* h \ Bouma Sequence (cm) y g O A B C D E 3 S* ( D W W W 20 20 0.5 20.5 (uncovered) 1 1 16 1 17 3 1 4 3 1 4 19 1 20 2 1 3 1 1 2 2 3 0.5 25.5 1.5 1.5 3 5.5 1 6.5 1.5 4 5.5 14 0.2 14.2 2 0.2 2.2 1 2 0.5 5.5 2 0.5 2.5 6 0.5 6.5 4 0.5 4.5 1 10 3 15 45 1 46 25 0.5 25.5 7 0.5 7.5 10 7 17 1 3.5 4.5 6.5 1 7.5 5 1 6 7.5 1 8.5 2 1 3 2 9 3 14 2 2 4 14 5 19 1 17 1 26 18 1 19 18 0.5 18.5 1 2 3 1 0.5 1.5 3 0.5 3.5 2 3 5 10 2 12 33 1 34 9 0.5 9.5 10 0.5 10.5 Tee. Tee. Tee, Tcde. 172 cn c + H f u c + H 3 c + C D 3 $ u I —1 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1628 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 Sequence B C (cm) D E Total Thickness Lith./Samples 15 1 16 14.5 1 15.5 1 0.5 1.5 4 0.5 4.5 7 1.5 1 9.5 15 0.5 15.5 7 0.2 7.2 4 4 4.5 Tee. 12 1 13 1.5 1 2 2.5 15 6 2 Tee. 40 3 43 4 1 5 3 1 4 12 1.5 13.5 7 0.5 7.5 5 4 0.5 9.5 20 20 3 Tcde. Tee. 2 3 5 Tee. 16 0.5 16.5 6.5 0.5 7 1 1 2 2 1 3 1 1 2 Tee 1 1 2 15 2 17 3 4 7 Tee. 5 24 4 33 7 1 8 1 2.5 3.5 Tcde. 5 4 9 10 1 11 2 1.5 3.5 1 7 3 11 Tee. 4 1 5 22 4.5 3 1 30.5 2 1 3 4.5 2 6.5 i unmeas. 35 3 38 173 cn rt H 0 ) rt H 3 rt C D H < 0 ) M 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 Bouma Sequence (cm) D E 5.,5 1 1 0.5 6 0.5 5 1.5 4 2 3 1.5 1 0.5 5 0.5 1 1 2 1 3 3 11 1 15 0.5 6 . 5 0.5 13 4.5 4 3 17 1 32 1 7 3 2 1 4 2 1 1 2.5 4 40 1 2.5 1 20 1 6.5 2.5 13 22 3 1.5 2 1 7 0.5 14 1 3.5 2 7 1 19 0.5 2.5 2 5 0.5 3 1 10 4.5 5 1 H- 3 O f Q f t * H 3 C D C D W W cn 6.5 1.5 6.5 6.5 6 7.5 1.5 5.5 3 3 6 12 15.5 7 17.5 Tcde. 7 18 33 10 3 6 2 6.5 41 3.5 21 9 13 7 25 3 Tee. 3 7.5 15 5.5 8 19.5 4.5 5.5 3 5 Tee. 14.5 Tcde. 5 174 cn rt P > rt H 3 rt C D 3 P J H 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 Bouma Sequence (cm) ►3 tr* o H - p i ! ? ►3 cn 3 * I A B O D E o' *0 3 C D C D W cn cn 5 1 6 m unmeas. 18 3 21 13 2 15 12 6 18 3 1 4 1 1.5 2.5 3 1 4 11 1 4.5 16.5 30 1 31 8 0.5 8.5 3 3 6 12 1 13 2 1 3 1 4 5 8 2.5 10.5 3 14 5 22 7 3 10 5 2 7 3 2 5 4 1 5 13 1 14 4 6 1 7 2 1.5 3.5 3 1 4 5 1 6 13 0.5 13.5 3 0.5 3.5 2 1 3 1.5 1 2.5 8 10 18 2 4 1.5 7.5 4 2 6 10 2 12 6 1 7 5 5 4 2 6 2 1.5 3.5 8.5 0.5 9 6 2 8 6 1 7 5 1 6 Tee. Tee. Tee. Tee. Tee. 175 cn r+ H 0 > r+ 3 r+ O h 0 H ( 0 0 1 1743 1744 20 1.5 21.5 1745 2 0.5 2.5 1746 5 3 8 1747 8 2.5 10.5 1748 4 1 5 1749 1 2 3 1750 1 4 5 1751 1752 1753 1754 2 4 0.5 3 2 2 0.5 7 1755 2 1 3 1756 6 1 7 1757 2 8 1 11 1758 18 1 19 1759 1 1 2 1760 1 1 2 2 6 1761 5 6 11 1762 38 1 39 1763 1 0.5 1.5 1764 10 2 12 1765 4 2 6 1766 2.5 1 3.5 1767 6 1 7 1768 10 1 11 1769 3 1 4 1770 1771 3.5 7 2 7 5.5 1772 9 1 10 1773 2 1 3 1774 7 5 12 1775 6 4 10 1776 1777 2.0 m unmeas. 17 1 4 18 1778 6 0.5 6.5 1779 4 2.5 6.5 1780 5 2 7 1781 1 2 16 0.5 19.5 1782 3 1 4 1783 1784 4 7 12 3 7 19 1785 12 2 14 Tee, Tee, Tee, 176 cn rt H P J rt H 3 rt C D H i < 1 P J f —1 1786 1787 1788 1789 1790 1791 1792 1793 1794 1794 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 h 3 I t* O H - r+ rt P > S' i — 1 • Bouma Sequence (cm) \ i - 3 cn A B O D E O H ** H 3 C D C D t o t o t o 26 1 27 17 17 11 0.5 11.5 10 0.5 10.5 8 2 10 2 1 3 1 1.5 2.5 1 1.5 2.5 33 3 36 2 0.5 2.5 1 0.5 1.5 1 2 3 18 0.5 18.5 5.5 0.5 6 1.5 9 1 11.5 5 1 6 5 2.5 7.5 4 9 2 15 9 1 10 15 1 16 4 2 6 4.5 5 9.5 2 1 3 10 1 11 5 2 7 2 1.5 3.5 4 4 18 2 5 1 8 1.5 16 1 18.5 4 1.5 5.5 4 0.5 4.5 3 2 1 6 1 10 0.5 11.5 Tee. 10 4 4 18 Tbce (end of detailed measured section) 45 m of grossly measured section, with increasing frequency of medium to thick- bedded quartz wackes. Top of formation and contact with Scorpion Mountain Formation is covered with talus. 177 Green Lake Limestone, Muldoon Canyon Formation 178 cn r t K s j r t H 3 f t C D < f l > I - 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 BASE OF SECTION O h- ft ( T fl) if Bouma Sequence (cm) i - 3 cn p i A B C D E o t n I —1 P C D C D c n c n c n 1.5 1 8 1 9 9 2 11 8 1 9 1 1 2 sas. (covered) 1 1 2 17 0.5 17.5 0.5 0.5 1 2 3.5 8 ;as. (covered) 15 4 19 5 1 8 7 2 9 5 0.1 5.1 13 0.1 13.1 10 0.5 10.5 8 1 9 1 3 2 2 4 3 0.5 3.5 2 Q. 5 2.5 7 2 9 3 2 5 3 2.5 5.5 1 1 3 15 5 20 2 1 3 1 0.5 1.5 2 0.5 2.5 3.5 2 5.5 2 2 4 1 0.5 1.5 3 2 5 2 1 6 3 0.5 3.5 2 0.2 2.2 6 0.2 6.2 1 0.5 1.5 9 0.5 9.5 1.5 0.2 1.7 3 0.5 3.5 5 1 7 0.5 1 1.5 0.5 1 1.5 179 h3 t r * O H - r+ r+ in rt 2 p J B * r+ H ‘ Bouma Sequence (cm) ^ ^ i - r 1 C i i H H - 3- A B C D E g. £ 2 3 © q n > w S w P * w 43 2 0.2 2.1 44 14 0.2 14.2 45 3.5 .5 4 46 20 1 21 47 1.5 0.5 2 48 5 2.5 7.5 49 30 1 31 50 9 1 2 12 51 4 1 5 52 13 1 14 53 2.5 0.5 3 54 1 1 2 55 4 3 7 56 1 1. 2 57 1 2.5 3.5 58 3 0.5 3.5 59 5 1.5 1 7.5 60 1 3 4 61 7 1.5 8.5 62 3.5 0.3 3.8 63 0.5 0.5 1 64 0.5 0.5 1 65 0.5 3 3.5 66 0.5 0.5 1 67 2.5 2.5 5 68 1.5 0.5 2 69 2 0.2 2.2 70 4.5 1 5.5 71 4 0.5 4.5 72 3 0.5 3.5 73 4 2.5 6.5 74 2 0.5 2.5 75 8.5 1 9.5 76 10 2 12 77 10 2.5 12.5 78 1 0.5 1.5 79 0.5 1 1.5 80 0.2 0.3 0.5 81 0.5 1 1.5 82 42 0.5 42.5 83 4 2.5 6.5 84 2.5 3 5.5 85 7 5 12 86 3 2 5 180 Strat. Bouma Sequence (cm) i - 3 0 rt & H F H- rt P* \ Interval A B C D E i - 3 P* H- O ** P CD cn cn cn J i - * CD cn 87 3 6 9 88 24 2 26 89 1 1.5 2.5 90 1 1 2 91 1.5 2.5 4 92 3 1 4 93 2.5 1 3.5 94 7.5 1 8.5 95 7 14 21 96 1 1 2 97 11 20 31 98 3 1 4 99 3 1 4 100 3 m contorted Td & te 300 101 13 2 15 102 4 2 6 103 3.5 0.5 4 104 1 1.5 2.5 105 12 2 14 106 1 0.5 1.5 107 1 1 2 108 1 1.5 2.5 109 45 3 48 3 110 1 1 2 111 14.5 0.5 15 112 3 2 5 113 5 2 7 114 23 0.7 23.7 115 0.7 1.5 2.2 116 4 1 5 117 2 0.5 2.5 118 1 0.5 1.5 119 1 0.2 1.2 120 2 1 3 121 10 2 12 122 13 7 20 123 4 2 5 124 7 3 10 125 3.5 1 4.5 126 3 1 4 127 4 3.5 7.5 128 1 1.5 1 4.5 1 9 129 1 1 2 130 0.5 0.5 1 131 1.5 0.5 2 132 2.5 1 3.5 181

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Creator Condra, Darlene A (author)

Core Title Stratigraphy and sedimentology of the Drummond Mine Limestone, Starhope Creek, Idaho

Degree Master of Science

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

Tag OAI-PMH Harvest,Sedimentary Geology

Language English

Contributor Digitized by ProQuest (provenance)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c30-85350

Unique identifier UC11225668

Identifier usctheses-c30-85350 (legacy record id)

Legacy Identifier EP58673.pdf

Dmrecord 85350

Document Type Thesis

Rights Condra, Darlene A.

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 au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA