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Petrology And Depositional History Of Late-Precambrian - Cambrian Quartzites In The Eastern Mojave Desert, Southeastern California
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Petrology And Depositional History Of Late-Precambrian - Cambrian Quartzites In The Eastern Mojave Desert, Southeastern California
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INFORMATION TO USERS This material was produced from a microfilm copy of the original docum ent. While the m ost advanced technological means to photograph and reproduce this docum ent have been used, the quality is heavily dependent upon the quality of the original subm itted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the docum ent photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected th at the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite m ethod in "sectioning" the material. It is custom ary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate th at the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Departm ent, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Zeeb Road Ann A rbor, M ichigan 48106 74-17,359 LOBO, Cyril Francis, 1940- PETROLOGY AND DEPOSITIONAL HISTORY OF LATE PRECAMBRIAN-CAMBRIAN QUARTZITES IN THE EASTERN MOJAVE DESERT, SOUTHEASTERN CALIFORNIA. University of Southern California, Ph.D., 1974 Geology University Microfilms, A XEROXCompany, Ann Arbor, Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. PETROLOGY AND DEPOSITIONAL HISTORY OP LATE PRECAMBRIAN-CAMBRIAN QUARTZITES IN THE EASTERN MOJAVE DESERT, SOUTHEASTERN CALIFORNIA by Cyril Francis Lobo A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (Geological Sciences) January 197^ UNIVERSITY O F S O U T H E R N CALIFO RNIA TH E GRADUATE SC H O O L U N IV ER SITY PARK LOS A N G ELES. C A L IF O R N IA 9 0 0 0 7 This dissertation, written by .........CYRIL..FI^CIS..LOBO......... under the direction of h..^3.. Dissertation Com mittee, and approved by all its members, has been presented to and accepted by The Graduate School, in partial fulfillment of requirements of the degree of D O C T O R OF P H I L O S O P H Y Dean DISSERTATION COMMITTEE .... Chairman CONTENTS Page ILLUSTRATIONS ................................... iv TABLES • • . • « • . . . « « . . « . . . . « « vii ABSTRACT....................................... x INTRODUCTION ..... ........................ 1 Purpose 1 Stratigraphic nomenclature and background . 7 ACKNOWLEDGMENTS ................................. 13 PROCEDURES..................................... 14 Field and sampling procedure ......... 14 Laboratory procedure ...... ......... 15 Petrographic procedure .. . • • • • • • • 16 Statistical procedure • • • . . . • • . . • 19 RESULTS......................................... 21 Petrology and sedimentary structures . . . 21 Cratonal quartzites . . . . . . . . . . . . 22 Mesquite Pass section 23 Taylor Mine section . . . . . . . . . . 27 Mountain Pass section . . « • •• •• • 32 Oro Wash section...................... 36 Marble Mountain section ^3 ii Page Miogeoclinal quartzites . . • • . • • • • • 53 Providence Mountain section • ••••• 53 Kelso section . . . . . . . . . . . . . 57 Old Dad Mountain section............. 65 Winter's Pass section ........... 70 Zabriskie section •••.. ........... 83 Statistical analysis .... 115 Normality testing .................... . 115 Analysis of variance .................. 12k Discriminant function analysis .... 133 DISCUSSION OF RESULTS .......................... 150 Classification of quartzites ....... 150 Mineralogical maturity and provenance . . . 157 Depositional environments .................. 163 Paleontological evidence ....... 163 Mineralogical evidence . ............. 16k Textural evidence . . . .............. 166 Sedimentary structures ....«..• 167 Depositional history • . . . . • • • • 171 Comparison with other environments . . 183 Basin analysis .......... 185 CONCLUSIONS..................................... 189 REFERENCES . ............... 192 iii ILLUSTRATIONS Figure Page 1. Index map showing location of* sections • • . 2 2, Time-trend curves for six variables in the Mesquite Pass section ................. 25 3« Time-trend curves for six variables in the Taylor Mine section ............. ..... 29 4. Time-trend curves for six variables in the Mountain Pass section • • • . • • • . . . • 34 5. Dendrograph depicting mutual relationships between and within twelve variables measured in the Oro Wash section.......... 38 6. Time-trend curves for eight variables measured in the Oro Wash section ...... 4l 7. Dendrograph depicting mutual relationships between and within twelve variables measured in the Marble Mountain section.......... 47 8. Time-trend curves for five variables measured in the Marble Mountain section . . 49 9. Time-trend curves for six variables measured in the Marble Mountain section ....... 51 10. Dendrograph depicting mutual relationships between and within twelve variables measured in the Kelso section 60 Time-trend curves for eight variables measured in the Kelso section ....... 62 12. Time-trend curves for eight variables measur ed in the Old Dad Mountain section......... 68 iv Figure Page 13. Dendrograms showing mutual relationships among the twelve variables measured in the Winter's Pass section . . . . .. .. . 7^ lb. Time-trend curves for five variables measured in the Winter's Pass section . . . 76 15. Time-trend curves for five variables measured in the Winter's Pass section . . . 78 16. Photomicrograph of typical immature sub- arkose from the Johnnie Formation in the Winter's Pass section ............. 87 17. Photomicrograph showing micaceous silt- clay laminae in fine-grained immature quartzarenite from the Johnnie Formation in the Kelso section .......... 89 18. Contact print of X-radiograph showing even laminations and vertical burrows in a sample from the Johnnie Formation in the Winter's Pass section ...... ......... 91 19. Contact point of X-radiograph showing laminations and cross-laminations in samples from the Johnnie Formation in the Kelso section ........ 93 20. Photomicrograph of mature quartzarenite from the Stirling Quartzite in the Winter's Pass section .......................... 95 21. Photomicrograph of a subarkose sampled from lower Stirling Quartzite in the Old Dad Mountain section................. 97 22. Contact prints of X-radiographs of samples from the Stirling Quartzite in the Winter's Pass section.......... 99 23. Photomicrograph of subarkose from the Tapeats Sandstone in the Oro Wash section showing granitic rock fragment ............. 101 v Figure Page 2k. Photomicrograph of subarkose from the Stirling-Wood Canyon transition in the Winter's Pass section . . . . . . . . . . 103 25. Photomicrograph of a typical sublith- arenite from the Tapeats Sandstone in the Oro Wash section . • ...................... 103 26. Contact print of X-radiograph showing cross-laminations, diastems, ripple marks and clay-silt laminae in sample collected from the Wood Canyon Formation in the Providence Mountain section . . . . . . . 107 27. Contact point of X-radiograph showing tabular, planar cross-stratification in sample collected from the Tapeats Sand stone in the Taylor Mine section ..... 109 28. Contact prints of X-radiographs from the Wood Canyon Formation in the Providence Mountain section .......................... Ill 29. Paleocurrent and elasticity data......... 122 30. Ternary diagram depicting classification of cratonal and miogeoclinal quartzites . 152 31. Ternary diagram depicting classification of quartzites assigned to the Johnnie Formation, Stirling Quartzite and Wood Canyon Formation from the Winter's Pass section 15^ 32. Depositional model for the Johnnie Forma tion ................... 172 33* Depositional model for the Stirling Quartzite................. 175 3k. Depositional model for the Wood Canyon Formation .......................... 178 vi Table Page 1. Location of stratigraphic sections .... 4 2. Upper Precambrian and Lower Cambrian stratigraphy ....... ............... 10 3. Mineral composition of quartzites col lected from the Tapeats Sandstone at the Mesquite Pass section............... 23 4. Mineral composition of quartzites col lected from the Tapeats Sandstone at the Taylor Mine section ............. 28 5. Mineral composition of quartzites col lected from the Tapeats Sandstone at the Mountain Pass section.................... 33 6. Mineral composition of quartzites col lected from the Tapeats Sandstone at the Oro Wash section..................... 37 7. Mineral composition of quartzites col lected from the Tapeats Sandstone at the Marble Mountain section .. ............. 45 8. Mineral composition of quartzites col lected from the Stirling (?) and Wood Canyon Formations at the Providence Mountain section .......................... 55 9. Mineral composition of quartzites col lected from the Johnnie, Stirling and Wood Canyon Formations at the Kelso section . . 59 10. Mineral composition of quartzites col lected from the Johnnie and Stirling Formations at the Old Dad Mountain section 66 11. Mineral composition of quartzites col lected from the Johnnie, Stirling and Wood Canyon Formations at the Winter's Pass section................................. . 72 vii 84 85 113 114 116 117 118 120 126 127 129 131 Mineral composition of quartzites col lected from cross-stratified, laminated and massive units at Winter's Pass section Mineral composition of quartzites col lected from the Zabriskie Quartzite at the Zabriskie section ......... Mineral composition of quartzites col lected from the cratonal sections at locations 7» 6, 5, 1 and 3 • ..«»••• Mineral composition of quartzites col lected from the Miogeoclinal sections at locations 8, 4, 12, 9 and 1 0 .......... . Mineral composition of quartzites col lected from the northern section at loca tions 7, 6, 5, 1, 9 and 10 Mineral composition of quartzites col lected from the southern sections at loca tions 3» 8, 4 and 1 2 ................... . Summary of sedimentary structures (Cra tonal quartzites) Summary of sedimentary structures (Mio geoclinal quartzites) Statistical analysis of total quartz in the Johnnie Formation Statistical analysis of total quartz in the Stirling Quartzite Statistical analysis of total quartz in the Wood Canyon Formation............. Statistical analysis of total quartz in the Zabriskie Quartzite.......... , . . . viii Table Page 24. Statistical analysis of total quartz in the Tapeats Sandstone 132 25. statistical analysis of total quartz in the Cratonal-Miogeoclinal samples .... 134 26. Statistical analysis of total quartz in the northern-southern sections ...... 135 27. Stepwise discriminant function analysis (12 variables)....................... 137 28. Stepwise discriminant function analysis (9 variables) 138 29. Stepwise discriminant function analysis (7 variables) . . . . . . . . . . . . . . 139 30. Tests of significance for two-group dis criminant function analysis (Cratonal- Miogeoclinal samples) . . . . • • • . • • 142 31. Tests of significance for two-group dis criminant function analysis (northern- southern sections ............. 143 32. Tests of significance for two-group dis criminant function analyses (Tapeats Sandstone-Johnnie Formation; Tapeats Sandstone-Stirling Quartzite; Tapeats Sandstone-Wood Canyon Formation )....« 145 33« Tests of significance for two-group dis criminant function analysis (Winter's Pass section) ...................... 147 34. Tests of significance for two-group dis criminant function analysis (Marble Mountain section-dendrogram clusters) . . 149 35* Classification of quartzites .............. 156 36. Summary of depositional environments . . . 184 ix ABSTRACT Petrographic and radiographic analyses were con ducted on oriented samples of quartzites collected from five cratonal and five miogeoclinal stratigraphic sections in the eastern Mojave Desert, southeastern California. Twelve petrographic variables were measured in each of k9k samples. Cratonal quartzites are dominantly subarko- sic, whereas miogeoclinal quartzites are subarkosic and quartzarenitic in almost equal proportions. Sediments were derived mainly from granitic and gneissic rocks as well as older sedimentary rocks. The cratonic source areas were to the east and southeast. Samples collected from six northern sections within the Cordilleran frontal thrust belt have a high content of undulatory quartz and silica cement and are partially re crystallized. Samples from four southern sections show no evidence of major deformational episodes within the formations tinder study. Polynomial time-trend analysis showed substantial variation in mineral composition with thickness. Areal variation of total quartz was estimated from analysis of variance models. The difference was not highly signifi cant for the Johnnie and Wood Canyon Formations but high ly significant for the Stirling Quartzite. Sediment dis persal was probably inhibited by sand barriers during deposition of the Stirling Quartzite. Much of the cratonal Tapeats Sandstone can be statistically cor related with the Wood Canyon Formation, and the upper part of the Tapeats Sandstone with the Zabriskie Quartz ite. Depositional models were inferred for each forma tion on the basis of petrography, elasticity and sedi mentary structures. The Johnnie Formation shows fining upwards, which may suggest a marine transgression or change from open to partially restricted shelf environ ments. The Stirling Quartzite coarsens upwards and con sists largely of prograding mature shelf sands or migrat ing bars and barrier beaches. The Wood Canyon Formation shows short-period fluctuation indicating pulsations in sediment supply or local transgressions and regressions. x It is dominantly subtidal with local evidence for inter tidal deposition. A time-transgressive model is favored with transgressions and regressions of a shallow sea, per haps related to eustatic fluctuations in sea level during infra-Cambrian glaciation. INTRODUCTION Purpose Sedimentary sequences of late Precambrian-Cambrian age are well exposed in several stratigraphic sections in the eastern Mojave Desert, San Bernardino county, Cali fornia (Fig. l). This study is primarily concerned with the depositional history of sedimentary quartzites which form part of the cratonal facies associated with the Cordilleran geosyncline, as well as the thicker miogeo- clinal(?) units to the west. In this study cratonal quartzites have been called the Tapeats Sandstone, whereas the miogeoclinal units include the Johnnie Formation, Stirling Quartzite, Wood Canyon Formation and Zabriskie Quartzite (Burchfiel and Davis, 1971)• The location and lithostratigraphic units present in each section are listed in Table 1. Stratigraphic sections assigned to the "era- tonal” facies range in thickness from h3 to 132 m. The strata included in the cratonal facies are predominantly quartzites, and the base of each section is well defined by an unconformable contact with PreCambrian gneiss. The sections assigned to the cratonal facies are located with- 1 Figure 1. Index map showing location of sections. Dark circles represent location of cratonal sections, light circles show location of miogeoclinal sections. Locality Cratonal Sections 7 Mesquite Pass 6 Taylor Mine 5 Mountain Pass 1 Oro Wash 3 Marble Mountain Miogeoclinal Sections 8 Providence Mountain 4 Kelso 12 Old Dad Mountain 9 Winter’s Pass 10 Zabriskie 2 3 B aker U . S . 66 Amboy 34°30' SCALE 116 k Table 1. Location of stratigraphic sections Section Location Thickness measured Sample size Units sampled Mesquite Pass(7) Taylor Mine(6) Mountain Pass(5) Oro Wash(l) 2.5 km east of 43 m Mesquite Pass; Sec. 29, T. 17% N., R. 13 E. 1 km north of 43 m Taylor Mine; Sec. 9, T. 17 N., R. 13 E. 6 km northwest of 37 m Mountain Pass; Sec. 35, T. 17 N., R. 13 E. 0.6 km east of 93 m Allured Mine; Sec. 22, T. 15 N., R. 14 E. 29 Tapeats Sandstone 29 Tapeats Sandstone 25 Tapeats Sandstone 62 Tapeats Sandstone Marble Mountain(3) 3 km northeast of Cadiz; 132 m 86 Tapeats Sandstone Sec. 12, T. 5 N., R. 14 E. Providence Mountain(8) 0.5 km east of Kelso Sec. 29, T. 10 N., R. 13 E. 151 m 73 Stirling Quartz ite Wood Canyon Form ation Kelso Hills(4) 4 km northwest of Kelso Sec. 14, 15; T. 11 N., R. 12 E. 361 m 83 Johnnie Formation Stirling Quartz ite Wood Canyon Form ation 5 Table 1. Location of stratigraphic sections (continued) Section Location Thickness measured Sample size Units sampled Old Dad Mountain(12) Winter's Pass(9) Zabriskie(lO) 0.8 km northeast 133 m 29 of Branigan Mine Secs. 25, 26, T. 13 N., R. 10 E. 8 km northwest of 738 m 131 Winter's Pass Sec. 36, R. 11 E., T. 19 N. 2.5 km west of 12 m 12 Taylor Mine Johnnie Formation Stirling Quartz ite Johnnie Formation Stirling Quartz ite Wood Canyon Form ation Zabriskie Quartz ite Sec. 17, T. 17 N., R. 13 E. in the "eastern region" described by Stewart (1970). Stratigraphic sections assigned to the "miogeoclinal" facies are greater them. 300 m thick, and consist prominent ly of interbedded siltstones and carbonates. The westward- thickening wedge of strata assigned a late Precambrian- Cambrian age favors the usage of the term miogeoclinal rather than miogeosynclinal in this study. The five stratigraphic sections assigned to the miogeoclinal facies in this study lie within the "central region" demarcated by Stewart (1970). Although the assignment of strati— graphic sections to cratonal and miogeoclinal facies seems justifiable at this lime, the possibility exists that strata assigned to the miogeoclinal facies may represent offshore cratonal deposits with a rapidly-thickening sedi mentary prism located further to the west. Much of the work done on late Precambrian and early Cambrian sequences in the southern Great Basin has been limited to general geological investigation and strati graphic correlations. Petrographic work on these strata has been meager, consequently little systematic data has been recorded on the mineral composition and texture of these rocks. Moreover, no detailed study of sedimentary structures using X-radiographic techniques have been re ported. As a result, problems relating to provenance and depositional history have yet to be resolved. The main objective of this study relates to investi- 7 gation of the depositional history of the cratonic and miogeoclinal quartzites assigned a late Precambrian-early Cambrian age. This paleoenvironmental analysis is based on a quantitative petrology of 494 sedimentary quartzite samples and the examination of over a thousand radiographs to determine textures and primary sedimentary structures often obscured by desert varnish and weathering in the field. Other pertinent questions to be resolved by this study include the possibility of correlation of cratonal and miogeoclinal units and the nature of the transition across the hinge, provenance for the quartzites and ascer taining whether they represent time-transgressive or iso chronous lithologic units. Univariate and multivariate statistical analyses are employed to unravel these environ mental and lithologic correlation problems. Stratigraphic Nomenclature and Background There has been considerable variation in strati graphic nomenclature and age assignment for the quartzites under investigation (Hazzard, 1937; Hewett, 1956; Wheeler, 1944; McNair, 1951; Burchfiel, 1964; Stewart, 1970). The name Tapeats Sandstone which refers to cratonal quartzites in the study was first named by Noble (1914) for exposures of sandstone along Tapeats Creek in Arizona. Prospect Mountain Quartzite has a more diverse usage. It was em ployed by Hague (1883) for basal sedimentary rocks of Cambrian age exposed in Prospect Ridge near Eureka, Nevada. Wheeler (l9***0 claimed that the Prospect Mountain Formation of late PreCambrian and Early Cambrian age was found throughout the Great Basin and locally designated as Tapeats Sandstone, Tintic and Bingham Quartzites. Hewett (1956) recognized two facies in the Cambrian sedi mentary rocks older than the Cambro-Devonian Goodsprings Dolomite. The eastern facies is represented by the Tapeats Sandstone and overlying Bright Angel Shale, where as the western facies is represented by Noonday Dolomite, Prospect Mountain Quartzite and Pioche Shale. Hewett (1956) also suggested that the Prospect Mountain Quartzite is equivalent to three units (Wood Canyon Formation, Stirling Quartzite and Johnnie Formation) which were recog nized by Nolan (1929) near Johnnie and by Hazzard (1937) in the Nopah Range. Burchfiel (196* 1) assigned a Pre- cambrian age to the Johnnie Formation and Stirling Quartz ite because of a lack of fossils and a Precambrian- Cambrian age to the Wood Canyon Formation. The Zabriskie Quartzite was first named by Hazzard (1937) and was later redefined by Wheeler (19*^8) and raised to the status of a formation. It overlies the Wodd Canyon Formation and is assigned an early Cambrian age. The name Prospect Mountain Quartzite is no longer used. The stratigraphic nomenclature and correlation is best summarized by Stewart (1970) in his extensive study of* upper Precambrian and lower Cambrian strata of the southern Great Basin (Table 2). Stewart suggests that these rocks comprise the initial deposits of the Cordil- leran geosyncline, which formed a wedge of sediment rang ing in thickness from about 400 feet in the eastern region to 21,000 feet in the western region. The Tapeats Sand stone, as employed by Stewart (1970), refers to a thin shelf deposit in the eastern region equivalent to parts of the Upper Wood Canyon Formation and Zabriskie Quartzite lithologically to the west. The base of the Cambrian system is placed by Stewart (l970» P» 13) in the Upper Wood Canyon Formation on the basis of first appearance of olenellid trilobites and archaeocyathids. More recently, Stewart (1972) proposed the initiation of the Cordilleran geosyncline by rifting at less than 850 m.y. on the basis of diamictite and diabase in the Kingston Peak Formation in the southern Great Basin and other equivalent formations. He suggests a change in the tectonic framework of North America after deposition of the Belt supergroup (1250 - 850 m.y.). However, the depositional environment of the Belt sediments and equivalents including the Crystal Spring Formation and Beckspring Dolomite must be better establish ed and more radiometric data is needed before Stewart's conclusion can be substantiated. The timing seems adequate to account for thick clastic sedimentation in the Upper Precambrian and lower Cambrian on the basis of plate Table 2. Upper Precambrian and lower Cambrian stratigraphy (after Stewart, 1970) Age Central region Eastern region Western region Middle Cambrian Bright Angel Shale Monola Formation ' Carrara Formation Mule Spring Limestone Saline Valley Formation Tapeats Sandstone Zabriskie Quartzite Harkless Formation Poleta Formation Wood Canyon Formation Campito Formation Deep Spring Formation Reed Dolomite Stirling Quartzite Wyman Formation (base not exposed) rliatus' Johnnie Formation Noonday Dolomite Kingston Peak Formation Beck Spring Dolomite Crystal Spring Formation -a 2.5 0*1 Gneiss and schist Gneiss and schist * Stewart (1972) excludes this formation from the Pahrump Group. 11 tectonic concepts for the origin of miogeosynclines or miogeoclines. Structural investigations in the general area (Hewett, 1956; Wright and Troxel, 1966; Stewart, 1967) and more particularly the detailed mapping and radiometric dating in the Clark Mountain thrust complex (Burchfiel and Davis, 1971» 1972) has added greatly to the understand ing of problems in the sedimentary reconstructions in the southern Great Basin, Three major thrust plates are recog nized in the Cordilleran Frontal thrust belt (Burchfiel and Davis, 197l)» From east to west they are the Keystone, Mesquite Pass (Hewett's Mesquite thrust) and the Winter's Pass plates. The eastward directed Mesozoic thrusting is progressively younger eastwards. The Mesquite Pass, Taylor Mine, Mountain Pass and Oro Wash stratigraphic sections were sampled east of the Keystone basal thrust and are therefore cratonal and autochthonous. The Winter's Pass section was collected from the Winter's Pass plate and comprises the Johnnie Formation, Stirling Quartzite and Wood Canyon Formation, The Zabriskie section was measured in the Mesquite Pass plate and consists of two replicate sections of Zabriskie Quartzite, Recognition of the southward continuation of the thrust belt is hindered by emplacement of the Teutonia Quartz Monzonite, but recent evidence (Davis, personal communication, 1972) suggests that south of Oro Wash the thrust belt has a southeast trend compared to a northeast trend north of the Clark Mountain area. The Marble Mountain section is cratonal but allochthonous (Davis, personal communication, 1972). The Providence, Kelso and Old Dad sections are collected across this transition zone, and all appear to lie within the Winter's Pass plate of Burchfiel and Davis (l97l)# Dunne (1973) reports that Eocambrian and early Cambrian strata in the Devil's Play ground area (west of Kelso) could be autochthonous, but may be carried northeastward on thrusts involving basement. No such thrusts were reported in his study area. Therefore the Kelso, Old Dad, Providence, and Marble Mountain strati- graphic sections are probably allochthonous carried east ward on intracratonic thrusts behind a Mesozoic plutonic- volcanic arc. ACKNOWLEDGMENTS I wish to thank Dr. Robert Osborne for suggesting the study and for his invaluable advice on various phases of this research. I also wish to thank Drs. Gregory Davis, Donn Gorsline and Gibson Reaves for critically reviewing the manuscript and serving on my dissertation committee. Gratitude is also expressed to my colleagues Timothy Cross, James Gibson, Stephen Pavlak and Robert Rice for their as sistance in the field work, and to Robert Smith for the use of his Dendrogram computer program. The research was supported by grant #PRF 39^2-A2 of the Petroleum Research Fund, administered by the Ameri can Chemical Society. Part of the manuscript preparation was assisted by a Grant-in-Aid of Research from The Society of the Sigma Xi. 13 PROCEDURES Field and Sampling Procedure Fifteen stratigraphic sections were investigated in southeastern California and southern Nevada during the summers of 1969 and 1970* Reconnaissance surveys were conducted to ascertain the nature of the rocks under study. No samples were collected from sections where the quartz- ites showed considerable metamorphism and recrystalliza tion, where the rocks were excessively friable or where the section consisted dominantly of float or scree which prevented collection of oriented samples. A five-foot Jacob’s staff and Abney level were used to measure and sample the sections. Oriented samples were collected from stratigraphic sections exposed at each locality in Figure 1. The sampling method was a random spot sampling tech nique considering the quartzites as massive homogeneous units, A predetermined interval of 5 feet (l.52 m) was employed in sampling the cratonal quartzites. A 10 or 15 foot interval was generally adopted in sampling the thick er miogeoclinal sequences. Sampling was initiated at the contact with the Precambrian gneiss for the cratonal sections, and was continuous except for a few locations where collection was hampered by friable samples or float lh 15 in a covered interval. Sampling at regular intervals was more difficult in the thicker miogeoclinal sections, since interbedded carbonates and siltstones were not collected. Laboratory Procedure Slabs (approximately 3 nun thick) were sawed from each sample parallel to the strike and dip directions and perpendicular to the stratification, and then radiographed using a Penetrex 50 KV Industrial unit. The following factors, among others, affect the quality of the resultant radiographs: the excitation potential (40 KV), the cur rent (8 milliamps), film (Kodak Industrial type M) the dis tance from the source set at 80 cms and the exposure time (100 seconds) which varied almost linearly with thickness. Plates were then processed using three and a half minutes for developing and fixing. The contrasts observed in the radiographs are due to differential absorption, the lighter areas are more opaque to X-rays and the darker portions are more easily penetrated by the X-rays. Thus, more obscure internal structures and textures may be re vealed by density differences of the material comprising the rock. The rock samples and slabs were usually studied alongside, and utilized for confirming certain characterist ics noted in the radiographs. Analysis of each radiograph included the general description of texture and measurement 16 of the apparent maximum grain diameter which may indicate the mechanical energy in the environment. Sedimentary structures were also sought and appropriate data recorded to infer paleocurrent directions and depositional history. Petrographic Procedure Petrographic procedures are similar to those adopted in a pilot study (Lobo, 1972). One oriented thin section was prepared for each sample normal to the stratification but either parallel to the field strike or dip direction. The volume of constituents comprising each sample was estimated by using a point counting technique. Three hundred counts per thin section were sufficient to infer that the correct volume of each variable lies within about 5 percent on either side of the obtained value with a 95 percent confidence (Van der Plas and Tobi, 1965)• A one mm point distance was generally employed such that the point distance was nearly always greater than the largest particle diameter in the thin section. Moreover, the starting point in the grid was determined from a random numbers table (Dixon and Massey, 1967) so as to reduce bias in the point counting procedure. Each primary variable was uniquely defined to form a basis for more meaningful interpretations in the analysis of sedimentation patterns, provenance and depositional environments. The variables counted were subdivided on the 17 basis of operationally sound criteria governed by internal and external discontinuity (Griffiths, 1967). These vari ables formed mutually exclusive classes which were general ly easy to identify. Primary variables include: normal quartz, undulatory quartz, orthoclase, microcline, plagio- clase, mica, accessory minerals, chert, rock fragments, silica cement, other cement (hematite, limonite, calcite) and matrix. Derived variables include total quartz, total feldspar, quartz/feldspar ratio and grain/matrix ratio. Mineral components that are internally and external ly continuous include quartz, feldspar, mica and accessory minerals. Quartz was subdivided into normal (non- undulatory) and undulatory on the basis of strain extinc tion on the rotation of few degrees in the case of the latter. Quartz is easily identifiable by its clear, color less grains, low relief (little higher than the mounting medium Canada balsam), low birefringence and positive uni axial figure. Feldspars were counted separately as orthoclase, microcline and plagioclase with the distinction based on twinning and extinction properties. Untwinned plagioclase may have been counted as orthoclase to constitute a minor error. Generally microcline and plagioclase are easily recognized by their twinning, while orthoclase may pose a more difficult problem. It is distinguished from quartz by its cleavage, lower relief than Canada balsam, lower 18 birefringence negative biaxial figure and clouding as a result of alteration to sericite and clays. Mica is almost exclusively muscovite occurring in tiny flakes frequently wrapping around detrital clasts of quartz or feldspar. Accessory minerals included heavy minerals such as magnetite, zircon, tourmaline, rutile, and monazite. Rock fragments and chert constitute elements that are externally continuous but internally heterogenous. Quartzose rock fragments composed of interlocking or silica cemented quartz grains having a distinct outline of their own were predominant. Polycrystalline quartz, ortho- quartzite, and metaquartzite fall in this category. Granitic rock fragments with aggregates of quartz and feld spar were noted separately. Argillaceous, schistose and volcanic(?) fragments comprise the unstable rock fragments. Silica cement refers to quartz overgrowths in opti cal continuity with contiguous quartz grains. Frequently the detrital boundary can be discerned by coatings of clay, iron oxides or sericite rims. Other cement included iron oxides (hematite, limonite) which is dominant in the cratonal quartzites and calcite which is more characteris tic of miogeoclinal quartzites specially in proximity to interbedded carbonates. Matrix consisted of a very fine grained admixture of sericite-illite-chlorite and silt sized quartz. Statistical Procedures 19 Two primary geological objectives of the study con sist of unraveling the depositional history of quartzites assigned to the Late Precambrian-Carabrian age, and investi gating the possibility of lithologic correlation between the cratonal and miogeoclinal units. Statistical analysis designed to carry out these objectives were expedited by facilities available at The University Computing Center. Three different models of IBM computers (Sys 360/65* Sys 370/l55» Sys 370/158) have been used during the course of this research. Simple statistics of each variable measured in the modal analysis was carried out using systems library programs BMD01D (Dixon, 1970)• Correlation matrices were computed and the lower half of the matrix used as input to generate R-mode dendrographs (McCammon, 1968; McCammon and Weineger, 1970) which provide mutual relationships between and within the twelve measured variables, Q-mode dendro grams were also plotted to draw inferences regarding sample clusters. Variation in composition and elasticity with thickness for each stratigraphic section was investigated using polynomial time-trend analysis (Fox, 1964). The ap proximation of each variable to a normal distribution (Preston, 1970) was assessed prior to use of more sophisti cated statistical models. The sample size required to de tect a given difference between means was determined using procedures suggested by Sokal and Rolf (1969)# A one-way analysis of variance (BMD07V, Dixon, 1970) was designed to determine variation between sections for each variable with sufficient sample size* The New Duncan Multiple Range test was applied to locate the source of variation. Multivariate discriminant function analyses were employed to assess significant difference between sections and areal variation in composition of individual formations. RESULTS Petrology and Sedimentary Structures Petrology and sedimentary structures are summarized for each stratigraphic section. Megascopic characteris tics are described from fresh sawed surfaces of samples and a GSA rock color chart (Goddard, 1963) was used to discern variable hues in the rocks. R-mode dendrographs were plotted for each stratigraphic section to determine relationship between each pair of variables. Meaningful clusters were recognized in several sections with rela tively large sample size. These are elaborated in the description that follows. Other sections with small sample size and insignificant amounts of some variables show clusters which may not be reliable. Q-mode dendrograms were also plotted, but showed no definite stratigraphic clusters, except in the Marble Mountain section where two clusters are apparent. One corresponding to that portion of the Tapeats Sandstone equivalent to the Wood Canyon Formation and the other corresponding to Tapeats Sandstone equivalent to the Zabriskie Quartzite. Variation in mineral composition is also evident from polynomial time- trend analysis, which is a moving averages technique which facilitates smoothing of noisy data and accentuating a 21 22 systematic trend. The curve that explains the greatest percent of total variance may be used to ascertain trends in sedimentation for each variable. Thus fluctuations in mechanical energy and sedimentation patterns in the deposi tional environment may be estimated from these curves. Sedimentary structures observed in the field are often obscured by desert varnish or weathering. Hence great reliance is placed on description of sedimentary structures from two radiographs for each sample, oriented parallel to the strike and dip directions of the strata. It is possible that some large-scale structures are missed by this process. Cratonal Quartzites The five cratonal sections (Table l) range in thick ness from 43 m to 132 m. All the quartzites are assigned to Tapeats Sandstone which rests with a heterolithic un conformity on Precambrian gneiss. Mesqu;Ltfi..Bass Section (Location 7) Quartzites in this northernmost section range in color light brownish gray (5YR6/I) to moderate red (5R5/*0» Grain size is generally medium to coarse grained with a few conglomeratic units. Pebbles in these include red jasper, quartz, chert and agate. Mineralogical composition (Table 3) is fairly con- 23 Table 3* Mineral composition of quartzites collected from the Tapeats Sandstone at the Mesquite Pass section Mean 0 Maximum ° h . Minimum Normal Quartz 67.9 84.0 46.6 Undulatory Quartz 6.8 12.3 2.6 Total Quartz* 7^.7 88.3 59.0 Orthoclase 4.2 8.0 0.3 Microcline 1.0 7.0 0.3 Plagioclase 1.2 3.6 0.0 Total Feldspar* 6.4 11.6 1.0 Mica 0.1 0.6 0.0 Accessories 0.5 1.6 0.0 Chert 1.3 7.6 0.0 Q ,R»F . 3.1 10.0 0.6 Silica cement 7.2 i4.o 2.6 Other cement 1.9 7.0 0.0 Matrix 3.8 9.0 0.6 Others** 1.1 4.0 0.0 * Derived variable. ** Includes unstable rock fragments. sistent with thickness. Normal quartz shows little varia tion with thickness and gradually increases above 30 m. Undulatory quartz shows an inverse relationship whereas total quartz is constant. Feldspar occurs throughout the section with some variation, the same is true for quartzose rock fragments. An approximate change in the facies is suggested between 23 and 25 m, with the lower 23 m showing increases in normal quartz and silica cement and a gradual decrease in undulatory quartz and matrix. Above 25 m variables displaying increase include normal quartz and quartzose rock fragments with a decrease in feldspars and matrix. The source area is generally consistent throughout deposition of the Tapeats Sandstone in this section, but the depositional energy varies. The quartzites are medium to coarse-grained, moderately well sorted with a maximum grain diameter rang ing from 1 to 26 mm and fining upwards. Eight samples show good cross-bedding, predominantly westerly currents, with two easterly trends. Cross-bedding is dominantly planar with upper bounding surfaces truncated. One sample showed good trough cross-strata. Other structures include normal graded bedding, uniform lamination and current ripple marks. Figure 2. Time-trend curves for six variables in the Mesquite Pass section. Line plot: weighted data (percent of maximum point-count) smoothed once. Circled plot: smoothed data with percent of total sum of squares indicated (l). 25 NORMAL QUARTZ METERS 43t 21 % 30- 80 40 P€g 4 3t 2 9 % so- is- 40 QUARTZOSE ROCK FRAGM EN TS P€g 80 UNDULATORY T O T A L QUARTZ 55 % % 80 40 F E L D S P A R 72 % 40 7 5 % 40 SILICA 80 % CEMENT 22% 40 % 80 27 Taylor Mine Section (Location 6) The quartzites range from light brownish gray (5YR6/l) and light gray (N7) with a couple of samples pale red purple (5RP6/2). The grain size is medium to coarse grained sand with traces of pebbles composed of chert, jasper, agate and quartzite. Dark argillaceous clasts occur occasionally, some showing excellent stratification and angular quartz grains. Mineral composition is summarized in Table 4. The detrital composition is apparently depleted with corres ponding increase in matrix and silica cement. Feldspars, specially orthoclase, are highly altered to sericite-clay admixtures and counted as matrix. Mica is rare and acces sories are restricted to traces of magnetite which tend to be concentrated along laminations. Detrital chert is often encountered through the section and has a high correlation with quartzose rock fragments and undulatory quartz. Other significant clusters include microcline and plagio clase; normal quartz with silica cement and mica matrix with hematite cement. The composition is mineralogically submature• Time-trend plots (Fig. 3) show normal quartz in creasing gradually in the lower 21 m and decreasing the upper 21 m. Traces of ghost feldspar occur at the base, followed by an increase throughout the lower 21 m and 28 Table 4. Mineral composition of quartzites collected from the Tapeats Sandstone at the Taylor Mine section Mean 1 ° Maximum ° / o Minimum % Normal Quartz 41.9 57.6 18.0 Undulatory Quartz 19.9 32.3 10.0 Total Quartz* 61.8 72.6 48.6 Orthoclase 0.1 0.3 0.0 Microcline 1.5 2.6 0.0 Plagioclase 0.5 2.3 0.0 Total Feldspar* 2.1 4.6 0.0 Mica 0.1 0.3 0.0 Accessories 0.2 1.0 0.0 Chert 1.0 5.0 0.0 Q.R.F. 2.0 5.6 0.6 Silica cement 11.4 22.6 5.6 Other cement 3.8 12.0 0.3 Matrix 17.3 30.3 5.0 Others** 0.4 3.0 0.0 * Derived variable. ** Includes unstable rock fragments. Figure 3# Time-trend curves for six variables in the Taylor Mine section. Circles: weighted data (percent of maximum point count indicated by (2)). Line plot: smoothed data with percent of total sum of squares indicated (l). 29 NORMAL Q U A R T Z METERS 43v 55 173 30- 80 PCg U N DU LA T O R Y QUARTZ 37% 97 40 80 % T O T A L QUARTZ 45% 40 80 METERS 81% 95% 431 30- 80 PCg TOTAL F E L D S P A R 40 80 % MATRIX 67% 27 40 80 QUARTZOSE ROCK FR AG M EN T S ° thereafter decreases. Silica cement and matrix vary throughout, the former displaying decreasing trends upwards while the latter shows increasing trends. Although dia- genetic alteration and possible deformation strain in the upper part of the section tend to confuse the results, these trends suggest increasing mineral maturity in the basal half of the section and a corresponding decreasing maturity in the upper 21 m. The maximum grain diameter ranges from 1 to 17 mm with a mean of 4.1 mm and a general fining upward. Pebbles are more prominent in cross stratified units with a mean of 4.9 nun, whereas the mean for non-cross stratified samples is 3.4 mm. Eighteen of the 29 samples show cross-bedding, six are dominantly laminated and four show no apparent strati fication (massive). The cross-stratification is mostly tabular, with the lower bounding surface commonly planar and tangential foresets. One sample displays good trough cross-bedding. The foreset dip azimuths appear to be bimo- dal-bipolar with a vector mean azimuth of 252° and a con sistency of 35 percent. Some heavy mineral laminae (very fine-grained magnetite) frequently accentuate the cross strata sets, probably deposited earlier on the basis of hydraulic equivalence. The upper bounding surface of the cross-strata sets is often truncated by erosional action which is possible in tidal bars and channels in the near shore or deltaic environments. Other structures include 32 ripple marks, scouring and convolute laminations (?)• Some minor faulting (post-lithification) is also present. Mountain Pass Section (Location 5) The rocks are predominantly light brownish gray (5YR6/1). Grain size varies from medium- to very coarse grained sand with a few conglomeratic horizons. Pebbles are composed of quartz, feldspar, quartzose rock frag ments, chert, banded agate and jasper. Feldspars are dominant in the basal 26 m with large clasts of pink ortho clase typical of the basal samples. Mineral composition is summarized in Table 5» A low quartz content with corresponding increase in feld spars, quartzose rock fragments and matrix is characteris tic of this stratigraphic section. Undulatory quartz is more conspicuous, probably a function of deformation and close proximity to thrusts. Quartz sometimes shows granu lated borders, specially near the base and top of the section. Feldspars near the base are fragmented and highly altered. Time-trend plots (Fig. 4) show an increase of total quartz upwards, whereas feldspar has an inverse relation ship decreasing from 20 percent near the base to zero per cent near the top. Rock fragments are common near the base and appear throughout the section. Matrix is abundant near the base and increases upwards. It is dominantly secondary 33 Table 5» Mineral composition of quartzites collected from the Tapeats Sandstone at the Mountain Pass section Mean ° / o Maximum .. ° / o Minimum i o Normal Quartz 48.3 64.6 7.6 Undulatory Quartz 15.5 27.3 3.6 Total Quartz* 63.8 79.9 23.0 Orthoclase 5.0 15.3 0.0 Microcline 0.9 3.6 0.0 Plagioclase 0.6 1.6 0.0 Total Feldspar* 6.5 20.0 0.0 Mica 0.2 1.3 0.0 Accessories 0.5 1.3 0.0 Chert 0.7 4.0 0.0 Q.R.F. 8.7 44.0 1.3 Silica cement 6.0 12.6 1.3 Other cement 1.4 3.3 0.0 Matrix 9.8 24.0 2.6 Others** • C M 5.6 0.0 * Derived variable. ** Includes unstable rock fragments, voids. Figure k, Time-trend curves for six variables in the Mountain Pass section. Line plot: weighted data (percent of maximum point- count) smoothed once. Circled plot: smoothed data with percent of the total sum of squares indicated (l). 3k NORMAL QUARTZ METERS 37T 2 6 % '" V J- PCg 80 40 METERS 37t . 20% 30 80 % 40 Q U A R TZO SE ROCK FRAGM ENTS UNDULATORY QUARTZ 20% % 80 40 3 6 % 80 40 % SILICA CEMENT T O T A L F E L D S P A R 14% % 80 40 41% 40 80 % MATRIX u V ji 36 at the expense of feldspars and mica, but could also be partly detrital. Pro Wash Section (Location l) Quartzites in the section are light gray (N7) and light olive gray (5Y6/I) with few samples that are pale red purple (5RP6/2) or pale yellowish brown (1OYR6/2). They are mainly medium- to very coarse-grained sand size with pebbles and argillaceous clasts occasionally observed. Pebbles and granules comprise vein quartz, with rose quartz quite common, banded agate, chert and quartzite. Modal analysis is summarized in Table 6. The detri tal components are generally below the mean for the cratonal sections examined whereas the cement and matrix is higher. The mutual relationship among the variables as depicted in a dendrograph (Pig. 5) which shows the follow ing clusters: X. orthoclase, p1agioclase, mica, chert and microcline; II. undulatory quartz and quartzose rock fragments; III. other cement,accessory minerals and matrix; IV. normal quartz and silica cement. Cluster I relates to source area, mineralogical maturity and pos sible diagenetic alterations; Cluster II comprises less stable members of the detrital silica group, which may infer a shorter history of abrasion and/or lower energy at the depositional site. Cluster III includes cement and matrix occupying the interstices between the grains and 37 Table 6. Mineral composition of quartzites collected from tbe Tapeats Sandstone at the Oro Wash section Mean ° / ° Maximum ¥ > Minimum i o Normal Quartz 50.7 65.0 26.6 Undulatory Quartz 13.9 24.6 6.0 Total Quartz* 64.7 77.0 37.0 Orthoclase 0.4 2.6 0.0 Microcline 2.7 6.0 0.0 Plagioclase 0.9 3.3 0.0 Total Feldspar* 4.0 8.0 0.0 Mica 0.6 4.0 0.0 Accessories 0.2 3.0 0.0 Chert 1.2 6.3 0.0 Q.R.F. 2.7 15.3 0.0 Silica cement 9.4 16.6 2.3 Other cement 4.1 15.3 0.0 Matrix 12.4 36.0 3.0 Others** 0.7 5.0 0.0 * Derived variable. ** Includes unstable rock fragments. Figure 5» Dendrograph depicting mutual relation ships between and within twelve variables measured in the Oro Wash section. Correlation coefficient ranges from -1.0 to +1.0. 38 ON C\ -C 1 > V* -O® >* jP .^o ■ * 2 £ ^ ' * * * & -ro - o o -ro “ 2*0 -£*0 - K O -so -90 •ro -80 -60 - O l also accessory minerals which, occur in minor amounts. Cluster XV consists of normal quartz and silica cement. Normal quartz has sin inverse relationship with the other variables. A higher content of normal quartz with sin arenite framework favors pressure solution sind the forma tion of quartz overgrowths (Dapples, 1967). Magnetite is a common accessory mineral which occurs chiefly as con centrations along laminae sind cross lsuninae. Zircon is rare. Time-trend plots (Pig. 6) show marked fluctuations in total feldspar content, with several maxima at 11, Zk$ h9 and 79 m above the Precambrian basement, and minima at 20, 3k and 66 m. Some sstmples show the feldspars to be considerably altered to matrix, in others feldspars specially microcline are relatively fresh. Variation in total quartz is less pronounced. Normal quartz and un- dulatory quartz show similar trends in the basal 6l m but display inverse relationships above that. Silica cement increases upward in the section while quartzose rock frag ments decrease. Matrix shows considerable variation from dominantly primary in the silty quartzites to dominantly secondary chiefly at the expense of feldspars. Mineral- ogical maturity apparently increases upwards in the section, although periodic fluctuations in composition may be related to source and variation in energy in the deposi- tional environment. Figure 6. Time-trend curves for variables measured in the Oro Wash section. Circles: weighted data (percent of maximum point-count indicated by (2). Line plot: smoothed data with percent of total sum of squares indicated (l). hi M ETERS 93 75 60 45 30* 40 60 PCg NORMAL QUARTZ METERS 55% 24 93 75 60* 45 30 40 80 PCg TOTAL FELDSPAR 85 % 74 80 40 % U N O U LA TO RT QUARTZ 95% ioe 80 % MATRIX 75 % 231 40 80 % 47% 50 40 80 % TOTAL QUARTZ S fL IC A CEM ENT 76% 46 40 80 % 50% , I 9 m m 80 40 % QUARTZOSE ROCK FRAGMENTS CLASTICITY ■JS- to 43 Quartz is well-rounded in the coarse-grained sand fraction and subangular to subrounded in fine-grained fraction, suggesting transport by traction and suspension in a current dominated environment. Cross-stratification is well displayed in 28 samples, even lamination in 22, and massive bedding in 12. Cross-stratification is pre dominantly tabular, grouped into small-scale sets. The lower bounding surface of cross-strata is commonly planar and nonerosional. The upper bounding surface is frequent ly truncated. Migration from upper to lower flow regimes is displayed in few samples from even laminations to ripple cross-strata. The mean foreset dip is 18° and the vector mean azimuth 224°. The foresets appear to be bi- modal at 90° predominantly westerly and southerly. Other structures include ripple marks, scouring and minor channels containing argillaceous rip-up clasts deposited parallel to the stratification. Marble Mountain Section (Location 3) Quartzites in the basal 105 m are dominantly coarse grained, with a pale red (5R6/2) to medium dark gray (n4) color. The upper 27 m consist of fine- to medium-grained pinkish gray (5YR8/I) to light red (5R6/1) quartzites. Al though few conglomeratic horizons are present, one prominent at 25 m above the basal contact with Precambrian gneiss. Pebbles are well-rounded and composed of quartz, kk chert, jasper and agate. Feldspar clasts are prominent in the basal part showing pink and white rectangular to subrotmded shapes. Argillaceous clasts, occasionally of pebble or cobble size, occur in this section. Mineral composition is summarized in Table 7» Quartz is predominantly tinstrained with a smaller propor tion exhibiting undulose extinction. This is more con spicuous in the upper 27 ni where the arenites are more mature. Feldspar clasts are either fresh or highly altered to clay or sericite. Occasionally both varieties may ap pear in the same sample, which may suggest a dual source, fresh igneous or altered sedimentary, or it could be related to differential post-depositional alteration. Heavy mineral segregations (chiefly magnetite) are observ ed in a few thin sections. Chert is commonly well- rounded and hence detrital. Quartzose rock fragments in clude well-rounded to sub-rounded orthoquartzite, igneous (granitic) and gneissic. One sample contained 51 percent of hematite cement. Other authigenic minerals include glauconite and collophane (phosphorite) found in the tran sitional zone between the submature and supermature ortho- quartzites. Matrix is partly detrital occurring as fine laminae or filling interstices or derived from post- depositional alteration of mica sind feldspars. The twelve variables point counted in this section display clusters which appear to be meaningful, which is 45 Table 7. Mineral composition of quartzites collected from the Tapeats Sandstone at the Marble Mountain section Mean 1 ° Maximum i o Minimum i Normal Quartz 65.2 89.3 27.2 Undulatory Quartz 9.9 28.4 1.6 Total Quartz* 75.1 92.6 44.6 Orthoclase 3.3 7.6 0.0 Microcline 1.3 3.9 0.0 Plagioclase 1.1 3.3 0.0 Total Feldspar* 5.7 14.0 0.0 Mica 0.5 3.6 0.0 Accessories 0.6 5.6 0.0 Chert 0.8 2.6 0.0 Q.R.F, 2.8 23.6 0.0 Silica cement 4.2 11.6 0.0 Other cement 4.5 51.6 0.0 Matrix 5.3 24.9 0.3 Others** 0.7 20.0 0.0 * Derived variable. ** Includes unstable rock fragments, glauconite, collo- phane. 46 probably a function of the relatively large sample size (N = 86) and lack of post depositional deformation (Fig. 7). Cluster I comprises microcline, plagioclase and orthoclase. Cluster IX consists of undulatory quartz and quartzose rock fragments. Cluster III is made up of mica and matrix. Cluster IV consists of normal quartz and silica cement. Cluster V includes chert and accessory minerals; both have a mean value of less than one percent, so this relationship may be fortuitous. Cluster VI in cludes other cement which is almost exclusively hematite- limonite, and is independent of other variables. The above clusters are related to stability of the detrital mineral components and post-depositional diagenesis. Time-trend plots show considerable variation in mineralogy and texture with thickness (Figs. 8, 9)» Con sidering the whole section, normal quartz shows an in crease upward while undulatory quartz has an inverse rela tionship. Total feldspar gradually decreases upwards from 14 percent near the base and is absent in the top 28 m. Quartzose rock fragments are more prominent in the basal portion of the section and only occasionally occur higher in the section. Silica cement fluctuations correspond well with those for normal quartz, and mica with matrix. Two clusters can be recognized in the Q-mode dendro gram plotted for this section. Samples collected between 15 m to 101 m (N = 63) form one cluster and probably cor- Figure 7. Dendrograph depicting mutual relation ships between and within the twelve measured variables in the Marble Mountain section. Correlation co efficient ranges from -1.0 to +1.0. 48 % o . • y - V ^A \ \ O j L >JL So 'V V v*- A ^A. V I o I o o I <D o I < 0 o I in d I o I ro d I I ‘ N 3 o o I o d o Figure 8. Time-trend curves for five variables measured in the Marble Mountain section. Line plot: weighted data (percent of maximum point count) smoothed once. Circled plot: smoothed data with percent of the total sum of squares indicated (l). NORMAL UNOULATORY QUARTZ QUARTZ 15% 120 105 901 75- 60H 45- 301 Peg 25% TOTAL F ELD S PA R 40 SO % Q UA RTZOSE SILICA ROCK FRA G M EN TS CEMENT 40 80 % 23% 40 % V J 1 O Figure 9« Time-trend curves for six variables measured in the Marble Mountain section. Straight line plot: weighted data (percent of maximum point count or textural value smoothed once). Circled plot: smoothed data with percent of the total sum of squares indicated (l). 51 MICA MATRIX METERS 132 120' 105 90' 75 CO- 45' 30 40 80 Peg 43 % 80 % 40 OUARTZ SO RT IN G 21 % 40 80 « QUARTZ 1. R O UN D NESS (8,,) 2. S I Z E ( £ ■ ■ ) (2) 12% 1296(1) 40 80 MAXIMUM GRAIN D IA M ETER 33 « 40 80 % m ro 53 relate with the Wood Canyon Formation, whereas the samples from the upper 27 m (N = 18) form another cluster which probably corresponds to the Zabriskie Quartzite lithologic equivalent of Tapeats Sandstone, Only four samples are excluded from either cluster because of high content of one variable, namely quartzose rock fragments in the basal sample, magnetite and matrix in two others, and hematite cement in a sample collected near the transition between the Wood Canyon and Zabriskie equivalents of the Tapeats Sandstone. Miogeoclinal Quartzites The five miogeoclinal sections have a sampled thick ness ranging from 133 m to 738 m. The quartzites sampled have been assigned to the Johnnie Formation, Stirling Quartzite, Wood Canyon Formation and Zabriskie Quartzite. The base and boundaries of formations at each stratigraphic section are more difficult to interpret than in the cra- tonal sections. Providence Mountain Section (Location 8) The rocks in this section are medium- to very coarse-grained quartzites commonly pale red (10R6/2) or light brownish gray (5YR6/1). Pebbles of quartz, quartzose rock fragments and chert, floating in a sandy matrix are common through most of the section. Pebbles of pink and white fine-grained orthoquartzite are prominent in samples 30.5 m above the base. No red jasper was encountered in the section. The interbedded siltstones are light olive gray (5Y6/1) with dark gray mottles. The quartzites have been assigned to the Upper Stirling (?) and Wood Canyon Formation. This section was measured on a north-trending ridge with the base at Prospect Mountain-C member (Quinn, 1968). Quartzites below the section are highly recrystal lized. Petrographic modal analysis is based on point counts of 25 samples selected at random from the section (Table 8). Normal quartz is dominant (63 percent) when compared with undulatory quartz (4 percent). Feldspars are subordinate in amount, orthoclase was encountered sparsely through the section and is highly altered to matrix. Only trace amounts of microcline or plagioclase are observed which is unique in this study. Rock frag ments are occasionally observed, predominantly quartzose (granitic or orthoquartzitic) with minor argillaceous clasts and mica schists. The amount of matrix is rela tively high, being micaceous as well as chloritic in composition. It is largely derived from the alteration of detrital clasts (feldspars and rock fragments), but some primary matrix is also evident which consists of fine silty laminae or filling interstices between the coarse detritus. 55 Table 8. Mineral composition of quartzites collected from the Stirling (?) and Wood Canyon Forma tions at the Providence Mountain section Mean Maximum Minimum °L- °k Normal Quartz 62.8 76.6 45.3 Undulatory Quartz 3.8 12.0 0.3 Total Quartz* 66.6 77.6 47.0 Orthoclase 2.5 9.0 0.0 Microcline 0.0 0.0 0.0 Plagioclase 0.0 0.0 0.0 Total Feldspar* 2.5 9.0 o • o Mica 0.8 4.0 o * o Accessories o • 0 0 4.0 0.0 Chert 0.2 1.6 0.0 Q.R.F. 4.8 17.6 o • o Silica cement 3.6 9.6 0.0 Other cement 2.2 10.0 0.0 Matrix 18.4 49.3 3.6 Others** 0.2 2.6 0.0 * Derived variable. ** Includes unstable rock fragments. 56 Cross-lamination is ubiquitous in the Providence Mountain section and is commonly tabular with minor in stances of trough or wedge shaped cross-strata. The units are mostly grouped, with sets ranging from small- to large-scale (Allen, 1963a). The lower bounding surface is commonly nonerosional, planar with foresets tangential or discordant. The greater the grain size, the greater is the possibility of high angle cross-strata and dis cordance with the lower bounding surface. Light and dark layers are common in cross laminated samples, silty laminae, heavy mineral segregations or iron oxide cements are commonly responsible for these contrasts in lithology. Cross-stratification is unimodal with a vector mean azimuth of 3^8° suggesting dominantly northerly currents. The foreset dip azimuth vary locally from northeast to south west. Even or irregular laminations are more rare. A few apparently massive units are observed occasionally showing graded bedding. Other structures include ripple marks, flaser and lenticular bedding in the middle Wood Canyon Formation (?) 76 m above base of the measured section. The texture is dominantly conglomeratic with granules and pebbles embedded in a sand matrix. Quartz grains are pre dominantly well rounded, ranging in size from medium to very coarse sand which is moderately to well sorted. The well-rounded quartz grains are often associated with high matrix which is partly detrital. A dominant sedimentary 57 source (multi cycle) is employed to explain the well- rounded nature of the quartz grains. Although, much re working in a surf zone may also explain this phenomenon. Kelso Section (Location 4) The base of this section consists of light brown gray (5YR6/l) carbonates which are in fault contact with the Precambrian gneiss. The basal carbonates (9»1 m) are laminated calcilutites with some iron oxide cubes (hema tite after pyrite?). These carbonates and the overlying quartzites and siltstones probably belong to the Johnnie Formation, although the contact with the overlying Stirl ing Quartzite is not easily discernible. The basal 76 m are assigned to Johnnie Formation, in which the quartzites range in color from medium dark gray (N5) to gray pink (5R8/2) and are dominantly fine- to medium-grained sand. Argillaceous intraclasts and laminae are common with the quartzites. Interbedded siltstones also occur. Above 76 m the quartzites (Stirling) are more prominent and dis play lighter colors from white (N9) to pinkish gray (5YR8/l). Grain size is mainly coarse, with some quartz ite pebble conglomeratic rocks in the upper part of the unit. The Wood Canyon Formation which overlies the Stirl ing Quartzite comprises dark gray (N3) to light gray (N7) quartzites. The texture is dominantly medium- to coarse grained sand, with few conglomeratic units. 58 The mineral composition is summarized in Table 9» The following clusters (Fig. 10) were found to be signifi cant: Cluster I consists of microcline, orthoclase and plagioclase, their presence together is related to the source area; Cluster XI, mica and matrix; Cluster III, un dulatory quartz, quartzose rock fragments and chert; Clust er IV, normal quartz and silica cement. The matrix is dominantly detrital in the Johnnie Formation, whereas it tends to be more related to diagenetic alteration in the Stirling and Wood Canyon Formations. For the whole section, quartz is dominantly normal (58 percent), with undulatory quartz making up 9 percent of the total volume. Orthoclase is the dominant feldspar, followed by micro cline and plagioclase. These are fresh or highly altered to sericite-clay. Time-trend plots (Fig. 11) show considerable varia tion in composition with thickness. The Johnnie Formation (basal 76 m) shows a decrease in normal quartz with minor fluctuations. An increase in matrix corresponds to quartz ites collected within siltstone units, followed by marked decrease from ^3 to 76 m. Undulatory quartz and total feldspar show a gradual increase upward. The Stirling (76 to 137 m) shows marked increases in total quartz and maximum grain diameter (coarsening upward), accompanied by a corresponding decrease in total feldspar and matrix. The Wood Canyon is characterized by short period fluctua- 59 Table 9. Mineral composition of quartzites collected from the Johnnie, Stirling and Wood Canyon Formations at the Kelso section Mean Maximum Minimum I o % ° / o Normal Quartz 57.5 78.3 14.6 Undulatory Quartz 8.9 29.6 1.0 Total Quartz* 66.4 88.7 27.3 Orthoclase 3.7 11.3 0.0 Microcline 1.1 5.6 0.0 Plagioclase 0.9 3.3 0.0 Total Feldspar* 5.7 16.6 0.0 Mica 0.3 3.6 0.0 Accessories 0.2 5.0 0.0 Chert 0.4 4.3 0.0 Q.R.F. 5.7 41.3 0.0 Silica cement 6.7 16.3 0.0 Other cement 1.4 11.0 0.0 Matrix 12.9 63.6 0.0 Others** 0.2 5.6 0.0 * Derived variable. ** Includes unstable rock fragments. Figure 10. Dendrograph depicting mutual relation ships between and within the twelve variables measured in the Kelso section. Correlation coefficient ranges from -1.0 to +1.0. 60 6l \ V O ' *'**- \ ^ y O V o V - o K ° % >A. '« *£, V * V*. t» ° o U \ + o °- 0 ^ *v % V % f. •*. °, *• X % I o I 0> I CO I N- l (0 I IO — o I «• o i ro i OJ i o 0.0- Figure 11. Time-trend curves for eight variables measured in the Kelso section. Plots show smoothed data with percent of the total sum of squares (l) and maximum point count (2) indicated. 62 NORMAL QUARTZ U NDUIATORY QUARTZ SIL IC A C E M EN T TOTAL FE L D SPA R 352 59% 49 90% 89 70% 235 300 240 180 1 2 0 srmimt QUANTZITE 60 80 80 40 80 40 80 40 40 352 05% 78% 124 55% 191 72% 21.5mm 300 240 180 srtttuftt q u a r t z i t c 120 srmuMt Q O M H T z/re 00 JO H N N IE FO RM ATIO N ' 40 80 40 80 40 80 40 80 Q U A R T Z O S E ROCK FR A G M E N T S C L A S T IC IT Y 6b tions, probable pulsations in sediment supply related to current directions and changes in depositional environ ments with time. Sedimentary structures are predominantly laminations in the Johnnie Formation. Some ripple marks are also ob served. One sample displays obscure cross-lamination. Argillaceous laminae and intraclasts are common. The clasts are fine- to medium-grained sand, and are sub- angular to subrounded. Deposition is probably low to moderate energy environment. Quartzites between 76 to 137 m (Stirling) show good tabular planar cross-stratification above 117 m» The cross-strata sets are small- to large- scale with foresets generally discordant with the lower bounding surface. The mean foreset dip angle is about 20°. The Wood Canyon Formation in the Kelso section show abundant cross-lamination between 140 and 238 m above base. These are predominantly tabular, planar with tangential or discordant foresets. Trough and wedge-shaped cross-strata are rare. The upper bounding surface is commonly trun cated suggesting erosive action by tidal or longshore cur rents. The cross-beds show unimodal distribution, sug gestive of northerly currents, and frequently occur within this interval whereas even-laminated samples are rare. Other structures include ripple marks, flaser bedding, diastems and bioturbation. The overlying Zabriskie Quartz- ite shows faint laminations and obscure low angle cross- 65 bedding, vertical tubes Scolithus (?), and bioturbation. Old Dad Mountain Section (Location 12) Tbis section was collected in the northern Old Dad Mountains. The terrain has several high angle faults making sampling difficult. Moreover, the base of the section is a quartzite/igneous sill contact within the Johnnie Formation. The section sampled includes part of the Johnnie Formation and Stirling Quartzite on the basis of lithology and published stratigraphy (Stewart, 1970)# Although the quartzites vary in color, they are commonly light gray (N7)# The carbonates are pale yellowish brown (10YR6/1) in color with an oolite unit 90 m above the base grading upwards into an oolitic calcilutite. The quartz- ites are dominantly fine- to medium-grained sand with few conglomeratic units 11, 23 and 101 m above the base of the section. The pebbles are composed of quartz and quartzose rock fragments. Petrographic study (Table 10) shows that quartz is predominantly non-undulatory (66 percent) compared with 8 percent showing undulose extinction. Orthoclase is the dominant feldspar with plagioclase and microcline less important. Except for one sample collected lU m above the base, feldspar occurs throughout the section in varying proportions related t o provenance and reworking in the depositional environment. Mica and chert are rarely en- 66 Table 10. Mineral composition of quartzites collected from the Johnnie and Stirling Formations at the Old Dad Mountain section Mean Maximum Minimum 1 ° % Normal Quartz 66. 4 83.3 27.3 Undulatory Quartz 8.7 13.0 0.6 Total Quartz* 75.1 88.3 44.6 Orthoclase 4.2 12.0 0.0 Microcline 1.0 6.3 0.0 Plagioclase 1.4 3.6 0.0 Total Feldspar* 6.6 19.0 0.0 Mica 0.1 1.6 0.0 Accessories 0.1 0.3 0.0 Chert 0.1 0.3 0.0 Q. R. F . 3.8 30.0 0.0 Silica cement 4.7 9.6 0.0 Other cement 0.4 6.0 0.0 Matrix 9.0 51.6 1.0 Others** 0.0 0.0 0.0 * Derived variable. ** Includes unstable rock fragments. 67 countered in this section. Quartzose rock fragments are common and include metaquartzite, composite quartz and granitic fragments. The matrix is dominantly detrital and alteration of feldspars is limited. Accessory minerals are rare, traces of zircon, magnetite occur as do cubes of hematite (pseudomorphous after pyrite?). Calcite cement is observed in some quartzite samples associated with carbonates. The dendrograph suggests a strong correlation (0.92) between mica and matrix, which is probably related to their hydraulic equivalence. Mica was observed in only three samples which are fine-grained and silty. Other clusters of some significance include orthoclase and microcline associated with quartzose rock fragments, chert, undulatory quartz, and plagioclase. Normal quartz, the most dominant constituent in the Old Dad Mountain quartz- ites, exhibits a negative correlation with the other vari ables. Time-trend plots (Fig. 12) show similar relation ship between undulatory quartz and normal quartz in the basal 82 m and an inverse relationship thereafter. Total feldspar is fairly consistent throughout the section with a sharp increase above the oolitic limestone unit. The amount of matrix is also fairly uniform and in small pro portions except for two maxima corresponding to silty units. Mica occurs at these maxima and hence the high Figure 12. Time-trend curves for eight variables measured in the Old Dad Mountain section. Plots: smoothed data with percent of the total sum of squares (l) and maximum point count (2) indi cated. 68 1 3 3 t S j 1*0 1 0 9 •o 73 60 49 30- NORMAL QUARTZ METERS 133 31% 37 ISO- 103 SO- 75- 60 45- 30 3 40 80 % TOTAL FELDSPAR 21% • 3 40 60 % UNDULATORY ‘ QUARTZ 43% 90 40 60 % QUARTZOSE ROCK FRAGMENTS 22 % 2S5 % 40 60 TOTAL QUARTZ 42% 29 40 60 % SILICA CEMENT 20 % 1 5 3 40 60 40 80 % MICA 70 correlation between mica and matrix. Quartzose rock frag ments occur in conjunction with the two conglomeratic units. Vinter’s Pass Section (Location 9) This section was sampled in the Vinter's Pass thrust plate. The base of measured section consists of a con glomeratic unit near the base of the Johnnie Formation. Quartzite samples were collected at intervals of 10 feet (3.28 m) where possible, and are assigned to the Johnnie Formation, Stirling Quartzite and Vood Canyon Formation on the basis of changes in lithology. Top of the section is within the Upper Vood Canyon Formation. Quartzites assigned to the Johnnie Formation (o to 252 m) are dominantly light gray (N7) weathering to light brownish gray (5YR6/1). The quartzites are generally fine grained with conglomeratic units at the base with pebbles of quartz, quartzose rock fragments and chert. The Stirl ing Quartzite is dominantly pinkish gray or very light gray, fine- to coarse-grained sand with conglomeratic units near the top. Pebbles in these units include quartz, chert, quartzite and red jasper. Quartzites in the Vood Canyon Formation are commonly olive gray (5Y4/l), and more rarely medium gray (N5) to light gray (N7), and the section ends in a unit that is pale red purple (5RP6/2). Con glomeratic units are common near the base, with pebbles and granules of quartz, red jasper, chert, agate, granite and other rock fragments. The upper units are dominantly medium- to coarse-grained sand. Thus, the Johnnie and Wood Canyon Formations show a general fining upward sequence, whereas the Stirling Quartzite shows a coarsen ing upward sequence. This stratigraphic section is perhaps the most reliable of the miogeoclinal sections, being un affected by substantive major structural disturbances within the section. The mineralogical composition for each formation as well as the mean composition for the whole section is sum marized in Table 11. In all three formations the ratio of normal quartz to undulatory quartz is relatively low when compared to other stratigraphic sections. Much of the strain in quartz is probably post depositional. Orthoclase is the dominant feldspar followed by microcline and plagioclase in the Stirling Quartzite and Wood Canyon Formation, whereas plagioclase barely exceeds microcline in the Johnnie Formation. Feldspars occur through most of the section, being absent only in a few samples in the Stirling Quartzite. Quartzose rock fragments are more abundant in the Wood Canyon (6 percent) as compared with Johnnie (2 percent) and Stirling (2.6 percent) Formations. Matrix is dominantly detrital in the Johnnie Formation, and mainly diagenetic in the Stirling Quartzite and Wood Canyon Formation. 72 Table 11. Mineral composition of quartzites collected from the Johnnie, Stirling and Vood Canyon Formations at the Winter's Pass section (Mean Y ° ) Johnnie Forma tion Stirling Quartz ite Wood Canyon Forma tion Whole Section Normal Quartz 51.0 62.5 49.0 55.0 Undulatory Quartz 17.7 19.3 20.4 19.3 Total Quartz* 68.7 81.8 69.4 74.3 Orthoclase 2.3 2.6 3.2 2.7 Microcline 0.4 0.9 2.3 1.2 Plagioclase 0.7 0.5 0.6 0.6 Total Feldspar* 3.4 4.0 6.1 4.5 Mica 0.7 0.1 0.2 0.3 Accessories 0.2 0.1 1.1 0.4 Chert 0.6 0.1 0.6 0.4 q.r .f . 2.0 2.6 6.2 3.7 Silica cement 5.3 5.9 7.4 6.3 Other cement 7.1 0.3 0.2 2.0 Matrix 12.1 5.^ 8.5 8.2 Others** 0.2 * Derived variable. ** Includes unstable rock fragments 73 R-mode dendrogram for the whole section show the following clusters: Cluster I comprises other cement (hematite, calcite), matrix and mica. Cluster IX includes plagioclase. Cluster III consists of quartzose rock frag ments, undulatory quartz and chert, the less stable members of the detrital silica group cluster with micro cline. Several samples, particularly within the lower Wood Canyon, show large clasts of microcline associated with chert and granitic rock fragments suggesting a prob able proximal derivation. Accessory minerals and silica cement seem to be independent, whereas normal quartz has an inverse relationship with other variables combined. Dendrograms for each formation are also shown separately and their clusters depicted. In the Johnnie Formation, other cement is exclusively calcite and occurs in associa tion with silty and carbonate units. Hence the high cor relation with mica and matrix. Clusters in the Johnnie and Wood Canyon Formations are related to depositional history and maturity of the sediments, whereas clusters within the Stirling Quartzite may be ascribed to deforma- tional history and partial recrystallization (Fig. 13). Time-trend plots (Figs. 14, 15) accentuate the variation in composition with thickness which facilitates delineating formational boundaries. In the Johnnie Forma tion normal quartz is fairly consistent, except for two marked minima at 85 and 213 n> which correspond to samples Figure 13* Dendrograms showing mutual relations among variables measured in the Winter's Pass section. Dendrogram for each formation is also shown. 74 75 100 90 eq_ 79 60 20 1 0 -c OTHER C E M E N T (OC) MICA ’ MATRIX (MX) • PLAOIOCL A SE (PL) • O R T H O C L A S t (on) • QUARTZOSE ROCK FRA Q M I N I MICRO CLI NE (MR) UNOUL AT ORV QUARTZ (UQ) CH E RT (CM) A CC t 33 ON IE S (AC) SILICA C E M E N T (SC) NORMAL QU AR T Z (NO) MICA MR Wood Canyon Form ation ■ c E UQ S tirlin g O u a rtz ita CH OC MICA AC MX NO Seal* F a cto r MICA OC CH MR QRP UP SC OR PL NO Johnnie Form ation Figure 1^. Time-trend curves for five variables measured in the Winter’s Pass section. Plots: smoothed data with percent of the total sum of squares (l) and maximum point count (2) indi cated. 76 77 srt» ti» 0 BtMnrztrr Figure 15. Time-trend curves for five variables measured in the Winter's Pass section. Plots: smoothed data with percent of the total sum of squares (l) and maximum point count (2) indicated. 78 79 80 collected within siltstone units. Inflections in the time-trend plots can be used to predict positions of carbonate or siltstone units which are not sampled. Quartzites collected in proximity to carbonates have a higher calcite cement whereas samples collected near silt- stones are more micaceous and silty. Mica and matrix show remarkable similarity in plots with maxima at 91*5 and 2lk m. Feldspars occur in small amounts throughout the Johnnie Formation. Quartzose rock fragments are found near the base of the measured section. The maximum grain diameter is mainly in the fine to coarse sand range, with pebbles and granule size clasts near the base. Detrital matrix and silty laminae suggests low to moderate deposi- tional energy. The Stirling Quartzite is marked by increasing total quartz and silica cement. One extremely sharp maxima for undulatory quartz, with a corresponding minima for normal quartz, is probably related to local deformational stress es, as evident in the field from quartz veins of recrystal lization. Total feldspar decreases in the Stirling quartz ites and quartzose rock fragments and matrix are found occasionally, especially near the base and at the top of this unit. Mica is scarce throughout this formation. The maximum grain diameter matches the plots for QRF fairly well, being more coarse near the top (coarsening upward). Mineralogical and textural maturity suggest relatively high depositional energy. The Wood Canyon Formation is marked by short period sedimentological fluctuations. The variation in mineral composition with time may also be related to vari ation in currents which are dominantly bimodal, south westerly and northeasterly, with some westerly currents. Westerly currents correspond to increases in undulatory quartz, feldspar, quartzose rock fragments and maximum grain diameter and decreases in normal quartz. A reversal in trends can be inferred for dominantly easterly currents, with decreases in the above variables. In the Johnnie Formation two samples showed obscure cross-stratification suggesting southeasterly currents; twenty samples displayed good laminations and eight samples are massive. Some mottling and leaching effects may be consequences of weathering. Vertical burrows (?) are sug gested in two samples with abrupt truncation of laminae. Quartz in this formation is dominantly very fine to medium grained subangular sand which is poorly to moderately sorted. Interbedded units include siltstones, silty carbonates and the dolomitic Johnnie oolite (which is a good marker bed) with oolites ranging up to 2 mm in diameter. There is a sharp change in lithology with the Stirl ing Quartzite which is highly quartzose and contains well- rounded and mostly well sorted clasts. These quartzites 82 are dominantly massive (28 samples) with no evident strati fication in the radiographs. Fourteen are laminated and seven samples exhibit cross-stratification. Normal graded bedding is quite common in the apparently massive quartz ites , possibly representing storm deposits (?) laid down in shallow water in single events. There is a general coarsening upwards within this formation suggesting pro grading shelf sands or barrier bars and beaches. Cross bedding is faint, planar or trough, low to moderate angle with predominantly northwesterly trends. The vector mean azimuth is 299 degrees. Primary sedimentary structures in the Wood Canyon Formation include cross-bedding in 27 samples, even laminations in eight, and no evident lamination in seven samples. The cross-bedding is apparently bimodal, with dominantly southwesterly and northeasterly trends and some westerly trends. Although the cross-bedding is mainly tabular, small to large-scale, there is evidence of trough cross-strata and the upper bounding surface is com monly eroded possibly by tidal currents. The lower con tact is frequently asymptotic. Other structures include ripple marks, bioturbation, diastems and mudcracks (?). The quartzites are composed of medium to coarse grained, subangular to subrounded quartz clasts with poor to moderate sorting. Few graded units are observed and some alternations of coarse and fine sand (textural leminations) 83 occur. Table 12 summarizes the compositional variation among the three dominant sedimentary structures. Zabriskie Section (Location 10) This section is collected in the Mesquite Pass thrust plate (Burchfiel and Davis, 1971)* The quartzites are assigned to the Cambrian Zabriskie Quartzite. The base of the section is in contact with dark gray Wood Canyon Formation. The rocks are dominantly white (N8) to pinkish gray (5YR8/l). The quartz grain size is fine to coarse sand, the clasts are well rounded and sorted and silica cemented to form a saccharoidal, mosaic texture. Traces of granules and pebbles are seen in the basal sample followed upwards by coarse and then fine sand. The mineral composition (Table 13) is fairly uni form. Quartz (mean 87 percent) is predominantly normal (7^ percent) with 13 percent undulatory. These quartzites are totally devoid of feldspars suggesting a high energy depositional site or derivation from source area lacking feldspars. Rock fragments are chiefly restricted to the basal samples and consist of quartzite, granite, schistose quartz. Traces of mica, chert and accessories (zircon, tourmaline and rutile) are observed. Matrix constitutes nearly 13 percent of the basal sample and decreases there after. Mineral and textural maturity increase upwards in the section. Table 12. Mineral composition of quartzites collected from cross-stratified, laminated and massive units at Winter’s Pass section Units: Total Quartz* Total Feldspar* Mica Accessories Chert Q.R.F. Matrix Sample size (n ) Cross stratified Mean - 0 / ° . ____ 72.8 4.7 0.2 1.2 0.4 4.9 8.0 37 Laminated Mean .. 73.2 3.9 0.2 0.2 0.2 1.5 10.7 42 Massive Mean ° k__ 76.4 5.1 0.1 0.1 0.5 4.9 5.9 43 * Derived variable 85 Table 13* Mineral composition of quartzites collected from the Zabriskie Quartzite at the Zabriskie section Mean ° / ° Maximum ° / o Minimum . ° / o Normal Quartz 73.8 79.6 64.6 Undulatory Quartz 13.5 19.0 7.6 Total Quartz* 87.3 92.3 80.6 Orthoclase 0.0 0.0 0.0 Microcline 0.0 0.0 0.0 Plagioclase 0.0 0.0 0.0 Total Feldspar* 0.0 0.0 0.0 Mica 0.1 0.3 0.0 Accessories 0.03 0.3 0.0 Q.R.F. 1.6 8.0 0.0 Silica cement 6.4 13.3 0.6 Other cement 0.3 1.3 0.0 Matrix 4.4 13.3 o • o Others** 0.0 0.0 0.0 * Derived variable 86 The quartzites are predominantly massive with few samples exhibiting faint laminations. The marked homo geneity of composition 95 percent silica) results in poor contretsts in the radiographs, and the recognition of primary structures if present are made difficult. A de crease in elasticity is apparent up section, ranging from h mm at the best to less than 1 mm near the top. Mineralogical and textural characteristics from the petrographic study and primary sedimentary structures from analysis of X-ray radiographs are depicted for each forma- tional unit in Figures 16 through 28. Table 14 summarizes the mineralogical data for cratonal quartzites (Tapeats Sandstone) from 231 samples collected at five localities. Table 15 summarizes the mineral composition of miogeoclinal quartzites comprising the Johnnie Formation, Stirling Quartzite, Wood Canyon Formation and Zabriskie Quartzite. Statistics are com piled from 263 samples collected in five miogeoclinal sections. There is a remarkable similarity in the general composition of the cratonal and miogeoclinal quartzites. The variation between individual formations and strati graphic sections may be evaluated from statistical models discussed below. Qualitative differences can be seen from the dominant interbedded siltstones and carbonates in the miogeoclinal sections. Other cement which is almost exclusively hematitic in the cratonal rocks is composed of Figure 16. Photomicrograph of* immature subarkose from the Johnnie Formation in the Winter's Pass section. Sample was collected 10 m below Johnnie oolite. 87 88 0.2mm Figure 17. Photomicrograph, showing micaceous silt-clay laminae (dark) in fine-grained immature quartzarenite sampled within the Johnnie Formation in the Kelso section. 89 £j2mm Figure 18. Contact print of X-radiograph show ing even laminations and vertical burrow in a sample from the Johnnie Formation in the Winter's Pass section (Scale bar 1 cm). 91 92 Figure 19. Contact print of X-radiograph showing laminations and cross-laminations in samples from the Johnnie Formation in the Kelso section (Scale bar 1 cm). 93 4-15 S 4- I 6 D Figure 20. Photomicrograph of mature quartzarenite from the Stirling quartzite in the Winter's Pass section. Note the well- rounded, well-sorted quartz grains with sericite rims defining the detri- tal boundaries. 95 uuuigo 96 Figure 21. Photomicrograph, of* a subarkose sampled from lower Stirling quartzite in the Old Dad Mountain section. Well- rounded and well-sorted quartz. Feld spar altered to sericite in lower right corner. 97 98 0.5mm Figure 22. Contact prints of X-radiographs of samples from the Stirling quartzite in the Winter's Pass section. Sample 9-^2 shows no evident stratification. Feldspar (dark) and quartz (light) display good contrasts. Sample 9-58 shows irregular laminations and re- crystallized quartz veins. Sample 9-59 shows good even laminations, (Scale bar 1 cm). 99 100 S 9:59 D Figure 23. Photomicrograph of subarkose from the Tapeats Sandstone in the Oro Wash section showing granitic rock frag ment . 101 0.5 mm Figure 2h. Photomicrograph of* subarkose from the Stirling-Wood Canyon transition in Winter's Pass section. Sample is conglomeratic with very coarse sand and gravel size clasts of microcline, orthoclase, quartz in a chloritic matrix. 103 ixjuj g*o Figure 25* Photomicrograph of typical sub- .litharenite from the Tapeats Sand stone in the Oro Wash section. Argillaceous clasts (dark) are prominent. 105 106 i ji 0.5mm Figure 26. Contact print of X-radiograph showing cross-laminations, diastems, ripple marks and clay-silt laminae. Sample collected from the Wood Canyon Forma tion in the Providence Mountain section. (Scale bar 1 cm) 107 108 Figure 27. Contact prints of* X-radiograph show ing tabular, planar cross-stratifica tion. Sample collected from Tapeats Sandstone in the Taylor Mine section. (Scale bar 1 cm) 109 110 Figure 28, Contact prints of X-radiographs from ° the Wood Canyon Formation in the Providence Mountain section. Sample 8-47 shows good small-scale, cross lamination and planar lower bounding surfaces. Sample 8-48 shows flaser cross-bedding and erosional lower bounding surface,(Scale bar 1 cm). 111 8 : 4 7 S 8:48 S H H 113 Table 14. Mineral composition of quartzites collected from the Cratonal sections at locations 7f 6, 5» 1 and 3 Mean f o Maximum ° / o Minimum i o Normal Quartz 56.9 89.3 7.6 Undulatory Quartz 12.5 32.3 1.6 Total Quartz* 69.4 92.6 23.0 Orthoclase 2.4 15.3 0.0 Microcline 1.6 6.0 0.0 Plagioclase 0.9 3.6 0.0 Total Feldspar* 4.9 20.0 0.0 Mica 0.4 4.0 0.0 Accessories 0.4 5.6 0.0 Chert 1.0 7.6 0.0 Q.R.F. 3.2 44.0 0.0 Silica cement 7.1 22.7 0.0 Other cement 3.6 51.6 0.0 Matrix 9.0 36.0 0.3 Others** 0.7 15.0 0.0 * Derived variable. ** Includes unstable rock fragments. 114 Table 15. Mineral composition of quartzites collected from the Miogeoclinal sections at locations 8, 4, 12, 9 and 10 Mean io Maximum ° i ° Minimum °/ o . Normal Quartz 58.4 83.3 17.0 Undulatory Quartz 13.4 49.6 0.3 Total Quartz* 71.8 92.3 27.3 Orthoclase 3.0 12.0 0.0 Microcline 1.0 12.6 0.0 Plagioclase 0.7 3.6 0.0 Total Feldspar* 4.7 19.0 0.0 Mica 0.3 4.0 0.0 Accessories 0.3 8.6 0.0 Chert 0.3 15.0 0.0 Q.R.F. 4.3 41.3 0.0 Silica cement 6.0 17.0 0.0 Other cement 1.6 22.3 0.0 Matrix 10.5 63.6 0.0 Others** 0.2 5.6 0.0 * Derived variable. ** Includes unstable rock fragments. 115 calcite in several samples of* miogeoclinal quartzites. Table 16 summarizes data for six sections sampled north of the Teutonia Quartz Monzonite pluton within the Cordilleran frontal thrust belt, whereas Table 17 provides mean mineral composition of four sections analyzed south of this Mesozoic pluton. Although total quartz shows marked similarity, the substantially higher content of undulatory quartz and silica cement in the northern sections can be ascribed to deformational stresses rather than provenance. Sedimentary structures and paleocurrent data (vector mean azimuths) are summarized for each stratigraphic section in Tables 18 and 19. Location of stratigraphic sections in relation to the thrust plates and Teutonia Quartz Monzonite pluton is shown in Figure 29. Composite paleocurrent and elasticity data (Johnnie through Zabriskie Formations) are depicted graphically in Figure 29. Statistical Analysis Normality Testing A prerequisite for many statistical procedures (e.g., analysis of variance and discriminant function analysis) is that each variable is normally distributed. Each variable in each stratigraphic section was tested for normality by means of the chi-square and Kolmogorov- 116 Table 16. Mineral composition of quartzites collected from the northern sections at locations 7, 6, 5, 1, 9, and 10 Mean Maximum Minimum f o i o _ io Normal Quartz 54.2 84.0 7.6 Undulatory Quartz 16.3 49.6 1.3 Total Quartz* 70.5 92.3 23.0 Orthoclase 2.2 15.3 0.0 Microcline 1.5 12.6 0.0 Plagioclase 0.7 3.6 0.0 Total Feldspar* 4.4 20.0 0.0 Mica 0.3 4.0 0.0 Accessories 0.3 8.6 0.0 Chert 0.7 15.0 0.0 Q.R.F. 3.6 44.0 0.0 Silica cement 7.6 22.6 0.0 Other cement 2.5 22.3 0.0 Matrix 9.6 36.0 0.0 Others** 0.6 5.3 0.0 * Derived variable. ** Includes unstable rock fragments 117 Table 17. Mineral composition of quartzites collected from the southern sections at locations 3» 8, 4, and 12 Mean < ? 0 Maximum °k Minimum io Normal Quartz 62.2 89.3 14.6 Undulatory Quartz 8.7 29.6 0.3 Total Quartz* 70.9 92.6 27.3 Orthoclase 3.5 12.0 0.0 Microcline 1.0 6.3 0.0 Plagioclase 0.9 3.6 0.0 Total Feldspar* 5.4 19.0 0.0 Mica 0.4 4.0 0.0 Accessories 0.4 5.6 0.0 Chert 0.5 4.3 0.0 Q.R.F. 4.1 41.3 0.0 Silica cement 5.1 16.3 0.0 Other cement 2.6 51.6 0.0 Matrix 10.0 63.6 0.0 Others** 0.3 15.0 0.0 * Derived variable. ** Includes unstable rock fragments. Table 18. Summary of sedimentary structures (cratonal quartzites) Stratigraphic Section Cross-Stratification (Vector Mean Azimuth) Laminations Massive Other Structures Mesquite Pass(7) Sample size (N = 29) Common (N = 8). Planar, tangential, small-scale. Six westerly, two easter ly trends. (V.M.A. 256°) Dominant (N == 14). Often accentuated by hematite cement. Apparently mas sive (N = 7) but mostly graded Graded bedding. Ripple marks. Taylor Mine(6) (N = 29) Dominant (N = 18). Mostly tabular, grouped, planar, tangential. Bimodal- bipolar (NE-SW). Rare trough cross strata. (V.M.A. 252°) Rare (N = 6) Rare (N = 4) Graded bedding, Scouring, minor channels rip-up clasts, minor faulting. Mountain Pass(5) (N = 25) Rare (N = 4). Tabular, westerly currents. (V.M.A. 292°) Rare (N = 5) Common (N = 15) Graded bedding, minor faulting. H H 00 Table 18. Summary of sedimentary structures (cratonal quartzites) (continued) Stratigraphic Section Cross-Stratification (Vector Mean Azimuth) Laminations Massive Other Structures Oro wash(l) (N - 62) Dominant (N = 28). Mostly tabular, planar, grouped in small-scale sets. Bi- modal at 90°. (V.M.A. 226°) Common, mostly uniform. (N = 22) Rare (N = 12) Ripple marks, channeling, argillaceous rip-up clasts. Marble Mountain(3) (N = 86) Dominant (N = 35), several are obscure. Mostly planar tangential, small - to large-scale. (V.M.A. 343°) Common, often evenly laminated. Common Ripple marks, bioturbation, diasterns, rip- up clasts, mottling. Table 19. Summary of sedimentary structures (miogeoclinal quartzites) Stratigraphic Section Cross-Stratification (Vector Mean Azimuth) Laminations Massive Other Structures Providence Mountain(8) (N « 73) Stirling - Wood Canyon Formations Ubiquitous (N = 49). Commonly tabular, minor trough or wedge-shaped cross-strata. Uni- modal . (V.M.A. 338°) Even laminations often separate cross-strata. Rare Graded bedding. Flaser bedding. Ripple marks. Diastema. Kelso Hills(4) (N = 79) Johnnie Formation Only one sample displays obscure cross-strata. Dominant, some irregular Rare Argillaceous intraclasts, ripple marks. Stirling Quartzite Good tabular, planar, small or large-scale sets, low to moderate angle. Rare Dominant Graded bedding. Diastems. Wood Canyon Formation Common, specially in middle member. Rare Common Flaser bedding, ripple marks, bioturbation Zabriskie Quartzite Low angle cross strata, obscure (V.M.A. 334°) Faint Dominant Bioturbation. Scolithus tubes. H to O Table 19. Summary of sedimentary structures (miogeoclinal quartzites) (continued) Stratigraphic Section Cross-Stratification (Vector Mean Azimuth) Laminations Massive Other Structures Old Dad Mountain(12) (N = 29) (Johnnie-Stirling) Obscure in two samples, northwesterly trends. Dominant Common Ripple marks. Winter's Pass(9) (N = 131) Johnnie Formation Two samples show obscure cross-strata with south east trends. Dominant Rare Ripple marks. Oolitic. Laminated micrites. Stirling Quartzite Rare (N = 7), low angle, accretion Common (N = 14) Dominant (N = 28) Graded bedding. Ripple marks. Wood Canyon Formation Dominant (N = 27). Bimodal, tabular, small to large- scale. Some trough cross-strata. Rare (N = 8) Rare (N - 7) Ripple marks, diastems, grad ed bedding, bio turbation, mud cracks(7). Zabriskie(lO) (N = 12) Obscure Faint lamina tions in few. Dominant H M H Figure 29. Paleocurrent and elasticity data. Location of stratigraphic sections is shown in relation to the Keystone, Mesquite Pass and Winter’s Pass thrust plates and the Teutonia Quartz Monzonite pluton. Composite current roses (Johnnie through Zabriskie Formations) with vector mean azimuths indicated for each section, where data was available. Maximum clast diameter with lithologic unit of occurrence in parentheses. f€^.) Tapeats Sandstone (€ ) Zabriskie Quartzite (€Z ) Wood Canyon Formation (p8s) Stirling Quartzite (PCj) Johnnie Formation 122 123 I KEYSTONE ¥ PLATE MESQUITE ’ PASS PLATE 268 W IN T E R S PASS PLATE 26 6 * a 16 mm WO 21 mm (Ct) 4mnv (CD 29 : 19mm (Ct) 19mm (Ct) . y?TEOTONIA I A vq u a r t z MONZONITE / ' f (MESOZOIC) 3 4 4 * 3 3 8 * 22mm (Pes) 13mm (Cwc) 3 4 3 27 mm 16 km 12 h Smirnov parametric tests (Preston, 1970)• The chi-square test compares the observed data values in a sample with the expected values from an a priori probability model. n p (OBSj - EXP j) j=l EXPj where n - number of class intervals into which data is divided OBSj - frequency of observed data in class j EXPj - frequency of data in class j expected from the model 2 The X statistic in the computer program used corresponds to a pooled minimum expected value of 1.5* The Kolmogorov- Smirnov test is based on the sample of distribution func tion, Fn = (x) where Fn (x) = l/n (number of observations = x) and a value of 0.3 standard deviation was used as a class interval (Preston, 1970). Normal quartz, undulatory quartz, total quartz and silica cement were found to satisfy a normal distribution in each of the stratigraphic sections under study. Analysis of Variance A one-way analysis of variance model was utilized to study the variation of mineral composition for each formation among the stratigraphic sections. The New Duncan Multiple Range test was used to pinpoint the source of variation (Dixon, 1970)* The sample size was esti- X 125 mated on the basis of an 80 percent probability of detect ing a 10 percent difference between two means at the 5 percent level of significance (Sokal and Rohlf, 1969» P» 246). However, only total quartz fell within the range of samples (N = ll) available. Total quartz is also the most reliable variable available in the study in that it is not affected by diagenesis or deformation. Several one-way analysis of variance models were set up. In each case the null hypothesis was that there is no difference among means of the various sample groups considered (i.e., the samples are drawn from parent popu lations with the same mean). The F-ratio in each model refers to the "among sections mean square" divided by "within sections mean square." 1. The null hypothesis was rejected for total quartz in the Johnnie Formation, but the difference is not highly significant (Table 20). (The hypothesis is re jected at the 5 percent level of significance but ac cepted at the 1 percent level.) Two homogeneous subsets are recognized; one includes the Kelso Hills and Winter's Pass sections, whereas the other comprises the Winter's Pass and Old Dad sections. 2. The null hypothesis is rejected for total quartz in the Stirling Quartzite even at the one percent level of significance (Table 2l). The source of variation being the high quartz content in the Old Dad and Winter's 126 Table 20. Statistical analysis of total quartz in the Johnnie Formation A. One-way Analysis of Variance Source of Variation Sum of Squares DF Mean Square F-ratio Among Sections Within Sections Total 9klk.3 9037^.7 99788.9 2 68 70 4707.1 1329.0 3.54* B. Duncan's New Multiple Range Test (°< = 0.05) Rank Section Sample Size Mean 1. Kelso Hills 15 195.5 2. Winter's Pass 31 206.5 3. Old Dad Mountain 25 225.4 Homogeneous Subsets 127 Table 21. Statistical analysis of* total quartz in the Stirling Quartzite A. One-way Analysis of Variance Source of Variation Sum of Squares Mean DF Square F-ratio Among Sections 57041.4 3 19013.8 30.04** Within Sections 68346.6 108 632.8 Total 125387.9 111 B. Duncan's New Multiple Range Test (oC = 0.05) Hank Section Sample Size Mean 1. Kelso Hills 13 184.61^ 2. Providence Mountain 25 199.8 3. Old Dad Mountain 25 225.4 4. Winter's Pass 49 245.3 Homogeneous Subsets 128 Pass sections and the lower quartz content in the Kelso Hills and Providence Mountain sections. There is a marked increase in quartz content in the northerly direction with a corresponding decrease in total feldspar, quartzose rock fragments, chert and matrix. This suggests a mineralogi- cal maturity northwards, possibly related to increased distance from the source of higher energy at the deposi- tional site or a different provenance for the northern and southern locations. A source of error may stem from the fact that the Stirling Quartzite boundaries are not well established in the Kelso Hills and Providence Mountain sections and some of the samples may belong to the Wood Canyon Formation (?). 3. The null hypothesis is rejected for total quartz in the Wood Canyon Formation at the 5 percent significance level. The difference is not highly significant (Table 22). Two homogeneous subsets are recognized, one compris ing the miogeoclinal sections (Providence Mountain, Kelso Hills and Winter's Pass) and the other includes the Winter's Pass and Marble Mountain (Tapeats equivalent to Wood Canyon Formation) sections. There is little varia tion in mineral composition among the miogeoclinal sections with slight increases in total quartz, total feldspar, quartzose rock fragments and chert in the northerly direction and a corresponding decrease in matrix in the same direction. The general uniformity of composi- 129 Table 22• Statistical analysis of total quartz in the Wood Canyon Formation A. One-way Analysis of Variance Source of Variation Sum of Sauares DF Mean Square F-ratio Among Sections 6433.7 3 2144.6 3.50* Within Sections 111395.2 182 612.1 Total 117828.9 185 B. Duncan's New Multiple Range Test (<*= 0.05) Rank Section Sample Size Mean 1. Providence Mountain 25 199.8 2. Kelso Hills 51 203.8 3. Winter's Pass 42 208.3 4. Marble Mountain 68 215.6 Homo gene ou s Subsets 130 tion across this wide region probably reflects effective dispersal of sediment possibly by tidal or longshore cur rents without the presence of barriers which may have inhibited dispersal of sediment during the deposition of the Stirling Quartzite. 4. Total quartz for the Zabriskie Quartzite shows variation within samples but no difference among sections (Table 23). The two sections containing this formation include the Zabriskie section collected within the Mes quite Pass thrust plate and the other is cratonal (?) and includes the upper part of the Tapeats Sandstone in the Marble Mountain section correlative with the Zabriskie Quartzite (Stewart, 1970)• 5. For the Tapeats Sandstone, total quartz shows significant variation in means among the cratonal sections (Table 24). The Taylor Mine, Mountain Pass and Oro Wash sections form one homogeneous subset, whereas the Mesquite Pass and Marble Mountain section form another. The last two mentioned contain supermature quartzites that correspond to the Zabriskie Quartzite, whereas the three other sections located in the central region are characterized by higher matrix, feldspar and mica content and probably better correspond with quartzites of the Wood Canyon Formation (?). Another possible reason for these two homogeneous subsets may be a lower depositional energy and rapid deposition of sediment in the central three sec- 131 Table 23. Statistical analysis of total quartz in the Zabriskie Quartzite * v A. One-way Analysis of Variance Source of Variation Sum of Squares Mean DF Square F-ratio Among Sections 0.0056 1 0.0056 0.00 Within Sections 3499.85 28 124.9 Total 3499.86 29 B. Duncan's New Multiple Range Test (oc= 0.05) Rank Section Sample Size Mean 1. Zabriskie 12 261.92 n Homogeneous 2. Marble Mountain 18 261.94 ▼ Subsets (upper 27 m) 132 Table 24. Statistical analysis of total quartz in the Tapeats Sandstone A, One-way Analysis of Variance Source of Sum of Mean Variation_____________Squares______ DF____Square F-ratio Among Sections 67270.2 4 16817.5 25.82** Within Sections 147191-9 226 651-3 Total 214462.1 230 B. Duncan's New Multiple Range Test (cC= 0.05) Rank Section Sample Size Mean 1. Taylor Mine 29 185-5 2. Mountain Pass 25 191-4 3- Oro Wash 62 194.2 4. Mesquite Pass 29 224.7 5. Marble Mountain 86 225.3 V Homogeneous Subsets 133 tions (probably in a bay?) and higher energy in the two extreme sections which may represent a beach-shelf facies environment with better reworking. Two additional one-way analysis of variance models were considered on a regional scale and utilizing all the samples (N = 494) analyzed in this study, 6, The null hypothesis for no difference is re jected for total quartz between the miogeoclinal (N = 263) and cratonal (N = 23l) sections. However, the difference is not highly significant (Table 25), No homogeneous sub sets were observed. 7, The northern and southern sections are statis tically homogeneous with respect to total quartz (P-ratio = 0,152), The Teutonia quartz monzonite pluton is em ployed to demarcate the Northern and Southern sections. Samples collected at locations 7» 6, 5» 1» 9 and 10 are assigned to the northern sections whereas quartzites col lected at locations 3» 8, 4, and 12 are assigned to the southern sections (Table 26), Discriminant Function Analysis Discriminant function analysis was employed to select variables which are best statistical discriminators among the stratigraphic sections. A classification pro cedure was also adopted to determine how the samples cluster into the various groups considered. Five assump- 134 Table 25* Statistical analysis of total quartz in the cratonal-miogeoclinal samples A. One--way Analysis of Variance Source of Variation Sum of Squares Mean. DF Square F-ratio Between Groups 6515.9 1 6518.9 6.21* Within Groups 516320.4 492 1049.4 Total 522839.3 B. Duncan's New Multiple Range Test (<2C = 0.05) Rank Section Sample Size Mean 1. Cratonal Quartz- 231 208.2 ites 2, Miogeoclinal 263 215.5 Quartzites No homogeneous subset 135 Table 26. Statistical analysis of* total quartz in the northern-southern sections A. One--way Analysis of Variance Source of Variation Sum of Squares Mean DF Square F-ratio Between Groups 161.9 1 161.9 0.15 Within Groups 522676.5 492 1062.3 Total 522838.5 493 B. Duncan's New Multiple Range Test ( oC = 0.05) Rank Section Sample Size Mean 1. Northern sections 2. Southern sections 279 211.6 A Homogeneous 215 212.7 J , Subsets 136 tions concerning the structure of data must be considered before testing the significance of separation of the groups in discriminant function analysis (Davis, 1973). These are: the observations in the groups are randomly chosen, the probability of an unknown observation falling in either group is equal, variables are normally distribut ed within each group, the variance-covariance matrices of the groups are equal in size, and none of the observations used to calculate the function are misclassified. The function, however, is not highly affected by limited departures from normality or limited inequality of vari ances (Davis, 1973). A stepwise discriminant function analysis (BMD07M, Dixon, 1970) was used to assess those variables which are the most effective discriminators. At each step the vari able with the largest P-value is entered into the set of discriminating variables. Discriminant functions and a classification matrix are generated at each step. A final summary for each case includes the posterior probability of coming from each group and the value for the Mahalanobis 2 D statistic from each group. Results of this analysis for all ten stratigraphic sections is summarized in Tables 27, 28, and 29. In the first example (Table 27) twelve measured petrographic variables are considered, but a number of these show mark ed departures from normality (especially orthoclase, 137 Table 27. Stepwise discriminant function analysis (12 variables) Step No. A. Summary Table Variable F Value Entered to Enter No. of Variables U- Statistic 1. Undulatory Quartz 29.82 1 0.64 2. Orthoclase 21.72 2 0.46 3. Microcline 27.10 3 0.30 4. Normal Quartz 18.87 4 0.22 5. Silica Cement 18.24 5 0.16 6. Matrix 9.81 6 0.14 7. ORF 10.00 7 0.12 8. Plagioclase 7.28 8 0.10 9. Chert 3.67 9 0.09 10. Other Cement 3.65 10 0.09 11. Accessory Min. 3.57 11 0.08 12. Mica 3.27 12 0.08 B. Classification Matrix Locations 7 6 5 1 3 8 4 12 9 10 7 18 0 0 0 7 0 0 3 0 1 6 0 28 0 1 0 0 0 0 0 0 5 2 2 15 0 0 0 1 0 5 0 1 1 14 0 42 2 0 1 0 2 0 3 8 0 2 0 51 2 1 2 2 18 8 0 0 1 0 1 20 2 0 0 1 4 6 0 8 3 2 7 38 6 3 6 12 0 0 1 0 0 2 2 16 1 3 9 1 5 11 4 8 7 5 15 52 14 10 0 0 0 0 0 0 0 0 0 12 138 Table 28* Stepwise discriminant function analysis (9 variables) A. Summary Table Step Variable F Value No. of U- No. Entered to Enter Variables Statistic 1. Total Quartz 18.86 1 0.74 2. Silica Cement 23.18 2 0.52 3. Matrix 12.97 3 0.42 4. QRF 10.35 4 0.35 5. Total Feldspar 7.95 5 0.30 6. Chert 3.94 6 0.28 7. Other Cement 4.44 7 0.26 8. Mica 3.07 8 0.25 9. Accessory Min. 3.17 9 0.23 B. Classification Matrix Locations 7 6 5 1 3 8 4 12 9 10 7 12 0 4 1 5 0 0 2 4 1 6 0 27 0 2 0 0 0 0 0 0 5 3 2 16 0 1 2 0 0 0 1 1 4 17 2 29 3 1 3 0 3 0 3 11 0 4 0 46 3 0 3 2 17 8 1 0 0 0 1 18 2 0 2 1 4 3 6 6 11 1 5 25 0 6 6 12 0 0 1 0 0 2 1 15 2 4 9 7 1 5 14 6 11 7 29 15 27 10 0 0 0 0 0 0 0 0 0 12 139 Table 29. Stepwise discriminant function analysis (7 variables) Step No. A. Summary Table Variable F Value Entered to Enter No. of Variables U- Statistic 1. Total Quartz 18.86** 1 0.74 2. Total Feldspar 13.36** 2 0.59 3. Chert 6.29** 3 0.53 4. QRF 6.34** 4 0.47 5. Matrix 8.95** 5 0.61 6. Mica 5.67** 6 0.37 7. Accessory Min. 4.76** F .95 (8,484) = 1.88 F .99 (9,486) = 2.41 B. Classification Matrix 7 0.34 Locations 7 6 5 1 3 8 4 12 9 10 7 16 0 0 0 5 0 0 2 5 1 6 0 27 0 2 0 0 0 0 0 0 5 4 2 10 0 2 2 1 0 4 0 1 1 21 1 11 9 0 2 0 1 0 3 21 3 3 5 23 3 1 4 6 17 8 1 0 1 2 2 15 2 1 0 1 4 5 2 13 4 4 9 16 10 10 6 12 0 0 2 0 0 2 1 JL5 1 4 9 9 3 10 8 6 10 5 30 13 28 10 0 0 0 0 0 0 0 0 0 12 140 microcline, plagioclase, mica, accessory minerals, chert and other cement). Moreover, undulatory quartz in some sections is formed through post-depositional stresses and is not always a primary detrital characteristic. The second example, with nine variables (Table 28) minimizes the error as it considers the variable total quartz and furthermore total feldspar is either normal or near normal in its distribution for each stratigraphic section. The third example (Table 29) considers only the detrital components and thus relates better to depositional history without much concern for diagenetic changes. The source of error in this case is matrix, which is partly detrital and partly secondary alteration of feldspars. The sample clusters of the individual stratigraphic sections and the effectiveness of certain variables as discriminators is evident. Based on these results and on the assumptions to test the significance of the discriminant functions, four variables (total quartz, total feldspar, silica cement and matrix) were considered in further analysis employing two groups at a time. Linear functions were computed employing a program (BMDO^M, Dixon, 1970) taking two groups at a time. The output included discriminant function coefficients, the 2 Mahalanobis D statistic (distance between the two multi variate means) and the associated F-statistic. The null hypothesis tested by this statistic is that two multi- Ikl variate means are equal or that the distance (d ) between them is zero. Thus, if* the two groups have very similar mean values, discrimination will be difficult especially if the dispersion of each group is large. On the other hand, discrimination is facilitated if the two means are far apart and the scatter about the means is small. Table 30 summarizes the results for the cratonal (N = 23l) versus miogeoclinal (N = 263) quartzites using four variables: total quartz, total feldspar, silica cement and matrix. There is significant difference be tween the two groups with the four variables taken to gether. Hence there is compositional difference between the cratonal and miogeoclinal quartzites of Eocambrian- Cambrian age. The difference is not highly significant for total quartz between the cratonic and miogeoclinal quartz ites and there is no difference between the two groups with respect to total feldspar, or total feldspar and matrix taken together. The second pair of groups considered are the sections located to north and south of Teutonia Quartz Monzonite (Table 3l)» The southern facies (collected at locations 3» 8, 4, and 12) were not described until Stewart (1970) found correlative units with Precambrian- Cambrian strata to the north. Northern facies in this test include samples collected at locations 7* 6, 5» 1» 9 and 10. There is no significant difference in the total 142 Table 30. Tests of significance for two-group dis criminant function analysis Group X: Cratonal samples (N = 23l) Group XI: Miogeoclinal samples (N = 263) Variables 1. Total quartz, total feld spar, silica cement, matrix 2. Total quartz 3. Total feldspar 4. Total quartz, silica cement 5. Total feldspar, matrix 2 Mahalonobis D_____F-ratio 0.29 9.01** 0.05 6.21** 0.01 0.71 0.13 8.25** 0.03 1.79 143 Table 31* Tests of significance for two-group dis criminant function analysis Group I. Samples from six northern sections (N = 279) Group IX. Samples from four southern sections (N = 215) Variables 1. Total quartz, total feld spar, silica cement, matrix 2. Total quartz 3. Total feldspar 4. Total quartz and silica cement 5. Total feldspar, matrix 2 Mahalonobis D_____F-ratio 0.47 14.08** 0.00 0.15 0.09 10.75** 0.4l 24.53** 0.09 5.84 l kb quartz content of the two groups, but all other variables are highly significant especially total feldspar, and total quartz and silica cement. The cratonal units were also compared with Johnnie Formation, Stirling Quartzite and Wood Canyon Formation (Table 32). Total quartz cannot be used to discriminate between the cratonal quartzites (Tapeats Sandstone) and the Johnnie Formation or the Wood Canyon Formation, but the difference is highly significant between the Tapeats Sandstone and the Stirling Quartzite. Total feldspar is not useful in distinguishing one group from another but taken along with matrix may distinguish the cratonal units from the Johnnie Formation, The cratonal quartzites and the Wood Canyon Formation are indistinguishable with re spect to all four variables if the Zabriskie Quartzite equivalent samples of the Tapeats Sandstone (upper 18 samples in the Marble Mountain section) are not used in the analysis. The Winter’s Pass section has the best strati graphic correlation and sufficient sample size to warrant significant discriminant coefficients to separate the Johnnie Formation, Stirling Quartzite and Wood Canyon Formations (Table 33)• Distinction between the Johnnie and Wood Canyon Formations is not possible on the basis of total quartz, but discrimination is relatively easy be tween the Johnnie Formation and Stirling Quartzite or the 145 Table 32* Tests of significance for two-group dis criminant function analyses A. I. Tapeats Sandstone (N = 231) Variables 1. Total quartz, total feld spar, silica cement, matrix 2. Total quartz 3. Total feldspar 4. Total quartz, silica cement 5. Total feldspar, matrix B. I* Tapeats Sandstone (N = 231) Variables 1. Total quartz, total feld spar, silica cement, matrix 2. Total quartz 3. Total feldspar 4. Total quartz, silica cement 5. Total feldspar, matrix IX, Johnnie Formation (N = 71) Mahalanobis D 0.69 0.01 0.01 0.18 0.19 F-ratio 9.3** 0.36 0.22 4.95** 5.26** II. Stirling Quartzite (N = 112) Mahalanobis D 0.89 0.24 0.00 0.48 0.01 F-ratio 16.6** 18.07** 0.01 18.34 0.31 146 Table 32. Tests of significance for two-group dis criminant function analyses (continued) C. I. Tapeats Sandstone II. Wood Canyon Formation (N = 231) (N = 118) 2 Variables Mahalanobis D F-ratio 1. Total quartz, total feld spar, silica cement, matrix 0.13 2.59 2. Total quartz 0.00 O.89 3. Total feldspar 0.27 2.07 4. Total quartz, silica cement 0.04 1.85 5. Total feldspar, matrix 0.10 4.07 Table 33. Tests of significance for two-group discriminant function analysis of Winter's Pass section A B C Variables D2 F-ratio D2 F-ratio D2 F-ratio 1. Total quartz, total feldspar, silica cement, matrix 3.06 13.97** 1.2 5.27** 4.8 26.1** 2. Total quartz 2.16 41.03** 0.00 0.08 3.64 82.5** 3. Total feldspar 0.04 O.76 0.87 15.4** 0.34 7.8** 4. Total quartz, silica cement 2.25 21.15** 0.22 1.96 4.1 45.8** 5. Total feldspar, matrix 0.96 9.04 1.05 9.3** O.65 7.35** Groups: A - I. B - I. C - I. (N = 3l)• II# Stirling Quartzite (N = 49)# (N = Johnnie Formation Johnnie Formation (n = 3l). II# Wood Canyon Formation (N = 42). Stirling Quartzite (N = 49). II# Wood Canyon Formation (N = 42), H ■ P - -a Ik8 Wood Canyon Formation and Stirling Quartzite, Total feld spar serves to distinguish between the Johnnie-Wood Canyon or the Stirling-Wood Canyon formations but not the Johnnie- Stirling formations. All three formations can be dis criminated when all four variables are considered together. In the Marble Mountain section the two stratigraphic clusters determined from a dendrogram were found to be staitstically significant (Table 3*0 • 149 Table 3^. Tests of* significance for two-group dis criminant function analysis Marble Mountain Section (Dendrogram clusters) Group I. Samples 1 through 67 excluding samples 1, 26, 53f 66. Tapeats Sandstone equivalent to Wood Canyon Formation. Group XI. Samples 68 through 86 (upper 27 m) Tapeats Sandstone equivalent to Zabriskie Quartzite Variables Mahalanobis D F-ratio 1. Total quartz, total feld spar, silica cement, matrix 2. Total quartz 3. Total feldspar 13.7 6.78 9.22 48.2** 48.9** 66.5** DISCUSSION OF RESULTS Classification of Quartzites Classification is based on the volume of con stituents determined by the petrographic modal analysis. The choise of end members is based on the classification of sandstones proposed by McBride (1963) and Blatt, Middle ton and Murray (1972). The Q-pole comprises total quartz, quartzose rock fragments (polycrystalline quartz, ortho- quartzite and metaquartzite) and chert. The F-pole is es sentially total feldspar and also includes granitic rock fragments (aggregates of feldspar and quartz). The R-pole includes all other (unstable) rock fragments (shale, slate, schist, volcanics, etc.). Thus, the common stable frame work constituents (detrital silica) are grouped in one pole indicating the end products of weathering and abrasion and the two poles of unstable components (feldspar and unstable rock fragments). The types of quartzites present in each section are summarized in Table 35* It can be seen that 60 percent of the cratonal quartzites are subarkoses, 39 percent are quartzarenites, and 1 percent are sublitharenites. Ap proximately 52 percent of the miogeoclinal samples are sub- 150 151 arkoses and 48 percent are quartzarenites. In the Winter's Pass section 58 percent of the quartzites in the Johnnie Formation are immature quartzarenites. The lower Stirling Quartzite is predominantly subarkosic in composition, whereas the upper Stirling is almost exclusively made up of mature quartzarenites. The Wood Canyon Formation is predominantly subarkosic, whereas the Zabriskie Quartzite exclusively consists of mature quartzarenites. The northern sections (at locations 7» 6, 5# 1» 9» and 10) taken together also display a similar distribution, being more subarkosic (53 percent of samples) than quartz arenites (46 percent) with 1 percent of sublitharenites. In the southern sections (locations 3» 8, 4, and 12) the spread is more pronounced with 59 percent of the samples being subarkosic, 40 percent quartzarenites and 1 percent of sublitharenites. The rarity of sublitharenites reflects the maturity of the quartzites being devoid of unstable rock fragments. Argillaceous clasts of shale, argillite and some mica schists are the only recognized unstable rock fragments, and these are sparsely distributed in the samples under study. However, the subarkosic nature of the rocks may infer mineralogical immaturity. The high feldspar content is related to the source area and rapid deposition. Some samples with almost rectangular feldspar clasts suggest a proximal source. Supermature quartzarenites, on the other Figure 30. Ternary diagram depicting classifica tion of cratonal quartzites(c) and miogeoclinal quartzites (M). Classi fication after Blatt, Middleton and Murray (1972). 152 153 Q QUARTZAREN ITE SUBLITHARENITE SUBARKOSE .25 25, 50 Figure 31* Ternary diagram depicting classifica tion of quartzitesassigned to the Johnnie Formation (j), Stirling quartz ite (s) and Wood Canyon Formation (w). sampled in the Winter's Pass section. 15k 155 Q ,QUARTZARE NITE SUBARKOSE 23, 10 50 156 Table 35* Classification of quartzites Stratigraphic samples classified as: Total Quartz Sub- Sublith Sample Section arenites arkoses arenites Size Percent Percent Percent Cratonal Mesquite Pass 17 83 0 29 Taylor Mine 83 17 0 29 Mountain Pass 28 72 0 25 Oro Wash 39 6o 1 62 Marble Mountain 35 63 2 86 Cratonal samples 39 6o 1 231 Miogeoclinal Providence Mountain 84 16 0 25 Kelso Hills 37 62 1 79 Old Dad Mountain 24 76 0 25 Winter's Pass 47 53 0 122 Zabriskie 100 0 0 12 Miogeoclinal samples 48 52 0 263 Winter's Pass Johnnie Formation 58 42 0 31 Stirling Quartzite 59 4l 0 49 Wood Canyon For mation 24 76 0 42 Northern sections 46 53 1 279 Southern sections 40 59 1 215 157 hand, are also texturally mature with well-rounded grains, good sorting, and lack of detrital matrix. Mineralogical Maturity and Provenance Monocrystalline quartz is the most dominant mineral constituent but has little significance in determining specific provenance. Presence of distinct mineral inclu sions of zircon, apatite, mica, tourmaline in quartz are characteristic of magmatic rocks but could also be present in quartz grains derived from gneisses and schists. Few quartz grains in the section showed inclusions of vermi cular chlorite suggesting a hydrothermal source. Clasts of milky quartz, rose quartz and chalcedony are possibly derived from silica veins. Monocrystalline quartz is dominantly nonundulatory and thermodynamically more stable than undulatory quartz which has a greater dislocation density (Cotrell, 1961), Undulose extinction in quartz is probably more useful in understanding sediment history rather than provenance. Blatt (1963) showed that there is no way of distinguishing between quartz grains from plutonic igneous rocks, schists and gneisses. He reported that less than 15 per cent of quartz was nonundulatory in 101 rocks with no sig nificant difference among the three rock groups. Quartz in extrusive rocks was predominantly nonundulatory, but these rocks supply little quartz to the sedimentary cycle and the 158 presence of associated rock fragments and zoned plagio- clase is required to confirm a volcanic source. No such, evidence is suggested in the present study. Thus the source of quartz on the basis of undulatory extinction is not war ranted. Furthermore, strain in quartz may be induced by structural deformation after lithification (Bailey, Bell and Peng, 1958). This is well evidenced in some of the northern sections where excessive quantities of undulatory quartz occurs in close proximity to thrust faults (e.g., Mountain Pass section) or on thrust plates carried from depths (e.g., Winter's Pass section). Undulatory quartz in the southern sections is probably chiefly of detrital origin, since there is no evidence of deformation in this region. Rock fragments present in the quartzite samples are predominantly quartzose. Polycrystalline quartz grains of plutonic derivation are formed of only 2 to 5 quartz crystals whereas similar grains from gneisses are made up of more than five crystals (Blatt, Middleton and Murray, 1972). Quartz crystals in schistose polycrystal line quartz are reported to be intermediate between granitic and gneissic quartz. Metamorphic polycrystal line quartz is also characterized by elongate and crystal- lographically oriented crystals, and their grain size dis tribution is frequently bimodal (Blatt, Middleton and 159 Murray, 1972). Recognition of granitic fragments is made easier by the presence of feldspar and mica. Ortho- quartzites are made up of cemented quartz grains derived from older sediments and metaquartzites are recognized by suture borders and strained grains. All of the above rock fragments occur in varying proportions, but the most abundant fragments are polycrystalline quartz grains of granitic or gneissic derivation. Chert (microgranular quartz) is detrital and is characteristic of reworked sediments. Barring post-depositional deformation, relative amounts of detrital quartz could throw light on the maturity of the sediment. The stability among these minerals in the decreasing order is normal quartz, undulat ory quartz, polycrystalline quartz (quartzose rock frag ments), and chert (Blatt, 1963)* R-mode dendrograph clusters support this relationship (Figs. 7» 10). Thus, an increasing proportion of nonundulatory quartz as is seen in supermature orthoquartzites is probably related to the sedimentary history of abrasion rather than provenance. The relative abundance of feldspars in a sediment is related to the availability in the source area, maturity of the sediment and diagenetic processes at the site of deposition. Next to quartz, feldspars form the most important detrital components. Feldspar clasts are almost ubiquitous, being absent only in the supermature quartzites of the upper Stirling and Zabriskie Quartzites. Orthoclase is the most abundant feldspar and is frequently highly altered. Microcline is commonly fresh and rounded. Granule- and pebble-sized clasts of microcline occur in the conglomeratic horizons of the Wood Canyon Formation in the Winter's Pass section and suggest a pegmatitic deriva tion. Plagioclase is the least abundant of the feldspars and is dominantly sodic in composition. Although several samples did display authigenic feldspar and overgrowths, most of the feldspar encountered in the modal analysis is detrital. Detrital clasts, identifiable only as feldspar ghosts, are frequently altered to kaolinite and sericite matrix. Stewart (1970) reports that feldspar tends to be concentrated in finer grained sediments on account of its high susceptibility to breakage. Lobo (1972) and in the present study noted feldspar accumulation is relat ed to the maturity of the sediment and is found in coarse- as well as fine-grained sediments. The apparent size difference between quartz and feldspar was also not pro nounced (Quartz X = 1.16 0, Feldspar X = 1.48 0). Micro cline and dominantly sodic plagioclase suggest plutonic, acid igneous source rocks. An average of 5 percent feld spar in both the cratonal and miogeoclinal quartzites indicates a mineralogically mature sediment. If the source area, is dominantly granitic or gneissic rocks, as much as 60 percent of the sediment supplied might be feldspar. l6l Some of the highly weathered feldspar may be derived from older sedimentary source, but it could also be due to diagenetic alteration. Accessory or heavy minerals may be useful in recog nizing parastratigraphic units. In the present study they are sparsely distributed and include magnetite, zircon, tourmaline, hematite, pyrite, rutile, monazite. Magnetite is the most prominent accessory mineral frequently segre gated along fine laminae and may constitute as much as 8 percent of the volume. Other opaque minerals are rare. Hematite cubes (pseudomorphous after pyrite?) are occa sionally seen especially in the Kelso Hills, Old Dad Mountain and Providence Mountain sections. They are often concentrated along veins and are probably diagenetic. Hence no environmental significance may be attached to their occurrence. One sample showed brass yellow pyrite in the Providence Mountain section, which may suggest a restricted environment. The composition and nature of the crystalline rocks cannot be ascertained from the identifi cation of opaque minerals encountered in the study. Zircon and tourmaline, the ultrastable accessory minerals, are the most dominant nonopaque minerals. Zircon is color less, elongate and rounded, occurring in traces in most of the stratigraphic sections. Tourmaline displays more variegated colors including blue, green and yellow. It is particularly characteristic of the Johnnie and Stirling 162 formations in the Winter's Pass section. Blatt, Middleton and Murray (1972) report that yellow-brown (dravites) are almost exclusively derived from metamorphic rocks, whereas other colors are most common in granites or pegmatites. Rutile and monazite(?) are extremely rare. There is no evidence of heavy minerals such as garnet, staurolite, sil- limanite and kyanite which are characteristic of high grade metamorphic rocks. No hornblende, pyroxene or detrital epidote were reported. Muscovite mica was especially noted in quartzites collected in proximity to siltstones. There is no evidence of detrital biotite or other micas. Unstable rock frag ments limited to siltstones, shales, argillites and mica schists are extremely rare. The argillaceous fragments are often intraclasts ripped up by currents and deposited near by. There is some evidence of volcanic rock fragments. Unstable rock fragments are obviously destroyed more easily than feldspars by sedimentary processes whereas the detrital silica group is the most stable. The quartz ites in this study range from submature (parts of Johnnie Formation, Wood Canyon Formation and lower Stirling) to supermature (upper Stirling and Zabriskie Quartzites). The sediments are derived from granitic and gneissic rocks as well as older sedimentary rocks. The source area is the Precambrian craton to the east and perhaps the southeast, based on paleocurrent directions (Fig. 16) and decreasing elasticity and better sorting and reworking with increased distance from the source. Depositional Environments Reconstruction of paleoenvironments for sedimentary quartzites poses problems; however, the major problem is the paucity of paleontological control. Other important factors include limited exposures of the strata under study, structural complications which make palinspastic reconstructions of the sedimentary units difficult, and diagenetic and metamorphic changes. Great reliance has been placed on lithology, primary sedimentary structures and stratigraphy. Paleontological Evidence Fossil evidence in the present study suggests a shallow marine environment, perhaps nearshore. Paleont ological evidence is mainly restricted to trace fossils— bioturbation and Scolithus(?) tubes— which are observed in the middle Wood Canyon and younger strata. Possible algal structures (?) and burrowing are present in the Johnnie Formation in the Winter's Pass section. Stewart (1970) reports the occurrence of trilobites, brachiopods and other marine and brackish water forms in siltstones, shale and carbonate strata in the upper part of the late Pre- cambrian-Cambrian sequence described by him. He also re 164 ports finding carbonate trilobite fragments and pelmatazoan debris in quartzites of the Upper Wood Canyon in the Spring Mountains, just north of the present study area. Mineralogical Evidence Although clastic deposits reflect to a large extent the source area supplying the material, inferences can be made for the wave or current energy operative at the site of deposition. Petrographic analysis showed the quartz ites to be mineralogically submature to supermature. Quartzites assigned to the Johnnie Formation are dominant ly immature quartzarenites with detrital matrix and mica filling interstices or occurring as fine laminae deposited during stillstands below wave base. The lack of detrital matrix and mica in the upper Stirling and Zabriskie Quartz ites suggests higher wave or current energy at the de- positional site. The Wood Canyon is dominantly subarkosic in composition, but feldspar content (mean 6 percent) may also imply limited mineral maturity if the source is dominantly granitic or gneissic supplying as much as 60 percent feldspar. Decline in feldspar may be related to efficiency of the environment or distance from the source. Rapid deposition without much action of the shoreline processes favors an immature to submature deposit whereas sediments which have experienced the full effects of the surf zone before deposition offshore will tend to be mineralogically mature. Glauconite and phosphorite may also suggest a marine environment. Glauconite forms at water depths between 30 and 880 m whereas optimum conditions for phosphorite pre cipitation occurs in shallow warm water between depths ranging from 30 and 300 m (Heckel, 1972). Both these minerals are rare. Their scarcity may be a consequence of destruction in a nearshore high energy environment during regressional episodes. Kukal (l97l) reports that glau conite in recent sediments is confined mainly to the central and outer parts of the continental shelf region, which are characterized by slow deposition or nonsedimenta tion. A chlorite-illite matrix is suggestive of a marine rather than a nonmarine environment. The presence of interbedded carbonates, calcite cement in the quartzites also may suggest possible marine conditions of deposition. The quantity of heavy minerals and the difference in size of the light and heavy fractions may be useful in distinguishing ancient sedimentary environments (Kukal, 1971)• The difference in grain size between the two fractions is less if the density of the transporting medium and sedimentation environment is low. Heavy minerals in this study are generally of silt-size of fine sand size and contrast with medium- to coarse-grained quartz which implies an aqueous rather than eolian deposition. 166 Textural Evidence Detailed quantitative textural analyses were not carried out. A pilot study (Lobo, 1972) showed the quartz ites to be submature to supermature. Improved sorting was related to fining of sediment upwards in the cratonal quartzites whereas poorer sorting was associated with in crease in matrix, mica and argillaceous rock fragments and possibly related to textural inversions or changes in paleocurrent directions. Quartzites assigned to the Johnnie Formation are dominantly fine-grained and moderate ly sorted with high detrital matrix. Quartzites assigned to Stirling Quartzite are composed of mostly medium- to coarse-grained quartzose sediment with little or no detrital matrix. They also display good sorting which sug gests a depositional site of high energy and excellent re working. The same characteristics may be applied to the supermature quartzites assigned to the Zabriskie Quartzite. The quartzites assigned to the Wood Canyon Formation are moderately well sorted and consist of medium- to coarse grained sand. Argillaceous intraclasts and mica are com mon in the Wood Canyon Formation. Roundness of quartz ranges from subangular to subrounded in the Johnnie and Wood Canyon Formations, to well-rounded in the Stirling and Zabriskie Quartzites. The apparent maximum grain diameter (elasticity) was determined for each sample and its vertical and areal variations were investigated for each formation. The fol lowing general trends are evident. The Johnnie Formation shows fining upwards suggesting a transgressive sequence or possible change from open marine to restricted marine. Coarsening upwards in the Stirling Quartzite suggests pro grading shelf and beach sands or perhaps barrier islands and bars migrating seaward. Coarse gravel size fragments which include large clasts of feldspar in the Stirling- Wood Canyon transition possibly represent relict sediments or lag deposits during Stirling regression, elasticity within the Wood Canyon shows considerable fluctuations indicating periodic influx of coarse detritus, but shows a general fining upwards. The Zabriskie Quartzite also shows slight fining upwards, but data is not sufficient to warrant any significant conclusions. Best evidence for variation in elasticity within the Johnnie, Stirling and Wood Canyon Formations can be seen in time-trend plots for the Winter’s Pass section where the formational boundaries are well defined (Fig, 15)• Sedimentary Structures Sedimentary structures commonly observed in the quartzites under study include cross-stratification, even or irregular laminations and the absence of stratification (massive quartzites). Structures more rarely seen are ripple marked surfaces, normal graded bedding, bioturba- tion, flaser bedding and diastemic surfaces. Cross stratification is perhaps the most useful in ascertaining the nature of depositional environments and basin analysis. The character of the cross-stratification varies, but most commonly is tabular, grouped into small-scale sets with the lower bounding surface planar and nonerosional. They can be classified mainly as mu- or omicron-cross-stratification (Allen, 1963a). The foresets are either discordant or tangential, depending on the grain size. The maximum foreset dip varies from less than 10° to almost 30°. Coarse sand and gravel have steeper foreset dips than fine grained rocks. The lithology of the cross-strata is com monly homogeneous, but occasionally accentuated by heavy minerals or silty laminae. In many cross-laminated units, the foreset strata are steeper near the top, but the con tact with the lower bounding surface may be asymptotic. Low angle, tabular or wedge shaped cross-strata are re ported to be common in the nearshore marine environment, particularly in beach accretion deposits (Conybeare and Crook, 1971) • Both high angle avalanche and low angle accretion cross-bedding were observed. The former are more common in the Wood Canyon Formation, whereas the latter are more common in the Stirling Quartzite and the Zabriskie Quartzite. Moderate- to high-angle tabular cross-strata may be characteristic of migrating sand waves or longshore 169 bars or tidal bars in a marine environment. The inclina tion varies directly with grain size. Such cross-strata have been well described in tide dominated shelves (Narayan, 1971; Klein, 1970)• Migration is by avalanching in the direction of" foreset inclination. Nonmarine deposits that may show tabular, planar cross-bedding of“ moderate angle include delta foresets and alluvial point bar deposits (Heckel, 1972). Trough festoon cross beds are rarely encountered in this study and may represent spill over lobes or backshore beach or tidal and alluvial chan nels (Heckel, 1972). No definite criteria are available to relate geometry of cross-bedding to unique depositional environments. They are useful in deciphering paleo- currents and paleogeography (Pettijohn, Potter and Sevier, 1972, p. 112). Evenly laminated sands may originate due to dif ferences in composition or texture. Thompson (1937) related evenly laminated sands with beach foreshore and Allen (1963b) related laminations in sandstone with upper flow regimes which may be reached in the swash-backwash region of a beach environment. Such laminated sands will, however, be mature with fine-grained material winnowed out. Laminations can be found wherever there is intermittent deposition or changes in provenance or velocity of trans porting agent without considerable organic activity. The Johnnie Formation commonly shows sand with interstitial 170 silty matrix and laminae, which probably formed below surf base where fine sand and silt is carried in suspension and deposited. The laminations in these rocks are accentuated by composition difference chiefly the amount of matrix. Laminations in samples assigned to the Stirling Quartzite are characteristic of beach deposits. Massive quartzites can also be part of the shelf facies. Lack of structure may be a function of homogeneity due to uniform mineral composition. Supermature beach or barrier quartz sand may display an absence of cross- stratification or lamination. Massive units with graded bedding may be generated by processes of short duration such as floods, storms and spring tides. Goldring and Bridges (1973) describe sublittoral sheet sandstones that may be caused by storms, tsunami, floods, rips or turbid ity currents. They describe recent sediments in the North Sea and Gulf coast (off Texas) with such characteristics. The absence of lamination is probably due to lack of traction and possibly very rapid deposition from suspension. Ripple marks infer movement of fluid and can be found in several environments including marine, littoral, fluvial and aeolian. Flaser and lenticular bedding seen only in a few samples in the Upper Wood Canyon Formation are typical of intertidal flats (Reineck, 1972), whereas mud cracks and runzel marks are characteristic of emergent conditions. 171 Considering the sedimentary structures along with mineralogy, texture, trace fossils and interbedded carbon ates and siltstones of the formations, a shallow marine shelf which varied from open to restricted. Deposits are dominantly subtidal and more rarely intertidal. Sub environments include barrier bars and beaches, lagoonal, tidal channels and possibly intertidal flats. A discus sion of depositional history with models is further elaborated, Depositional History Older sedimentary sequences in the southern Great Basin include the Crystal Spring Formation, Beck Spring Dolomite and Kingston Peak Formation which are not ex posed in the area under study, and Noonday Dolomite (Table 2). The Noonday Dolomite in the Winter's Pass section rests unconformably on Precambrian granite gneiss. The lower part is reported to be algal whereas the upper part is sandy with detrital grains of quartz common (Stewart, 1970). The contact with the overlying Johnnie Formation is not sharp but transitional with an increasing clastic influx upwards and possibly represents prograding sands. The base of the Johnnie in this study is the low est massive conglomeratic unit in the transitional zone. Depositional history may be best inferred from the Winter's Pass section, where a complete section with well-defined Figure 32. Depositional model for the Johnnie Formation. 172 JOHNNIE FORMATION 1 . «S * n— r. • .% i • < * • V. V ______l | . ', ^ v* ,'„ > 2 , ■ ■ •* OOLITE 3 T - OPEN MARINE SILTS SILTY SANDY S IL T Y PROGRADING CARBONATE S IL T S SANDS SHELF SANDS (P A R T IA L L Y R E ST R IC T E D ) CONGLOMERATIC SANDS 17^ formational boundaries is measured. The Johnnie Formation provides an example of a fining upward sequence. The basal 10 feet are conglomeratic quartzites with clasts up to 15 mm diameter, suggesting a nearshore or beach deposition possible. The next 6 m consist of poorly sorted, medium- to coarse-grained sands followed by well-sorted to bimodal prograding shelf sands dominantly laminated with some low angle cross-laminations. Reworking has enriched the quartz content and rounded grains are common. The fining upwards sequence which may be suggestive of deepening con ditions is accompanied by interbedded siltstones and carbonates. The quartzites also display an increase in calcite cement and detrital matrix and mica (Figs, l4, 15). The siltstones are probably open marine silts, whereas the silty carbonates and silty quartzites may be deposited in a partially restricted environment with the development of an oolitic or carbonate barrier perhaps near the structural hinge(?). The Johnnie Oolite possibly repre sents this migrating barrier, which coalesced to form a platform deposit. Quartzarenites between the siltstones and carbonates may represent local prograding shelf sand or storm deposits or inter bar deposits. Deposition of the Johnnie Oolite was followed by deposition of siltstones, silty quartzites and silty carbonates, followed by a re gression that continues into the overlying Stirling Quartz ite. Figure 33* Depositional model for the Stirling Quartzite. 175 STIRLING QUARTZITE O F FSH O R E SA N D S CARBONATE SILTS SILTY SANDS BARRIER SILTS C O N G L O M E R A T I C b e a c h or s a n d s BAR SANDS (P R O G R A D IN G ) H ON 177 During the deposition of* Johnnie Oolite and associ ated carbonates and siltstones, there may have been a sand barrier or bar which cut off* terrigenous influx to the offshore areas. The change in lithology at the base of the Stirling Formation may reflect the destruction of the barrier with a corresponding influx of mature well-sorted and well-rounded quartz sand. Massive bedding is very com mon, whereas low angle accretion bedding and laminations are more rare. The depositional energy was relatively high as reflected by the excellent sorting, good rounding and high quartz content. This increasing textural and mineral maturity is also accompanied by a general coarsening up wards sequence suggestive of a general regression or pro grading barrier bars/beaches. Some of the interbedded siltstones may be lagoonal. The Food Canyon Formation marks another transgres- sive episode with several conglomeratic horizons near the base followed by gradual fining upwards. The sands are poor to moderately well sorted and subrounded. Short per iod fluctuations are common within the Food Canyon Forma tion. Feldspar and quartzose rock fragments (dominantly granitic) are common. Argillaceous clasts occasionally occur. Sedimentary structures include bimodal cross bedding, numerous diastems, ripple marks, and rare flaser bedding bioturbation and mudcracks. Mineral and textural immaturity of the sediments indicates rapid deposition and a high terrigenous influx possibly due to uplift in the Figure 3^» Depositional model for the Wood Canyon Formation. 178 WOOD CANYON FORMATION S I L T S SIL T Y SANDS CARBONATE s_... .->^V*V"— "" CO N G LO M ER A TIC S H E L F SANDS SA ND S 179 180 source area or more probably incorporation of alluvial and coastal plain deposits without sufficient reworking. The Zabriskie Quartzite collected in the Mesquite Pass plate (Burchfiel and Davis, 1971) consists of super- mature arenites possibly reworked in a stable shelf environ ment. There is a slight fining upwards in this formation, which may reflect deepening conditions with the sediment passing through the surf filter before deposition offshore. Stewart (1970) suggests two hypotheses to explain the environment of deposition of upper Precambrian and low er Cambrian strata in the southern Great Basin. The first proposes a nearshore marine environment with repeated trans gression and regression of the sea, whereas the second sug gests an open-ocean environment with the shoreline far to the east. Stewart (1970) favors the latter hypothesis from the general uniformity of strata and their time-conformable relationships. His open ocean sedimentary model combines a north-south depositional strike and westerly currents (high velocity tidal) to account for the dispersal of sediments. The main drawback of his model is the spread of coarse elastics (up to 35 mm diameter) across a broad shelf. Stewart (1970) suggests that high tidal velocities, ascrib ed to the origin of the earth-moon system as envisioned by Merrifield and Lamar (1968). These authors also suggest abundant large scale cross-strata in the late Precambrian marine sediments were formed by these increased tidal cur- 181 rents. However, the shorter-than-present earth-moon dis tance and extremely high tidal velocities from 4 to 14 times those of the present (Merrifield and Lamar, 1968) or high tidal amplitudes of over 100 m (Olson, 1970) required to transport coarse material and produce large-scale cross strata are not justified from evidence available. Most of the sedimentary structures are characteristic of lower flow regimes. The lower bounding surfaces in the cross-strati fied units are predominantly nonerosional, which rules out the possibility of lower flow regime structures formed dur ing waning activity of high velocity tidal currents. Klein (1972) believes that late Precambrian and lower Cambrian tidal ranges and bottom currents were similar in magnitude to Holocene conditions. The presence of extremely wide tidal flats (Lochmann-Balk, 1970) measuring up to 900 km also seem improbable and the width in the geologic record could be explained by prograding over a relatively long time span. The model proposed in this study calls on repeated transgressions and regressions of the shallow marginal sea. The coarse shelf deposits probably correspond to former strand lines during lower sea level, Eustatic rise in sea level could relate to the consequences of Precambrian glaciation 800 to 600 m.y. (Schopf e_t al. , 1973; Harland and Rudwick, 1964; Harland, 1964) comparable to the Holo cene melting of glaciers. Such rapid transgressive epi sodes could result in relict sediments on the shelves 182 similar to the present day. Emery (1968) reports that sediment of modern shelves is dominantly relict. If de position is rapid, the coarse sediment will not attain textural or mineralogical equilibria with its new environ ment of deposition. Klein (1971a, 1971b, 1972) favors a tidal environ ment for strata assigned to the Stirling Quartzite, Wood Canyon Formation and the Zabriskie Quartzite from an as sociation of textures and sedimentary structure character istic of the lower flow regime or emergence. He suggests an intertidal deposition for the Wood Canyon Formation from a study of outcrops in the Nye county of Nevada and in the Salt Spring Hills and Nopah Range in eastern Cali fornia, all north of the present study area. The author favors a dominant subtidal or partially restricted environment for the Johnnie Formation which shows general fining upwards and consists of laminated quartz sands with interbedded siltstones and carbonates. The Stirling Quartzite, which generally coarsens upward, is dominantly a mature quartz sediment which tends to be massive or dis play low angle cross-lamination and is perhaps character istic of prograding shelf sands or barrier beaches migrat ing seaward. The Wood Canyon Formation is dominantly subarkosic indicating rapid deposition dominantly sub- tidal with limited evidence for intertidal deposition. Sedimentary structures include bimodal or unimodal cross 183 bedding, flaser bedding, abundant small scale ripples and bioturbation, The cross-bedding is of moderate angle, com monly tabular with upper surfaces truncated by tidal or longshore (?) currents. The Zabriskie Quartzite consist of a mature quartzarenites typical of a stable shelf environment with good reworking. A transgression is also implied for the deposition of the Zabriskie Formation which shows a slight fining upwards. Table 36 provides a summary of depositional environment for each unit on the basis of mineralogical and textural maturity, areal varia tion of total quartz, variation of elasticity with thick ness and primary sedimentary structures. Comparison with Other Environments The Wood Canyon exposed in the Kelso Hills, Provi dence Mountain and Marble Mountain sections, displays abundant moderate angle cross-bedding with unimodal dis tribution and general fining upwards sequences, which re sembles alluvial channel deposits perhaps formed during a regressive episode. But fluvial deposits would be commonly characterized by thick sets of trough cross-strata, climb ing ripples and numerous channels which are all con spicuous by their absence. The cross-strata are dominantly tabular with truncated upper surface, which may represent sand waves migrating by tidal or longshore currents. Furthermore, alluvial sediments would be texturally and 184 Table 36* Summary of depositional environments Formation Maturity Analysis of Variance F Ratio elasticity Up-Section Don Sedi Sti Mineral Textural Tapeats - Zabriskie Mature Mature F = 0.0 Slight fin ing. (Data not suffi cient. ) Lamina angle lamina Tapeats - Wood Canyon Submature Submature F - 3.4* Fining Cross- tion. planai angle. cross- Stirling Upper - mature Lower - submature Mature F = 30.0** Coarsening Massi-v tions. accret ding. Johnnie Submature Immature to sub mature. F = 3.5* Fining Lamina 1 iments al Analysis of Variance F Ratio elasticity Up-Section Dominant Sedimentary Structures Bio- turbation Depositional Environment F = 0.0 Slight fin ing. (Data not suffi cient. ) Laminations. Low angle cross lamination. Common Prograding shelf sands. ure F = 3.4* Fining Cross-stratifica- tion. Tabular, planar, moderate angle. Flaser cross-bedding. Common Near-shore - shallow marine. Tide dominated. F = 30.0** Coarsening Massive lamina tions. Low angle accretion bed ding. None ob served. Prograding shelf sands. Barrier beaches or bars (migrating seaward). re • F = 3.5* Fining Laminations. Some. Shallow marine dominantly below surf base or in partially restricted (back barrier) marine environment. 185 mineralogically immature and restricted laterally and would not show flaser bedding, or bimodal, bipolar cross-bedding or bioturbation. Eolian deposits are characterized by high angle, wedge shaped cross-strata frosted sand grains. Only a few instances of such sedimentary characters are recognized which may have occurred on or along barrier islands. Sedimentary structures typical of turbidites or contourites such as sole marks and other features found in a Bouma sequence are also not encountered in the study. Thus negative evidence also favors a nearshore and shallow marine shelf environment. Basin Analysis Stewart (1970) regards the upper Precambrian and lower Cambrian strata as a thickening wedge of sediment lying to the west of the North American craton which pro vides the detritus. More recently he (1973) refers to this wedge as a miogeocline, formed at a rifted continental margin of the Atlantic type which shows no differential movement in terms of plate tectonics. His isopach maps (1970) indicate a sinuous belt of sediment from southern Canada to northern Mexico. Another view of paleogeography during the late Pre- cambrian-Cambrian time was proposed by Wright and Troxel (1966). On the basis of isopach contours base of Noonday 186 Dolomite to top of* the Zabriskie Quartzite and facies pat terns, they suggest a north-northwest trending trough with the Mojave block to the southwest occurring as a topo graphic high. This interpretation relies primarily on negligible displacement along the Death Valley-Furnace Creek fault system inferred from several linear features which limits the right lateral displacement (Wright and Troxel, 1967). Stewart (1967* 1970) suggests about 50 miles of right lateral offset across the Death Valley and Furnace Creek fault zones, some of which is ascribed to oroflexural folding in the terrane between them. Recent evidence including ERTS imagery puts the total displace ment of 80 to 120 miles within the Walker Lane comprising the three northwest-southeast right lateral strike slip fault zones, namely, the Death Valley-Furnace Creek fault system, Pahrump fault zone, and Las Vegas shear zone (Stewart and others, 1968; Liggett and Childs, 1973)* Wright and Troxel (1966, 1967) also ignore the eastward directed Mesozoic thrusting in their palinspastic recon structions. Davis (1973, personal communication) suggests at least 50 miles of cumulative telescoping on the Key stone, Mesquite Pass and Winter's Pass thrusts, and states that some of Wright and Troxel's thinner western sections may lie within windows in thrust plates carrying thicker, originally still more westward sections. The present study suggests a cratonic source area to the east and southeast for the coarse detritus. There is no evidence of a western source nor any indication of source rocks other than granitic, gneissic and older sedi mentary rocks. Data are not sufficient for a detailed basin analysis for each formation. There is no evidence for more than one basin during the deposition of these late PreCambrian and early Cambrian strata. There may have been local barrier beaches and bars which could have inhibited sediment dispersal. The northern and southern facies are statistically homogeneous with respect to total quartz. Local variations in mineralogy and texture are apparent between individual sections and formations. There may be some differences in content of heavy minerals based pri marily on the proximity of source area and effectiveness of dispersal. The textural and mineral maturity is based largely on the energy at the depositional site and the rate of burial. Rapid deposition with little reworking favors immature quartzites whereas a stable shelf with excellent reworking of the sediment over long spans of time favors mature quartzites. The Johnnie and Wood Can yon Formations fall into the first category with dominant ly immature to submature sediments whereas the Stirling and Zabriskie Formations are largely mature and belong to the second category. Quartzites from six northern sections within the Cordilleran frontal thrust belt show a higher content of 188 undulatory quartz and silica cement and are partially re crystallized, The amount of displacement on the individual thrusts cannot be estimated from the petrologic data avail able, The southern sections show no thrusting or major deformational episodes within the formations under study, and hence the sedimentary characteristics and the craton- miogeocline transition is more obvious. According to this transgressive model, the formations get younger eastwards favoring time-transgressive units. CONCLUSIONS Sixty percent of the samples collected from craton- ic quartzites are subarkosic, whereas quartzarenites com prise 39 percent and sublitharenites about 1 percent. The spread is less in miogeoclinal quartzites with 52 percent of the samples classified as subarkoses and 48 percent as quartzarenites. Rarity of sublitharenites reflects maturity of the quartzites which are devoid of unstable rock fragments. The sediments are derived chiefly from granitic and gneissic rocks as well as older sedimentary rocks of the Precambrian craton to the east and southeast. Samples collected from six northern sections within the Cordilleran Frontal Thrust Belt have a high content of undulatory quartz,silica cement and show some evidence of recrystallization. Samples from four southern sections show no evidence of major deformational episodes. Polynomial time-trend analyses for each strati- graphic section suggest considerable variation with thick ness. Quartzites from the upper Stirling and Zabriskie Formations are mature quartzarenites, the Johnnie Forma tion is dominantly composed of immature (silty) quartz arenites, whereas the lower Stirling and Wood Canyon Forma tions are mainly subarkosic. 189 190 An areal variation in total quartz was investigated using a one-way analysis of variance model. The null hypothesis for means was rejected for each formation. However, the test was not highly significant for the John nie and Wood Canyon Formations, but highly significant for the Stirling Quartzite. Total quartz could not be used to discriminate be tween cratonal quartzites (Tapeats Sandstone) and Johnnie Formation (F = O.36) or the Wood Canyon Formation (F = O.89), but the difference is highly significant between the Tapeats Sandstone and Stirling Quartzite (F = 18,07**). Much of the Tapeats Sandstone can be statistically cor related with the Wood Canyon Formation, and the upper part of the Tapeats Sandstone with the Zabriskie Quartzite. Reconstructions of paleoenvironments has problems primarily due to a lack of paleontological control. Evi dence is restricted to trace fossils in the middle Wood Canyon and younger strata. Depositional models are established for each forma tion on the basis of quartzite petrology, elasticity and primary sedimentary structures. The Johnnie Formation shows fining upwards and consists largely of laminated im mature quartzarenites with interbedded siltstones and carbonates, which suggests a marine transgression or pos sibly a change from open to restricted shelf environment. The Johnnie Oolite within the formation possibly represents a carbonate barrier or platform deposit. The Stirling Quartzite coarsens upwards and is dominantly a mature highly quartzose sediment, commonly massive or showing low angle cross lamination and may represent prograding shelf sands or high energy bars or barrier beaches migrating sea ward. The Wood Canyon Formation shows considerable short period fluctuations, possibly related to local trans gressions sind regressions or pulsation in sediment supply. The quartzites are dominantly subarkosic with tabular, intermediate angle cross-bedding, which is either dis cordant or asymptotic with the lower bounding surface, possibly representing sand waves migrating by tidal or long shore currents. Upper Wood Canyon strata locally shows some resemblance to intertidal deposits with flaser bed ding and mudcracks. A time-transgressive model is favored for the de position of these coarse clastic deposits with trans gressions and regressions of a shallow sea, perhaps related to eustatic fluctuations in sea level during infra-Cambrian glaciation. REFERENCES REFERENCES Allen, J. R, L., 1963a, The classification of cross stratified units with notes on their origin: Sedi- mentology, v. 2, p. 93-114. . 1963b, Internal sedimentation structures of well- washed sands and sandstone in relation to flow condi tions: Nature, v. 200, p. 326-327* Bailey, S. W,, Bell, R. A., and Peng, C. J,, 1958, Plastic deformation of quartz in nature: Geol. Soc. America Bull., v. 69, p. 1443-1466. Blatt, H., 1963, The character of quartz grains in sedi mentary rocks and source rocks: Ph.D. dissertation, Univ. California, Los Angeles, 203 p. Blatt, H., Middleton, G. , and Murray, R., 1972, Origin of sedimentary rocks: Prentice-Hall, New Jersey, 634 p. Burchfiel, B. 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C., 1973* Statistics and data analysis in geology: John Wiley and Sons, New York, 550 p. Dixon, M. J. and Massey, F. J,, 1969, Introduction to statistical analysis: McGraw-Hill, New York, 638 p. Dixon, M. J., 1970, Biomedical computer programs: Univ. of California Press, Berkeley, 600 p. Dunne, G. C., 1972, Geology of the Devil’s Playground area, eastern Mojave Desert, California: Ph.D. dis sertation, Rice University, Houston, 79 P. Emery, K. 0., 1968, Relict sediments on continental shelves of the world: Am. Assoc. Petroleum Geologists Bull., v. 52, p. 445-464. Fox, W. T., 1964, Fortran and Fap program for calculating and plotting time-trend curves using an IBM 7090 or 7094/1401 computer system, Kansas Geol. Survey Spec. Distrib. Pub. 12, 24 p. Goddard, E. N., chm., and others, 1948, Rock color chart: Washington, Natl. Research Council (repub. by Geol. Soc. America, 195l)* 6 p. Goldring, R. and Bridges, P., 1973, Sublittoral sheet sandstones: Jour. Sed. Petrology, v. 43, p. 736-747. Griffiths, J. C., 1967* Scientific method in the analysis of sediments: McGraw-Hill, New York, 508 p. Hague, A., 1883, Abstract of report on the geology of the Eureka district, Nevada: U. S. Geol. Survey 3rd Annual Report, p. 237-290. Harland, W. B., 1964, Evidence of late Precambrian glaciation and its significance, in Nairn, A. E. M,, ed. Problems in paleoclimatology: Wiley, New York, p. 119- 149. Harland, W. B. and Rudwick, M. J. S., 1964, The great infra- Cambrian ice age: Scientific American, v. 211, p. 28- 36. 195 Hazzard, J. , 1933» Notes on the Cambrian rocks of* the eastern Mojave desert, California: Calif, Univ. Publ, in Geological Science, v, 23, p« 57-70. I, . 1937, Paleozoic section in the Nopah and Resting Springs Mountains, Inyo County, Calif.: California Jour. Mines and Geology, v. 33* P. 273-339. Heckel, P. H., 1972, Recognition^of ancient shallow marine environments: in Recognition of ancient sedimentary environments, J. K. Rigby and W. K. Hamblin, eds.. Soc. Econ. Paleontologists and Mineralogists, Spec. Pub. no. 16, p. 226-286. Hewett, D. F., 1956, Geology and mineral resources of the Ivanpah quadrangle, California and Nevada: U. S. Geol. Survey Prof. Paper 275♦ 172 p. Klein, G, de'tt, 1970, Depositional and dispersal dynamics of intertidal sand bars: Jour. Sed. Petrology, v. 4o, p. 1095-1127. . 1971a, A sedimentary model for determining paleo- tidal range: Geol. Soc. America Bull., v. 82, p. 2585-2592. _______ , 1971b, Environmental model for some sedimentary quartzites: (Abs,), Am. Assoc. Petroleum Geologists, v. 5, P. 347. . 1972, Sedimentary model for determining paleo- tidal range: Reply: Geol. Soc. America Bull., v. 83, P. 539-546. Kukal, Z., 1971* Geology of recent sediments: Academic Press, New York, 490 p. Liggett, M. A. and Childs, J. F., 1973* Evidence of a major fault zone along the California-Nevada state line, 35 30' to 36°30' N. latitude - An application of ERTS imagery: NASA report of investigation, NASA CR-133l40, 13 P. Lobo, C. F., 1972, Petrography and statistical analysis of the Tapeats Sandstone (Late Precambrian-Cambrian), southeastern California: M. S. thesis, Univ. Southern California, 112 p. Lochman-Balk, C., 1970* Upper Cambrian faunal patterns on the cratons Geol. Soc. America Bull., v. 81, p. 3197-3224. McBride, E. F., 1963, A classification of common sand stones: Jour. Sed. Petrology, v. 33, p. 664-669. McCammon, R. B,, 1968, The dendrograph: a new tool for correlation: Geol. Soc. America Bull., v. 79, p. 1663-1670. McCammon, R. B. and Wenninger, G., 1970, The dendrograph: Kansas Geol. Survey Computer Contr. 48, 28 p. McNair, A. H., 1951* Paleozoic stratigraphy of part of northwestern Arizona: Am. Assoc. Petroleum Geologists Bull., v. 35, p. 503-541. Merrifield, P. M. and Lamar, D. L., 1968, Sand waves and early earth-moon history: Jour, Geophys. Research, v. 73, P. 4767-4774. Narayan, J. , 1971, Sedimentary structures in I r.e Lower Greensand of the Weald, England, and B ; o-' unllanais, France: Sedimentary Geology, v. 6, p., •/3-109. Noble, L. F., 1914, The Shinumo quadrangle, Grand Canyon district, Arizona: U. S. Geol. Survey Bull., v. 549, 100 p. Nolan, T. B., 1929, Notes on stratigraphy and structure of the northwestern portion of Spring Mountains, Nevada: Am. Jour. Sci., v. 17, p. 461-472. Nolan, T. B., Merriam, C. W. and Williams, J. S., 1956, The stratigraphic section in the vicinity of Eureka, Nevada: U. S. Geol. Survey Prof, Paper 276, p. 6-7. Olson, W, S., 1970, Tidal amplitudes in geological history: New York Acad. Sci. Trans., Ser. 2, v. 32, p. 220-233. Pettijohn, F. J,, Potter, P. E., Siever, R., 1972, Sand and Sandstone: Springer Verlag, New York, 6l8 p. Preston, D. A., 1970, Fortran IV program for sample normality tests: Computer contribution 4l, Kansas Geological Survey, 28 p. 197 Quinn, H, M., 1968, Precambrian, Eocarabrian and Cambrian rocks of* the Basin and Range Province of eastern California: M. S. thesis, Univ. Southern California, 133 P. Reineck, H. E., 1972, Tidal flats: in Recognition of ancient sedimentary environments, J. K. Rigby and ¥. K. Hamblin, eds., Soc. Econ. Paleontologists and Mineral ogists, Spec. Pub. no. 16, p. 146-159. Schopf, J. ¥. and others, 1973, On the development of metaphytes and metazoans: Jour, of Paleontology, v, 47, p. 1-9. Sokal, R. R. and Rohlf, F. J., 1969, Biometry, ¥. Freeman and Company, San Francisco, 776 p. Stewart, J. H., 1967* Possible large right-lateral dis placement along fault and shear zones in the Death Valley-Las Vegas area, California and Nevada: Geol. Soc. America Bull., v, 78, p. 131-142. _______ , 1970, Upper Precambrian and Lower Cambrian strata in the southern Great Basin, California and Nevada: U. S. Geol. Survey Prof. Paper 620, 206 p. _______ , 1972, Initial deposits of the Cordilleran geo- syncline: evidence of a Late Precambrian (85O m.y.) continental separation: Geol. Soc. America Bull., v. 83, p. 1345-1360. _______ , 1973* Upper Precambrian and lower Paleozoic mio- geocline in Great Basin, western United States: (Abs.), Am. Assoc. Petroleum Geologists Bull,, v. 57, p. 807. Stewart, J. H., Albers, J. P., Poole, F. G., 1968, Summary of regional evidence for right-lateral displacement in the western Great Basin: Geol. Soc. America Bull., v. 79, P. 1407-1414. Thompson, ¥. 0., 1937, Original structures of beaches, bars and dunes: Geol. Soc. America Bull., v. 48, p. 723-752. Van der Plas, L. and Tobi, A. C., 1965, A chart for judg ing the reliability of point-counting results: Am. Jour. Sci., v. 263, p. 87-90. Wheeler, H. 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Lobo, Cyril Francis
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Petrology And Depositional History Of Late-Precambrian - Cambrian Quartzites In The Eastern Mojave Desert, Southeastern California
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