Some Aspects of Lower and Middle Devonian Stratigraphy in Eureka County, Nevada

AN ABSTRACT OF THE THESIS OF

GEORGE WARNER KENDALL for the degreeMaster of Science (Name of student) in Geology presented on February 14, 1975 (Major department) (Date) Title: SOME ASPECTS OF LOWER ANDMIDDLE DEVONIAN

STRATIGRAPHY IN EUREKA COUNTY, NEVADA Redacted for Privacy Abstract approved: D . G. Johnson

During much of the Early and MiddleDevonian, dolomite was deposited in shallow restricted environmentsin eastern Nevada, and limestone was deposited in norrnal shallowt*}^ marine environments in central Nevada.The dolomite was deposited on a nearsea-level carbonate mud flat, and the limestone wasdeposited on a continental margin shelf.Lithofacies boundaries trend approximatelynorth- south and pass through central EurekaCounty, Nevada.The transition zone in Eureka County movedonshore and offshore with changes in sea level and sedimentation.Neither the McColley Canyon-Denay nomenclature of western Eureka County northe Sevy-Simonson nomenclature of eastern Nevada isappropriate for rocks deposited in the transition zone.Tongues of Sevy Dolomite andMcColley Canyon Formation require that partsof both nomenclatures be recog-

nized.Deposition of dark subtidaldolomite in the transition zone requires that a new formationbe named: SadlerRanch Formation. Significant late Emsian and early Eifelian eventsin central

Eureka County include:1) westward progradation of the Sevytidal flat (late Bartine time); 2) eastward transgressionand deposition of the Bartine Tongue (early Coils Creek time);3) development of a southward prograding barrier bar during earlyOxyoke Canyon time (Quartzose Member of the Oxyoke CanyonFormation); 4) deposition of the Sadler Ranch Formation (late CoilsCreek and early Denay times); and 5) westward progradation ofthe Coarse Crystalline Member of the Oxyoke Canyon Formation(late Oxyoke Canyon time). The character of the edge of the carbonateplatform in Nevada changed from mid- Emsian to early Eifeliantime.During the mid to late Emsian, the Bartine Member of the McColley Canyon Formation was deposited in shallow water over abroad area of the shelf.Later, several lithofacies were deposited in the same area.Shallow facies "migrated" offshore, and deep facies"migrated" shoreward.The result was a sedimentation-induced steepeningof the shelf gradient by early Eifelian time. Some Aspects of Lower and Middle Devonian Stratigraphy in Eureka County, Nevada

by George Warner Kendall

A THESIS submitted to Oregon State University

in partial fulfillment of the requirements for the degree of Master of Science Commencement June 1975 APPROVED: Redacted for Privacy

Assoate Professor of Geo lo in charge of major Redacted for Privacy

C,iairman of the Department of Geology

Redacted for Privacy

Dean of Graduate School

Date thesis is presented February 14, 1975 Typed by Opal Grossnicklausfor George Warner Kendall ACKNOWLEDGMENTS

Many people contributed to thethoughts expressed in this thesis, and I cannot thank them allhere. Dr. J.G. Johnson is especially appreciatedfor his stimulating discussions and wealth of knowledge.The intellectual environment he cultivates was essential to thecompletion of the project. Dr. A. R. Niem critically readthe manuscript and offered valuable criticisms.Dr. M. A. Murphy of theUniversity of Cali- fornia discussed Devonian sedimentationand stratigraphy with the writer.Dr. C. A. Nelson, also of theUniversity of California, provided a geologic map of part of theSulphur Spring Range.Dr. Gilbert Klapper of the Universityof Iowa made conodont age determinations essential to the thesis.Dr. C. Kent Chamberlain ofOhio University made some helpfulenvironmental determinations on the basis of burrows. Mary Fisher kindly draftedseveral figures and columnar sections.Claudia DuBois graciously andpatiently prepared the numerous conodontsamples. Walt Niebuhr, Roy Smith,Dick Flory, Bill Koch, DaveRohr, and Pete Isaacson allcontributed through many interestingdiscus-

sions. And the joy of living providedthe impetus to write this crazy

thing. TABLE OF CONTENTS

INTRODUCTION 1

Geologic Setting 1 Purpose 3 Previous Work 4 Location and Accessibility 5 Methods of Investigation 8

FORMATIONAL NOMENCLATURE 11

SEVY DOLOMITE 14 General Statement 14 Diamond and Pirion Ranges 17 Basal Quartzite 17 Middle Dolomite 18 Upper Quartzose Unit 23 Mahogany Hills 29 Sulphur Spring Range 31 Transitional Unit 32 Upper Quartzose Unit 38 Age and Correlation 49

BAR TINE TONGUE OF THE McCOLLEYCANYON FORMATION 52 General Statement 52 Lower Limy Dolomite 56 Middle Limestone 58 Upper Limy Dolomite 73 Combined Upper and Lower Units of thePirion and Diamond Ranges 73 Age and Correlation 79

SADLER RANCH FORMATION 82 General Statement 82 Lower Dolomite 85 Middle Crinoidal Dolomite 98 Upper Dolomite 102 Age and Correlation 105 OXYOKE CANYON FORMATION 112 General Statement 112 Quartzose Member 112 Diamond Range 116 Outcrop Character 116 Thin Section Description 118 Pion Range 121 Outcrop Character 121 Thin Section Description 124 Depositional Environment 125 Coarse Crystalline Member 130 Outcrop Character 130 Thin Section Description 137 Depositional. Environment 138 Age and Correlation 140

SEDIMENTARY PETROLOGY 143 Grain Size Analysis 143 Heavy Mineral Analysis 148 Organic Carbon Content 149 Provenance 150

GEOLOGIC HISTORY 154 164 CONCLUSIONS REFERENCES CITED 167 APPENDIX I 174

APPENDIX II 177

APPENDIX III 190

APPENDIX IV 193 195 APPENDIX V 197 APPENDIX VI

APPENDIX VII 199 (in pocket) PLATES 1-21 LIST OF FIGURES Figure Page

1. Index map of Eureka County, Nevada,showing major geographic features.Outlined areas are Devonian outcrops. 6

2. Index map of Eureka County, Nevada,showing the locations of sections studied.Map areas are shown in green. 7

3. Correlation chart for part of the Lower andMiddle Devonian of Nevada. 12

4. Lithofacies distribution during mid-Kobeh time. 15 16 5. Lithofacies distribution during mid-Bartinetime.

6. Transitional zone of upper Sevy Dolomite inOxyoke Canyon.Oxyoke Canyon Formation is in upperright corner of photo. 25

7. Vertical sand-filled burrows in the upper partof the Sevy Dolomite in Oxyoke Canyon. 25

8. Mudstone covered ripples in the quartzose upperunit of the Sevy Dolomite in Oxyoke Canyon. 27

9. Bartine Tongue interbed in the quartzose upperunit of the Sevy Dolomite in Oxyoke Canyon. 27

10, Lithofacies distribution during late Bartinetime. 30

11. Conformable contact between the BartineMember of the Mc Colley Canyon Formation andthe overlying transitional unit of the Sevy Dolomite inthe Sulphur Spring Range. 33

12. Photomicrograph of intraclasts from thetransitional unit of the Sevy Dolomite in theSulphur Spring Range. 33

13. Photomicrograph of a silicified brachiopodshell in the transitional unit of the Sevy Dolomite inthe Sulphur Spring Range. 37 Figure Page

14. Hand sample of a quartz arenite bed in the upperunit of the Sevy Dolomite in the SulphurSpring Range showing basal scour and graded bedding. 41

15. Facies tract model for deposition of theBartine Limestone and upper tongue of the SevyDolomite in central Eureka County, Nevada.No vertical scale. 46

16. Successive steps in the westward progradationof the Sevy tidal flat.Depths are approximate. 48

17. Schematic diagram of facies relationships inthe Bartine Tongue (early Coils Creek age).No vertical or horizontal scale. 54

18. Lithofacies distribution during early CoilsCreek time. 55

19. Typical exposure of the middle limestoneof the Bartine Tongue in the Sulphur Spring Range. 61

20. Slabbed sample of the middle limestone ofthe Bartine Tongue showing variations in texture. 61

21. Weathered surface of a stromatoporoidboundstone lense from the middle limestone of theBartine Tongue (Sadler Ranch Section). 64

22. Slab through a sediment "smothered"Favosites sp. from the middle limestone of the BartineTongue (Telegraph Canyon Section). 64

23. Poorly exposed lense in the middle limestoneof the Bartine Tongue (Telegraph CanyonSection). 67

24. Photomicrograph of microlaminated limemuds tone overlain by packs tone with patchy sparrycement, Sample from the Bartine Tongue atTelegraph Canyon. 67

25. Facies tract model for depositionof the Bartine Tongue and corresponding part of theSevy Dolomite in central Eureka County, Nevada.No vertical scale. 72 Figure Page

26. Laminated limy dolomite mudstone from the Bartine Tongue (Oxyoke Canyon Section). 77

27. Lithofacies distribution during early Sadler Ranch and Oxyoke Canyon time. 84

28. Sharp contact between the Bartine Tongue andSadler Ranch Formation in Telegraph Canyon.Note the clast of Bartine Tongue lithology in the overlyingSadler Ranch Formation. 86

29. Slab of KDL-183 showing burrows, silicifiedbrachi- opods, and siliceous fracture fillings. 89

30. Photomicrograph of KDL-183 showing a silicified brachiopod in a pseudospar matrix. 89

31. Facies tract model for deposition of theSadler Ranch Formation, Quartzose Member of the Oxyoke Canyon Formation, and upper Sevy Dolomite in centralEureka County,No vertical scale. 97

32. Typical exposure of the crinoidal unit of theSadler Ranch Formation in the Sulphur Spring Range. 100

33. Loading at the base of a crinoidal packstone bedin the upper dolomite of the SadlerRanch Formation. 100

34. Contact between the Sadler Ranch Formation andthe overlying Coarse Crystalline Member of theOxyoke Canyon Formation (Sadler Ranch Section). 103

35. Generalized cross section perpendicular todeposi- tional strike during mid-Oxyoke Canyon time.Five miles is hypothesized distance betweenUnion Mountain and Telegraph Canyon prior to faultingin Bruffey Canyon.Depths are in feet and are approximate. 108

36. Generalized cross section perpendicular todeposi- tional strike during late Oxyoke Canyontime.Five miles is hypothesized distancebetween Union Mountain and Telegraph Canyon prior to faultingin Bruffey Canyon.Depths are in feet and are approximate. 110 Figure Page

37. Lithofacies distribution during late Oxyoke Canyon time. 113

38. Generalized lithofacies distribution during the late Emsian for part of Nevada. 115

39. Cross-bedded and laminated dolomitic quartz arenite in the Quartzose Member in Oxyoke Canyon. 119

40. Possible rounded quartz overgrowth from the Quartzose Member in the Fish Creek Range. 119

41. Bold outcrop of the Quartzose Member in the Slagowski Ranch Map Area. 123

42. Erosional surface between quartzite and dolomite beds in the Coarse Crystalline Member in the Alhambra Hills. 134

43. Laminated vuggy dolomite of the Coarse Crystalline Member in Oxyoke Canyon. 134

44. Plots of environmentally significant combinationsof textural parameters, after Moiola and Weiser,1968. 144

45. Basic CM plots of thesis samples, after Passega (1957).On the basis of lithology and sedimentary structures: closed circles representbeach/bar environments, open circles represent wash-over fans, and X's are uncertain or quiet water. 145

46. Generalized cross-section perpendicular to thedepositional strike during mid-Bartine time.Depths are in feet and are approximate. 157

47. Generalized cross-section perpendicular tothe depositional strike during latest Bartine time.Depths are in feet and are approximate. 158

48. Generalized cross-section perpendicular tothe depositional strike during early Coils Creektime.Depths are in feet and areapproximate. 159 Figure Page

49. Generalized cross-section perpendicular tothe depositional strike during mid-OxyokeCanyon time.Depths are in feet and are approximate. 160

50. Generalized cross-section perpendicular tothe depositional strike during latest OxyokeCanyon time.Depths are in feet and are approximate. 161

51. Generalized cross-section perpendicular tothe depositional strike during latest OxyokeCanyon time.Depths are in feet and are approximate. 162

52. Eustatic curve for strata at TelegraphCanyon and Union Mountain.No vertical scale.Tide lines are approximate. 163 LIST OF TABLES

Table Page

1. Brachiopod Abundances in the Bartine Tongue (Sulphur Spring Range) and Coils Creek Limestone (Modoc Peak). 71

2. Conodonts from the Bartine Tongue. 79

3. Brachiopod Abundances in the Sadler Ranch Formations Sulphur Spring Range. 92

4. Average Textural Parameter Values for Beach and Aeolian Flat Deposits. 146 LIST OF PLATES Plate

1 Geologic Map of the Nevada Group, Garden Valley Quadrangle, Nevada in pocket

2 Geologic Map of the Slagowski Ranch Map Area in pocket

3 Geologic Map of the Oxyoke Canyon Area in pocket

4 Oxyoke Canyon Section in pocket

5 Phillipsburg Mine Section in pocket

6 Coffin Mountain Section in pocket

7 Slagowski Ranch Section in pocket

8 Pirion Range Section in pocket

9 Union Mountain Section in pocket

10 Fish Creek Range Section in pocket

11 Modoc Peak Section in pocket

12 Sadler Ranch Section in pocket

13 Shipley Hot Springs Section in pocket

14 Summit 7466 Section in pocket

15 Summit 7476 Section in pocket

16 Bald Mountain Section in pocket

17 Telegraph Canyon Section in pocket

18 Fera Well Section in pocket

19 Williams Canyon Section in pocket

20 Newark Mountain Section in pocket

21 Alhambra Hills Section in pocket LIST OF APPENDICES

Appendix Page 174 I Map Area and Section Locations

II Megafossil Collection Lists 177

III Modal Analyses of Selected Samples 190

IV Textural Parameters of Selected QuartzoseSamples 193

V Heavy Mineral Analysis 195

VI Organic Carbon Content of SelectedSamples 197

VII Paleocurrent Statistics 199 SOME ASPECTS OF LOWER AND MIDDLE DEVONIAN STRATIGRAPHY IN EUREKA COUNTY, NEVADA

INTRODUCTION

Geologic Setting

During much of the Emsian and Eifelian Stages of the Devonian, the limestone-dolomite facies boundary of the CordilleranGeosyncline passed through what is now Eureka County, Nevada.Limestone was deposited on a shallow, open marine shelf adjacent to thecontinental- margin while dolomite was deposited in restricted areas betweenthe normal marine environment and land.Slight transgressions and regressions of the sea, variations in the influx of terrigenous material, and other changes resulted in a complex interfingering of the rock units deposited during this time.The Lower and Middle Devonian rock units deposited in Eureka County and discussedherein are the Sevy Dolomite, Bartine Tongueof the Mc Colley Canyon Formation, Sadler Ranch Formation, and Oxyoke CanyonFormation. The Sevy Dolomite is a light gray aphanitic-appearingdolomite of Early Devonian age that contains quartz arenite bedsin its upper part.In the Pion and Diamond Ranges and at ModocPeak, it unconformably overlies the Lone Mountain Dolomite.In the Diamond and Pinon Ranges, the Sevy grades into the massivequartz arenites of the Oxyoke Canyon Formation; but at ModocPeak the Sevy (lower 2 tongue) conformably underlies theBartine Member of the Mc Colley

Canyon Formation.In the Sulphur Spring Range theSevy (upper tongue) conformably overlies the BartineMember and underlies the

Bartine Tongue. The Bartine Tongue is a yellow-grayargillaceous limestone lithologically similar to the Bartine Memberof the Mc Colley Canyon

Formation.The tongue is of Early Devonian ageand crops out in the Sulphur Spring Range and parts of theDiamond and Pirion Ranges. It conformably overlies theSevy Dolomite and underlies the Sadler Ranch Formation in the SulphurSpring Range with apparent dis con- formity.To the east it interfingers withthe Sevy Dolomite. The Sadler Ranch Formation (newname) in the Sulphur Spring

Range and Mahogany Hills,disconformably overlies the Bartine Tongue and Coils Creek Limestone.The formation consists of light olive gray dolomite muds tone tocrinoidal packs tone.Quartzite interbeds are common in theSulphur Spring Range.The Coarse Crystalline Member of the Oxyoke CanyonFormation locally overlies the Sadler Ranch Formation. The Oxyoke Canyon Formation cropsout in the Sulphur Spring, Pinon, and Diamond Ranges and inthe Mahogany Hills.The formation is of Early to Middle Devonian ageand consists of two members. The lower member is a massivequartzite, and the upper memberis a coarsely crystallinedolomite with quartzite interbeds.The Lower 3

Alternating Member of the Simonson Formationconformably overlies the Oxyoke Canyon Formation. During the Antler Orogeny of Late-Devonian-Early Mississip- pian time in Nevada, the Late Devonianand older shelf sediments of Eureka County were emplaced beneath the upperplate of the Roberts

Mountains Thrust.Faulting in lower plate rocks during the orogeny (Carlisle and others, 1957) and during the Cenozoiccombine to limit the number of large Paleozoic stratigraphicsections available for

study.Basin-and-Range-topography provides excellent exposuresof Devonian and older rocks, but faciesrelations are obscured by the north-south trend of the ranges and the absenceof exposures in intervening valleys.

Purpose

The purpose of this project has been tostudy the stratigraphy and sedimentation of selected Lowerand Middle Devonian rock units in Eureka County, Nevada, and to reconstruct aviable sequence of events for that period.The major objective has been to definerock units in the Sulphur Spring Range and toaccurately correlate these rock units with established rock units tothe east and west.An attempt has been made to usethe depositional models developed for Sulphur Spring Range stratigraphy toexplain the stratigraphy in the

Mahogany Hills.A second objective has been todetermine the 4 depositional environments and provenanceof the various rock units. A third objective has been to obtainbrachiopod and conodont data for accurate time correlations andenvironmental interpretation.

Previous Work

C. W. Merriam first mapped anddefined strata of Devonian age at Lone Mountain(Merriam, 1940) and in the RobertsMountains (Merriam and Anderson, 1942).Later, the Devonian stratigraphic section in the southern Diamond Range wasdescribed by Nolan and

others (1956).These workers divided the NevadaFormation (Devon- ian) into five members in ascendingorder: Beacon Peak Dolomite, Oxyoke Canyon Sandstone, SentinelMountain Dolomite, Woodpecker Limestone, and By State Dolomite.Carlisle and others (1957) correlated Devonian strata in theSulphur Spring and Pinon Ranges with the section in the southernDiamond Range.They believed that their "Union Mountain Member" of theNevada Formation and the Oxyoke Canyon Member werecorrelative and that their Mc Colley Canyon Member and the BeaconPeak Dolomite were correlative. These workers also prepared anunpublished map of the Mineral Hill Quadrangle (C. A. Nelson,personal communication, 1972). Johnson (1962) raised the Mc ColleyCanyon Member to forma-

tional rank; and Gronberg (1967)recognized three members, the Kobeh, Bartine, and Coils Creek,of the Mc Colley Canyon Formation 5 at Lone Mountain and Table Mountain,Murphy and Gronberg (1970) correlated the Bartine Member in the RobertsMountain with Bartine rocks in the Sulphur Spring Range, and theCoils Creek Member in the Roberts Mountains and at Lone Mountainand Table Mountain with the lower part of the "Union Mountain Formation." Osmond (1954, 1962) studied the Sevy andSimonson Dolomites in the eastern Great Basin and dividedthe Sevy into three members in ascending order: dolomite member,cherty argillaceous member, and sandy member. He proposed a tidalflat or mud flat environment of deposition for the Sevy Dolomite and an eastern(cratonic) source for the quartz sand of the sandy member.However, Johnson (1962) proposed a northern source for the sand.

Location and Accessibility

The study area is located in parts ofEureka, Elko, and White Pine Counties, Nevada.Detailed stratigraphic sections were measured in the Sulphur Spring, PiWon, and Diamond Ranges and at Modoc Peak (plates 4-21).Reconnaissance work was carried out inthe Roberts Mountains, Fish Creek Range,Mahogany Hills, and at Lone

Mountain.Detailed mapping was done at threelocations in the Sulphur Spring, Pirion, and DiamondRanges (plates 1 -3).Figure 1 is an index map showing themajor geographic features ofEureka County, and Figure 2 shows alllocalities visited.Appendix I lists ELKO COUNTY 6 ...... , .

i .,

r i 0 .. , 0c) -.. NEVAD . 'Ns i

.'4012 _ ..

81 8 % , I 0 1 HZ 1-4 1 t-C

I E.0

c3 /1 toturrEY CANYON

r1.12 \

1 WHITE PINE COUNTY I a if:5

1 o) I w 4# ii \ (70 1° 4- rt o.,,. , ,..g.:. ,9 . eig 8 % g -4

'...---, -Xi z 14 LONE MOUNTAIN . txi

3- 11 - NYE COUNTY 10 0 10 20 30 miles

Figure 1.Index map of Eureka County, Nevada, showing major geogr7inni c features.Outlined yretsre Devonian outcrops. 7

1 I

18 I I

1 s., 1 .

I 1

\ PINE MOUNTAIN\1

lk \ PINON RANGE

SLAGOWSKI RANCH OFFIN MOUNTAIN O .r.cCOLLEY CANYON :04NION MOUNTAIN edILLIANS CANYON yank PH CANYON 4A AID uUNTAIN mem7476 WILLOW a e St.1MMIT't7466 Q11 "--,SADLERcRANCH O SHIPLEY:HOT SPRINGS 0

PHILLIPSBURG MINE

LONE MOUNTAIN

DoMODOC PEAK ff NEWARK MOUNTAIN

ABLE MOUNTAIN ALHAMBRA HILLS KE CANYON

153 eFISHFREEK RANGE g __a__ -j

10 0 10 20 30 40 miles

Figure 2. Index map of Eureka County, Nevada, showing the locations of sections studied. Map areas are shown in green. 8 the precise locations of the columnar sectionsand map areas included in the thesis. Well maintained paved and gravel roads allow accessto within about three miles of all sections and map areas.Jeep trails on open range land permit better access to somelocalities.

Methods of Investigation

Eighteen measured sections, three map areas,and reconnaissance visits to selectedlocalities provide the framework of the thesis.Geologic and topographic maps were consulted priorto measurement of sections; and sections weremeasured at locations thought to have well exposed, unfaulted outcropsof Lower and Middle Devonian strata.It was hoped that the distribution of measured sections would yield as much information aspossible about facies changes perpendicular to the depositionalstrike. Litho logic samples, keyed to the measuredsections, were taken where significant or unusuallithologies or sedimentary structures occurred. Many of thesesamples were cut and polished in order to better observe sedimentarystructures.Thin sections of samples representative of the mainlithologic units were studied to determine composition, texture andpaleocurrents. Samples taken for megafossils averagedabout 25 pounds and consisted of large blocks of limestone ordolomite.Samples taken 9 solely for the purpose of obtainingmicrofossils (conodonts) averaged about 12 pounds.Non-silicified fossils were separated from the limestone blocks by using a hydraulicrock-splitter.Silicified fossils were etched from theenclosing dolomite by concentrated hydrochloric acid.After the fossils were cleaned and sorted,they were submitted to Dr. J.G. Johnson, Oregon State University,for identification and age determination.To obtain conodonts, the enclosingcarbonate matrix was dissolved in dilute formicacid; and the conodont-bearing heavy fraction of the insoluble residue washand-picked by Claudia

DuBois.The conodonts were sent to Dr. GilbertMapper of the University of Iowa for identification and agedetermination. Litho logic descriptions in the text and oncolumnar sections use the following conventions:1) Dunham's (1962) classification of carbonate rocks isused for hand sample descriptions;2) Folk's (1962) classification of carbonate rocks is usedfor thin section descriptions; 3) Plumley and other's(1962) energy index was used to aid environmental interpretations;4) color names were determined from the Rock Color Chartdistributed by the Geological Society of America (1963). Grain-size analysis and heavy mineralanalysis were done according to procedures outlined byRoyse (1970).Determination of paleocurrent directions fromcross-bed strike and dip data was done as suggested by A. R. Niem(personal communication, 1974), 10

Dolomite and limestone rock slabs werestained according to the method of Friedman (1959). The following data for selected samples aresummarized in the appendices: Fossil collections,Appendix II; modal analyses, Appendix III; textural parameters, AppendixIV; heavy mineral contents, Appendix V; organic contents,Appendix VI: and paleocurrent statistics, Appendix VII. 11 FORMATIONAL NOMENCLATURE

Several changes in the nomenclature of Lowerand Middle Devonian strata in central Nevada areproposed here.It is hoped that a better understanding of the regionalstratigraphy will result

from:1) applying the same name to the samerock unit in different mountain ranges and 2) recognizinginterfingering rock units as tongues of different formations.Figure 3 summarizes the nomenclature used in the past and in this paperfor part of the Lower and

Middle Devonian of Nevada. The name "Union Mountain Formation" ofCarlisle and others (1956) is abandoned because it consists ofseveral distinct rock units recognized elsewhere as formations ormembers of formations.The earlier established Sevy and Oxyoke CanyonFormations are applied to "Union Mountain" strata inthe Pion Range.The Oxyoke Canyon Formation is divided into two members, alower Quartzose Member and an upper Coarse CrystallineMember. "Union Mountain" strata in the Sulphur Spring Range aredivided into four parts in ascending order:1) Sevy Dolomite (upper tongue),2) 13artine Tongue of the Mc Colley Canyon Formation, 3)Sadler Ranch Formation, and 4) Coarse Crystalline Memberof the Oxyoke Canyon Formation (western tongue).The Sadler Ranch Formation is a new namefor a rock unit which isalso recognizable at Modoc Peak,Table MOk111"- tain, and Lone Mountain.The Bartine Tongue is prevent in aorne Roberts 1 Lone Modoc 1 Sulphur Pi on Diamond area-b Pilicm and "Diammd :D. Egan Mountains Mtn. Peak Spring Ra. Ra, Ra. Diamond Ra, Ra. Ra. (E.Nevl

Murphy andGronberg, This Paver Carlisic Nolan & Kellogg, ref. -i 1970 othere,1954others,1956 1963 i Simonson Pm. Telegraph z Sentinel IfI L. tat, Lower Alternating Mbr, Canyon Mb4 Mtn. Mb. 8 Mb. Denay "Simonson R I C-.gr N Ls. Coarse Crystalline Mbr. rt Mb. Rh. j Oxyoke lal 5andy mb IC Sadler Ranch Fm. Quartzose Mbr. o Union Cyn. Mbr,

ill Mtn.

Coils Coils 1 cl 1 i Mbr. Creek Creek B.T. Coils Bartine Mbr. g Mbr. z Creek Mbr. Tongue .o Beacon il PI Sevy Fin. Bartine 4) Bartine up. tongue Peak O Sevy Fin. Mbr, Mbr. Bartine Mbr. Mbr McCelley

Cyn, Mbr. Kobeh M, Kobeh M. Sevy Fm. Kobeh M. .josaLw.,,,,,...,,,,,,,,,,...1,,,,,,-,...... ,..j.,,,,,J...... ,...,... one Mountain Dol.om.te Figure 3. %. relation chart for part of the Lower and MiddleDevonim of Nevada. 13 exposures in the Pion andDiamond Ranges as well as in the Sulphur Spring Range.At Modoc Peak a lower Sevy tongue is presentbeneath the Bartine Tongue. The name Sevy Dolomite is used in placeof Beacon Peak Dolomite in the Diamond and Pion Ranges,Lower Alternating Mem- ber of the Simonson Formation is used inplace of Sentinel Mountain Dolomite in the Diamond Range and in placeof lower Telegraph Canyon Formation in the Sulphur Springand Pion Ranges, 14

SEVY DOLOMITE

General Statement

The Sevy Dolomite is very uniform inlithology, thickness, and stratigraphic relationships in easternNevada (Osmond, 1954, 1962); but it is less uniform in these respectsin central Nevada, where it interfingers with deeper-water marinecarbonates.In the Diamond and Pirion Ranges, the stratigraphyof the Sevy is similar to that in eastern Nevada, except for thelocal presence of a basal quartzite and the replacement of the sandy uppermember by the lower part of the Oxyoke Canyon Formation.Lone Mountain Dolomite orLaketown Dolomite or an unnamed transitionalunit (Sheehan, 1972) everywhere underlies the Sevy in eastern Nevada;the basal, coarsely crystalline dolomite of the Simonson Formationoverlies the Sevy.Farther west and southwest, inthe Sulphur Spring Range andMahogany Hills, the stratigraphic relationshipsof the east break down completely. A lower tongue of Sevy isrecognized in the Mahogany Hills,and an upper tongue isrecognized in the Sulphur SpringRange.Figures 4,

5,10, and 18 are lithofacies mapsshowing the changing distribution pattern of the Sevy Dolomitein Eureka County frommid-Kobeh time to early Coils Creektime.Rose diagrams indicatepaleocurrent dispersal patterns, based oncross-bedding attitudes. 15

1 ,

i W I

Kobeh Mbr. of ' 0 McColley I % \ f. Canyon Fm.

..61% / Sevy Dolomite: 0 \,...;),

! V in ,---V.9 Basal quartzitr

I of the Sevy 1

I Dolomite 1

, E , l______J

10 0 10 20 3C 40 miles

Figure 4 . Lithofacies distriburion during mid-Kobeh time. 16

Bartine Mbr. of McColley Canyon -zm.

Sevy Dolomite

10 0 10 20 30 40 miles

Figure 5. Lithofacies distribution duringmid-Bartine time. 17

Diamond and Piiion Ranges

The Sevy Dolomite of the Diamond andPirion Ranges is composed of three units:1) a basal quartz sandstone that pinches out toward the south, 2) a thick middledolomite, and 3) an upper unit of dolomite with interbeds of quartz sandstone.At some localities there is a thin yellow-gray limy dolomitein the upper quartzose unit.This unit is the Bartine Tongue and is discussedunder that heading. In the Pi-lion Range the total thickness of theSevy was not determined because of structural complications and cover.At least 850 feet of Sevy is present north of Coffin Mountain,including approximately 100 feet of basal quartzite (Carlisle andothers, 1957).The thickness in the Diamond Range varies from over 940feet near the Phillipsburg Mine to approximately 620 feet in OxyokeCanyon.The basal quartzite varies from 225 feet at PhillipsburgMine to 80 feet at Black Point (Nolan and others,1956).At Oxyoke Canyon the basal quartzite is represented by 17 feet of slightlyquartzose dolomite.

Basal Quartzite

The basal sandstones of the Sevy arelithologically similar to the sandy beds in the upper part of theSevy and in the Quartzose Member of the Oxyoke Canyon Formation.The dolomite matrix and 18 interbeds of the basal quartzite are identical to the overlying non- quartzose dolomites.The basal sandstone was not studied in detail, and its distribution in figure 4 is only approximate.

Middle Dolomite

The middle dolomite unit is the thickest, most uniform, and most widely distributed unit of the Sevy.Figure 5 shows the facies distribution during deposition of the dolomite unit.The finely crystalline dolomite is yellowish gray (5 Y 7/2) to pale yellowish brown (10 YR 6/2) on fresh surfaces.Weathered surfaces are light gray (N7 to N8) to bluish white (5 B 9/1).The rock has a dense, porcel- laneous texture and a jagged to subconchoidal fracture.Faint rounded intraclasts are visible in some beds, but the clastic nature of much of the dolomite is masked by the uniform, aphanitic- appearing weathered surfaces.Bedding plane partings are usually six to eighteen inches apart and are defined by laminations and orange-weathering stylolites.The orange color of the stylolites is due to concentrations of iron oxide (hematite) possibly derivedfrom insoluble, iron-rich clay minerals.In outcrop the Sevy forms moderately resistant, step-like slopes partially covered bycolluvium. The Sevy is less resistant than the underlying LoneMountain Dolomite and the overlying Oxyoke Canyon Formation. Scattered, rounded, silt-sized to medium-grained quartzgrains 19 are suspended in the dolomitematrix or occur along stylolites, in thin discontinuous laminations, and in brown-weatheringdolomitic quartz arenite beds up to one foot thick.These quartzose beds and laminations are rare, but they are identical to the much more numerous quartzose beds in the upper partof the Sevy and in the Oxyoke

Canyon Formation. Laminations are the most common sedimentary structure,but many beds are structureless.The laminations are due to changes in the amount of carbonate matrix and intraclasts.Wavy and undulatory laminations are present locally and indicatepenecontemporane- ous deformation of the sediment.Intraformational conglomerates occur in thin discontinuous bedsand lenses up to six inches thick. Individual clasts are angular to rounded, up to oneinch long, and are composed of laminated to structureless dolomite mudstonesimilar to the matrix in which the clasts occur. White to clear, medium- to coarse-grained dolomitecrystals occur in pea-sized blebs scatteredin the dolomite matrix and in elongate bodies parallel to laminations.These blebs and elongate bodies of dolomite spar are up to 1/4 inch acrossand one inch long. The structures are probably birds-eye andfenestral structures that formed when pore spaces were filled by carbonate spar.Such structures are common in modern intertidaland supratidal carbonate mud environments and result when algal mats orother organic matter 20 decay and leave gas-filled pore spaceswhich are later filled by carbonate cement (Niem, personalcommunication, 1974). In thin section the laminated, non-quartzoseSevy is a dolomite pelmicrite to intraclast-bearingdolomicrite.Well-rounded, moderately well sorted, silt-sized tofine-grained dolomicrite intraclasts comprise less than 20% of the rock,The grains float in a matrix of dolomicrite and dolomite microspar or areconcentrated in thin laminae.The intraclasts appear identical incomposition to the dolomicrite matrix.The borders of the intraclasts areslightly fuzzy, due to partial recrystallization ofneighboring matrix to microspar. Present with the intraclasts are roundedsilt-sized to a very fine- grained clasts resembling fecal pellets(Niem, personal communication, 1974).Both the intraclasts and dolomicrite aredarker in color than the cloudy microspar part of thematrix.The microspar occurs in irregular patches up to1/2 inch across that are surrounded by and include un-recrystallizeddolomicrite.Medium- to coarse- grained dolomite spar fills thesharply bounded pores previously referred :o as birds-eye and fenestralstructures,Rare spherical and needle-like, silt-sized massesof clear dolomite spar have filled pores of organic origin,possibly fecal pellets or unrecognizable microfossils.The structures are obscure becauseof their size and marginal obliteration bymicrospar.Iron oxide, mostly hematite, occurs as finely disseminated massesor is concentratedalong 21 stylolites.Terrigenous clay and quartz silt andsand are minor constituents (<10%).Organic carbon content is lessthan 1/2% (see Appendix VI). An intermittently agitated tidalflat depositional environment varying between quiet and slightlyagitated conditions is suggested for the dolomite unit by the variableamounts of intraclasts and dolomicrite in laminated portions ofthe unit.Thin beds of intraformational conglomerate and quartz areniteindicate that strongly agitated conditions occasionallyoccurred. The extremely fine crystallinityof the dolomite in both intra- clas ts and matrix, the preservationof delicate sedimentary structures, and the absence ofcoarsely crystalline diagenetic dolomite indicate that dolomitization ofthe Sevy was early and very uniform. Seepage refluxion or capillaryconcentration (evaporative pumping) on a tidal flat couldeach explain such early dolomitization(Zenger, 1970; Bathurst, 1970). Osmond (1962) suggested earlydolomitization of the Sevy Dolomite on a broad, near sealevel mud flat, and the writer agrees. The laminations, birds-eye andfenestral structures, intraformational conglomerates, scarcityof organic activity or remains,early dolomitization, and variable energyconditions strongly suggest an intertidal to supratidal environmentof deposition for the middle dolomite of the Sevy.Laporte (1971) interpretedsimilar 22 sedimentary structures in the Hamilton Group of NewYork.High salinities favoring early dolomitization and hinderingorganic activity could have resulted from evaporation of sea water onthe Sevy tidal flat.Poor circulation with the normal marine waters tothe west could have allowed the brines to become enrichedenough in magnesi- um to form dolomitizingsolutions as calcium was removed during formation of micrite.Poor tidal exchange with normal marine waters is suggested for the upper quartzose unit ofthe Sevy because of the predominance of onshore (E) paleocurrents and nearlycomplete absence of offshore (W) ones (figure 10).Similarly poor exchange may also have existed earlierin Sevy time. Interbedded with the light gray dolomites aresharply defined beds of dark dolomite mudstone to wackestone.On freshly broken surfaces these beds are olive gray (5 Y4/1) to light olive gray (5 Y 6/1), and on weathered surfaces they arelight olive gray.When broken, the rocks emit a slightly fetid odor.Individual beds are laminated to massive.Contacts with the light gray dolomitebeds are planar and conformable.The aphanitic-appearing dolomite is composed of a matrix of dolomicrite anddolomite microspar and a framework of scattered silt-sized to fine-graineddolomicrite intraclasts and quartz grains.The beds pinch-out along strike and were apparently deposited in shallow depressions onthe Sevy tidal flat. These dark beds may be lagoonal deposits,and the fetid odor is 23 probably due to a higher content of organic matter. Most of the dark interbeds are less than twofeet thick, but some are over 20 feet thick.Scattered thin beds predominate in the Diamond Range, but thicker beds are commonin the Piton Range in an interval 130 to 300 feet below the OxyokeCanyon Formation. The slightly deeper conditions that gave rise tothe lagoonal(?) sediments appear to be limited to the westernmargin of the Sevy outcrop area.Osmond (1954, 1962) did not mention similarrocks interbedded in his dolomite member of the Sevy.

Upper Quartzose Unit

The upper 50 to 100 feet of the Sevy in theDiamond Range contains more quartzose interbeds than theunderlying middle dolomite unit and is transitional to the overlyingmassive quartzites of the Oxyoke Canyon Formation.The transitional quartzose zone is thicker in the Piton Range than in the DiamondRange; but in the Piton Range quartzose beds are thinner and less numerous,and the contact with the Oxyoke Canyon Formation is moreabrupt. At Union Mountain approximately 50feet of Bartine Tongue and Sadler Ranch Formation (lowertongue) conformably separate the Sevy and Oxyoke Canyon Formations.Elsewhere in the Piton and Diamond Ranges, the Sadler RanchFormation is absent and the Bartine Tongue is thin or absent. 24 Light gray- (N7) to bluish white- (5 B9/1) weathering, slightly quartzose to non-quartzose,dolomite mudstones and wackestones predominate in the upper part of theSevy and are identical to the underlying dolomite unit.Very quartzose dolomite beds ( >25% quartz) and dolomitic quartz arenitebeds weather rusty brown (10 R 4/6), yellowish gray (5 Y8/1), and light olive gray (5 Y 6/I). Freshly broken surfaces of very quartzosebeds are light olive gray. The darker weathering colors of thetransitional unit and the greater resistance to weathering of the unitmake it distinct from the underlying monotonously gray middledolomite unit (figure 6). The quartzose interbeds range inthickness from laminations less than one inch thick to beds tenfeet thick.Most of the quartz occurs in medium bedsand in thin discontinuous lensesand laminations.Individual beds have either gradational upperand lower contacts or sharp basal contactsand sharp to gradational upper contacts. Thin dolomite-rich beds usuallyhave gradational upper and lower contacts.The thicker sandstone beds arelaminated (plane bed laminated) and cross-bedded tostructureless.The cross-beds are low-angle and planar, and nearlyall the cross-beds are truncated above and below by othercross-beds or by horizontal laminations. Except for a few molds ofpelecypods or brachiopods, no megafossils were found in thesandy unit.Some vertical sand-filled burrows were found in OxyokeCanyon (figure 7).These burrows Figure 6.Transitional zone of upper Sevy Dolomite in Oxyoke Canyon. Oxyoke Canyon Formation is in upper right corner of photo.

Figure 7.Vertical sand-filled burrows in the upper part of the SevyDolomite in Oxyoke Canyon. 111 26 are concentrated in onebed and are 1/4 to 1/2 inch in diameter and one to three inches deep.The burrows are completely filled with quartz sand in a dolomicrite matrix.The erosional surface of the non-quartzose dolomite mudstone intowhich they were dug was scoured prior to the deposition of a three inch bedof homogeneous to faintly laminated quartz arenitethat in-filled the burrows.The upper contact of the quartzsandstone is gradational over one inch, and dolomite micrite and intraclasts graduallyreplace the quartz. A rapid change from quiet to moderately orstrongly agitated conditions is indicated by the sudden influx of quartzsand.Conditions quieted again as deposition of dolomite mudresumed. Fluctuating energy conditions are suggested byfeatures of another bed of the sandy unit.Figure 8 shows poorly formed ripples of dolomitic quartz arenite that are partiallycovered by dolomite mud, the accumulation of which is thickerin the ripple troughs than on their crests.The relatively strong current that formed theripples gave way to a more gentlecurrent that allowed more mud tosettle in the protected troughs than onthe exposed crests. In thin section the quartzose dolomitesand dolomitic quartz arenites consist of 30% to 60% quartzsilt and sand in a 30% to 60% medium crystalline dolomite matrix.Small amounts of dolomicrite intraclasts are also present.Quartz is silt-sized to coarse-grained but is more commonly fine- tomedium-grained.Grains are very Figure 8.Mudstone covered ripples in the quartzose upper unitof the Sevy Dolomite in Oxyoke Canyon.

Figure 9.Bartine Tongue interbed in the quartzose upperunit of the Sevy Dolomite in Oxyoke Canyon. 28 well rounded, moderately well sorted,and nearly spherical.The matrix consists of clear medium-crystallinedolomite spar in the quartz arenites and dolomicrite,dolomite microspar, and dolomite pseudospar in the less quartzose beds.Chert, clay, iron oxide, and secondary quartz overgrowths are minor constituents.The dolomicrite intraclasts are identical to theintraclasts and matrix of the non-quartzose dolomite beds.The clastic origin of the intraclasts is suggested by their variability in size(silt-sized to gravel-sized) and shape and by the presence ofgravel-sized intraclasts of identical composition in intraformational conglomerates.The dolomite spar in the quartz arenites appears to bepore-filling carbonate cement. The original sediment was probably aclean, loose sand that was cemented by dolomite during early diagenesis. The sedimentary structures and variationsin the lithology and thickness of beds imply an intertidal environmentof deposition for the rocks of the quartzose upper part ofthe Sevy.Thicker cross- bedded and plane-bed laminated quartzarenites were probably deposited in high-energy beach or barenvironments.The thin beds of quartz arenite and quartzose dolomite wereprobably deposited rapidly by tidal or wind-driven currentsin very shallow water. Wind transport alone may beresponsible for some of the scattered fine-grained quartz scattered inlaminations and thin beds lacking features of current transport. 29

At Oxyoke Canyon the Bartine Tonguerocks are interbedded with the quartzose upper part ofthe Sevy (figure 9).These yellow- gray limy dolomites areof intertidal origin (see discussionunder Bartine Tongue).The intimate relationship betweenBartine Tongue and Sevy rocks at Oxyoke Canyonand the absence of Bartine Rocks farther east (shoreward) supportsthe idea that the Sevy is of an intertidal to supratidal origin. During late Bartine time (figure10) the southern Diamond Range was closer to the westernedge of the Sevy tidal flat than the northern Diamond Range and PionRange.The proximity of the southern Diamond Range to the higher energyintertidal environments that probably existed along the westernmargin of the Sevy tidal flat can explain whycross-bedded quartz arenite interbeds arethicker and more numerous there thanelsewhere in the Diamond andPiiion

Ranges.Areas away from the westernmargin of the tidal flat received smaller amounts of quartzsand via tidal and aeolian action. Grain-size analysis (pages143-148) supports the conclusion that quartzose beds were depositedby both littoral and aeolian processes.

Mahogany Hills

A lower tongue of the Sevy cropsout in the Mahogany Hills, where it unconformably overliesthe Lone Mountain Dolomiteand conformably underlies the BartineMember of the Mc Colley Canyon 30

Bartine Mbr. of McColley Canyon Fm.

Sevy Dolomite Upper Tongue

10 0 10 20 30 40 miles 1117=CIMICI

Figure 10.Lithofacies distribution during late Bartine time. 31

Formation.At Modoc Peak the Sevy tongue islithologically identical to the middle dolomite unitof the Sevy at Oxyoke Canyon.Minor scattered quartz grains and quartzosebeds are present in the upper part of the unit, but these beds arethinner and less numerous than at Oxyoke Canyon.Total thickness of the unit is uncertaindue to faulting, but at least 256 feet are present.At Table Mountain rocks of Sevy lithology are included inthe Kobeh Member of the Mc Colley Canyon Formation and are interbeddedwith limestones (Gronberg, 1967, sections). Figure 4 shows the distribution of theSevy Dolomite during mid-Kobeh or early Sevy tongue time.Interestingly, the lower tongue is absent in the Sulphur SpringRange, but the upper tongue is present.

Sulphur Spring Range

The upper tongue of the Sevy Dolomite cropsout along the main Devonian outcrop belt of the SulphurSpring Range and conformably overlies and underlies Bartine-likeargillaceous limestones.The underlying rocks are part of theBartine Member of the Mc Colley Canyon Formation, and theoverlying rocks are part of the Bartine Tongue of the Mc Colley CanyonFormation.The thickness of the Sevy tongue varies from 195 feet atBald Mountain to approximately 400 feet at Sadler Ranch.Two distinct facies are present inthe

tongue:1) a lower one transitionalbetween the Bartine and Sevy 32 proper and 2) an upper facies of moretypical Sevy Dolomite with interbeds of quartz sandstone and dark dolomite mudstone.

Transitional Unit

The transitional unit is observable in most complete sections of the Sevy because of its greater resistance than theunderlying Bartine.Particularly good exposures occur at Summit 7466, Bald Mountain, Fera Well, and Williams Canyon.Thicknesses of 15 to 25 feet are typical in the northern and southern partsof the range; but at Bald Mountain and near the Old Whalen Mine,the unit is as much as 56 feet thick. Niebuhr (1973) noted an upward shallowing and an increasein quartzose and dolomitic interbeds in the upper25 feet of the Bartine Member in the Sulphur Spring Range.The base of the transitional unit is here defined as the lowest abruptly resistant,massive, quartzose dolomite of Sevy-like lithology that iscontiguous with the main body of the Sevy tongue.The contact between the Bartine Member and transitional unit is sharp andplanar (figure 11) and is easily recognized on the basis of color,resistance, and lithology. The transitional unit is composed ofstructureless to faintly laminated, very light gray- (N8) to yellowish gray-(5 Y 8/1) weathering quartzose dolomite.Beds range from six inches to three feet thick.The basal three to five feet containscattered, thin (1/2 to six 33

Figure 11.Conformable contact between the BartineMember of the McColley Canyon Formation and the overlying transitionalunit of the Sevy Dolomite in the Sulphur Spring Range.

Figure 12.Photomicrograph of intraclasts from thetransitional unit of the Sevy Dolomite in the Sulphur Spring Range. 34 inches thick) lenses and bedsof rusty brown-weathering (10 YR5/4), siliceous, dolomitic quartz arenite.These lenses and beds exhibit scoured bottom contacts (relief to1/2 inch) and planar to undulating top contacts, and containdisarticulated, silicified brachiopodshells to 3/4 inch in diameter.The shells are oriented parallel tothe bedding,Overall the texture and lithologyof the unit are very uniform.The upper contact of the unit isgradational over several feet into the dolomites and quartzarenites of the upper unit of theSevy tongue. In thin section the unit is adolomite intramicrite to pelmicrite, It is composed of dolomicriteintraclasts (21%) and quartz silt and fine sand (8%) in a matrix ofdolomicrite, dolomite microspar, and dolomite pseudospar (62%).There are also small quantities ofchert (7%), silicified shell fragments(<1%), iron oxide (2%), and terrigenous clay (<1%).Partial recrystallization tomicrospar and pseudospar has obscured manyintraclast boundaries. A few elongate, medium-grained intraclastsand irregularly shaped intraclasts, otherwise identical tothe majority of well roundedand sorted intraclasts, indicate aclastic (mud rip-up) ratherthan bio- genic origin for these particles. The well rounding of silt-sizedto fine-grained quartzsand and dolomicrite intraclasts,the clastic origin of theintraclasts, and the presence ofabraded, current-transportedshells concentrated 35 in thin washes and lenses,alternating with thin lenses (to 1/4 inch thick) of dolomicrite indicate that carbonatedeposition occurred in an intermittently agitated,shallow, marine environment (energy index II of Plumley and others, 1962).A low intertidal or shallow subtidal environment probably existedduring deposition of this unit. The upward shallowing trend andlithology changes in the Bartine Member and transitional unit, and thegradational contact between the transitional unit and upper (intertidal)unit of the Sevy tongue further support a low intertidal to shallowsubtidal environment of deposition for the transitional unit. Current-transported brachiopod shells arepresent in many sections, and one collection (KDL-17) wasmade at Summit 7466. Specimens of Eurekaspirifer pinyonensisand Atrypa nevadana only are present in thiscollection.The community represented by the collection is probably the EurekaspiriferCommunity of Niebuhr (1973), his shallowest and simplest.The large size of the fossils and the associated sedimentary structuressuggest a shallow, moderate- to high- energy environmentof deposition for the transitional unit. After the transitional unit wasdeposited as fine carbonate sand and mud, minor local compactionof the soft particles occurred. Partially flattened and alignedintraclasts in one sample from Bald Mountain attest to this and suggestrapid deposition and burial 36

(figure 12).The extreme fineness of dolomicrite inintraclasts and matrix material and the paucity of sparrydolomite rhombs strongly suggest uniform syndepositionaldolomitization.The seepage refluxion model of dolomitization could explainearly dolomitization in this setting (Deffeyes and others, 1965).The source of the Mg-rich dolomitizing brines could have been the Sevytidal flat to the east, and these brines could have seepedwestward and downslope the short distance to the site of deposition of thetransitional facies.Many of the intraclasts may have been derivedfrom the Sevy tidal flat muds and already have been dolomitized. Sometime after burial, calcareous shell debris waspreferenti- ally replaced by silica (polycrystallinequartz) which subsequently partly recrystallized to spherulitic chalcedonicquartz.Partial silicification (to chert) also occurred in thethin rusty-brown quartzose lenses and beds in the basal fewfeet of the unit.Later, probably with deeper burial and morealkaline conditions (Siever, 1959), sparry dolomite rhombs anddolomite microspar partially replaced quartz, chalcedony, and chertthroughout the rock (figure 13). Etched and partially embayed quartz sandgrains are common and attest to the late replacement ofsilica by dolomite.Partial recrystallization of the dolomicrite matrixand dolomicrite intraclasts may have also occurred at this time toproduce blurred intraclast boundaries and scattered irregular patchesof microspar and pseudospar. Figure 13.Photomicrograph of a silicified brachiopod shell in the transitional unit of the Sevy Dolomite in the Sulphur Spring Range. 38

Authigenic iron oxides, mostly hematite with minorlimonite, occur as fine disseminated masses or areconcentrated along small stylolites.They may have been derived from oxidation ofiron-rich clay minerals.

Upper Quartzose Unit

The upper unit of the upper Sevy tongue is moretypical of exposures of the Sevy to the eastand north than is the lower transitional unit.Thickness of the unit varies from 85 feet at BaldMoun- tain to approximately 400 feet near SadlerRanch.In general the upper unit is thin where thetransitional unit is thick. The bulk of the upper unit is dolomite mudstoneand slightly quartzose dolomite wackestone.Quartz arenite and very quartzose ( >25% quartz) dolomite interbeds areconcentrated in the lower part of the unit in many sections (notably TelegraphCanyon, Fera Well, and Williams Canyon) but are more randomlyscattered in other sections.Dark dolomite mudstone immediatelyunderlies the Bartine Tongue in at least two sections (WilliamsCanyon and Telegraph

Canyon). The light colored dolomite and slightlyquartzose dolomite of the upper unit are virtually the same asthe pure dolomite beds in

the Pirion and Diamond Ranges.Freshly broken surfaces are yellowish gray (5 Y 8/1), light olive gray (5Y 6/1), and medium to light 39 gray (N5 to N7).Weathered surfaces are medium light gray(N6) to very light gray (N8) and lightbluish gray (5 B 7/1).Bedding plane partings are usually four inches to eighteeninches apart and are defined by laminations, orange-weatheringstylolites, and variations in quartz content.Many thin beds, lenses, and discontinuouslamina- tions of slightly quartzose dolomite occurbetween bedding plane partings, and the matrix of these slightlyquartzose beds is the same as the matrix of the puredolomite beds.The resulting rock is a well cemented and dense rock and isof monotonous lithology. In thin section the pure and slightlyquartzose dolomite beds are composed ofintraclast-bearing dolomicrite that is partly recrystallized to dolomite microspar andpseudospar.The intraclasts and matrix have identical compositions.The size of the intraclasts and relative amounts of dolomicrite matrixand intraclasts vary in different laminae. The environment of deposition of theselocally slightly quartzose dolomites ranged between quiet andmoderately agitated conditions. Early dolomitization similar to that inother Sevy rocks is suggested by the fine crystallinity of thedolomite matrix.The lack of obvious current features in many ofthe slightly quartzose laminationsand beds and the fineness of the quartzsuggest that wind transport may be responsible for at least partof the contained quartz. Two types of quartz-rich beds occur:1) thick, cross-bedded 40 and plane-bed laminated beds and2) thin, laminated to structureless beds.The basal contacts of both types ofbeds are commonly erosional surfaces, and the upper contactswith less quartzose beds are sharp to gradational. The cross-bedded units vary in thicknessfrom less than one foot to over ten feet.These units thin and thicken along strike,and many pinch-out within onemile.They appear to be wide, thin, lens- like deposits.The low-angle accretionary cross-beds arein most places truncated above and below byother cross-beds or by horizontal laminations.Many of the cross-beds resemble thecross-beds present in intertidal mega-ripples(G. deVries Klein, oral communication, 1974).The dominant paleocurrent dispersaldirection is toward the east and southeast (figure10).A second and much smaller paleocurrent mode is toward the north.These cross-bedded quartz arenites are interpreted as intertidalbeach and bar sands deposited by onshore waves (E) and longshore(N and S) currents. The thinner, laminated to massivequartz-rich beds are one inch to one foot thick and alsopinch-out along strike.Dolomite rip-ups up to one inch across are common nearthe base of these beds, and basal contacts are nearlyalways erosional surfaces

(figure 14).A crude normal grading is presentin many of these beds: dolomite mudstone rip-ups,medium- to coarse-grained quartz sand, and rare shellfragments near the base gradeupward l i rmemillinoetimlm

Figure 14.Hand sample of a quartz ar enite bed in the upperunit of the Sevy Dolomite in the Sulphur Spring Range showingbasal scour and graded bedding. 42 to finer-grained, quartz-poordolomitic wackestone and mudstone. Upper contacts are usually gradational over aninch or more.These laminated and massive quartz arenites areinterpreted as tractive tidal deposits, such as wash-overfans and tidal flat sheet sands. These beds are distinguishable from the more numerousslightly quartzose beds and laminationsby their sharp, erosional basal contacts, higher quartz content, coarsergrain size, and concentration of dolomite mud rip-ups.The beds usually are more resistantand stand out in greater relief than theless quartzose dolomites. Both types of quartz-rich beds aremedium to light gray (N5 to N7) on freshly broken surfaces andlight gray (N7) to rusty brown (10 R 4/2) on weathered surfaces.Quartz-rich laminae stand out in slight relief where the alternatingdolomite-rich laminae have been leached away.The beds are moderately to veryresistant, and the thicker beds are ledge-formers. In thin section the quartz-rich beds arecomposed of fine- to coarse-grained, well rounded,moderately well sorted quartz grains (40% to 60%) and rounded andflattened, silt-sized to coarse-grained dolomicrite intraclasts (15% to20%), in 20% to 50% dolomicrite, dolomite microspar, and dolomitepseudospar matrix. Some quartzose cross-bedded bedslack fine-grained matrixesbut are cemented by clear mediumcrystalline dolomite spar.Terrigenous clay, secondary quartz overgrowths,and iron oxide are minor 43 constituents.Organic carbon content is also negligible.Insoluble residues of both types of quartz-rich bedscontain small amounts of silicified shell fragments.The intraclasts are identical in composition to the dolomicrite portion of the matrix,and their clastic origin is evident from their variableshapes and rounding and from their rare inclusion of quartz silt.In cross-bedded units, the cross - laminae are composed of both quartz andintraclasts. Partial recrystallization of the dolomicritematrix and some of the intraclasts to microspar andpseudospar has occurred, but coarse-grained diagenetic sparry dolomiteis absent.The extreme fineness of dolomite crystals in both thematrix and intraclasts suggests that both werethe product of early dolomitization ofcarbonate mud.Silicification of originally calcareous shells andthe formation of secondary quartz overgrowths asevidenced by tangential and concavo-convex quartz grain contactsprobably took place at relatively shallow depths during early diagenesis(Siever, 1959).Styloli- tization may have also occurred duringearly diagenesis, since some quartz grains concentrated alongstylolites have interpenetrating grain contacts characteristic of earlydiagenesis and/or shallow burial (Siever, 1959).Partial dissolution of quartzovergrowths and grains and replacement by dolomitemicrospar and pseudospar probably occurred later under higherpH and lower CO2 partial pressure during burial(Siever, 1959). 44

Dark dolomite interbeds of the upper part ofthe Sevy tongue are dense aphanitic dolomitemudstones.They have sharp planar contacts with the light colored dolomites and are notinterbedded with the thick cross-bedded quartz arenites.Beds generally are six inches to two feet thick, but some are over tenfeet thick.Most beds pinch-out along strike within 1/4 mile.The beds were apparently deposited in broad, shallow depressions onthe Sevy tidal flat. Fresh surfaces of the dark beds are medium dark gray(N4), olive gray (5 Y 4/1), and light olive gray (5 Y6/1); and freshly broken surfaces emit a fetid odor.Weathered surfaces are light olive gray (5 Y 6/1) to medium light gray (N6).Faint laminations are present in some beds, but most beds arestructureless. In thin section the dark beds are dolomicrites tointraclast- bearing dolomicrites and dolomite pelmicrites.The intraclasts appear identical in composition tothe dolomicrite of the matrix. Silt-sized dolomicrite pellets may be of fecal pellets.Intraclasts and quartz silt and sand comprise 5% to20% of the rock; dolomicrite, dolomite microspar, and dolomite pseudospar matrixform 80% to 90% of the rock; and sparry dolomite void-fillings,porosity, and iron oxide make up the remaining2% to 5% of the rock. The fine crystallinity of the dolomitemudstones suggests that predominantly quiet conditions prevailed duringdeposition of these dark mudstones.Occasional periods of slightly to moderately 45 agitated current conditions are responsiblefor the concentration of quartz grains and dolomicrite intraclastsin thin laminae.The fetid odor and higher content of fecal pellets inthese beds suggest greater organic activities and less oxidizing conditionsthan during deposition of the lighter colored Sevy.The blebs of sparry dolomite may be birds-eye or fenestral structures.Because of the intimate association of the light (intratidal to supratidal)and dark dolomites, the writer believes the dark beds were depositedin shallow, short-lived lagoons or protected depressions on theSevy tidal flat. Figure 15 is a facies tract model fordeposition of the Bartine Member of the Mc Colley Canyon Formationand upper tongue of the

Sevy Dolomite.A zone of bars and beaches separates normalshallow marine limestones (Bartine) fromintertidal to supratidal dolomite

(Sevy).The high-energy environments alongthe western edge of the Sevy Dolomite probably existed in athin (one to five miles wide) zone running roughlynorth-south through Eureka County.The carbonate facies tract model in figure 15closely resembles Wilson's (1974) carbonate platform marginmodel for quiet to moderate seas and low to intermediate shelfslopes,According to Niebuhr (1973) the Bartine sea had a very lowshelf gradient and was of low to moderate energy.The upper tongue of the Sevy (whichapproximately correlates with the upper quartzoseSevy in the Diamond and Pi lion Ranges) interfingers with thenormal marine shelf limestones ofthe BARTINE LIMESTONE SEVY DOLOMiT1

Aarine (sub-tidal) Transition Beach/bar Tidal Flat (intertidal and supratidal) (sub- to in (intertidal) I tertidal)

Quiet to moderately Moderately Moderately to Quiet to strongly agitated; agitated; abundantly agitated; strongly agita- Dolomite mudstone containing fossiliferous; lime Quartzose, ted; Quartzose occasional intraclasts and mudstone to packstone;intraclast- dolomite; cross- rip-ups; occasional interbedn common laminations bearing do-bedded and hor- of dolomitic quartz sandstone; and burruws; shallow lomite; izontally lam- unfossiliferous; rare vertical water del.,lition. sparsely inated; burrows burrows; common laminations. fossilifer- and fossils rare. ous; laminated. 0 1 mile

Figure 15. Facies tract model for deposition of the Bartine Limestone and upper tongue of the Sevy Dolomite in central Eureka County, Nevada. No vertical scale. 47 Bartine and is thought to represent a narrow zoneof quartzose beaches and bars and a much larger area of intertidal,supratidal, and lagoonal environments behind the beach/bar zone. The writer believes that the transitionalunit of the upper tongue of the Sevy Dolomite in the SulphurSpring Range represents gradual shallowing along the eastern margin of the Bartine sea.This shallowing may have been brought about by a greatersedimentation rate than subsidence rate, resulting in the westwardprogradation of the Sevy tidal flat.Figure 16 shows the westward faciesshift that the writer believes occurred across the SulphurSpring Range during late Bartine time. As the Sevy tidal flat prograded westward acrossthe Sulphur Spring Range, the leading edge (thehigh-energy beach/bar zone) moved across the range early and isrepresented by the concentration of lenticular cross-bedded andplane-bed laminated quartz at enites near the base of the upperunit of the Sevy tongue.The high-energy zone moved farther west,and only scattered thin quartz beachand bar deposits are represented in the restof the tongue (in the Sulphur Spring Range).The quartz beach and bar environmentsin the Sulphur Spring Range were displaced by intertidaland supratidal carbonate mud environments.Lagoons or other depressions werealso locally present.The quartzose beds that weredeposited behind (shoreward of) the western belt of beaches andbars were wash-over fans, tidal 48

Roberts Sulphur Spring Union Mountains Range Mountain Le1/ D) Latest Bartine Time A = S

Sevy Sevy Dolomite Dolomite Transitional Upper Tongue Unit

vertical scale (feet) S = Subsidence A = Accumulation

C) Late Bartine Time A > S -- Bartine Limestone

B) Late Bartine Time A> S

A) Mid- Bartine Time A = S

Figure 16.Successive steps in the westward progradation of the Sevy tidal flat.Depths are approx. 49 sheet sands, or aeolian flat deposits. A coastline of such low relief as thatbetween the Sevy tidal flat and the Bartine sea was bound to have someirregularities.In the central part of the Sulphur Spring Range,the transitional unit is thicker and the overlying upper unit isthinner than elsewhere in the range.The central part of the range wasprobably an initially deeper part of the Bartine Sea thanother parts of the range, and more shallowing by deposition of the transitional unit wasrequired there before intertidal Sevy deposition (upper unit)could take place.During much of late Bartine time there may havebeen a shallow embayment in the central part of the Sulphur Spring Range.The entire Sulphur Spring Range may have been a similarembayment in the Sevy-Kobeh coastline during deposition of the lowerSevy tongue in the Mahogany Hills.

Age and Correlation

The scarcity of fossils in the SevyDolomite makes dating the formation difficult.However, sparce faunal data fromthe transitional unit of the upper tongue, goodconodont and brachiopod data from the Bartine Member andTongue, and lithologic similaritiesdo allow correlation of the SevyDolomite with the more fully understood Devonian sections in centralNevada. The top of the underlying LoneMountain Dolomite is Early Devonian in age.Litho logic similarities suggestthat the lower 50 tongue of the Sevy in the Mahogany Hills isthe lateral correlative of the Kobeh Member of the Mc Colley Canyon Formationand is therefore of early Emsian age (Grorberg, 1967).The lower tongue is probably the same age as the basal quartzite in thePirion and northern Diamond Ranges and as the lower part of the thick dolomite unitin the southern

Diamond Range. The upper tongue of the Sevy overlies the BartineMember of the Mc Colley Canyon Formation and underlies theBartine Tongue of the Mc Colley Canyon Formation in the SulphurSpring Range.Brachi- opods immediately underlying and in the transitionalunit yield a Eurekaspirifer pinyonensis zone fauna.Conodonts from the upper part of the Bartine Member in theSulphur Spring Range suggest an early to mid-Bartine age (Klapper, written communication,1974) compared to the Bartine at Lone Mountain.The Bartine Tongue is of latest Bartine to earliest Coils Creek age, on thebasis of conodonts and brachiopods (see discussion under BartineTongue), also by com- parison with Lone Mountain.The upper Sevy tongue is therefore of mid- to late-Bartine or Emsian age. The upper Sevy tongue of the SulphurSpring Range is partly equivalent to the upper quartzose Sevy in theDiamond and Pi lion

Ranges.This lithologic correlation is only partiallyvalid for time correlation; because the Bartine Tongueinterfingers with the upper- most beds of the Sevy in Oxyoke Canyon,and the Bartine Tongue and 51

Sadler Ranch Formation (lower tongue) overlie the Sevy at Union

Mountain. The base of the Sevy may be diachronous; deposition of the Sevy Dolomite may have begun at different times above the uncon- forznity on top of the Lone Mountain Dolomite.The writer believes that westward progradation of tidal flat sediments could be responsible for the introduction of Sevy Dolomite in the Mahogany Hills after its appearance farther east. 52 BAR TINE TONGUE OF THE McCOLLEY CANYON FORMATION

General Statement

Strate herein termed Bartine Tongue wereformerly considered to be part of the Union MountainFormation and Beacon Peak Dolomite. In the Sulphur Spring Range the BartineTongue is separated from the Bartine Member of the Mc Colley CanyonFormation by up to 400 feet of Sevy Dolomite (upper tongue),which it overlies conformably.In the Sulphur Spring Range and at UnionMountain, the Sadler Ranch Formation overlies the tongue in apparentslight disconformity. Elsewhere in the Pition and Diamond Rangesthe upper quartzose Sevy conformably underlies, interfingerswith, and overlies the tongue. The thickness of the tongue in theSulphur Spring Range varies from 92 feet at Sadler Ranch to 64 feet atTelegraph Canyon and less than 50 feet in the northern part of the range.At Union Mountain and Coffin Mountain, the tongue is verypoorly exposed and is probably less than 2.0 feet thick.In Oxyoke Canyon two beds ofBartine Tongue rocks totaling 21 feet in thickness areseparated by 16 feet of quartzose Sevy.The Bartine Tongue was notobserved elsewhere in the Diamond andPirion Ranges. Superimposed on the northward and eastward thinning of the BartineTongue are some radical thinnings and subsequent thickenings.Two such thinnings occur in the 53 northern part of the map area in the Garden Valley Quadrangle

(Plate 1). Although there are some differences, rocks of the Bartine Tongue closely resemble rocks of the Bartine Member.Similarities of the two units include high argillaceous contents,yellow-gray weathering, locally poor exposure, and platyness.Three distinct units form the Bartine Tongue in the SulphurSpring Range, but only one unit is present in the Diamondand Pion Ranges.The three units are:1) a lower limy dolomite, 2) a middle limestone, and 3) an upper limy dolomite.The Bartine Tongue of the Pion and Diamond Ranges is represented by limy dolomite alone.Because of their pronounced yellowish weathering, the upper and lower units of the tongueresemble the Bartine Member more than does the middle unit. The eastward and northward pinching out of theBartine Tongue actually includes two pinch-outs:1) the pinch-out of the middle limestone unit and 2) the pinch-out of the combined upperand lower limy dolomite units (figure 17).The middle limestone extends part way across Diamond Valley,but the limy dolomite extends into parts of the Pion and Diamond Ranges.Figure 18 is a lithofacies map for early Coils Creek time and shows the maximumextent of the Bartine

Tongue. ROBERTS MOUNTAINS, SULPHUR SPRING DIAMOND and LONE MOUNTAIN, RANGE PINON RANGES MAHOGANY HTLLS

COILS CREEK LIMESTONE * BARTINE TONGUE (lower part)

Upper yellow grey limy dolomite f\J Combined upper and lower uni;sj COILS CREEK vmsTon Middle limestone unit

Lower yellow grey limy dolomite

BARTINE LIMESTONE

Figure 176 Schematic diagram of facies relationships in the Bartine Tongue (early Coils Creek age). No vertical or horizontal scale. 55

Coils Creek Mbr. of McColley Canyon Fm.

Bartine Tongue of McColley Canyon Fm.

Sevy Dolomite

10 20 30 40 miles

Figure lg. Lithofacies distribution during early Coils Creek time. 56

Lower Limy Dolomite

The Bartine Tongue of theSulphur Spring Range is typically developed and well exposed inTelegraph Canyon. Most other sections are too poorly exposedto allow for detailed studyof all three units. At Telegraph Canyon the basal unitconsists of 14 feet of yellow-gray weathering, limy dolomite mudstone towackestone.Thicknesses in other areas vary from 16 feet atSadler Ranch to approximately 25 feet at Fera Well.The underlying Sevy at TelegraphCanyon is medium gray quartzose dolomitemudstone to dolomitic quartz arenite.The quartz arenite and quartzosedolomite occur in lenses and medium beds to one footthick and are horizontally laminated or cross-bedded.The contact with the Bartine Tongueis planar to gradational over six inches.Quartz content decreases abruptlyabove the contact, and the darkdolomite matrix of the Sevy is overlainby a lighter limy dolomitematrix of the Bartine Tongue.Bedding in the limy dolomite is thin to mediumand is defined by laminations and variations in quartz and clay content.Scattered in the very fine crystalline to aphanitic limydolomite are fine-grained quartz grains.Fresh surfaces of the rock aredark gray (N3) to light olive gray (5 Y 6/1)and weathered surfaces areyellowish gray (5 Y 8/1) to grayish yellow (5 Y8/4).Faint laminations, mottling, orburrow- ing is present in somebeds, but other beds appearstructureless. 57

Abraded and current-depositedbrachiopods (silicified) are common in the basal six inches of theBartine Tongue (at Telegraph Canyon), but megafossils were not foundelsewhere in the lower unit. The presence at many localities offetid, dark dolomite mudstone immediately below the BartineTongue suggests slight deepening or the formation ofshallow lagoons prior to deposition ofthe tongue. Deepening was probably slight sincecross-bedded quartz arenites are closely associatedwith the contact at many of the samelocalities. The basal six inches of the BartineTongue in Telegraph Canyon yielded silicified Brachyspirifer cf.pinyonoides and Megastrophia?

sp. (Sample KDL-5). The shells are oriented in the stable or concave down position indicating some current-transportoccurred.The shells are in a two inch bedof fine- to medium-grained bioclasticwacke- stone to packstone.Quartz grains form up to 10% of thebed. Before depositing the carbonate sandand mud and the brachiopod shells, shallow marine currentsscoured out an irregular surface in the underlying carbonate mud substrate.Fluctuations in the trans- portive capacity of the currentduring deposition is shown by vertical variations in the amount of finedetritus within the bed.Extensive winnowing did not occur, probablybecause deposition was probably too rapid and the currents weretoo variable.The larger shells provided enough protection fromcurrents during deposition toallow more mud to remainunder them than in less protected areas.In 58 cross-section the extra mud forms thin, flat-bottomed capsjust beneath the concave-down profiles of the shells. After deposition of the fossil-bearing horizon,currents continued to vary in strength, but were probablyweaker overall, because no coarse-grained lensesof bioclastic or terrigenous debris are present.This slackening of current energy is suggestiveof deepening conditions.Mud rip-ups to fine gravel-size and smallchannels and scoured bedding surfaces indicate intermittenterosion during

deposition.The current energy must have varied between veryquiet (to allow carbonate mud to settle) andmoderately agitated conditions (to transport fossil debris and erode and transportmud rip-ups).The unit fits Plumley and others' (1962) energyindex scheme as a type II rock, or one deposited under intermittently agitatedconditions.The writer believes a lagoonal environment ofdeposition at the base of the unit gradually deepened to the shallownormal marine environment of the overlying limestone unit.

Middle Limestone

The middle unit of the Bartine Tongue is thethickest part of the tongue but is the least widely distributed.It is 72 feet thick at Sadler Ranch, 36 feet thick at TelegraphCanyon, and thins to 0 farther north in the Sulphur Spring Range.Limestone is absent at the corresponding interval in Mc ColleyCanyon (Murphy and Gronberg, 59

1970) and in the Pion and Diamond Ranges.Limestone overlying the Bartine at Modoc Peak (the upper Sevy tongue is missing)is lithologically similar to both the Bartine Tongue and the Coils Creek Limestone and is considered to be part of the Coils CreekMember of the Mc Colley Canyon Formation. The upper and lower contacts of the middle unit are poorly exposed in most sections and are apparently gradational over oneto two feet.At Telegraph Canyon and Fera Well the basal contact is marked by a one foot bed of limy quartzose dolomite.Elsewhere the contact is marked by a change to fossiliferous limemudstone to packstone, a decrease of argillaceous matter, an increasein resistance to weathering, and a decrease in thecharacteristic yellowish weathering of the rock. Lithologies of the middle unit of the Bartine Tongue vary between two end members:1) sparsely fossiliferous lime mudstone and 2) moderately fossiliferous, platy, lime packs tone.Both end member lithologies and the gradational types betweenthem are intimately associated in the middle unit:the middle unit is characterized by lithologic heterogeneity. Hand samples of middle unit rocks are mediumdark gray to dark gray (N4 to N3) and olive gray (5 Y4/1) on freshly broken surfaces and are medium light gray (N6) toyellowish gray (5 Y 8/1) on weathered surfaces.The mudstone is moderately well bedded in 60 four inch to eighteen inch beds.The argillaceous wackestones and packstones occur in platy, thin to mediumbeds (one to six inches thick).These packs tone beds are less resistantthan the mudstones and form recessive interbeds withinthe more abundant mudstones. The platy beds are scattered throughoutthe unit and form less than

10% of the unit.Thin lenses and beds (1/4 to four inchesthick) of fossiliferous wackestone to packs tone are commonin the rest of the section, but they are thinner and lessplaty and argillaceous than the recessive beds.The mudstones break with a jagged tosub-conchoidal fracture, while the platy wackestones andpackstones break roughly parallel to bedding planes.Figure 19 is a typical outcrop of the Bartine Tongue. Polished slabs of the middle limestone unitshow the intimate association of different textures withinthe same beds (figure 20). Small lithologic variations occur alongstrike.However, nowhere are the variationssignificant enough to allow subdivisionof the unit. One trend within the unit isnoticeable over the length of the range: the amount of current transportedcarbonate debris and distinct bioclastic beds with sharp basal contactsincreases northward (obliquely shoreward). Most of the unit consists of limemudstone containing scattered, fine- to very coarse-grained,sub-angular bioclastic debris.This bioclastic material consists mostlyof crinoid fragments (one and 61

4110 'Ft;

°,1tel k 11S. A' , 1 PL.;

' 1:4110

, ilbAL;! Z;';;41ktill:

Figure 19.Typical exposure of the middle limestone of the Bartine Tongue in the Sulphur Spring Range.

Figure 20.Slabbed sample of the middle limestone of the Bartine Tongue showing variations in texture. 62 two ossicle) and brachiopod and bivalveshell fragments.Gastropod and cephalopod fragments, bryozoans, stromatoporoids,corals, ostracods, and trilobites are present in smaller amounts.Some fossil fragments are concentrated along fine, wavylaminations. Burrows are abundant in the mudstone beds and may beresponsible for the random dispersal and orientation of the shellfragments,The burrows are 1/4 to 1/2 inch in diameter and are parallel orsub- parallel to bedding planes.On bedding plane surfaces the burrows form randomly meandering patterns similar to those of somequiet water detritus feeders, The lime mudstones grade into wackestones where the amount of fossil debris exceeds 10%.The wackestones are also irregularly laminated and burrowed, and contain similar fossildebris.Mudstone- filled burrows stand out more in the wackestones thanin the mudstones because they are generally free of coarse bioclasticdebris, Scattered in the beds of mudstone and wackes tone arethin lenses of packs tone.The matrix of these lenses is lime mud identical to the mud elsewhere in the unit.The currents that disarticulated, partially fragmented, and transported the fossildebris must have been of short duration because only smalldifferences in amounts of fines occur between the lenses of packs toneand the thicker beds of mudstone and wackestone. More rare than the thin lenses of packs tone areirregular 63 masses of boundstone (figure 21).Bryozoans and stromatoporoids locally formed matlike frameworks that trappedlime mud to the exclusion of coarser bioclastic debris.The bodies of bounds tone are quite thin (usually less than one inch thick) andspread out along bedding surfaces.Numerous load casts and flame structures withinthe unit imply that the substrate was soft or even soupy.Such a substrate would not have been suitable for anchoring orsupporting large colonies of organisms.Stronnatopor old surfaces are lumpy and wavy.Either the substrate on which they lived was irregular or somesettling or loading caused the colonies to deform. Rapid deposition of carbonate and terrigenousmud apparently "smothered" colonies of rock-forming organisms. Onesample of Favosites sp. in growth position fromTelegraph Canyon (sample KDL-9) contains several layers of micritefilling the living chambers of the coralites along contemporaneous growthsurfaces (figure 22). Sporadic inundation by carbonate mud apparentlykilled several polyps within the colony.Enough of the colony remained alive to recover before it was finallykilled by the sudden influx of a one inch bed of crinoidal debris.The currents that transported the coral- killing sediment was probably short-livedand of variable energy. Winnowing of newly settled mud from thesurface of the coral would have occurred if the currents had persisted. Low energy conditions must havepredominated over areas 64

Figure 21.Weather ed surface of a stromatoporoid boundstone lense from the middle limestone of the Bartine Tongue (Sadler Ranch Section).

Figure 22.Slab through a sediment "smothered" Favosites sp.from the middle limestone of the Bartine Tongue (Telegraph Canyon Section). 65 where mudstone and wackestone were deposited.Infrequent sediment- laden currents swept through and quicklydropped their loads.The absence of regular current activity resultedin poorly stratified, muddy sediments.The sporadic currents responsible for the transport or redistribution of the sediment mayhave been generated by sporadic winds or storms. Scattered throughout the middle unit are thicklaminations and thin beds of platy-weathering bioclasticpackstone and wackestone. Unlike the smaller discontinuous lensesof packstone and wackestone referred to above, these beds are traceablealong strike for several yards.Most bivalve and brachiopod shells in thebeds are disarticulated and oriented concave down. Somesmall Trigonirhynchia and Atrypa shells are articulated.Some of the shells are concave up and currents may not have had time to orientthem more stably. Solitary tetracorals, high-spired gastropods,and cephalopod shells lie on their sides.Protected areas beneath curved shells are generally full of micrite, but coarse bioclasticdebris fills some of them. Variable amounts of clear sparry calcite act as acement in some packstone beds.The spar indicates that some winnowingdid occur. The contacts of the packstone beds withthe underlying lime muds tones and wackestones aresharp and irregular.Scouring and sudden loading of the fossil hash(packstone) onto the soft muddy substrate resulted in up to one inchof relief along the basal contacts. 66 Some small flame structures (to1/4 inch) are present where the underlying mud squeezed up into thefossil hash due to loading.Upper contacts of the packstone beds aregenerally gradational over 1/4 inch to one inch.Waning of current energy probablyallowed increas- ing amounts of carbonate mud tosettle along with the finer bioclastic debris near the tops of these beds. Seven feet below the top of the middlelimestone unit in Tele- graph Canyon is a large channel-likestructure (figure 23).A 1 1/2 foot thick bed of lime mudstone topackstone thins to 0 over approximately 15 feet (the other end ofthe apparently lens-like body is covered).Bedding within the channel is horizontal,and the lower contact of the channel or lens curvesgently upward to meet the top of the lens.The lithology of the lens isidentical to that of the host rock.No scour, rip-ups, or slumpblocks are present in the basal part of the lens.A change in circulation aftererosion of the channel probably allowed normal sedimentationto fill the channel.The position of the channel nearthe upper yellow-gray limy dolomite unit suggests shallowing conditionstoward the onset of limy dolomite

deposition. In thin section rocks of themiddle unit of the Bartine Tongue

vary depending onwhether mudstone, wackestone,packstone, or boundstone is being studied(figure 24).The proportions of framework clasts and matrix vary,but the constituents areessentially b%

Figure 23.Poorly exposed lense in the middle limestone of theBartine Tongue (Telegraph Canyon Section).

Figure 24.Photomicrograph of microlaminated lime mudstoneoverlain by packstone with patchy sparry cement.Sample from the Bartine Tongue at Telegraph Canyon. 68 the same in all samples.Lime micrite forms the bulk of most samples; it is partly recrystallized to lime microspar.Irregular patches of lime pseudospar also occur in the matrix.Sparry calcite cement is restricted to winnowed packs tonebeds and lenses,Calcite fossil debris forms most of the framework grains.Scattered lime micrite intraclasts and pellets and quartz silt areminor framework components.Diagenetic iron oxide occurs as very fine-grained opaque blebs or as tiny translucentparticles scattered throughout the matrix and concentrated around the opaqueblebs.Chert fills the chambers of some tetracorals and occurs along somefractures. Most shells have recrystallized to irregularaggregates of fine- to coarse-grained calcite.Partial recrystallization of lime micrite to microspar and pseudospar has alsopartly obscured out- lines of lime micrite intraclasts and pellets.These grains appear as slightly darker and finergrained rounded masses in the light brown matrix.They composed an uncertain amount of therock because their partial obliteration makes estimatesof their abundance difficult.The major diagenetic event was partialrecrystallization of fossil debris and the matrix.This event probably occurred during early diagenesis,The presence of fracture- and pore-filling chert suggests that silicification was alate diagenetic event. The fauna of the middle limestone is anormal marine fauna and is the most diverse fauna studied inthe thesis.Appendix II lists 69 the fossils and their abundancesfrom all collection localities,Table 1 summarizes the brachiopod speciesand abundances in the collections. Because of their abundance andvariety, the brachiopods were used to delineate a communityaffinity for the fauna of the BartineTongue. Many elements of the BartineTongue fauna are the same as

those in the Atrypa nevadanaCommunity defined by Niebuhr(1973), but there are some new formsand some missing forms.Atrypa nevadana, Trigonirhynchiaoccidens, "Schuchertellarr nevadaensis, Megastrophia sp.Chonetes sp. ,and Hysterolites sp. B arethe most common and widelydistributed species in the tongue.Of these, Hysterolites sp. B is a new form(Hysterolites sp. A is present in the Bartine Member).Athyris sp., Hedeina sp. ,and Cryptonella sp. are locally presentin the tongue, but are not presentin the Bartine Member.Forms present in the BartineMember that are absent in the tongue include Ambocoelia sp.and Eurekaspirifer pinyonensis. Other forms, such as Nucleospira sp.Brachyspirifer cf. pinyonoides, and Schizophoria sp. are rarein the tongue.Since the faunas of the Bartine Tongue andMember are so similar andsince the Bartine Tongue fauna closelyresembles the Atrypa nevadanaCom- munity, it is logical tocall the Bartine Tonguefauna a modified or slightly evolved form of theAtrypa nevadana Community.Hysterolites sp. B sp. B Communityis a suitable name for thefauna, because H. is ubiquitous in the tongueand is a new element in it. TABLE 1. BRACHIOPOD ABUNDANCES IN THE BARTINE TONGUE (SULPHUR SPRING RANGE) AND COILS CREEK LIMESTONE (MODOC PEAK). :- South COLLECTION NUMBER North

MP-1 270112 19 20 21 130 106 5 48 7 9 157165

Schizophoria sp. - - 1 ------1 Dalejina ? sp. 2 3 - 1 - 6 Carinagypa sp. (aseptate) - - 3 - - 3 - - 2 8 "Schuchertella" nevadaensis ?2 ?7 10 ?3 ?3 ?1 ?3 ?2 - ?1 21 - 21 ?3 37 Leptostrophia sp. (parvi.) - - 6 - - - - 6 Megastrophia sp. - ?40 ?7 - 220 ?5 20 22 - - 24 2 100 Phragmostrophia sp. ?2 - 3 - - 22 SID de 7 Chonetes sp. - 4 4 6 53 9 - - - - - 76 C "Strophochonetes" sp. .. .. - 5 - - re AM . Parachonetes macrostriatus do* M. - 2 2 - - - 2 6 Spinulicosta ? sp. 3 3 36 111. 2 - - - - 1 16 Trigonirhynchia occidens - - 27 - 7 26 15 23 ?2 6 T2 ?2 95 Atrypa nevadana 23 21 15 25 27 16 11 ?2 - 25 219 - 21590 Nucleospira sp. 2 - 2 3 7 - 21 - - - - 15 Athyris sp. 14 28 - - _. 1M MO MS .. - 12 Hedeina sp. 28 ?28 - - - - _. - 22 - - - 1351 Hysterolites sp. B 27 ?1 27 4 32 ?13 - - ?8 - - ?17 89 Brachyspirifer cf. pinyonoides - ON . ?6 - - - 32 - - ?3 - - hl El7thyna sp. 14 28 - - - 2 MD re, 1ND 24 CyrtIna sp. 9 - g...... a. an!, MP el al. 9 le MB VP Cryptonella ? sp. OM 13 .. 2 15

Totals 5696 109 22107131 61 9 34 9 19 23 3 59 738_, 71 Some trends in faunal make-up of the tongue arevaguely dis- cernible:1) fossils are most abundant in the middle partof the limestone unit and 2) abundance and diversitydecrease northward (obliquely shoreward) in the Sulphur SpringRange.Chonetes sp. ,

Elythyna sp. ,Nucleospira sp. ,and other forms occur in collections at Sadler Ranch or Modoc Peak (CoilsCreek Limestone), but not in ones farther north.Perhaps the larger abundance and diversity in the middle limestone and in the south reflectdeeper or more normal marine conditions there. Quiet water conditions predominated duringdeposition of the middle unit of the Bartine Tongue.Coarse bioclastic debris and clouds of carbonate and terrigenous mud werecarried into the area by sporadic currents.Bioturbation and other soft sediment deformation disturbed original laminations andhelped to randomly orient and break the fossil debris.The position of the Bartine Tongue rocksin the Sulphur Spring Range places themclose to the eastern limit of the normal marine realm (figure 18).The diversity of shallow-water brachiopod fauna (Niebuhr, 1973; Johnson,personal communication, 1974), presence of stromatoporoids,abundance of gastropods and pelecypods, and variable energy conditionssuggest a shallow, subtidal, carbonate bank environmentof deposition for the middle limestone unit of the tongue.Figure 25 is a facies tract model fordeposition of the Bartine Tongue and upperSevy Dolomite and is similar to BARTINE TONGUE SEVY DOLOPME

High tide

Low tide

4-)

Quiet to moderately agitated; intermittently agitated; Quiet to strongly agitated; Lime mudstone to packstone; sparsely to abundantly Dolomite mudstone with inter- fossiliferous; common laminations, packstone lenses, and beds of quartz sandstone; horizontal burrows; shallow unrestricted sub-tidal dolomite isaamdnated; sand- deposition; possibly a carbonate bank environment. stone is crossrlbedded and horizontally laminated; unfossiliferous; high energy 0 1 mile beaches and bars to intermittently agitated tidal flats.

Figure Facies tract model for deposition of the Bartine Tongue and correspondingpart of the Sevy Dolomite in central Eureka County, Nevada.No vertical scale. 73 the facies tract model fordeposition of the Bartine Member and upper Sevy tongue(figure 1 5).Irregular thinning and thickening along strike of the Bartine Tongue maybe due to the presence of mud mounds, similar to the carbonatemud mounds now forming in eastern Shark Bay, WesternAustralia; Florida Bay; and behind the Florida Keys (Bathurst, 1971).

Upper Limy Dolomite

The upper unit of the Bartine Tongueis lithologically similar to the basal unit.It is nine feet thick at SadlerRanch, thirteen feet thick at Telegraph Canyon, andapproximately ten feet thick at Fera

Well.The unit was not observed farthernorth in the Sulphur Spring

Range.At McColley Canyon and in thePiton and Diamond Ranges, the upper unit is not recognizablebecause of the absence of the middle limestone unit and the closelithologic resemblance of the upperand lower units.The Bartine Tongue of the Diamondand Pion Ranges is similar to the upper andlower units of the tongue in theSulphur

Spring Range.

Combined Upper and LowerUnits of the Pion and Diamond Ranges

At Union Mountain and CoffinMountain the Bartine Tongue is poorly exposed and only float wasobserved.The thickness of the 74 combined upper and lower units at these localitiesis estimated to be less than 20 feet.Contacts were not observed but are assumed to be conformable or slightly dis conformable.At Union Mountain the tongue overlies quartzose Sevy Dolomite andunderlies dark dolomite of an eastern tongue of the Sadler Ranch Formation.At Coffin Mountain the rocks underlying the tongue are quartzoseSevy Dolomite, but the overlying rocks are uncertain because of cover.At Oxyoke Canyon the tongue overlies, interfingerswith, and underlies quartzose

Sevy.The tongue has a total thickness of 21 feet in twobeds and occurs approximately 50 feetbelow the base of the Oxyoke Canyon Formation.At Phillipsburg Mine a single three foot bed oflaminated dark gray dolomite muds tone is conformablyinterbedded with quartzose Sevy and is 70 feet belowthe Oxyoke Canyon Formation.This bed is not of Bartine lithology but may representslightly deeper marine conditions, perhaps lagoonal, duringBartine Tongue time. Litho logic correlations between the Diamondand Pirion Ranges and between the Pinon and Sulphur Spring Rangessuggest that the lower tongue of the Sadler Ranch Formation atUnion Mountain correlates with the quartzose Sevy between the BartineTongue and Oxyoke Canyon Formation in the southern DiamondRange. The Bartine Tongue rocks at OxyokeCanyon are poorly to moderately well exposed and are conformablyinterbedded with the light gray quartzose Sevy (figure 9).The contacts between these 75 units are planar to slightly undulatory.Recognizable bedding in the tongue is thin to medium.The most noticeable outcrop feature of the unit is its yellowish gray weathering color.Where outcrop is lacking, the unit can be traced by the yellow colorof the soil it forms. The rocks of the Bartine Tongue in its eastern exposures are of very uniform lithology, and samples fromthe Pirion Range are easily mistaken for ones from the southernDiamond Range. On freshly broken surfaces the rock is medium gray(N5) to light olive gray (5 Y 6/1).Weathered surfaces are yellowish gray (5 Y8/1) to grayish yellow (5 Y 8/4).The rock is argillaceous and weathers to smooth, round, cobble-sized blocks. The presence of medium gravel-sized rip-upsof Bartine lithology in quartzose Sevy rocks several feetbelow the lowest exposed bed of the tongue in Oxyoke Canyonimplies close proximity of unexposed additional beds of Bartine Tonguelithology.The interfingering nature of the tongue and upperSevy Dolomite suggests that more Bartine Tongue bedsexist just west of Oxyoke Canyon.Partial erosion of these beds and shoreward transportcould explain the presence of the Bartine rip-upsin Oxyoke Canyon.An alternative explanation is that thin Bartine beds onceexisted in Oxyoke Canyon but were eroded and incorporated inthe Sevy Dolomite.The abundant evidence of intermittent erosion duringdeposition of the Sevy and the thinness of the Bartine Tongue (one bedis only one foot thick) supports 76 this hypothesis. The Bartine Tongue at Oxyoke Canyon is especiallyinteresting because of the variety of sedimentary structures it contains(figure 26). Very fine laminations are the most common structure,and they are defined by alternating yellow-gray and yellow-brownlaminae approximately 1/20 of an inch thick.Variations in organic carbon content, grain size, or fecal pellet content may explainthe observed color changes.Very thin beds of slightly quartzose dolomite mudstone and very fine gravel-sized intraformational dolomiteconglomerate occur and have sharp scoured basalcontacts. A small channel at least 3/4 of an inch deep and six inches across wasscoured into thin beds of dolomite mudstone and filled by irregularlylaminated dolomite mud. A second and smaller channel orslight depression is filled with micro-cross-laminateddolomite mudstone. Current strengths must have fluctuated widelybecause of the rapid reversals of erosion and deposition ofcarbonate mud and the wide range in grain sizes in different laminae.Some Bartine Tongue samples contain burrows; most are 1/10 to1/4 of an inch in diameter and are randomly oriented.The animals that made the burrows may have been soft-bodied since no megafossils werefound in the Bartine Tongue in the Pion and Diamond Ranges. In thin section dolomicrite, dolomite microspar,dolomite pseudospar, and terrigenous clay matrix compose over90% of the ,7t7-45,9"{w-ix,s1'91%114WIFWIRWr

Figure 26. Laminated limy dolomite mudstone from the Bartine Tongue (Oxyoke Canyon Section). 78 rock.Dolomicrite intraclasts and iron oxideform approximately 5% of the rock.Quartz silt and sand make up the remaining5% of the rock,Quartz grains are concentrated in distinctlaminae, but the intraclasts occur throughout the finelycrystalline dolomite.Both the quartz and the intraclasts are rounded,Many of the intraclasts are flattened or elongate.The intraclasts are darker coloredthan the dolomicrite matrix and have also undergoneless recrystallization. The true abundance of intraclasts isdifficult to determine in thin section because recrystallizationhas blurred many clast boundaries and probably has obliterated entireintraclasts.Few of the quartz grains are in grain contact, and theexceptions have tangential grain contacts. The following sedimentary structures presentin eastern exposures of the BartineTongue are typical of intertidal carbonateshelf environments of deposition: mud rip-ups,laminations and cross- laminations, channels, abrupt verticaland lateral lithology changes, and burrowing (Laporte, 1971).A sparse conodont fauna is present and is suggestive of at least some waterexchange with the normal marine environment to the west.The predominance of carbonate mudstone with a few quartzose andintraformational interbeds suggests a depositional environmentvarying between quiet and strongly agitated conditions (Plumley andothers, 1962).Currents were probably intermittent in nature and werepredominantly weak during deposition of the Bartine Tongue.Since the easternmost part of the 79 tongue is slightly limy, contains conodonts,and lacks some of the diagnostic tidal flat features of the Sevy, the writerbelieves it was deposited in a low intertidal to shallow subtidalenvironment.To the west the Bartine Tongue (middle limestone)becomes definitely subtidal and normal marine in origin.The easternmost portion of the tongue fits nicely as the subtidal-intertidaltransition zone between the normal marine environment on the westand the intertidal/supratidal environment on the east.

Age and Correlation

The Bartine Tongue was dated on the basis ofbrachiopods and conodonts; the conodonts proved most valuablefor age determination and correlation.The brachiopod fauna of the tongue is verysimilar to that of the Bartine Member and isplaced in the Pinyonensis Zone s. 1. by J. G. Johnson(personal communication, 1974).The sparse conodont collections from the tongue aresummarized in Table 2.

TABLE 2.CONODONTS FROM THE BA RTINE TONGUE.

Collection Numbers

4 112 130 293 165 215 269

Polygnathus sp. nov. X X X X X

Polygnathus "perbonusi, (late form) X X X X X

Pandorinellina exigua exigua X X X X X X 80 Polygnathus sp. nov. X and P. "perbonus" (late form) occur together at Lone Mountain only in the lower part of the basal unitof the Coils Creek Member (Unit 12) (Klapper, written communication, 1974; Murphy and Gronberg, 1970).The occurrence of both Polygnathus species in collections 130 and 215 strongly supports the partial age equivalence of the Bartine Tongue and the lower part of the Coils Creek Limestone.The lower part of the Bartine Tongue has not yet been dated by conodonts and contains brachiopods(KDL-5) more common in the Bartine Memberthan in the upper part of the Bartine Tongue (Johnson, personal communication, 1974).The lower part of the tongue may therefore be of latest Bartine age. Litho logic correlations indicate that the Bartine Tongue in the Sulphur Spring Range is the lateral equivalent of the Coils Creek Limestone at Modoc Peak and Lone Mountain.The same vertical change to the Sadler Ranch Formation occurs in all three areas. It is noteworthy that the Coils Creek Limestone atModoc Peak is lithologically transitional between the BartineTongue and the true Coils Creek Limestone.The brachiopod fauna in the Coils Creek Limestone at Modoc Peak also differs from that in theSulphur Spring

Range.The conodont faunas, however, are similar(KDL-269).The most obvious differences between the tongueand the Coils Creek is the yellowish weathering of the Bartine Tongue.The yellowish color is most noticeable in the easternmost and upperand lower parts of 81 the tongue.The Bartine Member also weathers moreyellowish in eastern exposures (SulphurSpring Range and Mahogany Hills). 82

SADLER RANCH FORMATION

General Statement

The Sadler Ranch Formation wasformerly considered to be the middle or crinoidal part of theUnion Mountain Formation but is herein recognized as a separateformation. The reasons for its recog- nition as a formation are itsdistinct lithology and distribution compared to overlying and underlyingrock units.The rock unit is a dark dolomite that crops outalong the east flank of the SulphurSpring Range, in the Mahogany Hills, atLone Mountain, and at Union Moun- tain.The formation is typicallydeveloped in the Sulphur Spring Range along a spur just west ofSadler Ranch.The spur on which the type section is locatedextends up to the saddle immediatelynorth of Summit 7466 from the easternside of the range.Section AA' of Plate 1 passes through the typesection. In the Sulphur Spring Rangethe formation overlies the Bartine Tongue in apparent disconformityand conformably underlies the Coarse Crystalline Memberof the Oxyoke Canyon Formation(western tongue).In the Mahogany Hills theformation conformably overlies the Coils Creek Limestoneand underlies the CoarseCrystalline

Member.At Lone Mountain the formationconformably overlies unit 12 of the Coils CreekMember of the Mc Colley CanyonFormation (Murphy and Gronberg, 1970)and underlies Denay-likelimestone. 83

At Union Mountain upper andlower tongues of the Sadler Ranch Formation are separated by theQuartzose Member of the Oxyoke Canyon Formation, and the upper tongueis conformably overlain by the Coarse Crystalline Memberof the same formation.Figure 27 shows that the Sadler Ranch Formationforms a belt parallel to the regional depositional strike between openmarine limestone (Coils Creek) to the west and shallow-waterrestricted dolomites to the east (Oxyoke Canyon Formation and Sevysand). The formation is 408 feet thick in its typesection and is at least 300 feet thick at Fera Well.Faulting and poor exposures make thickness estimates difficult at othersections in the Sulphur Spring

Range.At Modoc Peak the formation isapproximately 234 feet thick. At Table Mountain the formation isapproximately 450 feet thick, and at Lone Mountain it is about 410feet thick (Gronbet g,1967, sections).

At Union Mountain the combinedthickness of the upper and lower tongues of the formation is about90 feet; the total thickness between the lowest and highest dolomitebeds is about 300 feet (including the Quartzose Member of the OxyokeCanyon Formation). The Sadler Ranch Formation canbe divided into three units or informal members of the SulphurSpring Range and Mahogany Hills: 1) a lower dolomite, 2) a middlecrinoidal dolomite, and 3) an upper

dolomite.These three units are present atLone Mountain, but the lithologies there are slightly differentfrom those at the type section. k

Coils Creek Mbr. of McColley Canyon Fm.

Sadler Ranch Fm.

Quartzose Mbr. of Oxyoke Canyon Fm.

Sevy Dolomite (quartzoae upperpart) 10 0 10 20 30 40 miles IIILIMMIM7W111.1Mr..

Figure 27, Lithofacies distribution during early Sadler Ranch and Oxyoke Canyon time. 85 The crinoidal unit is thickestand best defined at Lone Mountainand in the Mahogany Hills.Toward the east (shoreward) the unitis thinner and less crinoidal.

Lower Dolomite

The lower dolomite of theSadler Ranch Formation is 230 feet thick at Mc Colley Canyon (Murphyand Gronberg, 1970, sections), 130 feet thick at Fera Well, at least114 feet thick at Telegraph Canyon, 238 feet thick at Sadler Ranch, and75 feet thick at Modoc Peak.At Table Mountain the unit isapproximately 110 feet thick, and at Lone Mountain it is about 120 feet thick(Gronberg, 1967, sections).The lower tongue of the Sadler RanchFormation at Union Mountain is approximately 40 feet thick. The basal contact of the formationis sharp and planar or slightly undulatory (figure 28).At Telegraph Canyon the contactis a scoured surfacewith up to two inches of relief.There is an abrupt lithologic change across the contactfrom yellow gray limy dolomite mudstone (below) to very light gray,finely crystalline, quartzose d olomite (above).Gravel-sized rip-ups of Bartinelithology are present in the basal six inchesof the formation.Erosion of the upper unit of theBartine Tongue was probably veryminor since erosional features are small andthe thickness of the upper unitof the tongue varies littlealong strike.A disconformable contact is 8 6

Figure 28.Sharp contact between the Bartine Tongue and Sadl erRanch Formation in Telegraph Canyon.Note the clast of Bartine Tongue lithology in the overlying Sadler Ranch Fm. 87 suggested by the sharpness of the contactand the abrupt lithologic change. The lower dolomite is made up ofmoderately well bedded, medium- to thick-bedded, very finelycrystalline dolomite.The dolomite weathers yellowish gray (5 Y8/1) to olive gray (5 Y 4/1). Fresh surfaces emit a strong petroliferousodor and are light olive gray (5 Y 6/1) and olive gray(5 Y 4/1) to brownish black (5 YR2/1), medium gray (N5), and dark gray (N3).The rock breaks with a jagged fracture and weathers to sharpangular blocks. The extremely fine crystallinity hasresulted in the excellent preservation of delicate sedimentary structuresand framework grains.Most beds of the lower unit are composedof finely or wavy laminated dolomite mud stone and crinoidalwackestone.Some thin beds and lenses of crinoidal packs tone areintercalated with the mudstones and wackestones.The crinoidal debris consists of one- and two-holed ossicles up to one mm across.At Sadler Ranch the basal 41 feet of the formation is highlycrinoidal and contains beds of crinoidal packs tone up to two feet thick.The crinoidal zone contains solitary tetracorals oriented parallel tothe bedding.The zone is lithologically similar to the crinoidal unit. Carbonate- and sand-filled burrows are verycommon in the lower dolomite, and several typesof burrows are present. Asterosoma, a nearshore indicator, occursin several of the Figure 29.Slab of KDL-183 showing burrows, silicified brachiopods, and siliceous fracture fillings. 414

Figure 30.Photomicrograph of KDL-183 showing a silicifiedbrachiopod in a pseudospar matr ix. 90 burrows are present.The absence of obviously current-oriented shells and coarse terrigenous detritus, the finelaminations, and the abundant burrowing argue that predation,scavenging, and bioturbation are responsible for the disarticulationand fragmentation of the shell debris. Sample KDL-12 contains abundant Elythyna sp. andSchizophoria sp.(bisulcate) and occasional Nucleospira sp.Two small colonies of silicified Favosites sp. and abundant recrystallizedcrinoid debris are also present. Samples KDL-25 and 183 are from a two foot thickbrachiopod- rich horizon in the Sadler Ranch Section.KDL-183 is lithologically identical to KDL-12, but KDL-25 is more quartzoseand less fossiliferous.The fossils are mostly disarticulated and orientedparallel to the fine wavy laminations.Many Schizophoria sp. are articulated and exhibit geopetal fabric.Asterosoma and Planolites burrows are present and have disturbed the orientations of manyfossils.One geopetal has been rotated90°.Gentle currents were probably responsible for the introduction of some fossildebris, such as the crinoid debris.The brachiopods were probably not transportedfar from their life positions, because brachialand pedical valves of Schizophoria sp. ,Elythyna sp. ,and Alatiformia sp. C are approximately equal in number in sampleKDL-183. This equality, the presence of articulatedspecimens, the overall fine crystallinityof 91 the dolomite and lack of terrigenous detritus, the fine laminations, and the lack of erosional features suggest quiescent depositional conditions. Sample KDL-183 contains abundant Schizophoria sp. (bisulcate), and Elythyna sp. and common to rare Alatiformia sp. C,Nucleospira sp. ,Atrypa sp. ,and Carinagypa? sp.Small silicified solitary tetracorals are also present.Sample KDL-25 contains Schizophoria sp.(bisulfcate), Elythyna sp. ,and Nucleospira sp. Sample KDL-68, from the basal part of the Sadler Ranch Forma- tion between Bald Mountain and Telegraph Canyon, containsdolomit- ized Elythyna? sp. and Atrypa sp. Table 3 summarizes the abundances of brachiopod species collected from the Sadler Ranch Formation in theSulphur Spring

Range.The three large silicified collections are all very similar and appear to belong to the same community.The abundance of the bisulcate Schizophoria sp. suggests that the communitybe called the Schizophoria sp.(bisulcate) Community.This community inhabited a quiet, shallow, restricted, nearshoreenvironment. In thin section the original texture of theSadler Ranch Forma- tion is partly obscured by dolomitization.Dolomite pseudospar and minor amounts of dolomite microsparconstitute the matrix, and optically continuous microcrystalline dolomiteforms most bioclastic grains.Small amounts of fine quartz sand and silt are presentand 92 are partially replaced by dolomite pseudospar.Iron oxide occurs as small opaque blebs and as finely disseminated specks along micro- fractures.Organic carbon forms approximately 4% of the darker dolomite beds (Appendix VI), the highest value of any thesis sample. Minor quantities of terrigenous clay are also present.

Table 3.BRACHIOPODS IN THE SADLER RANCH FORMATION, SULPHUR SPRING RANGE.

Collection Number Totals 25 183 68 12

Schiz ophoria s p.(bisulcate ) 15 159 77 251

Carinagypa? sp. 2 2

A trypa s p. 7 1 8

Nucleospira sp. 9 ?2 11

Alatiformia sp. ?3 24 27

Elythyna sp. 33 65 ?17 ?1 116

Totals 51 266 18 80 415

The dolomite matrix is a tightly interlocking mass (porosity < 1%) of dolomite crystals from 0.10 mm to over 0. 50 mm in diameter. Individual crystals are bounded by cleavage planes or by indistinct, jagged borders.The crystals are light gray to light brown in plane polarized light and are clouded with numerous inclusions.A few amber-colored globules up to 0.03 mm in diameter are visible under 93 high magnification and are probablysapropel and responsible for the fetid odor emitted from freshly brokensurfaces. Silicified brachiopod shells are present in somesamples and are composed of chertand fibrous chalcedonic quartz.Micro- fractures filled with chert indicate thatsilicification occurred after induration and the dominant dolomitizationperiod, probably during late diagenesis.Calcite in the fossils was probablydissolved, leav- ing voids that were later filled bychert.The source of the silica may have been the quartzdissolved earlier along quartz grain contacts in the interbedded quartzites.An even later diagenetic event was partial replacementof silica by dolomite.Dolomite rhombs replace quartz along the edges ofsilicified shells and locally replace entire shells (figure 30).In one sample solitary tetracorals were silicified and subsequently nearlyentirely replaced by sparry dolomite.This late phase of dolomitization maybe responsible for scattered dolomite rhombs up to 0.10 mmin diameter in the matrix. Intraclasts or pellets are not visible in anyof the sections. Because of the fine crystallinity ofmuch of the matrix, the cloudiness of the crystals, and the excellentpreservation of fine laminations and other structures, the writerbelieves that much of the matrix was originally a carbonate mud.The presence of initially calcareous fossil debris requires that theoriginal sediment was at least partly

limy. 94

The fineness of the sediment and the presence of sapropel suggest that large volumes of dolomitizing fluids did not pass through the relatively impermeable sediment, as the reflux dolomitization theories of Adams and Rhodes (1960), Deffeyes and others (1965), and Shinn and others (1965) necessitate,The writer believes that the texture of the dolomite matrix can be explained by early dolomitization of the type suggested by Boucot (1975) for subtidal sediments. According to his theory, gradual dolomitization would have occurred while the sediment was still in close contact with sea water.The optically continuous microcrystals that form the dolomitized crinoid fragments are strong evidence for a slow (molecule by molecule) initial process of dolomitization.Later recrystallization of the dolomitized mud matrix to microspar and pseudospar could have occurred sometime during diagenesis. A second phase of dolomitization occurred during late diagenesis and is responsible forpartial replacement of silicified fossils by dolomite spar. Quartzose beds occur higher than 40 feet above the base ofthe formation in the Sulphur Spring Range and vary from quartzose dolomites to siliceous quartzites.Quartz content of the dolomite increases near quartzite beds, but the quartzite bedshave sharp contacts with the adjacent dolomites.The quartzite beds are more resistant than the dolomite beds and form ledgesthat are easily traced along strike.Most of the quartzite beds thin and pinch-out 95 within two miles along strike.Quartzite forms a minor part of the Sadler Ranch Formation in the northern partof the Sulphur Spring Range; but quartzite is more significantat Telegraph Canyon and Bald Mountain, where it forms up to20% of the formation. Fresh surfaces of the quartzite anddolomitic quartz sandstone beds are white to light gray (N9 toN7).The quartzite weathers white and shades of orange and brown,and the dolomitic beds weatherlight olive gray (5 Y 6/1).The quartzite beds weather into block-like vertical columns up to two feethigh and one foot wide, and the dolomitic beds form a blocky talus. Poorly defined horizontal laminationsand low-angle planar cross-beds are the most commonsedimentary structures in the thick quartzites.Irregular vugs and small burrowsinclined at 45° to the bedding are present in somebeds.Other small meniscate burrows (1/4 to 1/2 inch indiameter and up to several inches inlength) were found at BaldMountain.These burrows are like Scalarituba and are known from intermediatedepths (Chamberlain, written communication, 1974).Late diagenetic leaching ofcarbonate mud or carbonate-richfecal matter explains the presenceof the crescent shaped voids within these burrows. In thin section the quartzosebeds are composed of well- rounded, moderately sorted, fine- tomedium-grained quartz grains with variable amounts of sparrydolomite matrix, iron oxide, and 96 void space.Fine - grained garnets and recrystallized clay are also present in very small amounts.The quartz grains exhibit planar and concavo-convex contacts with other quartz grains that is indicative of only minor pressure solution during diagenesis (Siever, 1959). Secondary quartz overgrowths were not observed. The lower Sadler Ranch dolomite was deposited in a shallow nearshore environment with energy conditions ranging from quiet to strong agitation.The fine laminations, abundance of finely crystalline dolomite, articulation of brachiopods, and presence of sapropel suggest low energy, low oxygen depositional conditions for much of the unit.Strong current activity is indicated by abundant fine quartz sand and crinoidal debris in some lenses and thin beds.The cross- bedded and horizontally laminated quartzite interbeds were deposited in high-energy environments, possible offshore bars.Other thin quartzose beds are probably quieter water nearshore sands.Crinoid- rich beds were deposited in or near crinoid gardens in intermittently agitated, slightly wave(?) agitated water. The contemporaneous development of a linear clastic shoreline or barrier-bar to the east is representedby westward thinning tongues of quartzite.These quartzite fingers resemble nearshore sands and offshore bars in the Gulf of Mexico (Hoyt and Henry, 1967). Figure 31 is a facies tract model for deposition during early Sadler Ranch and Oxyoke time.No carbonate banks or mud mounds SADLER RANCH FORMATION OXYOKE CANYON FORMATION MT DOLOMITE Quartzose Member quartsese upper part

High tide Low tide

Quiet to moderately Moderately to strongly agitated; Quiet to strongly agitated; agitated; dolomite Siliceous quartz arenite; cross- Dolomite mudstone with inter- mudstone to crinoidal bedded and horizontally laminat- beds of cross-bedded quartz packstone; moderately ed; unfossiliferous; rare near- sandstone; dolomite is lam- fossiliferous; dolomite shore burrows; high-energy, inated; unfossiliferous; is massive to laminated intertidal beach/bar environment. intertidal sheet-like sand and is locally burrower?; bodies deposited with inter- occasiona: quartzite intertidal to supratidal early beds; sha2low, restricted dolomite. sub-tidal 'r--,-qit4on.

0 1 mile

Figure 31 . Facies tract model for deposition of the Sadler Ranch FM., Quartzose Mbr. of the Oxyoke Canyon Fin., and upper Sevy Dolomite in central Eureka Co. No vertical scale. 98 are inferred forthe Sadler Ranch Formation asthey were for the Bartine Tongue. A change in thecharacter of the shelf from that of Bartine Member time is suggestedby the absence of a uniform, shelf-wide limestone unit (figures 4,5, and 10).The Bartine Mem- ber was such a broad shelf depositof uniform lithology (Niebuhr,

1973).During Bartine Tongue time andearly Sadler Ranch time, however, several facies developed(figures 18 and 27).Perhaps the shelf gradient was steepened by a greateraccumulation of sediment close to shore than offshoreallowing deeper shelf environments to narrow and "migrate"shoreward.

Middle Crinoidal Dolomite

The crinoidal unit is 50 feet thick atMc Colley Canyon, approximately 97 feet thick at Fera Well,47 feet thick at Telegraph Canyon, and only 37 feet thick at SadlerRanch.Thicknesses to the south and west are more uniform: the unitis 80 feet thick at Modoc Peak,85 feet thick at Table Mountain, and120 feet thick at Lone Mountain (Gronberg, 1967, sections).At Willow Creek the crinoidalunit at the base of the Denay Limestoneis approximately 40 feetthick (Johnson, personal communication,1974). The crinoidal unit is characteristically acrinoidal packstone

containing abundant two-holedcrinoid ossicles, at least someof which were derived fromGasterocoma? bicaula (Johnsonand Lane, 1968). 99

Because of the rarity of two-holedcrinoids in other beds and their abundance in the crinoidal unit, thecrinoidal unit is a marker horizon in much of Nevada.The writer is unaware of the reasonfor the existence of the prolific crinoid gardensthat had to exist to produce the large volume of crinoid debris inthe crinoidal unit. The contact between the lower dolomiteunit and the crinoidal unit is marked by an abrupt increasein crinoid debris.The dolomite matrix of the unit is identical to thatof the lower and upper dolomites, but the rock is a packstone with thinlenses and laminations of mudstone and wackestone.The combined thickness of thesefine-grained interbeds amounts to less than 10% of theunit.Thin beds of quartzite are present in somesections and are even less voluminous.Figure 32 shows a typical outcrop of thecrinoidal unit. The crinoid debris in the unit consistsof white (N9) recrystallized dolomite.Ossicles are fine sand-sized togravel-size, poorly to moderately sorted, andunrounded.Segments of crinoid columns up to three inches long are commonin some beds and are oriented parallel to the bedding.Poorly defined, wavy laminations arethe most common sedimentary structure,Some polished slabs exhibit poorly developed cross-laminations. Fresh surfaces of crinoidal unitrocks are light olive gray (5 Y 6/1) and medium light grayto medium dark gray(N6 to N4). The crinoid debris gives freshsurfaces of the packstone a lighter 100

Figure 32.Typical exposure of the crinoidal unit of the Sadler Ranch Fm. in the Sulphur Spring Range.

Figure 33.Loading at the base of a crinoidal packstone bed in the upper dolomite of the Sadler Ranch Fm. 101 color than the mudstones and wackestones.Weathered surfaces are light olive gray (5 Y 6/1) to yellowish gray(5 Y 8/1).Bedding in the unit is poorly to moderately definedby variations in crinoid content and by laminations.Bedding thicknesses range from four inches to three feet, and most beds are one to twofeet thick. The bases of many crinoid beds, especiallythose overlying dolomite mudstone beds, are locally markedby load casts composed of crinoid hash.Rapid deposition and uneven loading ofthe crinoidal sand resulted in the densitysettling of the sand into the underlying semi-cohesive carbonate mud. Such rapiddeposition and loading is responsible for the mottling and wavy laminationsthroughout the crinoidal unit. The large amount of carbonate mud inthe crinoidal unit and the large size of some of the unfragmentedstalks suggest a quiet to moderately agitated environment ofdeposition for the unit.The lack of winnowing, poor sorting, and absenceof scouring supports this contention.The crinoids themselves are indicativeof a normal shallow marine environment, and indeed,they are present far out to sea (Lone Mountain).The rapid deposition and loading of some packstone beds onto soft dolomitemudstone suggest intermittent bottom currents of moderatestrength.Thin horizontally laminated and cross-bedded quartzites suggesthigher energy conditions (e. g. waves) and a shallow environment. 102 Upper Dolomite

The upper dolomite of the SadlerRanch Formation is lithologically similar to the lowerdolomite.The major exception is that the siliceous quartzite interbeds commonin the lower and middle units are absent in the upperunit.Quartzose dolomite beds near the top of the unit resemble theoverlying Coarse CrystallineMember of the Oxyoke Canyon Formation.The basal contact of the unit is gradational, like the upper contact ofthe lower dolomite unit.Crinoid debris decreases markedly as one passesfrom the crinoidal unit into the upper dolomite.Interbeds of crinoidal packstone(up to four feet thick) with sharp basal andgradational upper contacts are common in the upper unit.Load structures are presentalong many of the lower contacts of these beds(figure 33).It is unclear whether these thin crinoidal packstones arefingers of a thicker crinoidal unit further offshore or thedeposits of small crinoidal gardensthat existed intermittently after thedeposition of the middle crinoidal

unit. The upper contact of the SadlerRanch Formation in the Sulphur Spring Range is excellentlyexposed near Sadler Ranch (figure34). There the contact is gradational over40 feet: light gray beds of quartzose dolomite similar tothose in the overlying CoarseCrystal- line Member of the OxyokeCanyon Formation areinterbedded with Figure 34.Contact between the Sadler Ranch Formation andthe overlying Coarse Crystalline Member of the Oxyoke CanyonFormation (Sadler Ranch Section). 104 olive gray Sadler Ranchdolomite.The contact is placed atthe top of the highest dark dolomitebed.The top of this uppermostdark bed is undulatory with up tosix inches of scouredrelief.The lithology changes fromstructureless, fetid, olive graydolomite mudstone to medium light gray,laminated crystalline quartzose dolomite over an eight inchinterval.The interbeds of Coarse Crystalline Member lithology nearthe top of the Sadler RanchFor- mation have sharp, planarcontacts; and the overall quartzcontent of the dark dolomitesincreases upward.The prominently cross- bedded and horizontallylamintated quartzose dolomitesof the Coarse Crystalline Member do not occuruntil approximately 30 feetabove the base of the member. The sporadic incursionsof Coarse CrystallineMember sediments near the top ofthe Sadler Ranch Formationindicate that Coarse Crystalline Memberdepositional conditions musthave been present to the east whileSadler Ranch sedimentationprevailed in the Sulphur Spring Range.The interfingering of thequartzose beds represents an upwardshallowing, and the onset ofCoarse Crystal- line Member sedimentationrepresents a westwardfacies shift rather than the beginningof an entirely newdepositional regime. The exact extent of thelate Sadler Ranch regressionis uncertain, because suitable exposuresdo not exist betweenthe Sulphur Spring Range and the RobertsMountains or possibly notbetween the 105

Mahogany Hills and Lone Mountain.Sadler Ranch deposition may have existed in a north-south belt west of theSulphur Spring Range and east of the Roberts Mountains whileCoarse Crystalline sediments were deposited to the eastand Denay sediments were deposited to the west (figures 27, 37, and 50).The Sadler Ranch Formation would thus be a transitional unit between thedeep-water Denay and the shallow-water Coarse Crystalline Memberof the Oxyoke Canyon Formation.

Age and Correlation

The age of the Sadler Ranch Formation wasdetermined on the basis of conodont and brachiopod collections.The conodont collections provide good age resolution andcorrelation with other Devonian strata in Nevada.The brachiopod fauna correlates lessprecisely with faunas in other areas. Samples KDL-183 and 293X are from thelower dolomite unit at Sadler Ranch and Telegraph Canyon,respectively, and yield conodonts of late Emsian to early Eifelian age.KDL-183 contains Polygnathus sp. nov. D of Emsian to Eifelian age,which occurs in units 13 and 14 of Murphy andGronberg (1970) at Lone Mountain (Klapper, written communication, 1974).KDL-293X contains Pandorinellina exigua sp. nov. A, which aloneis not diagnostic for a precise age but isof late Emsian to early Eifelian age(Klapper, 106 written communication, 1974).Closer sampling in the lower dolomite may locate theEmsian-Eifelian boundary. Samples KDL-171 and 265 are fromthe crinoidal unit at

Mc Colley Canyon and Modoc Peak,respectively.KDL-171 contains Pandorinellina exigua subsp. nov. A andPolygnathus angustipennatus; and KDL-265 contains Polygnathuscostatus costatus, P. sp. nov. D, and Pandorinellina subsp. nov.A. Polygnathus costatus costatus and P. angustipennatus are both ofEifelian age (Klapper, written communication, 1974). One sample of a crinoidal bedin the upper dolomite was sampled for conodonts (KDL-115 atShipley Hot Springs) and contains Polygnathus costatus costatus, of Eifelian age(Klapper, written communication, 1974).Brachiopods 154 feet above the base ofthe Lower Alternating Member ofthe Simonson Formation at Union Mountain are of early to middleEifelian age (Johnson and Flory,

1972).The age of the upper Sadler Ranchdolomite is, therefore, early Eifelian. The brachiopods in samplesKDL-12, 25, and 183 (from the lower dolomite unit) arecharacterized by Schizophoria sp.and Elythyna sp. and correlate withthe late Emsian or Coils Creek age Elythyna fauna in the northernRoberts Mountains (Johnson,personal

communication, 1974). The conodont data allow forexcellent correlation be weenthe 107 lower unit of the Sadler Ranch Formationin the Sulphur Spring Range and units 13 and 14 of Murphy and Gronberg's(1970) Coils Creek Member of the Mc Colley Canyon Formation atLone Mountain.Based on information presentedhere, it is clear that the lower unit of the Sadler Ranch Formation in the Sulphur Spring Rangecorrelates with the upper part of the Coils Creek Limestone atWillow Creek. The middle crinoidal unit of the SadlerRanch Formation in the Sulphur Spring Range correlates with the crinoidaldolomite at Lone Mountain (unit 14 of Murphy and Gronberg,1970).The crinoidal unit in the Sulphur Spring Range alsocorrelates with the crinoidal unit at the base of the Denay Limestone atWillow Creek.The upper dolomite unit of the Sadler Ranch Formationcorrelates with the lower part of the Denay Limestone atWillow Creek and with the interfingering limestone and dolomite abovethe crinoidal unit at Lone Mountain. The lower tongue of Sadler Ranch dolomiteat Union Mountain is probably of late Emsian age, based onconodonts from the underlying Bartine Tongue and on lithologiccorrelations between Union Mountain and the Sulphur Spring Range.Most of the quartzite interbeds in the Sadler Ranch Formation inthe Sulphur Spring Range are in the lower or Emsian part of theformation.Therefore, the lower dolomite unit in the Sulphur SpringRange correlates approximately in

time of deposition with theQuartzose Member of the Oxyoke Canyon Formation.Figure 35 shows the inferredrelationship between the TE:LEGRAPH CANYON UNION MOUNTAIN

5miles

0 sea level " "

SADLER RANCH DOLOMITE tqapa CANTON rm.

QUARTZOSE MBR. 100

200 BARTINE TONGUE

UPPER TONGUE SEVY DOLOMITE 300

Soo strike during mid-Oxyoks Cavan Figure 35. Generalized cross section perpendicular to depositional time. Five miles is hypothesized distance between UnionMtn. and Telegraph Cyn. prior to 0 faulting in Bruffey Canyon. Depths are in feet and are approximate. 109 Quartzose Member and lower dolomite unit,Litho logic correlation between Union Mountain and Oxyoke Canyon suggeststhat the portion of Sevy Dolomite between the Bartine Tongue andOxyoke Canyon Formation at Oxyoke Canyon and the lower SadlerRanch tongue at Union Mountain are equivalent. The upper tongue of the formation at Union Mountainhas not yet been dated by conodonts.It is probably of Eifelian age, since it overlies the Quartzose Member of theOxyoke Canyon Formation and resembles the middle crinoidal unit in itshigh 2-hole crinoid ossicle content.Figure 36 shows the inferred relationship between the upper part of the Sadler Ranch Formationand the Oxyoke Canyon Formation.The presence of crinoidal dolomite above theQuartzose Member at Union Mountain represents a slighteastward (transgres- sive) shift of subtidal deposition.Interbeds of siliceous quartzite in the upper tongue of the Sadler RanchFormation indicate that Quartzose Member deposition also shiftedeastward.(Perhaps this slight transgression allowed enoughcirculation of normal marine waters in the Sulphur Spring Rangefor the crinoid thickets to proliferate. ) Detailed conodont sampling of the upper tongueand upper

dolomite unit of the Sadler RanchFormation in the Sulphur Spring Range may determine when CoarseCrystalline Member deposition began at Union Mountain and in theSulphur Spring Range.If the TELEGRAPH CANON UNION MOUNTAIN

K 5miles

0 sea level

OXYOKE CANYON FM.

COARSE CRYSTALLINE MBR. 100

UPPER TONGUE SADLER RANCH DOLOMITE CRINDIDAL UNIT ao ° 00 0 0 e ° 0 0o 0 ° o 0 200 0 o 0 0 (:,;`) 0 00 .0 °°° 0 0 o 0 *.-. rOXTOICE CAlital NI.

QUARTZOSE MBR: 300

500

Figure )5. Generalized cross section perpendicular to depositional strike during late Ox yoke Canyon time. Five miles is hypothesized distance between Union Mtn. and Telegraph Gym. prior to faulting in Bruffey Canyon. Depths are in feet and are approximate. 111 upper tongue at UnionMountain is the same age as the middle crinoidal unit in the Sulphur Spring Range,then the late Sadler Ranch or Coarse Crystallineregression began very early in theEifelian and slowly worked its way westward.Such a slow regression would be strong evidence for a depositionallycontrolled facies shift rather than an eustatically controlled one. 112

OXYOKE CANYON FORMATION

General Statement

The Oxyoke Canyon Formation consistsof two distinct rock units herein recognized as membersof the formation.The lower member is termed the Quartzose Memberand the upper member is called the Coarse Crystalline Member.The type section of the formation is located in Oxyoke Canyon, asdescribed by Nolan and others (1956).Plate 3 shows the precise location,and Plate 4 shows the lithologies present in the formation.The Coarse Crystalline Member is more widely distributedthan the Quartzose Member and represents a western tongue of theformation where the Quartzose Member is absent.Figures 27 and 37 show the distributionsof both members and of correlative rock units.

Quartzose Member

The Quartzose Member of theOxyoke Canyon Formation crops out within a narrow (five tofifteen mile wide) north-south beltfrom southwestern Elko County to southeasternEureka County (figure 27). The formation is not exposedfarther north.The trend of exposures of the member parallels thedepositional strike during the Lowerand Middle Devonian. At the northernmost exposure ofthe formation in the area 113

\ t \ i \ t \ I

\ 1 \ i 1 `..

Sadler Ranch Fm. (2)

Deasy Limestone

Ceara*Crystalline Mbr. of Oxyoke Canyon Fm.

Coarse Crystalline Member of Simonson Fm.

10 0 10 20 30 40 miles

Figure 37. Lithofacies distribution during lateOzyoke Canyon time, 1 1 4 studied, in the northern Pion Range,the Quartzose Member is 400 feet thick and consists of 110feet of siliceous quartzite overlainby 290 feet of dolomitic quartz areniteand quartzose dolomite.To the south the Quartzose Memberthins to 300 feet at Coffin Mountainand 180 feet of quartzite at UnionMountain.At the Phillipsburg Mine in the Diamond Range, theQuartzose Member is 129 feet thickand consists of interbedded quartzarenite and quartzose dolomite.At Oxyoke Canyon the member is 103feet thick.Interfingering of the Quartzose Member with the SadlerRanch Formation was observed in the Sulphur Spring Range(figure 36) but not in the MahoganyHills. To the east the QuartzoseMember thins drastically and isabsent over wide areas (figure 38).To the south the sandstone alsothins markedly and is best considered tobe part of the Sevy Dolomite.The Quartzose Member not only becomesprogressively thinner toward the south but also becomesless quartzose. Exposures of the QuartzoseMember are generally excellent because of the resistance ofthe quartzite, and the unit islocally a cliff-former.Commonly the base of themember and underlying strata are covered by quartzitetalus from the prominent outcrops of the member. In the Diamond Rangethe member lies on quartzoseSevy Dolomite that is transitionalin lithology to the QuartzoseMember. This transitional unitbecomes less similar to theoverlying massive 1 1 5

189 reacii:hgs

(,I

\ I

I L____ \ I. r...... LIMESTONE DOLOMITE QUARTZOSE DOLOMITE ' QUARTZ SANDSTONE

1 0 60 120 80 miles

Figure 38.Generalized lithofacies distribution during the late Emsian for part of Nevada. 1 1 6 quartz arenites in the northern Diamond Rangeand in the Pirion Range. In the Pion Range the underlying Sevy is nearly devoidof quartz. The contact is thus rather abruptly conformable inthe Pion Range. Locally there is evidence of scour and fill structures atthe base of the formation, but many quartzite beds above and belowthe contact exhibit similar scour and fill structures,

Diamond Range

Outcrop Character.In outcrop Quartzose Member rocks in the Diamond Range are of very uniform lithology.The major variations are changes in the quartz content and aslight upward coarsening of the dolomite matrix from aphanitic to very finelycrystalline dolomite.The rocks vary from quartzose dolomites with aslittle as 5% quartz to dolomitic quartzarenites with as much as 75% quartz. Most of the lower part of the member is very quartzosedolomite (quartz content > 25%) to very dolomitic quartz arenite.The upper part of the member is primarily quartzosedolomite with thin beds and laminations of dolomitic quartz arenite.The dolomite matrix throughout the member closely resembles theunderlying Sevy Dolomite and is strikingly different fromthe matrix of the overlying Coarse Crystalline Member.The base of the member is more resistant and more prominently laminatedand cross-bedded than the upper, more homogeneouspart.Rare burrows mostly occur in the 117 upper part of the member.The vertical variations mentioned here are most noticeable inthe southern Diamond Range.At Phillipsburg Mine the member resembles thelower part of the member at Oxyoke Canyon throughout. The member is indistinctly beddedand is predominantly thick bedded.Beds as thin as three inches and somemassive beds are present in the lower part ofthe member.Quartz- and dolomite-rich laminations, variations in quartz content,and stylolites define the bedding. In hand sample Quartzose Memberrocks are nearly identical to the quartz-rich interbeds inthe underlying Sevy Dolomite.The rock breaks with a jagged fracture exceptin the few dolomitic and siliceous beds, where sub-conchoidalfracturing occurs.Blocky to splintery weathering predominates.Freshly broken samples are very light to mediumlight gray (N8 to N6) or are lightbrownish gray (5 YR 6/1) or yellowish gray (5YR 8/1).Weathered surfaces are light gray (N7) to yellowish gray (5Y 8/1) and rusty brown (10 R4/6). The weathered brown shades are most commonin the lower part of the member and are especially commonon the quartz-richbeds and

laminae.The dolomite matrix is locallyleached away, and the rusty brown quartz-richlaminae stand out in slight relieffrom the surfaces of exposure. Cross-beds in the QuartzoseMember are low-angle (<10%) 118 and planar and are intimately associated withhorizontal laminations (figure 39).Each set of cross-beds is truncated above and belowby other sets of cross-beds or by horizontal laminations.Channels are absent, and the sets of cross-beds have long,low, wedge-like shapes in cross-section.The cross-beds have amplitudes up to 18 inches, but most are four to twelve inches.The profiles of cross-beds exposed in outcrop resemble the cross-sectionsof mega-ripples from intertidal sand bodies (Klein, oral communication,1974).Plane bed laminations (horizontal laminations) may haveformed under the same or slightly lower transportiveenergies as the cross-beds or may be due to slightly coarser grain-size inthe laminated sediments (Allen, 1970).The laminations may be sub-horizontal backsetsof mega-ripples of sand waves (Allen, 1970). Cross-bedding dip-directions were used todetermine paleotransport directions, and 37 measurementsfrom the Quartzose Member in Oxyoke Canyon and the Fish CreekRange indicate an eastward or onshore dispersal pattern(figure 27).A dominant shoreward transport direction is also found inmodern and Pleistocene beach and bar environments (Clifton andothers, 1971; Hill and others, 1958; Selley, 1970). Thin Section Description.In thin section the Quartzose Member in the Diamond Range closelyresembles the very quartzose dolomites and dolomitic quartz arenites ofthe Sevy Dolomite. A typical sample Figure 39.Cross-bedded and laminated dolomitic quartz arenite in the Quartzos e Member in Oxyoke Canyon.

Figure 40.Possible rounded quartz overgrowth from the QuartzoseMember in the Fish Creek Range. 120 consists of 30% to 60% quartz sand andsilt, 40% to 70% dolomite matrix, up to 10% dolomite intraclasts,and up to 8% secondary quartz and iron oxide.Detrital garnet, tourmaline, and zircon arepresent in small amounts. Quartz grains are predominantly fine- tomedium-grained, rounded to very well rounded, and well sorted.Quartz overgrowths are rare to common andusually occur between adjacent grains.Par- tial solution of quartz grains andovergrowths and some replacement by dolomite has increased the angularityof some grains.Contiguous quartz grains have planar to concavo-convexcontacts indicative of moderate diagenetic pressure solutionduring burial. Detrital garnet, tourmaline (brown),and zircon are silt-sized to fine-grained and are rounded towell rounded.Fractures in the tourmaline grains are partially filledwith secondary quartz.Rounded quartz overgrowths are rare constituentsof the rock (figure 40). The dolomite matrix is composed ofmedium-grained clear sparry dolomite in somecross-bedded quartz arenites but consists of microspar and pseudospar inless quartzose beds.Intraclasts in the quartzose beds are partlyobliterated by secondary dolomitization and occur as rounded, slightlydarker and finer-grained ghosts in the sparry matrix.In these beds the dolomite occurs as a pore- filling cement.In less quartzose beds thematrix appears to have originally been carbonate mudthat has subsequently recrystallized 121 to dolomite microspar and pseudospar. Intraclasts in these beds are composed ofdolomicrite and quartz silt.Sand-sized intraclasts also contain smallerdolomicrite intraclasts and pellets.The intraclasts are silt-sized to coarse- grained, well rounded, and moderately sorted.Many intraclasts appear flattened, as ifthey were once part of dolomite mud laminae ripped up by currents,The extreme fineness of the dolomite crystals forming the intraclasts and the strikinglithologic similarity of the dolomite matrix of the Quartzose Member tothe underlying Sevy Dolomite imply a similar origin for the dolomitesand and matrix in both formations.As discussed earlier, the dolomite of theSevy probably originated as carbonate mud thatunderwent early dolomitization.Erosion and transport of semi-consolidatedmud formed the rounded dolomite sand grains that occur inthe cross-bedded and horizontally laminated sandstones of the QuartzoseMember.The quartz silt and dolomite pellets occurringwithin the dolomite sand grains support the contention that much orall of the dolomite sand originated as dolomite mud rip-ups.

Pii-Ton Range

Outcrop Character.The detailed features of the Quartzose Member are less readily observed inthe Pion Range than in the Diamond Range, because there themember is a siliceous sedimentary 122 quartzite rather than a quartzose dolomite todolomitic quartz arenite.The basal contact of the member is sharpand planar.At Union Mountain the underlying tongue ofSadler Ranch Dolomite becomes increasingly quartzose close tothe contact but is abruptly overlain by the massive cliff of the QuartzoseMember (figure 41). At Slagowski Ranch the membersharply overlies slightly quartzose

Sevy Dolomite. In outcrop the quartzite is moderatelybedded in very thick to massive beds defined by laminations.Faint cross-bedding and horizontal laminations are visible in someoutcrops, but the rock is generally structureless.At the Pirion Range Section, threefourths of the member is dolomitic quartz areniteto quartzose dolomite similar to outcrops of the member in theDiamond Range; bedding, cross-bedding and laminations are morevisible than elsewhere in the range.The quartzite is white (N9) to pinkish gray(5 YR 8/1) on freshly broken surfaces, and on weatheredsurfaces it is white (N9), shades of gray (N6 to N8), brown (5YR 6/4), and pink (5 YR 8/4). The rock breaks with a subconchoidal tojagged fracture and weathers in splintery to roughly equidimensionalblocks up to several feet across. The interbeds of dark dolomite emit afetid odor when broken and are medium bedded andmoderately well bedded.Quartz grains in the dolomite are silt-sized tofine-grained, well rounded, and 123

Figure 41.Bold outcrop of the Quartzose Member in the Slagowski Ranch Map Area. 124 moderately sorted.They occur in distinct quartz-rich laminations or scattered in the veryfinely crystalline dolomite matrix.Except for the occasional quartzose laminations,other sedimentary structures are rare.The presence of these Sadler Ranch-likedolomite beds within the Quartzose Member is strongevidence for an interfingering relationship between the QuartzoseMember and Sadler Ranch Formation (figure 36). Thin Section Description. A faintgranularity is present in the quartzite of the Pion Range when it isviewed under a hand lens.In thin section the quartzite is of veryuniform composition and texture. Fine- to medium-grained quartz comprises upto 99% of the rock. Chert (1%-8%), iron oxide (1%-3%), andvoids (1%-11%) make up the remaining portion of the quartzite.A dolomite spar matrix is a rare constituent of somesamples, as are detrital garnet, tourmaline, and zircon.Adjacent quartz grains display planar to concavo-convex grain boundaries.Sutured quartz grain boundaries andovergrowths are rare. Alkaline conditions and compaction duringdiagenes is favored dissolution of quartz boundaries andthe development of slightly interpenetrating quartz grain contacts.Small spherical voids in the rock hint at the earlier presence ofintraclasts.These dolomite intraclasts were probably dissolved duringlate diagenesis under relatively high pressure and low partialCO2 pressure (Siever, 1959). 125 Depositional Environment

Evidence of organic activity is rare in theQuartzose Member in the Pi Tion Range.Carlisle and others (1957) reported a Pirionensis zone s. 1. fauna from thequartzite at Union Mountain.The writer found no brachiopods in the quartzite atUnion Mountain but did find molds of pelecypods (to 1 1/2 inch in diameter) inthe quartzite. Devonian pelecypods generally inhabitedshallow nearshore environments (William Koch, personal communication,1974).Burrows in the quartzite include Scalarituba from intermediatedepths and Anemonichnus from offshore bars and nearshoreenvironments (Chamberlain, written communication, 1974).Because of the coarseness and probablelooseness of the sand substrate, the benthic fauna was probably characterized bythick-shelled, rapid burrowing organisms (Stanley, 1970).The population of deposit feeders must have been low, since the high-energyintertidal conditions would not have allowed much organic-rich mud tosettle.Suspension feeders, on the other hand, wereprobably more numerous.The fauna was therefore probably dominated by vagilesuspension feeders and the carnivores feeding on them (Purdy,1964). The presence in the Quartzose Memberof vertical burrows, beds of early dolomite,intraformational conglomerates, abundant intraclasts, features of intermittenterosion like those in the underlying Sevy, and the scarcity ofmegafossils support an intertidal 126 environment of deposition for the quartzose anddolomitic sandstones of the Quartzose Member.Cross-bedding, horizontal laminations and well sorted and rounded quartz grains suggestthe Quartzose Member is a high-energy beach/bar deposit.The Quartzose Member fits neatly as a zone of high-energy beaches andbars separating the subtidal Sadler Ranch Formation and the intertidalto supratidal

Sevy Dolomite. Shoreward or eastward of the belt of QuartzoseMember rocks lay the Sevy tidal flat, and offshore orwestward were subtidal dolomite muds of the Sadler Ranch Formation.The amount of tidal exchange between the marine environment to thewest and the restricted tidal flats to the east was probablysmall.One would expect a bimodal distribution ofpaleocurrent directions with modes 180° apart (onshore and offshore) in an area of shoalingand tidal exchange (Klein, oral communication, 1974),but such is not the case (figure 38).Bathurst (1971) found a "negligible" tidal range at the center of the Bahama Platform.Ginsburg (1956) noted decreas- ing diurnal tidal exchange acrossFlorida Bay.Perhaps the tidal range along the inner marginof the Devonian sea was small andthe resulting tidal exchange across thelinear clastic shoreline of the Quartzose Member was also small.Irregular tides controlled by the piling up of water masses by thewind could have existed on the Sevy tidal flat. 127 The overall geometry and stratigraphicrelationships of the Quartzose Member are shown in figures 27,36, 38, and 50.Figure 3 is a facies tract model for deposition ofthe Quartzose Member and equivalent-aged rock units and shows that thesandstone body is flanked by subtidal carbonate muds and nearshore sands to the west and by tidal carbonate muds and quartzsheet sands with minor lagoonal sediments to the east.The depositional environment of the Quartzose Member was a probably high-energybeach/bar environment similar to that which occurredalong the western margin of the Sevy tidal flat (upper Sevy tongue inthe Sulphur Spring Range and upper quartzose dolomite in theDiamond Range).The main difference is that there was much more quartzsand deposited during early Oxyoke Canyon time.In light of the above and followingdis- cussion, the Quartzose Member is proposedto have been part of a long, narrow barrier bar that separatedthe subtidal and intertidal/ supratidal environments during part ofthe Devonian in central

Nevada. Rusnak (1960, figure 3) presented amodel of a barrier bar as

an upward growingdeposit flanked by lagoonal sediments onthe shoreward side and by shelf muds onthe seaward side.The shelf muds included seaward thinningnearshore sands.His model is similar to the facies tract model infigure 31.The Sadler Ranch Formation was largely a carbonatemud with interbeds of westward 128 thinning quartzite.The Sevy tidal flat was also largely carbonate mud with a few thin quartzose sheet sands.Although it was very broad (up to several hundred miles), the Sevy tidal flat was never- theless very shallow and greatly restricted. Hoyt and Henry (1967) stated that on a large scale, theshape of active barrier bars is elongate in the directionparallel to the shore and lens-shaped perpendicular to the shore.The widths of such deposits commonly range from six to eight miles.The length of the Quartzose Member barrier bar is at least120 miles and the width is five to fifteen miles (figure 38).The lens-like shape of the Quartzose Member perpendicular to the depositionalstrike is shown in figures 50 and 51.(The width of sandy rocks in figure 38 is based on generalizing the stratigraphicdata for several rock units. ) Modern examples of barrier bar environments occuralong the coasts of the Mid-Atlantic states, Georgia and easternFlorida, and the northwest Gulf of Mexico (Fisher, 1968).These quartzose deposits are all narrow and linear, with lengths up toseveral hundred miles.Barrier bar deposits have been recognized in manyancient rock sequences.Two sandstone bodies at the top of the UpperCreta- ceous Almond Formation inthe Rocky Mountains are interpreted as barrier bars and occur in a north-south trendthat is several hundred miles long and ten to forty miles wide(Weimer, 1966).The Permian Cedar Mesa Sandstone of the Colorado Plateauis a thick deposit of 129 nearshore marine and littoral sands that occur in anorth-south trend and are interpreted as a barrier bar (Baars,1961).The upper Cretaceous Fox Hills Sandstone of Wyoming is a 100foot thick linear sandstone separating swamp and lagoonal environmentsfrom normal marine environments (Weimer, 1966).The thickness of the Quartzose Member is greater than that of the Fox HillsSandstone and modern barrier bars but is approximately the same.Perhaps gradual subsidence would allow a barrier to build up a thicknessof 100 to 400 feet, as is present in the QuartzoseMember. Sediment transport directions in barrier sands of theCedar Mesa Sandstone are predominantly shoreward(Baars, 1961), as are the paleotransport directions in the QuartzoseMember. The large southerly component of paleocurrentsduring deposition of the Quartzose Member suggests thatthe longshore current transport of the sands was primarilysouthward.This suggests that growth of the Quartzose Member barrier bar wasalso southward. The absence of quartz sand over wide areas of easternNevada, and the fan-like dispersal pattern of sand in thesandy member of the Sevy into southeastern Nevada (figure 38)and southward thinning of the Quartzose Member are further evidencefor a southward migrating barrier bar.The barrier bar did not extend south ofEureka County and is represented there by the sheetsands of the Sevy. The scarcity of quartzose beds in the upperpart of the Sevy in 130 the Northern Diamond Range and in the Pilion Range suggests that the Sevy was deposited well behind thehigh-energy western margin of the tidal flat.At Union Mountain the QuartzoseMember overlies the lower tongue of the Sadler RanchFormation.The Quartzose Member barrier bar apparently straddledthe western margin of the immediately preceding Sevy tidal flat and wasdeposited for a short distance on both sides of the edge ofthe tidal flat.Just prior to the onset of Quartzose Memberdeposition there had been a slight transgression by the Bartine Tongue (andoverlying lower Sadler Ranch tongue).The barrier bar, therefore, overlappedinto areas where subtidal and intertidal environmentshad previously existed.

Coarse Crystalline Member

Outcrop Character

The Coarse Crystalline Memberof the Oxyoke Canyon Forma- tion is more widely distributedthan the Quartzose Member and is equivalent to the Simonson Formation.Figure 37 shows the distribution of the Coarse CrystallineMember.To the west the Sadler Ranch Formation(?) and DenayLimestone were deposited in deeper

water.To the east the Coarse CrystallineMember of the Simonson Formation was deposited in veryshallow water. The member is approximately830 feet thick in the Pirion 131 Range and thins to 279 feet thick at Union Mountain, 321 feet at the Phillipsburg Mine, and 296 feet at Oxyoke Canyon.In the Sulphur Spring Range the member is 296 feet thick at Williams Canyon,238 feet thick at Fera Well, and 229 feet thick at Sadler Ranch.Faulting hinders thickness estimates elsewhere in the Sulphur SpringRange. At Modoc Peak the member is approximately 132feet thick (thickness uncertain due to the presence of a sill).At Table Mountain the unit is approximately 210 feet thick (Gronberg,1967, sections).West of the Mahogany Hills and the Sulphur Spring Range theunit does not crop out. The feature of the Coarse Crystalline Member ofthe Oxyoke Canyon Formation that distinguishes it from its easterncorrelative is its high content of quartz.In eastern Nevada and in Utah the Coarse Crystalline Member of the Simonson Formation isreadily distinguished from the underlying Sevy because it is much coarser crystalline than the aphanitic Sevy.The Coarse Crystalline Member is readily distinguished from the overlying LowerAlternating Member of the Simonson Formation because its lithology isuniform and light in color, while the Lower Alternating Memberconsists of interbedded light and dark, fine crystalline beds. The upward change from quartz sandstoneswith Sevy-like dolomite matrixes and interbeds to coarselycrystalline dolomite at the Quartzose-Coarse Crystalline Member contactis easily 132 recognized in the Diamond Range.In the Pinon Range, the distinctive Sevy-like matrix is usually absent inthe Quartzose Member, and the contact between the members is placed atthe base of the first bed of coarsely crystalline dolomite. The contact between the two members of the OxyokeCanyon Formation is sharp, and exposures of the contact appearto be planar. Field evidence and the significant lithologicchange between the members suggest that the contact is disconformableand locally uncon- formable. A local unconformity between themembers mapped near Slagowski Ranch (Plate 2) is striking in its smallareal extent.Other local unconformities between the members orwithin the Coarse Crystalline Member may be masked by thicknessvariations along strike and by the poor bedding and obliterationof sedimentary structures. The basal part of the Coarse CrystallineMember is a quartzose dolomite to dolomitic quartz arenite.The number of dolomitic interbeds increases upward until quartz isconfined to a few quartzose beds or is scattered in the matrix.The basal one third to one half of the member at Union Mountain and inthe Sulphur Spring Range is quartzose and is most commonly a quartzosedolomite.This concentration of quartz beds near the base ofthe member is similar to the concentration of quartz beds at the baseof the upper Sevy tongue in the Sulphur Spring Range.Quartzite interbeds similar to Quartzose 133 Member rocks are common in the CoarseCrystalline Member at Union Mountain, but they usually occur nearsmall faults,In the Diamond Range the member is less quartzosethan at Union Mountain. Quartz is concentrated in siliceous orslightly dolomitic interbeds up to 15 feet thick.Quartzose beds occur throughout the sectionand are thinner and fartherapart near the top. Locally, as at Union Mountain and ModocPeak, quartzose dolomite is present near the top of themember.The increased quartz content and scatteredcross-bedding in the quartzose beds suggest slightly deeper conditions orhigher-energy conditions during late Coarse Crystalline time.The overlying Lower Alternating Member reflects a transgression overthe very shallow Coarse Crystalline Member. The Coarse Crystalline Member atModoc Peak and elsewhere in the Mahogany Hills isconsiderably less quartzose than in the Sulphur Spring, Diamond, or PionRanges.In eastern Nevada the Coarse Crystalline Member ofthe Simonson Formation is locally slightly quartzose but is rarelyquartzitic (Kellogg, 1963). In outcrop the quartzose bedsof the Coarse Crystalline Member are more resistantthan the interbedded dolomitebeds and locally form resistant ledges.Quartzose dolomite and dolomitic quartz arenite are both white to verylight gray (N9 to N8) on freshlybroken surfaces.Weathered surfaces are white (N9) tolight gray (N7) and 134

Figure 42.Erosional surface between quartzite and dolomite bedsin the Coarse Crystalline Member in the Alhambra Hills.

Figure 43.Laminated vuggy dolomite of the CoarseCrystalline Member in Oxyoke Canyon. 135 shades of brown (10 R 4/6 to 5 YR 4/4).Quartz-rich laminae in horizontal and cross-laminations arehigh-lighted by their brownish weathering and by the leaching of adjacentdolomite-rich laminae. Bedding is defined by laminations and variationsin quartz content or amount of vugs.Bedding is medium to thick, but massivebeds are common.Cross-beds are low-angle, planar, andtangential. Successive sets of planar cross-beds overlainby or interbedded with horizontal laminations occur in some quartziteinterbeds and indicate fairly continuous sedimentation of thebeds.Other beds of quartzite contain cross-beds that are truncatedabove and below by erosional surfaces (figure 42) or are confined to thin,wedge-like zones.These features indicate periods of exposure or intermittentperiods of deposition and erosion. The dolomite of the Coarse CrystallineMember is difficult to study because dolomitization andrecrystallization have obscured most of the original sedimentarystructures and textures. In hand sample the dolomite issaccharoidal and medium to coarsely crystalline.Scattered quartz grains are fine- tomedium- grained, well rounded, and moderatelysorted,They occur scattered in the matrix or in faintquartz-rich laminations.Faint laminations in the dolomite beds are definedby variations in resistance to weathering, color and grain size, andin concentrations of quartz. Cross-beds in the dolomite beds aretoo faint for paleocurrent 136 determinations.Most beds are structureless or contain only faint laminations or rare burrow-like structures,Vugs are the most common structure, and these varyfrom 1/4 to 1 1/2 inches in diameter.They are empty or are lined with medium- to coarse- grained calcite or dolomite (figure 43). Contacts between the quartzite beds and dolomitebeds of the member are sharp.The quartz content of the dolomite beds increases close to the quartzite beds.The matrix of the quartzite beds, where preserved, is coarsely crystalline dolomiteidentical to that of the dolomite interbeds,The dolomite matrix is absent from manyof the quartzite beds, probably because it wasremoved during formation of slightly interpenetrating quartz grain contacts orduring later slightly acidic conditions (Siever, 1959). In addition to the several quartzite bedswithin the member that exhibit erosional contacts, there is atleast one unconformity within the member. At the Slagowski Ranch map area(Plate 2), the Coarse Crystalline Member is about 30feet thick.The Quartzose Member thins from 400 feet at thePirion Range Section and 300 feet at Coffin Mountain to about 50feet in the map area.Apparently the erosion or non-deposition of about 300feet of Coarse Crystalline Member dolomite and 200 feet of QuartzoseMember quartzite occurred during Coarse Crystalline time. 137

Thin Section Description

In thin section the dolomite beds consist of nearly pure sparry dolomite (92%) with minor amounts of dolomite pseudospar and microspar (3%), chert (3%), iron oxide(1%), and voids (1%).In slightly quartzose beds rounded quartz silt and sand occur in laminations or scattered in the dolomite matrix.Dolomite rhombs are clear and up to one mm in diameter.They are randomly oriented in an interlocking crystalline network.Quartz grains are peripherially replaced by dolomite rhombs, and some are nearly completely replaced. Where quartz grains are in contact with each other, they contain planar to concavo-convex boundaries.Ghosts of intraclasts are present and are defined by slightly darker and finergrained masses within the dolomite matrix.Quartz-rich and dolomite-rich laminae in some samples indicate alternating conditions ofdeposition. High alkalinity and relatively high pressure during deep burial favored dissolution of quartz and formation of partially interpenetrating quartz grain contacts (Siever, 1959).Replacement of quartz by dolomite was a late diagenetic event that alsooccurred under high alkaline conditions and low CO2 partial pressure. The time of dolomitization is difficult to determine.No dolomitization front or gross variations in texture are presentin the unit, and the dolomitization ends abruptlytoward the normal 138 marine environment in the west (Lone Mountain andRoberts Moun- tains).Seepage reflux or evaporative pumping methods ofdolomitization, similar to those methods responsible fordolomitization of the Sevy, can explain the initial dolomitization of the CoarseCrystalline Member. A second recrystallization phase ofdolomitization may have occurred during the periods of exposure andpartial erosion of the member. Bathurst (1971) suggests that periodsof subaerial exposure may help cause earlyfine crystalline dolomite to recrys- tallize to a coarse crystalline dolomite.

Depositional Environment

The nature of the original sediment is difficultto determine because of dolomitization and recrystallization.Coarse Crystalline Member rocks are very widespread and wereprobably deposited in very restricted environments.The possible presence of ghosts of intraclasts, the presence of quartz-rich anddolomite-rich laminae, and the interbedded quartzites strongly suggest ashallow and highly variable environment of deposition.Intertidal or possibly supratidal conditions meet these requirements.The original sediment may have been similar to that on the Sevy tidalflat, since one bed of aphanitic Sevy-like dolomite mudstone was found inthe upper part of the member at the Phillipsburg Mine.The restriction of quartz sand in the Coarse Crystalline Member tothe western edge of the exposed 139

Coarse Crystalline rocks (figures 37 and 38 herein; Kellog,1963) suggest that the Coarse Crystalline Member ofthe Oxyoke Canyon Formation was deposited under higher energy conditionsand better circulation than the coarsely crystalline dolomite of theSimonson Formation. The features of intermittent exposure, presenceof cross-beds, possible presence of early dolomite, sheet-like quartzsandstones, abrupt variations in lithology, and absence of fossilssuggest a very shallow, highly variable, restricted environment of deposition.An intertidal to supratidal environment with poorcirculation can explain these features.The paleocurrent directions indicated by cross- bedding in the quartzite (figure 37) show a randomdistribution of directions that would arise from variable wind and stormdirections, not regular diurnal tidal exchange withthe normal marine environment to the west. The gradational contact betweenthe Sadler Ranch Formation and the Coarse CrystallineMember in the Sulphur Spring Rangehas already been described.The lithologic change acrossthe contact represents a change to shallowerconditions, and the Coarse Crystal- line Member is thinner than tothe east.A gradual regression that coincided with shallowing at theonset of Coarse CrystallineMember deposition is responsible forthe gradational contact.Unconformities onshore may not have existed inthe slightly deeper areas inthe 140

Sulphur Spring Range.

Age and Correlation

The absence of identifiable fossils in the OxyokeCanyon Forma- tion hinders dating and correlation of theunit.Fossils in units that interfinger with the formation and lithologiccorrelations do allow the Oxyoke Canyon Formation to be correlated toother areas of

Nevada. Sample KDL-215 from the Bartine Tongue atUnion Mountain contains conodonts of late Emsian or earlyCoils Creek age.Tongues of Sadler Ranch dolomite underlie andoverlie the Quartzose Member at Union Mountain.In the Sulphur Spring Range the lowerSadler Ranch Formation contains late Emsia.nbrachiopods and conodonts, and the upper part of the formation containsearly Eifelian conodonts. The Quartzose Member is therefore oflate Emsian to early Eifelian age.It is suggested here that the upper tongueof the Sadler Ranch Formation at Union Mountain represents aslight transgression and that there are Quartzose Memberrocks of latest Emsian to early Eifelian age east of Union Mountain. The Quartzose Member interfingerswith the upper part of the lower dolomite unit and with themiddle crinoidal unit of the Sadler

Ranch Formation.This part of the Sadler RanchFormation correlates with the upper part of unit 13and all of unit 14 at Lone 141

Mountain (Murphy and Gronberg, 1970).The Quartzose Member is therefore correlative with the upperapproximately one half of the Coils Creek Limestone and the basalcrinoidal unit of the Denay Limestone at Willow Creek. The Coarse Crystalline Member is aslightly diachronous, regressive unit.In the Sulphur Spring Range it isunderlain by the early Eifelian part of the Sadler RanchFormation, and at Union Mountain and in the Sulphur Spring Rangeit is overlain by the early to middle Eifelian LowerAlternating Member of the Simonson Forma- tion (Johnson and Flory, 1972).It is therefore of early Eifelian age. Litho logic comparisons suggest thatthe Coarse Crystalline Member correlates with the upper part of thelower unit of Gronberg's (1967) "Simonson Formation" at Lone Mountainand with the lower part of the Denay at Willow Creek (Denay Iof Murphy, unpublished data). It is the writer's opinion that theQuartzose Member is the lateral equivalent of Osmond's sandymember of the Sevy (1954, 1962), and that the Coarse CrystallineMember is the lateral equivalent of the basal coarsely crystallinedolomite of the Simonson For- mation.These correlations have beenproposed by earlier workers (Kellogg, 1963). Carlisle and others (1957) correctlysupposed that the quartzites in the Sadler Ranch Formation(not their name) in the SulphurSpring Range were replaced to thenorth by the thicker quartzite ofthe 142 Quartzose Member.However, the writer believes that the facies relationship is an east-west one, not a north-south one. The unconformity hypothesized by Johnson (1962) at the base of the Eifelian Union Mountain Formation does not exist.The base of he Eifelian is within the Quartzose Member. An unconformity exists within the Eifelian Coarse Crystalline Member in thePion Range but is of uncertain areal extent. 143

SEDIMENTARY PETROLOGY

Grain Size Analysis

Thirteen sand samples from quartzose dolomites weresieved at 1/4 intervals to determine grain sizestatistical parameters and to see if those parameters had environmental.significance.The dolomitic cement of the samples was dissolved inconcentrated HC1, and the organic matter was dissolved in 30%H202.Insoluble residues were collected, dried, and were sieved on aRo-tap shaker. A cumulative percentage size distributiongraph was plotted for each sample on the basis of the weightsretained between each sieve, and statistical textural parameters(mean diameter, standard deviation, skewness, and kurtosis) werecalculated using the formulas of Folk and Ward (1957).Appendix IV summarizes the textural parameter values for the thirteensamples analyzed. The textural parameters of each sample wereplotted on the graphs that Moiola and Weiser (1968)thought were most effective in distinguishing beach sand from inland dunesand (figures 44a and b) and coastal dune sand from inlanddune sand (figures 44c and d).On the basis of lithology and sedimentarystructures, the samples were considered to be from:1) beach/bar deposits, 2) aeolianflat or backbarrier flat deposits, and 3)wash-over fan or tidal current deposits.In general the samples fromaeolian flat or backbarrier flat deposits plot apart from thebeach/bar and wash-over fan sands. 144

QUARTER FNI INLAND DUNE X

COASTAL DUNE

1.00 KURTOSIS (B)

Probable environment of dspo- sition of thesis samples, based on lithology and sedimentary structures:

* AEOLIAN FLAT/BACKBARRIER PLLT O 11311-OVER FAN O UNCERTAIN Plots of environmentally significant combinations of textural parameters, after Moiola and Weiser, (1968). C 0 C. 4000 Eus.c PA-TY Lys 2/1.,ZEISM,VI SIQucT It kik %WIT* 21Z,fr 4 v 1 at RV° row /MINISrn 011111L6147$ / 0011 msC,Ichito I0 iC 11111115Mrdallint111111...Mar%=11111111PriMall Addli t C. lea N 1 EmmilmovAmilmaigisivANOW1111111111111111111UNFINIPAIMII01/101111111.1Wall11111101E71MIIMIN411111 "IMILIIIL Jill lirval11111'MIMEO'. MINUMINOUillINIIIIMINIMINIMMIIINIMIIIIIM IIIMMIIIMIIIIIM.1111...1111/1/ MI. 10 Fr Win IS 141.400,0N IN PlICIONS Figure 45, circlesClosedOnBasic the basiscirclesCMrepresent plots of represent lithologyof wash thesis -over beach/bar andsamples, fans, sedimentary and environments,after Z's Passegastructures:are uncertain open(1957). or quiet eater. 146 Figure 45 is a Passega CM graph(Passega, 1957) showing that samples thought to be from beach/barenvironments plot dominantly within the area designating beach sizecharacteristics. Table 4 gives the average values of meandiameter, standard deviation, skewness, and kurtosis forbeach/bar and aeolian flat/ backbarrier flat samples.These values are different from the averages found by Masonand Folk (1958, p. 214-215) forbeach, dune, and aeolian flat sediments; butthe relative magnitudes of the averages for each group comparefavorably.The average mean diameters of beach and dune/aeolianflat sands (from Oxyoke Canyon and Sevy quartzose beds) in Table 4 comparefavorably with values from similar modern environments inSouth Carolina (Adams and Thom, 1968).

Table 4. AVERAGE TEXTURAL PARAMETERVALUES FOR BEACH AND AEOLIAN FLAT DEPOS ITS.

Mean Standard Skewness Kurtosis Diameter Deviation

1. 11 Beach 2. 35 0.51 0. 10

Aeolian Flat 2.46 0.73 0. 28 1.44

The lithologies and sedimentarystructures of different beds provided the best clues to theirdepositional environments, but grain size analysis has aided inthe interpretation of beds withundiagnostic 147 structures.For example, beach/bar deposits have verydiagnostic structures; but wash-over fan/tidal currentdeposits and aeolian flat deposits are less distinctive and can beconfused with each other. The probable wash-over fan/tidal current depositshave grain size statistical values similar to those ofbeach/bar deposits, but the aeolian flat deposits have statistical sizedistributions similar to modern dune (inland dune) deposits. Osmond (1954, p.1924) found that the sorting of sand fromthe sandy member of the Sevy Dolomite increasedwestward and north- westward from the southeastern part of theGreat Basin.He con- cluded that the source of the sand was onthe craton to the southeast and that sorting of the sand increasedwith greater distance of transport.He also believed that wind transport wasresponsible for transporting much of the sand across theSevy tidal flat.The writer agrees that some of the quartzcould have been transported by wind but does not agree that better sortingin the west is the result of longer transport.The eastern part of the Sevy tidalflat was a great distance from the normal marine environment,and tidal currents were probably highlyvariable in strength and duration.The writer suggests that the western marginof the tidal flat was subjected to more regular and uniformlongshore and tidal current and wave activity and is therefore bettersorted. Osmond" s conclusions are based onwhat appears to be sparse 148 data.The lack of sand in eastern exposures of the Sevy (figure 38) and the scarcity of current features suggest that stronger currents were necessary for transport of theSevy (Oxyoke Canyon) sand than were present on the western partof the tidal flat.To be sure, much fine sand may have been transported by the wind; but many quartzose beds, especially near the western margin of the tidal flat aremedium- to coarse-grained.Wind does not have the competence to transport medium and coarse sand grains (A. R. Niem, personal communication, 1974).

Heavy Mineral Analysis

Sand from nine of the samples disaggregated for sieveanalysis was also processed for heavy mineralcontent by the method described by Royse (1970).Appendix V summarizes the location and heavy mineral content data for the nine samples. Rounded zircon, tourmaline, ilmenite/magnetite,and leucoxene are common to abundant in mostsamples; and garnet and rutile are common to rare.Hematite and pyrite are common to rare alteration products.The amount of heavy mineral residue in the samplesis very low.Less than 0. 05% (by weight) of each sampleconsisted of heavy minerals. The heavy minerals and alteration productsin the samples are extremely stable.Their chemical stability, high resistance to 149 abrasion, and low abundance combinedwith the preponderance of quartz and the absence of chemicallyless stable minerals such as feldspar indicate that the quartzose sedimentis compositionally supermature.This supermaturity suggests that the source area for the quartz was probably of lowrelief with sluggish streams where chemical weathering predominated overmechanical weathering.Such a source area may have originallybeen a craton or gentle upwarp of shelf sedimentaryrocks.No vertical or lateral trends in heavy mineral content were noticed.

Organic Carbon Content

Organic carbon contents were determinedfor four selected samples and are summarized in AppendixVI.The weight percent of organic carbonaceous matter wasdetermined after free carbonate in the samples was dissolved bydilute HC1 (<5% HC1).Organic matter was dissolved by 30% H202. One sample of nonquartzoseSevy Dolomite contains 0. 12% organic matter; two samples of theBartine Tongue average 2. 13% organic matter; and one sample ofthe Sadler Ranch Formation, contains 4. 08% organic matter.The dearth of organic matter in the Sevy is consistent with thescarcity of fossils in the formation and probable deposition in anoxidizing supratidal flat.The high organic content in the Sadler RanchFormation is consistent with 1 50 the dark color and strong petroliferous odor of freshly broken samples.The restricted circulation and environment of deposition of the Sadler Ranch Formation may not have allowed forcomplete oxidation of decaying organic matter.Extremely fine crystallinity and good cementation may also have hindered oxidation.The intermediate value of the Bartine Tongue samples is consistentwith the light color of the rocks and the shallow, normal marine environment of deposition of the rocks.

Provenance

The source of quartz sand in the Sevy and Oxyoke Canyon Formations and of terrigenous clay in the Bartine Memberand Tongue of the McColley Canyon Formation is a problem inthe history of the study of the Devonian in Nevada. Osmond (1962) suggested aneastern or cratonic source of unexposedearly Paleozoic sediments and thought the only other source could have been theeugeosyncline to the west.Johnson (1962), on the other hand, suggested anorthern source and cited the geographicdistribution of the sandstones as his evidence.The writer agrees with Osmondts choice of asedimen- tary source but agrees with Johnson'snorthern placement of that source. The well rounded heavy mineral suite of thenine samples analyzed is clearly characteristic of reworkedquartz sandstones 151

(Pettijohn, 1957, p.513).The presence of rounded quartz overgrowths in detrital sand (figure 39) is also strong evidence for a sedimentary source.The textural and compositional supermaturity of the sands could only come about through a long transporthistory, probably including two or more cycles of deposition and erosion. The textural and compositional supermaturity of Sevy andOxyoke Canyon sands suggest derivation from a low land plain(Folk, 1968). The thickness trend and geographic distribution of quartz sand bodies point to a northern source for the sand (Johnson andFlory, 1972; figure 38 herein).The Quartzose Member of the Oxyoke Canyon Formation thins from 400 feet in the Pinion Range to 103 feet at Oxyoke Canyon and also decreased in quartz contentsouthward.East of exposures of the Quartzose Member, the Sevy sand isonly locally present as thin quartzose beds.South of Eureka, the Sevy sand spreads out and forms a broad, thin, sheet-likedeposit stretching all the way to southeastern Nevada (figure 38).The easternmost exposures of the Sevy lack quartzsand.The southward and south- eastward thinning and spreading of quartz sand arehardly compatible with an eastern source and strongly suggest anorthern one. Paleocurrents show a primarily eastward or shorewarddis- persal pattern.Some are indicative of southerly currents that may have been longshore currents.Such a current distribution pattern is in agreement with a southwardprograding barrier bar (Hoyt and 1 52

Henry,1 967). The Bartine Member and Tongue and thelower part of the Coils Creek Limestone are highly argillaceous,but the Sadler Ranch For- mation is nearly free of terrigenousclay.The large scale introduction of clay during the earlyEmsian preceded the introduction of the Sevy and Oxyoke Canyon quartzsands; but the periods of deposition of sand and clay overlapped.By late Emsian time only quartz sand was being deposited, and byearly Eifelian time its source, too, had been exhausted.The writer believes that the timing ofthe appearance and disappearanceof terrigenous sediments in the nor- mally clear shallow shelf and tidalflat carbonate environments in Nevada during the early and middleDevonian is important in understanding the geologic history of the area.The writer suggests that the terrigenous sand and clay mayhave had the same source area, The clay could have been derivedfrom shales and mudstones and was deposited in quietenvironments.The quartz sand may have been eroded later or in different areasand was deposited in high- energy environments.Most argillaceous matter isconfined to the marine McColley Canyon Formation,and most of the sand is confined to high-energy intertidalenvironments of the Sevy Dolomite and Oxyoke Canyon Formation. The source of the terrigenousdebris may have been early Paleozoic or late Precambrian stratain Idaho or Montana.Quartz 153 sandstones such as theEureka and Prospect Peak Quartzites are present in the proposed northern source areaand could have served as a source of the quartzsand.Clay minerals could come from shales or from alteration of chemicallyunstable minerals and rock fragments in the sandstone. 1 54

GEOLOGIC HISTORY

During the Early and Middle Devonian,several interfingering rock units were deposited in a shallow seacovering Eureka County,

Nevada. Figures 46 -50 show the step by stepaccumulation of the Emsian and early Eifelian rock units acrosspart of central Eureka County. Figure 51 shows the Emsian and earlyEifelian rocks that accumulated across southern EurekaCounty.Figure 52 is a eustatic curve for strata deposited at Telegraph Canyonand Union Mountain. During early Emsian time the normalmarine Kobeh Member of the Mc Colley Canyon Formation wasdeposited in the western part of the Mahogany Hills, in theSulphur Spring Range, and in areas to the west.The intertidal environment of theSevy Dolomite existed at Modoc Peak and in theDiamond and Pi lion Ranges. A narrow wedge of quartzite was depositedin the Pion Range and northern Diamond Range, but only tidal flatdolomites were deposited in the southern Diamond Range.During mid-Emsian time, theBartine sea transgressedslightly to the east, and subtidallimestones of the Bartine Member were deposited atModoc Peak and other areas formerly receiving Sevy dolomitedeposition.While the upper one third of the Bartine Member wasbeing deposited at Lone Mountain, the Sevy tidal flat progradedwestward into the Sulphur SpringRange 155 but not into the Mahogany Hills.Subsequently, during earliest Coils Creek time, a slight transgressionoccurred and shallow marine carbonate sediments of the Bartine Tongue weredeposited in the Sulphur Spring, Pirion, and DiamondRanges. During latest Ems ian and early Eifeliantime the Sadler Ranch Dolomite was deposited in anorth-south belt between the Coils Creek Limestone, and later the Denay Limestonesto the west.The upper- most Sevy Formation andQuartzose Member of the Oxyoke Canyon Formation was deposited as a southwardprograding barrier bar between the restricted subtidalenvironment of the Sadler Ranch Dolomite and the intertidal tosupratidal environment of the sandy member of the Sevy Dolomite.There was a slight regression atthe onset of Quartzose Memberdeposition, and Quartzose Member rocks overlie the lower tongue of theSadler Ranch Formation at Union

Mountain.During early Eifelian time there was aslight transgression, and the subtidal upper tongueof the Sadler Ranch Dolomite overlies the Quartzose Member atUnion Mountain. The Coarse Crystalline Memberof the Oxyoke Canyon Forma- tion is an intertidal depositthat correlates with the coarselycrystalline dolomite of the lowerSimonson Formation and with thelower part of the Denay Limestone.Deposition of the Coarse Crystalline Member in Eureka County beganduring the early Eifelian in the Diamond and Pinon Ranges.Shallowing in the upper part ofthe 156 Sadler Ranch Dolomite in the Sulphur SpringRange and Mahogany Hills allowed Coarse Crystalline Memberdeposition to advance into those areas.The Coarse Crystalline Member regressiondid not reach Lone Mountain or the Roberts Mountains.Several unconformities are present within the CoarseCrystalline Member, and deposition of the unit was neither uniform norcontinuous. The source of the terrigenous clay inthe McColley Canyon Formation and of the quartz sand in theSevy and Oxyoke Canyon Formations was exposed sedimentary rocks tothe north.The clay was deposited first in quietEarly Devonian marine environments, and the sand lagged behind in a southwardmigrating barrier bar and in other high-energy environments. WILLOW TELEGRAPH UNION CREEK CANYON MOUNTAIN

0 -- sea level

100 SEVY DOLOMITE

BARTINE LIMESTONE 200

Figure i004. Generalized cross-section perpendicular to the depositional strike during mid- Bartine time. Depths are in feet and are approximate. WILLOW CREEK TELEGRAPHCANYON MOUNTAIN UNION 100 o sea level 200 _ BARTINE LIMESTONE BARTINE LIMESTONE SEVY DOLOMITE (upper tongue) 600500 SEVY DOLOMITE Figure 47. Generalizedlatest Bartine cross-section time. perpendicular to the depositional strike during Depths are in feet and are approximate. UTLLOCREEK0_ sea level _ _ TELEGRAPH CANYON MOUNTAIN UNION 100200 _ COILS CREEK LS (3-crgewkr) p---- SEVY DOLOMITE Figure 461. earlyGeneralized Coils Creek cross-section time. perpenoicular to the depositional strike during Depths are in feet and are approximate. WILLOW CREEK TELEGRAPH CANYON MOUNTAIN UNION 100 sea level QUARTZOSEOXYOKE CANTON MBR. FM. 200 DOLOMITERANCHSADLER SEP'Do COILS CREEK LS SEVY =AMITE (upper tongue) ',mem BARTINE LIMESTONE SEVY DOLOMITE Figure 49. Generalizedduring mid-Oxyoke cross-section Canyon perpendiculartime. to the depositional strike Depths are in feet and are approximate. WILLOW CREEK 0 sea level TELEGRAPH CANYON OXYOKE CANYON FM., COARSE CRYSTALLINE MBR. UNION MOUNTAIN 100 DENAY LIMESTONE SADLER RANCH DOLOMITE QUARTZOSEOXYOKE CANYON MBR. FM. LIMESTONECREEKCOILS BAIEnt TONGUE DOLOMITESEVY LIMESTONEBARTINE SEVY DOLOMITE (upper tongue) SEVY DOLOMITE Figure 50. latestGeneralized Oxyoke cross-section Canyon time. perpendicular to the depositional strike during Depths are in feet and are approximate. 162

LONE MODOC OXYDNE ALHAMBRA MOUNTAIN PEAK CANYON HILLS

0 sea level

COARSE CRYSTALLINE MBR. 100

OX/DKE CANYON W. QUARTZOSE MBR. 200

500 LONE

MOUNTAIN

DOLOMITE

B.T. = BARTINE TONGUE

Figure 51. Generalized cross-section perpendicular to the depositional strike during latest Oxyoke Canyon time. Depths are in feet and are approximate. 163

TELEGRAPH CANYON

Sevy Fm. BT Sadler R F Oxyoke Cn F C Xtal M Hi. Tide Low Tide

High Tide

Low Tide

Sevy F S Oxy Cn F S Oxyoke Cn F Bartine TR Qtzose M IR C Xtal M

Union Mountain

Figure 52.Eustatic curve for strata at Telegrap'a Canyon and Union Mountain.No vertical scale,Tide lines approximate, 164

CONCLUSIONS

The primary conclusions of this thesis are presented in the section on geologic history and in the four sections on ageand correlation of the rock units.The conclusions are lengthy and so are not repeated here.Secondary conclusions concern the different faunas encountered in the rock units and the factors that controlledfacies distributions. Three different brachiopod faunas are present in the rocks studied.The Eurekaspirifer pinyonensis Community was represented by one sample from the upper Sevy tongue in theSulphur Spring

Range.As Niebuhr (1973) suggested, this community inhabited a very shallow, strongly-agitatedenvironment.The Hysterolites sp. B Community is a slightly evolved form ofNiebuhr' s (1973) Atrypa nevadana Community and inhabited the shallow carbonatebank environment of the Bartine Tongue.The Schizophoria sp. Community is less diverse than the Hysterolites sp. BCommunity and inhabited the shallow, slightly restricted environmentof the lower part of the Sadler Ranch Formation. The westward progradation of the Sevy tidalflat (upper Sevy

tongue in the Sulphur Spring Range)and the westward facies shift of the Coarse Crystalline Member of theOxyoke Canyon Formation are two regressive events that do not appearto be eustatically controlled. 165 The progradation of the Sevy tidal flat appears similar to the progradation of modern sabkhas in the Persian Gulf.The nature of the Coarse Crystalline Member "regression" is more difficult todetermine because of the obliteration of many sedimentary structuresby dolomitization and recrystallization.It may have been similar to the westward progradation of the Sevy.Sediment accumulation rates seem to have been more important incontrolling the local distribution of these rocks than sea level changes. Greater sediment accumulation in the shallow subtidal,intertidal, and supratidal environments along the margin of theDevonian sea than farther offshore combinedwith uniform subsidence may have steepened the gradient of the continental shelf and causeddeeper facies to narrow and appear to "migrate" shoreward whileshallower facies prograded.The Bartine Limestone was a uniform, shelf-wide deposit of mid-Emsian age.Between the end of Bartine Member deposition in the Sulphur Spring Range and the end of OxyokeCanyon time, approximately 400 feet of sediment accumulatedat Willow Creek and approximately 750 feet of sediment accumulatedin the Sulphur Spring Range.Sediment accumulation was greater close to shore than offshore. Murphy (unpublished data) believes that the lower DenayLime- stone at Willow Creek was deposited in aquiet, deep, flat-bottomed basin.The slope between the Roberts Mountains (lowerDenay) and 166 Sulphur Spring Range (Coarse CrystallineMember) must have been much steeper than during Bartine Membertime, when a gradual shelf gradient existed (Niebuhr, 1973).The development of several facies on the shelf (figures 18 and 27)where formerly only one had existed (figure 10) supports the idea of achange of the shelf's slope (compare figures 46 and 49).The writer believes that the Sadler Ranch Formation or a similar rock unitpersisted on the shelf after it was displaced from the SulphurSpring Range by the Coarse Crys- talline Member.It was a transitional unit betweenthe deep-water Denay and the shallow, intermittentlyexposed Coarse Crystalline

Member. Bruffey Canyon is a northwest trending canyonseparating the Pirion and Sulphur Spring Ranges and isfault-bounded (Murphy, personal communication, 1973).The abrupt facies changes across Bruffey Canyon include:1) a change from Mc Colley CanyonForma- tion Limestone to Sevy Dolomiteand 2) a change from Quartzose Member quartzite to Sadler RanchDolomite.The writer believes that post-Devonian left lateraldisplacement of five to ten miles along a northwesttrending fault through the canyon (asshown on lithofacies maps) can explain such abruptfacies changes. 167

REFERENCES CITED

Adams, J. E. and Rhodes, M. L. ,1960, Dolomitization by seepage refluxion: Am. Assoc. Petroleum Geologists Bull. ,v.44, no. 12, p. 1912-1920. Adams, R. D. and Thom, B. G. ,1968, Relationship between coastal landforms and size distribution of surficial sediments, Houy and Marion Counties, South Carolina: Southeastern Geology, v.9, no.1, p. 39-56. Allen, J. R. L. ,1970, Physical Processes of Sedimentation: Amer- ican Elsevier Publishing Company, New York, 248 p. Baars, D. K. ,1961, Permian blanket sandstones of Colorado Plateau, in Geometry of sandstone bodies - A symposium: Am.Assoc. Petroleum Geologists, p. 179-207. Bathurst, R. G. C. ,1971, Carbonate sediments and their diagenesis: Elsevier, Amsterdam. Boucot, A. J. ,1975, Evolution and extinction rate controls: Amster- dam, Elsevier. Carlisle, Donald; Murphy, M. A. ; Nelson, C. A. ; andWinterer, E. K. ,1 957, Devonian stratigraphy of Sulphur Springsand Pih'yon Ranges, Nevada; Am. Assoc. Petroleum Geologists Bull.,v. 41, no.10,p. 2175-2191. Chamberlain, C. Kent, 1974, Assistant Professor of Geology,Ohio University, written communication. Clifton, H. E. ,Hunter, R. E. ,and Phillips, R. L. ,1971, Deposi- tional structures in the non-barred high-energy nearshore: Jour. Sedimentary Petrology, v. 41, no.3,p. 651- 670.

Deffeyes, K. S. ,Lucian, F.J.,and Weyl, P. K. ,1965, Dolomitiza- tion of Recent and Plio-Pleistocene sedimentsby marine evap- orite waters of Bonaire, Netherlands Antilles,in Dolomitiza- tion and limestone diagenesis - A symposium:Soc. Econ. Paleontologists and Mineralogists Spec. Pub. 13, p. 77-88. 168 Dunhan, R.J., 1962, Classification of carbonate rocks according to depositional texture, in Classification of carbonaterocks, a symposium: Am. Assoc.Petroleum Geologists Mem. 1, p. 108-121.

Fisher, J.J.,1968, Barrier island formation: Discussion: Geol. Soc. America Bull. ,v.79, p. 1421-1431. Folk, R. L. ,1962, Spectral subdivision of limestone types, in Classification of carbonate rocks, a symposium: Am.Assoc. Petroleum Geologists Mem. 1, p. 62-84.

, 1968, Petrology of sediments: Hampill, Austin. Folk, R. L. and Ward, W. C. ,1957, Brayos River Bar, a study in the significance of grain-size parameters: Jour.Sedimen- tary Petrology, v.27, p. 3-27. Friedman, G. M. ,1959, Identification of carbonate minerals by staining methods: Jour. Sedimentary Petrology, v.29, p. 87-97.

,1961, Distinction between dune, beach, and river sands from their textural characteristics: Jour.Sedimentary Petrology, v. 31, p. 514-529. Ginsburg, R. N. ,1956, Environmental relationships of grain size and constituent particles in some southFlorida carbonate sediments: Am. Assoc. Petroleum Geologists Bull. ,v.40, no. 10, p. 2384-2427. Gronberg, E. C. ,1967, Stratigraphy of the Nevada Group at Lone Mountain and Table Mountain, central Nevada:M. S.thesis, Univ. California, Riverside, California, 83 p.11 pls. (available on interlibrary loan). Hill, M. L. ,Carlson, S. A. ,and Dibble, T. W. ,1958, Stratigraphy of Cuyama Valley - Caliente Range area,California: Am. Assoc. Petroleum Geologists Bull. v.42, p. 2973-3000.

Hoyt, J.H., 1967, Barrier island formation: Geol. Soc.America Bull.,v. 78, p. 1125-1136.

Hoyt, J.H. and Henry, R. J. ,Jr., 1967, Influence of island migra- tion on barrier island sedimentation:Geol. Soc. America Bull. v.78, p. 77-86. 169

Johnson, J.G.,1 962, Lower Devonian - Middle Devonianboundary of central Nevada: Am. Assoc. PetroleumGeologists Bull. v. 46, no. 4, p.542-546.

, 1970, Great Basin Lower DevonianBrachiopoda: Geol. Soc. America Mem. No. 121, 421 p.74 pls. 1974, Associate Professor of Geology, Oregon State University, personal communication. Johnson, J.G. and Flory, R. A.1 972, A Rasenriff fauna from the Middle Devonian of Nevada: Jour.Paleontology, v. 46, no.6, p. 892-899.

Johnson, J.G.,and Lane, N. Gary, 1968, Two newDevonian Crin- oids from central Nevada: Jour. Paleontology, v.43, no.1, p.69-73. Kellogg, H. E. ,1963, Paleozoic stratigraphy of the SouthernEgan Range, Nevada: Geol. Soc. America Bull. ,v.74, p. 685-708, 4 pls. Klapper, Gilbert, 1974, Associate Professorof Geology, University of Iowa, written communication. Klein, G. DV. ,1974, Professor of Geology at Univ.of Illinois, oral communication. Koch, William, 1974, graduate student atOregon State Univ. , personal communication.

Laporte, L.F.,1971, Paleozoic carbonate facies of the Central Appalachian Shelf:Jour. Sedimentary Petrology, v. 41, no.3, p. 724-740. Mason, C. C. ,and Folk, R. L. ,1858, Differentiation of beach, dune, and aeolian flat environmentsby size analysis, Mustang Island, Texas: Jour. SedimentaryPetrology, v. 28, p. 211 - 220. Merriam, C. W. ,1940, Devonian stratigraphy andpaleontology of the Roberts Mountains region,Nevada: Geol. Soc. America Spec. Paper 125, 114 p.16 pls. 170 Merriam, C. W. and Anderson, C. A. ,1942, Reconnaissance survey of the Roberts Mountains,Nevada: Geol. Soc. America Bull., v.53, p. 1675-1728. Moiola, R. J. and Weiser, D. ,1968, Textural parameters - An evaluation: Jour. Sedimentary Petrology, v.38, no.1, p. 45- 53. Murphy, M. A. ,1973, Professor of Geology, University ofCali- fornia, Riverside, personal communication. Murphy, M. A. and Gronberg, E. C. ,1970, Stratigraphy of the Lower Nevada Group (Devonian) north and westof Eureka, Nevada: Geol. Soc. America Bull. ,v.81, p. 127-136. Nelson, C. A.1972, Professor of Geology, University of California, Los Angeles, personal communication.

Niebuhr, W. W. ,II,1 973, Paleoecology of the Eurekaspirifer pinyonensis Zone, Eureka County, Nevada.M. S.thesis, Oregon State Univ. ,Corvallis, Oregon, 152 p.(available on interlibrary loan). Niem, A. R.1974, Assistant Professor of Geology, OregonState University, personal communication.

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, 77 p. ,2 pls.

Osmond, J.C.,1954, Dolomites in Silurian and Devonian of east- central Nevada: Am. Assoc. of Petroleum GeologistsBull. , v. 38, no.9, p.1 911 -1 956.

, 1962, Stratigraphy of Devonian Sevy Dolomite in Utah and Nevada: Am. Assoc. PetroleumGeologists Bull. , v. 46, no. 11, p.2033-2056. Passega, R.1957, Texture as characteristic of elasticdeposition: Am. Assoc. Petroleum Geologists Bull. ,v.41, no.9,p. 1952-1984. Pettijohn, F. J. ,1957, Sedimentary Rocks: New York,Harper and Row, Publishers, 718 p. 171

Plumley, W. J. ,Risley, G. A. ,Graves, R. W. ,Jr.,and Kaley, M. E. ,1962, Energy index for limestone interpretation and classification, in Classification of carbonate rocks, a symposium: Am. Assoc. Petroleum Geologists Mem.1, p. 85-107. Purdy, E. G. ,1964, Sediments as substrates, in John Imbrie and Norman Newell (eds. ), Approaches to paleoecology,John Wiley and Sons, Inc., New York, p. 238-271.

Royse, Chester F.Jr., 1970, An introduction to sediment analysis: Tempe, Arizona, Arizona State University, 180 p. Rusnak, G. A.1960, Sediments of Laguna Madre, Texas, in Shepard, F. P. and others, ed. ,Recent sediments of northwest Gulf of Mexico: Tulsa, Okla. ,Am. Assoc. Petroleum Geologists, p. 153-196. Selley, R. C. ,1970, Ancient sedimentary environments - abrief survey: Ithaca, Cornell UniversityPress, 237 p.

Sheehan, P., 1972, unpublished PhD thesis, University California at Berkeley, Berkeley, California(available on interlibrary loan). Shinn, E. A. ,Ginsburg, R. N. ,and Lloyd, R. M. ,1965, Recent supratidal dolomite from Andros Island, Bahamas, inDolomiti- zation and limestone diagenesisA symposium: Soc. Econ. Paleontologists and Mineralogists Spec. Pub. 13, p.112-123. Siever, Raymond, 1959, Silica cementation ofPennsylvanian sandstone, in Silica in sediments, a symposiumwith discussions, Ireland, H. A. ,ed.,Soc. Econ. Paleontologists and Mineral- ogists Spec. Pub. no. 7, p. 55-79. Stanley, S. M. 1970, Relation of shell form to lifehabits of the Bivalvia (Mollusca):Geol. Soc. America Mem. 125, 296 p. Weimer, R. J. ,1966, Time stratigraphic analysis and petroleum accumulation, Patrick Draw Field, Wyoming:Am. Assoc. Petroleum Geologists Bull. ,v.50, no. 10, p. 2150-2175.

Wilson, J.L. ,1974, Characteristics of carbonateplatform margins: Am. Assoc. Petroleum Geologists Bull. ,v.58, no. 4, p. 810- 824. 172

Zenger, D. H. ,1972, Dolomitization and uniformitarianism: Council on education in the geological sciences Short Review No. 19, p. 107-124. 173

APPENDIX I

MAP AREA AND SECTION LOCATIONS 174

APPENDIX L MAP AREA AND SECTION LOCATIONS

Plate 1 Geologic Map of the Nevada Group in the northernGarden Valley Quadrangle. The map area is located in T24N, R52E, GardenValley Quadrangle.

Plate 2 Geologic Map of the Slagowski Ranch Area. The map area is located in T28N, R53E, PineValley Quadrangle.

Plate 3 Geologic Map of the Oxyoke Canyon Area. The map area is located in T18N, R54E, PintoSummit Quadrangle.

Plate 4 Oxyoke Canyon Section. Broken section.The Sevy Dolomite was measured in the N 1/2 SW 1/4 Sec. 16, T18N, R54E, Pinto Summit Quadrangle; sect iontrends N80E up the west side of Beacon Peak. The Oxyoke Canyon Formation wasmeasured in the SE 1/4 SE 1/4 SE 1/4 Sec. 17 and SW 1/4 SW 1/4 S W 1/4 Sec.16 of T18N, R54E, Pinto Summit Quadrangle; section trends N90E along the crestof a spur.

Plate 5 Phillipsburg Mine Section. Section is located in the NE 1/4 Sec. 35 andthe NW 1/4 Sec. 36 of T22N, R55E, Eureka Quadrangle.Section trends east along the east-west spurcontaining Hill 7403.Strata are overturned.

Plate 6 Coffin Mountain Section. Section is located in the SW 1/4 SW 1/4 ofSec. 28, T28N, R53E.Section trends S45E up the northwest corner of Coffin Mountain.

Plate 7 Slagowski Ranch Section. Section is located in the SW 1/4 NE 1/4 Sec.18, T28N, R53E.Section trends N40E up the main drainage SE of Summit7072.

Plate 8 Piiion Range Section. Section is located in the S 1/ 2 SE 1/4 Sec.16 and NE 1/4 NE 1/4 Sec. 21 of T3ON, R53E.Section trends southward and southeastwardfrom the saddle immediately north of Summit 7931 to the saddle immediatelysoutheast of Summit 7931.

Plate 9 Union Mountain Section. Broken s ection.The Sevy Fm. and Quartzose Mbr. of theOxyoke Canyon Fm. were measured in the W 1/ 2 E 1/4 Sec. 20,T27N, R53E; section trends N70E up to Summit 7325.The Coarse Crystalline Mbr. of the OxyokeCanyon Fm. was measured in the the E 1/ 2 E 1/ 2 Sec. 20, T27N, R53E;section trends N40E down a spur leading up to saddle immediately south of Summit 7325.Mineral Hill Quadrangle.

Pl ate 10. Fish Creek Range Section. Section is located in an unsurveyed partof the Bellevue Peak Quadrangle.T1 6N, 7663 and immediately north of the R52E.Section is 1.45 miles S55E of Summit road crossing the range.

Plate 11 Modoc Peak Section. Section is located in the SE 1/4 ofSec. 19, T1 9N, R53E, Whistler Mountainand the saddle south Bellevue Peak Quadrangles.Section trends northward from south of of Modoc Peak and up toward ModocPeak. 175

Plate 12 Sadler Ranch Section. Section trends east and downhill along a spurrunning down from the saddle immediately north of Summit 7466.The lower part of the section is in an unsurveyed area;the upper part is in Sections 13 and14 of T24N, R52E, Garden Valley Quadrangle.

Plate 13 Shipley Hot Springs Section. Broken section.The Sevy Fm. and Bartine Tongue were measured in anunsurveyed part of the Garden Valley Quadrangle0.3 miles west of Hill 6287 in Sec. 26, T24N, R5 2E; section trends N40E.The Sadler Ranch Fm. and Coarse Crystalline Mbr.of the Oxyoke Canyon Fm. were measured 0. 2miles SlOE of Hill 6287; section trends N40E.

Plate 14 Summit 7466 Section. Section is located in an unsurveyed part of theGarden Valley Quadrangle.Section trends SS5E up to summit 7476.T24N, R52E.

Plate 15 Summit 7476 Section. Section is located in an unsurveyed part ofthe Garden Valley Quadrangle.Section trends SSSE up to summit 7476.T24N, R52E.

Plate 16 Bald Mountain Section. Section is located in an unsurveyed part ofthe Mineral Hill Quadrangle.Section trends eastward and northeastward down a spurmeeting the crest of the Sulphur Spring Range at the unnamed summit midway betweenSummits 8149 and 7881.T2SN, R5 2E.Section is one mile southeast of Bald Mountain.

Plate 17 Telegraph Canyon Section. Section is located in the NE 1/4 NE1/4 Sec. 36, T26N, R52E, Mineral Hill Quadrangle.Section trends N65E and is approximately onethird of the way up from the bottom of Telegraph Canyon to the east-westridge connecting Summits 7 223 and 7538.

Plate 18 Fera Well Section. Section is located in the E 1/ 2 of Sec.25, T26N, R52E, Mineral Hill Quadrangle. Section trends east along the east-westridge leading up to the unnamed summit between Summits 7538 and 7582.

Plate 19 Williams Canyon Section. Section is located in the SE 1/4 Sec.13, T26N, R52E, Mineral Hill Quadrangle. Section trends S50E from the saddlenorthwest of Summit 7836 up toward Summit 7836.

Plate 20 Neward Mountain Section. Section is located in the SW 1/4 SW 1/4Sec. 9, T19N, R55E, Eureka Quadrangle. Section trends N25W up the steephill on the north side of the only drainage gulley in the SW 1/4 SW 1/4 Sec. 9.

Plate 21 Alhambra Hills Section. Section is located in the NW 1/4 NW1/4 NW 1/4 Sec. 31, T18N, R5SE, Pinto the Alhambra Hills. Summit Quadrangle.Section trends N15W up the south end of 176

APPENDIX II

MEGAFOSSIL COLLECTION LISTS 177

Sample: KDL-1 24 Location: Summit 7466 Section Footage: In the Bartine Member 10 feet below the Sevy Dolomite

Brachiopoda Phragmostrophia merriami 44 "Strophochonetes" filistriata 36 Atrypa. nevadana 29 Eurekaspirifer pinyonensis 28 Dalmanites sp. 3

Mollusca indet. bivalves 11 indet. gastropods 3

Sample: KDL-17 Location: Summit 7466 Section Footage: 2 feet above the base of the lower Sevy tongue, in the transitional unit

Brachiopoda Atrypa nevadana 14 Eurekaspirifer pinyonensis 12 178

Sample: KDL-19 Location: Sadler Ranch Section Footage: 18 feet above the base of the Bartine Tongue

Brachiopoda Carinagypa sp.(aseptate) 3 "Schuchertella" sp. 3 Chonetes sp. 4 Atry_pa sp. 5 Nucleospira sp. 3 Hysterolites sp. B 4

Mollusca bivalves, indet. (a few)

Sample: KDL- 20 Location: Sadler Ranch Section Footage: 3 2 feet above the base of the Bartine Tongue

Brachiopoda Dale' ina? sp. 3 "Schuchertella" sp. 3 Isztostrophia sp.(parvicostellate) 6 Megastrophia? sp. 20 Phragmostrophia sp. 3 "Strophochonetes" sp. 5 Chonetes sp.(1 with median furrow) 6 Parachonetes macrostriat us 2 Trigonirhynchia sp. 7 Atrypa sp. 7 Nucleospira sp. 7 Hysterolites sp. B 3 2 Brachyspirifer? sp. 6

Anthropod a Phacops sp. 4

Mollusca Pterinea? sp. 1 bivalves, inde t. (abund. ) Platyceras? sp. 1 3/4 gastropods, indet. 6 stromatoporoids, indet. 5 179

Sample: KDL- 21 Location: Sadler Ranch Section Footage: 48 feet above the base of the Bartine Tongue

Brachiopoda "Schuchertella" sp. 1 Megastrophia? sp. 5 Chonetes sp. 53 Parachonetes macr ostriatus 2 Trigonirhynchia occidens 26 Atrypa cf. nevadana 16 Hysterolites? sp. 13 Elythyna sp. 2 Cryptononella? sp. 13

Mollusca bivalves, indet. (abund. )

Sample: KDL-130 Location: Sadler Ranch Section Footage: 59 to 79 feet above the base of the Bartine Tongue

Brachiopoda "Schuchertella" sp. 3 Megastrophia sp. 20 Chonetes sp. (with median furr ow) 9 Spinulicosta? sp. 2 Trigonirhynchia occidens 15 Atrypa nevadana 11 Nucleospira? sp. 1 indet. spiriferid sp. 1

Arthropod a Phacops sp. 28

Mollusca gastropods 12 bivalves 5 2 Orthoceras sp. 11

Bryozoa bidet. bryozoans 16 180

Sample: KDL-37 Location: Sadler Ranch Section Footage: Float sample from the Bartine Tongue

Brachiopoda Carinagypa sp.(aseptate) 3 "Schuchertella" cf. nevadaensis 2 (on slab) Megastrophia? sp. 1 Parachonetes macrostriatus 1 Trigonirtynchia occidens 4 Hysterolites sp. B 9

Coelenterata indet. solitary tetracoral 1

Mollusca indet. gastropod 1 indet. bivalves 4

Sample: KDL- 25 Location: Sadler Ranch Section Footage: 99 feet above the base of the Sadler Ranch Formation

Brachiopoda Schizophoria sp. 15 hyna sp. 33 Alatiforrnia? sp. 3

Coelenterata indet. solitary tetracoral 1 Favosites sp. 2 181

Sample: KDL-183 Location: Sadler Ranch Section Footage: 100 feet above the base of the Sadler Ranch Formation

Brachiopoda Carinagypa? sp.(smooth) 2 Schizophoria sp. (bisulcate) 171 (peds. 80, bracs. 91) Atrypa sp. (fine ribs) 7 Nucleospira sp. 10 Elythyna sp. 70 (peds. 36, bracs. 34) Alatiformia sp. C 27 (peds. 11, bracs. 16)

Coelenterata indet. small tetracorals 29

Sample: KDL-5 Location: Telegr aph Canyon Section Footage: Basal 6 inches of the Bartine Tongue

Brachiopoda Megastrophia? sp. 2 Brachyspirifer cf. pluonoides 32 182

Sample: KDL-48 Location: Telegraph Canyon Section Footage: 20 feet above the base of the Bartine Tongue

Brachiopoda Dalejina? sp. 1 Carinagypa aseptata 3 "Schuchertella" sp. 1 indet. rhynchonellids 2 Hedeina? sp. 2

Mollusca Orthoceras sp. (large) 1 indet. bivalves 2

Coelenterata Indet. solitary tetracorals 15

Sample: KDL-7 Location: Telegraph Canyon Section Footage: 23 feet above the base of the Bartine Tongue

Brachiopoda "Schuchertella" sp. 1 Trigonirhynchia occidens 5 Atrypa sp. 5 Hysterolites sp. 8

Mollusca bivalves, indet. 35 orthocerids, indet. (abund. ) 183

Sample: KDL-9 Location: Telegraph Canyon Section Footage: 44 feet above the base of the Bartine Tongue

Brachiopoda Megastrophia? sp. 4 Trigonirhynchia occidens 6 A trypa sp. 10 Brachyspirifer? sp. 3

Mollusca bivalves, indet. (a few)

Sample: KDL-36 Location: Telegraph Canyon Section Footage: Float sample from the Bartine Tongue

Brachiopoda Carinagypa? sp. (aseptate?) 1 Nucleospira sp. 1 Brachyspirifer cf. pinyonoides 1 Hysterolites sp. B 16

Coelenterata indet. solitary tetracorals 2 1 84

Sample : KDL-1 2 Location: Telegraph Canyon Section Footage: 63 feet above the base of the Sadler Ranch Formation

Brachiopoda Schizophoria sp. 77 Nucleospira? sp. 2 Elythyna? sp. 1

Sample : KDL-11 2 Location: Shipley Hot Springs Section Footage: 40-63 feet above the base of the Bartine Tongue

Brachiopoda Schizophoria sp. 1 "Schuchertella" nevadaensis 10 Megastrophia? sp. 7 Chonetes sp. 4 Spinul i costa? sp. 36 Trigonirhynchia occidens 27 Atrypa nevadana 15 Nucleospira sp. 2 indet. spirifers 7

1 rthropoda Phacops sp.(small) 23

Mollusca indet. bivalves 57 indet. gastropods 3

Bryozoa indet. bryozoans 185

Sample: KDL-35 Location: Shipley Hot Springs Section Footage: Float sample from the Bartine Tongue

Brachiopoda Schizophoria nevadaensis 1 Dalejina? sp. 1 "Schuchertella" nevadaensis 1 Parachonetes? sp. 1 Atrypa sp. 2 Hysterolites sp. B 3 Elythyna sp. 1 Athyris sp. 1

Mollusca indet. bivalves 2 indet. gastropod 1

Coelenterata indet. solitary tetracoral 1

Trilobita Dalmanites sp. 3

Sample: KDL- 1 21 Location: 3700 feet S85W of Summit 6285 in Section 26, T24N, R52E Footage: Float sample from a fault sliver of the Bartine M ember

Brachiopoda Atrypa nevadana 140 Nucleospira sp. 8 Meristina? sp. 1 Spinella? sp. 4

Coelenterata Favosites sp. 16 J.86

Sample: KDL-106 Location: Bald Mountain Section Footage: Approximately the basal 10 feet of the Bartine Tongue

Brachiopoda "Schuchertella" sp. 2 Phragmostrophia? sp. 2 Trigonirhynchia? sp. 3 Atrypa sp. 2

Bryozoa indet. bryozoans

Sample: KDL-68 Location: Approximately 1 mile due west of Josephine Spring (Sec.7, T25N, R53E) Footage: In the basal 10 feet of the Sadler Ranch Formation

Brachiopoda Atrypa sp. 1 Elythyna? sp. 17 1 87

Sample: KDL-157 Location: Fera Well Section Footage: 26 to 55 feet above the base of the Bartine Tongue

Brachiopoda "Schuche r tell a" sp. 1 Trigonirhynchia? sp. 2

Coelenterata bidet. solitary tetracorals 7

Mollusca indet. bivalves 4

Sample: KDL-165 Location: Williams Canyon Section Footage: Approximately 11 feet above the base of the Bartine Tongue

Brachiopoda Carinagypa? sp. 2 "Schuchertella" sp. 3 Megastrophia sp. 2 Parachonetes sp. 2 Spinulicosta? sp. 1 indet. rhynchonellid sp. 2 Atrypa sp. 15 Hedeina sp. 13 Hysterolites sp. 17 Cryptonella? sp. 2 indet. brachiopods 3

Mollusca indet. bivalves

Coelenterata indet. solitary tetracorals 5 I88

Sample: KDL- 270 Location: Modoc Peak Section Footage: 85 to 100 feet above the base of the Coils Creek Limestone

Brachiopoda Alatiformia sp. 1 "Schuchertella" sp. 7 Megastrophia?? sp. 40 Sp inulicosta ? sp. 3 Atrypa? sp. 1 Elythyna? sp. 8 Hede ina ? sp. 28

Mollusca indet. gastropod 1

Bryozoa indet. bryozoan 1

Coelenterata indet. solitary tetracoral 3

Sample: KDL- 219 Location: SW 1/4, SE 1/4, SW 1/4, Sec. 36, T31N, R52E (Pine Mtn. ) Footage: Float sample from the Bartine Limestone (?)

Brachiopoda Atrypa sp. Eurekaspirifer? sp. 189

APPENDIX III

MODAL ANALYSES OF SELECTED SAMPLES SampleAPPENDIX III Unit',40DA.I. ANALYSES OF SELECTED SAMPLES intraclastsDolomicrite Dolomitemicrite microsparDolomite pseudosparDolomite Dolomite spar SLT &Quartz SD Secondaryquartz oxideIron Silicified shells 414404 SevySevy (4)* (4) 104 4088 155217 166181255 -- 21 37-- 5 -- 22 63 6 126125245 Sevy (4)(14) 102 85 882 221 145 62 827013 254 43 68 8 1 --14 5 105240 41 Sevy (10)(17)(16) 100 511315 --8220 122138 -- 4539 3 239 20 174255171 13 30 4 4 2 3053083 20297 SevySevyC Xtal (16)(12) (17) M (4) 227 91 169 48-- 3 113262 71 114284139 278 -- 9 106 20 1 461 Sample*refers to plate on which sample is plotted. Unit Dolomite spar SLT &Quartz SD Secondaryquartz oxideIron Voids 310212175197 QtzoseQtzoseSadlerC XtalM. R.M. (float) M. (16)(9) (7) 476107 -- 4 48391382 2 1438 37 16 46 55-- 65 Sample Unit Dolomicriteintraclasts Dolomitemicrite Dolomitemicrospar pseudosparDolomite Dolomite spar SLT &Quartz SD Secondaryquartz oxideIron Dolomiteshells 246291 B. T.T. (17) (4) 21 7 5328 264173 180164 1 13 9 2 10 7 85 .001--. APPENDIXSample III (Continued)Unit microsparDolomite pseudosparDolomite SLT &Quartz SD Secondaryquartz oxideIron Voids Silicified shells Dolomitized shells 131183115 Sadler R. (12)(13) 6612-- 364379307 1310 5 541 764 4 8 178 8050 Sample130 B. T. Unit (12) SLT &Quartz SD 2 Secondaryquartz 2 oxideIron 7 Calciteshells 52 micriteLime 382 microspar Lime 32 pseudospar Lime 13 Lime micriteintraclasts 10 192

APPENDIX IV

TEXTURAL PARAMETERS OF SELECTED QUARTZOSESAMPLES 1 93

APPENDIX IVTEXTURAL PARAMETERS OF SELECTED QUA RTZOSE SAMPLES

Sample Unit Mean Standard Skewness Kurtosis diameter deviation

41 Sevy (UT)(17)* 2.62 0.42 0. 23 1.40

105 Sevy (UT )(16) 1.80 0. 38 0.01 0. 98

117 CXtal M (13) 2. 33 1. 27 0.47 1.97

163 Sevy (T)(1 9) 3. 74 0. 34 -0, 18 1. 91

164 Sevy (UT)(1 9) Z 12 0. 58 0, 07 0. 98

237 Sevy (float) 2. 30 0. 66 0. 26 1. 44

239 Sevy (21) 2.46 0.60 0. 18 1.58

240 Qtzose M (10) 2. 19 0.51 0. 10 1.05

245 Sevy (4) 1. 99 0.46 -0.01 0.88

273 C Xtal M (11) 2. 48 0. 61 0. 10 1. 02

294 C Xtal M (17) 2. 76 0. 37 0. 19 0.78

301 Qtzose M (4) 2.47 0.56 0.08 1. 18

305 C Xtal M (4) 2. 14 0.59 -0.09 1. 21

Sevy (T) = transitional unit of the Sevy Formation in the Sulphur Spring Range;Sevy (UT) = upper Sevy tongue in the Sulphur Spring Range; Quartzose M = QuartzoseMember of the Oxyoke Canyon Formation; C Xtal M = Coarse Crystalline Member of the Oxyoke CanyonFormation.

*refers to plate on which sample is plotted. 194

APPENDIX V

HEAVY MINERAL ANALYSES Sample Unit Zircon A PPENDYX V Tourmaline HEAVY MINERAL ANALYSESGar net magnetiteIlrnenite/ Hematite Leucoxene Rutile Pyrite 105117 CSevy Xtal (UT)( M (13) 16)* A A CT A CC AA T 239240 QuartzoseSevy (21) M (10) A T AC C CA CT A 245 Sevy (4) AC AC CC AA AT A 301294 QuartzoseC Xtal MM (17)(4) T A A 305Sevy (UT) = upper Sevy tongue in the Sulphur Spring Range. C Xtal M (4) A A *refers to plate on which samples are plotted. C A T A 196

APPENDIX VI

ORGANIC CARBON CONTENT OF SELECTED SAMPLES 197

APPENDIX VI

ORGANIC CARBON CONTENT OF SELECTED SAMPLES Organic carbon Sample Unit content

165 Bartine Tongue (19)* 2. 91%

246 Bartine Tongue (4) 1. 36%

234 Sevy Dolomite (float) O. 12%

293X Sadler Ranch Fm. (17) 4. 08%

*refers to plate on which samples are plotted 198

APPENDIX VII

PALEOCURRENT STATISTICS 199

APPENDIX VII

PA LEOCURRENT STATISTICS

Location Unit No. of Mean 0 values direction

326° I C Xtal M 22 97o 75o II C Xtal M 11 156°

III Sevy 6 103° 47°

IV Qtzose M 37 86° 85°

II Qtzose M 23 112° 58°

V C Xtal M 12 102° 57°

V Sevy 69 116° 72° 370 VI C Xtal M 9 13°

I-VI All Units 189 105° 77°

1= Alhambra Hills, Phillipsburg Mine, and Newark Mtn. ;II = Piton Ra. ;III = Oxyoke Canyon; IV = Oxyoke Canyon and Fish Creek Ra. ; V = Main outcropbelt in the Sulphur Spring Range; C Xtal M = VI = Modoc Peak.Qtzose M = Quartzose Member of the Oxyoke Canyon Formation. Coarse Crystalline Member of the Oxyoke CanyonFormation.