Mississippian Stratigraphy of the Diamond Peak Area, Eureka County, Nevada

GEOLOGICAL SURVEY PROFESSIONAL PAPER 661

Mississippian Stratigraphy of the Diamond Peak Area, Eureka County, Nevada

By DAVID A. BREW

With a section on the BIOSTRATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS By MACKENZIE GORDON, JR.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 661

More than 7,000 feet of Late Mississippian synorogenic detrital clastic and limy sediments of the Chainman and Diamond Peak Formations were deposited in a narrow trough east of the Antler orogenic belt

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1971 UNITED STATES DEPARTMENT OF THE INTERIOR

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY

William T. Pecora, Director

Library of Congress catalog-card No. 70-608211

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS

Page Pare Abstract ______1 Stratigraphy Continued Introduction ______1 Cretaceous System _____ F9 Acknowledgments ______2 Newark Canyon Formation ______f? Location and geography ______3 Tertiary System ______F3 Previous work ______3 Fanglomerate and megabreccia _ F3 Terminology ______3 Igneous rocks ______JT4 Geologic setting ______4 Quaternary deposits ____ F4 Regional stratigraphy ______4 Alluvium ______F4 Regional structure ______5 Colluvium ______F4 Stratigraphic nomenclature ______5 Lake deposits ____ _ F4 Stratigraphy ______9 Biostratigraphy and age of the Carboniferous formations, Devonian System ______9 by Mackenzie Gordon, Jr F4 Devils Gate Limestone ______9 Introduction ______F4 Devonian and Mississippian Systems ______10 Joana Limestone and its regional relations f*5 Pilot Shale ______10 Chainman Formation ______F3 Mississippian System ______10 Diamond Peak Formation ______F7 Joana Limestone ______10 Member A ______F*» Relations of Chainman and Diamond Peak Member B ______f* Formations ______12 Member C ______F? Chainman Formation ______13 Member D ______40 Water Canyon facies ______13 Megafaunal evidence ______4-2 Black Point facies ______16 Microfaunal evidence ______42 Descriptive stratigraphy of Diamond Peak Correlation _____ 43 Formation ______17 Meramec-Chester boundary __ 4$ Contact of Diamond Peak and Chainman Member E ______Formations ______18 Member F ______Member A ______19 Faunal hiatus ______Member B 19 Member G ______Member C 20 Member H ______46 Member D 20 Diamond Peak Formation of the lower plate of Member E 21 the Bold Bluff thrust fault ______47 Member F 21 Regional relations of the Diamond Peak Formation Member G 22 and the Chainman Shale _ 47 Member H 23 Ely Limestone ______49 Contact of Diamond Peak Formation and Lower member ______PO Ely Limestone ______24 Criteria for recognizing the Mississippian- Diamond Peak Formation of lower plate Pennsylvanian boundary _____ 51 of Bold Bluff thrust fault ______24 Regional distribution of the Mississippian Depositional environments ______25 part of the Ely Limestone ____ PI Siltrock ______25 Correlation with Homoceras zone E\ Sandstone ______25 Upper member ______PI Conglomerate ______25 Conclusions _ 52 Clayrock ______27 Register of fossil collecting localities in the Diamond Limestone ______27 Peak area, Nevada ______f2 I-imestone-phenoplast conglomerate ____ 27 Collections from Diamond Peak measured section 54 Summary ______28 Foraminiferal collections ______£5 Mississippian and Pennsylvanian Systems ______28 Structure ______P5 Descriptive stratigraphy of Ely Limestone _____ 28 Folds ______re Lower member ______28 Cold Creek syncline ______£6 Upper member ______29 Lesser folds and gentle warps _ P6 Depositional environment ______30 Faults ______57 Permian System ______30 Low-angle faults __ 5? Carbon Ridge Formation ______31 Bold Bluff thrust fault ______57

III IV CONTENTS

Page Page Structure Continued Geologic history Continued Faults Continued Barly Mississippian deformation ______64 Low-angle faults Continued Late Mississippian through Middle Pennsylvarian Bold Bluff thrust fault Continued sedimentation ______64 Related minor thrusts and folds ____ 57 Chainman Formation ______64 Extent and significance ______57 Diamond Peak Formation ______64 High-angle normal faults ______59 Ely Limestone ______65 Boundary faults ______59 Post-Middle Pennsylvanian deformation ______65 Alpha fault ______59 Early Permian sedimentation ______66 Newark Valley fault ______59 Post-Early Permian deformation ______66 Faults within the range (internal faults) __ 59 Early Cretaceous sedimentation ______66 Newark fault ______60 Later events ______66 Sadler Canyon fault complex ______60 Conclusions ______67 Combination boundary and internal faults-_ 61 Stratigraphic section of the upper part of the Bl?ck Robinson Springs fault ______61 Point facies of the Chainman Formation, the type sec- Adobe Canyon fault ______61 tion of the Diamond Peak Formation, and the lo-^er Summary ______62 part of the Ely Limestone ______67 Geologic history ______62 References cited ______77 Late Devonian and Early Mississippian sedimentation 62 Index ______81

ILLUSTRATIONS Page PLATE 1. Geologic map and sections of Diamond Peak and vicinity, Eureka and White Pine Counties, Nev In pocket FIGURE 1. Index map of east-central Nevada ______2 2. Photograph of Diamond Range and Diamond and Newark Valleys from Diamond Peak 3 3. Nomenclature and correlation chart ______- 6 4. Generalized geologic map of the eastern part of the Eureka quadrangle __ 11 5. Correlation chart of rocks referred to the Chainman Shale, Diamond Peak Formation, and lithically equiva­ lent units ______14 6. Photograph of outcrop area of Black Point facies of the Chainman Formation ______-_ 16 7. Generalized columnar section of the type section of the Diamond Peak Formation ______18 8. Photograph of Diamond Peak and cliff-forming member H of the Diamond Peak Formation 23 9. Graph showing variation and proportion of major lithic types in members of the Diamond Peak Formatter at the type section ______26 10. Photograph of nodular and lenticular chert, limestone, and sandy or silty limestone in lower member of the Ely Limestone ______29 11. Correlation chart of Mississippian and earliest Pennsylvanian formations of the central part of the Great Basin, Utah and Nev. ______35 12. Photograph of south side of Diamond Table, showing nearly horizontal bedding in very thick conglomerates of Diamond Peak Formation above the Bold Bluff thrust fault ______57 13. Correlation diagram showing generalized thickness and lithologic character of rocks in the upper and lo^er plates of the Bold Bluff thrust fault ______58 14. Generalized fault map of the Sadler Canyon-Water Canyon area _ ___ 60 15. Photograph of the Ely Limestone downfaulted against the Diamond Peak Formation along Adobe Canyon fault- 61 16. Diagrams showing inferred evolution of part of the western edge of the Chainman-Diamond Peak depositional basin ______1______63

TABLES Page TABLE 1. Fauna from members B-D of the Diamond Peak Formation, Diamond Peak area, Nevada, and from Conical Hill, Eureka district, Nevada ______39 2. Fossils from beds assigned to member D of the Diamond Peak Formation on the east slope of the Diamond Range and at Conical Hill, Eureka district, Nevada _____ 41 3. Calcareous foraminifers from member D of the Diamond Peak Formation, Diamond Peak area, Nevada 43 4. Fauna from members E-H of the Diamond Peak Formation, Diamond Peak area, Nevada 45 5. Fauna of the Ely Limestone, Diamond Peak area, Nevada 49 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

By DAVID A. BREW

ABSTRACT deposition of the Chainman and the lower two members of fre Synorogenic clastic rocks of Mississippian age deposited in Diamond Peak; then more irregular pulses of conglomeratic an elongate rapidly subsiding trough east of the Antler erogenic debris accompanying proportionally smaller amounts of fleer belt in east-central Nevada consist of about 7,000 feet of the elastics; finally, a decrease in overall volume of terrigenous Chainman and Diamond Peak Formations. In the mapped area clastic material as the transition to Ely Limestone deposition these rocks unconformably overlie the Devonian and Mississip­ took place. pian Pilot Shale and the Mississsippian Joana Limestone and Most of the folds and low-angle faults probably formed in are overlain by the Ely Limestone of Mississippian and Pennsyl- response to east-west-oriented forces which affected the Paleo­ vanian age. Younger rocks present are the Carbon Ridge For- zoic rocks after deposition of the Permian Carbon Ridge Fcv- maton of Permian age, the Newark Canyon Formation of Early ination. The folds have horizontal axes, trend generally north- Cretaceous age, and a series of fanglomerates and megabreccias south, and are upright and open, except locally where greater of Cretaceous and (or) Tertiary age. compression caused slight overturning to the east. Low-angle Contrasting facies of the Chainman Formation occur above thrusting probably occurred shortly after the folding. A few and below a thrust fault of possible regional extent. The facies minor structures suggest that movement on the thrusts was to below the thrust is dominantly black shale but includes minor the southeast or east. During the Tertiary, high-angle faults amounts of sandstone; it is interpreted to be the eastern outlined the main part of the Diamond Mountain range and basinward correlative of the structurally overlying dominantly caused differential movements of subblocks within the range. silty and sandy facies that has been displaced eastward for an unknown distance. Scanty fossil evidence indicates that both INTRODUCTION facies are Meramec in age. The stratigraphic relations of the Diamond Peak Formation in the type locality at Diamond Peak Stratigraphic, structural, and petrologic methods are complicated by this same thrust. have been used to study and interpret part of the well- Eight members can be recognized in the relatively uncompli­ known stratigraphic section in the vicinity of Eureka, cated type section, here proposed, as well as elsewhere in the Nev. The results reported here are (1) revision of tl ^ type locality. Stratigraphic and petrologic evidence indicates Mississippian stratigraphy, including that of the type that the clayey siltrock, sandstone, and conglomerate of the Diamond Peak Formation; (2) recognition of a pre­ lower two members (A and B) were deposited rapidly in the subsiding marine basin during the Meramecian and that re­ viously undescribed thrust fault of possible regional worked sediments were few. Most of the conglomerate, lime­ significance; and (3) elucidation of the Carboniferous stone, siltrock, and sandstone of members C and D were rapidly biostratigraphy and age assignments. Brief prelimi­ deposited sediments; conditions were unstable, but subsidence nary reports on the first two subjects have been pub­ was less continuous than before. Some of the conglomerates lished (Brew, 1961a, b). The studies also resulted in were deposited in areas of marine limestone accumulation. The the description and classification of a sequence of cor'- overlying siltrock, sandstone, conglomerate, and liinestone- phenoplast conglomerate of members E-G were deposited under positionally mature, but texturally immature, siltstone, conditions which changed repeatedly, causing alterations of re­ sandstone, and conglomerate; these results, in turn, worked and rapidly deposited sediments. The highest member form the basic for a petrogenetic interpretation of tl °. (H) of the Diamond Peak Formation is transitional to the tectonic history of the dominantly synorogenic rocks conformably overlying Ely Limestone of Mississippian and Pennsylvania age. This member was deposited in an_ environ­ deposited to the east of the Antler orogenic belt ment similar to that of the underlying three members, but re­ (Roberts and others, 1958). These petrographic ard. worked sediments were more common, indicating longer periods petrogenetic interpretive results are contained in a of relative stability. separate article in preparation. The terrigenous debris in the Chainman and Diamond Peak The studies were restricted primarily to rocks of Formations was derived from a eugeosynclinical suite of rocks Mississippian and Pennsylvanian age exposed within of Ordovician age known to have been present in the Antler orogenic belt. Detritus was contributed from the provenance the Eureka 15-minute quadrangle (fig. 1), but older terrane as folows: steady influx of mostly silt-, clay- and sand- and younger formations were also mapped and studied. size debris with minor amounts of coarser material during Although the geology was studied over most of tH M1SS1SS1PPIAX STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

116° 115° 114°

Conica Hill ^-Secret Canyon ce Ui o o

39°

FIGUKE 1. Index map of east-centra I Nevada, showing the Eureka quadrangle and localities referred to in text. Outlined area within Eureka quadrangle is area of plate 1.

quadrangle, this report emphasizes the relationships ACKNOWLEDGMENTS in the vicinity of Diamond Peak (fig. 4). The studies described in this report were done as The fieldwork upon which the studies are based was part of the U.S. Geological Survey's regional mapping done during the summers of 1956-59. About 50 square program centered around Eureka mining district. miles were mapped on topographic maps at a scale of Thomas B. Nolan is chief of this project, and the 1:15,840 using open-sight alidade and planetable. author acknowledges with thanks his encouragement, During the summer of 1959 the proposed type section advice, supervision, and patience. Charles W. Merriam of the Diamond Peak Formation was studied in detail. contributed in similar measure suggestions and en- INTRODUCTION coiiragement. The report was improved greatly by the ern part of the quadrangle to a less regular series of suggestions of Professor Robert R. Compton, of Stan­ elevated knobs and saddles which have altitudes rang­ ford University, during the early stages of writing and ing from 8,250 feet to almost 9,000 feet (fig. 2). by those of T. B. Nolan, M. D. Crittenden, and Mac­ kenzie Gordon, Jr., in the final stages. PREVIOUS WORK Fossil determinations were made by various mem­ The Eureka mining district was visited by members bers of the U.S. Geological Survey, who are cited of the 40th Parallel Survey in the 1870's (Hague and individually in the text. Emmons, 1877, p. 547-548), and the first systematic study was undertaken by Arnold Hague in 1880. He LOCATION AND GEOGRAPHY published a series of articles (1880, 1882, 1883, 1892) The area of the field study (fig. 1) lies within the which included descriptions and discussions of the P^ureka quadrangle, Nevada, and is between lat 39°32' rocks exposed in the southern Diamond Mountains. N. and lat. 39°45' N. and between long 115°45' W. and C. D. Walcott assisted Hague in the field and in 1884 long 115°51' W. The area is centered in the Diamond published on the paleontology of the district. Mountains about 12 miles northeast of Eureka, Nev., In 1932, T. B. Nolan started a restudy of the Eureka a small town situated on U.S. 50. mining district, and in the late 1930's, C. W. Merriam Both flanks of the Diamond Mountains are acces­ began a study of the Devonian rocks in the vicinity of sible from county-maintained roads in Diamond Valley Eureka. These studies established the section in the to the west of the range and in Newark Valley to the vicinity of Eureka as a standard for the Paleozoic of east of the range. In addition, a gravel road crosses the the east-central Basin and Eange province and led to range at Newark Summit about half a mile south of the publication of two reports (Nolan and others, 1956; the southern edge of the mapped area. The area studied Nolan, 1962). Dott (1955) described the structure and straddles the single north-trending ridge that here stratigraphy of the northern Diamond Mountains and makes up the Diamond Mountains. The ridge ranges visited the southern Diamond Mountains. Langenheim in altitude from 10,614 feet at Diamond Peak to 7,469 (1956) attempted a partial regional analysis of the feet at Newark Summit and ranges in width from Mississippi an rocks of east-central Nevada, including about 5 miles at the southern limit of the mapped area the Diamond Peak Formation. Eiva (1957) studied to 2,1/2 miles at the northern edge of the quadrangle. the upper Paleozoic rocks north of the Eureka quad­ This long fairly uniform ridge gives way in the north- rangle on the east side of the range. Larson mapped several areas within the Diamond Mountains and pub­ lished (1959) an abstract on some structural features north of the Eureka quadrangle. Larson and Riva (1963) mapped the quadrangle north of the Eureka quadrangle. The geologic map of the Eureka quad­ rangle itself has been compiled by Nolan, Merriam, and Brew (1970). Lelmer, Tagg, Bell, and Roberts (1961) published a small-scale reconnaissance geologic map that includes the Eureka County portion of the Eureka quadrangle. Immediately following the author's fieldwork, two small nearby areas were mapped and studied by Stewart (1962).

TERMINOLOGY Thicknesses of strata described in this report are classified according to the scheme of McKee and Weir (1953) as modified by Ingram (1954). The color terms used are from Godclard and others (1948). FIGURE 2. Diamond Range and Diamond and Newark Valleys The terrigenous clastic rocks are classified by the from Diamond Peak. Prominent light-colored bands near size of their constituent particles according to the center of picture are the rocks transitional between the modified Went worth scheme proposed by Dunbar and Diamond Peak Formation (left) and Ely Limestone (right). Roclgers (1957, p. 161). The fine-grained terrigenous Ridge extending to the center left margin of photograph is Black Point and is underlain by Black Point facies of elastics are further classified by grain size and fissility Chainman Formation. as proposed by Dunbar and Rodgers (1957, p. 166). MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, ETJREKA COUNTY, NEVADA

Terrigenous clastic rocks containing between 5 and thrusting over (2) an eastern assemblage of lower 30 percent fragments greater than 2 mm in diameter and middle Paleozoic miogeosynclinal rocks, (3) a are termed "conglomeratic" in this report, and those western-eastern transitional assemblage, and (4) an with more than 30 percent of such particles are "con­ overlap assemblage of upper Paleozoic rocks deposited glomerates."' This usage is simplified from that pro­ on the western, eastern, and transitional assemblages posed by Folk (1954, p. 346). Modifiers describing the after the thrusting. Roberts and his coworkers con­ composition of the dominant gravel-size clasts precede sider the thrusting to be of Late Devonian and Early the term "conglomerate" throughout most of the Mississippian age. report. Rocks of the western assemblage exposed closest to The limestones described were found to be readily Eureka make up the upper plate of the Roberts Moun­ adapted to Folk's (1959) proposed classification of tains thrust fault and are assigned to the Vinini For­ carbonate rocks, and that classification was used with mation. The Vinini probably is the source of most of the single exception that 2 mm, rather than 1 mm, the debris in the synorogenic terrigenous clastic rocks was used for the limit separating the calcarenites from of Mississippian age. The lower part of the Vinini the calcirudites (Folk, 1959, p. 16). Formation (Merriam and Anderson, 1942, p. 1694- Throughout the report, references to roundness of 1698) includes dark-gray-brownish-weathering quartz- sedimentary particles are based on visual comparison ite, cross-laminated gray sandy limestone and limy with the chart prepared by Powers (1953), and par­ sandstone, fine-laminated brownish-gray and greenish- ticle shapes are described using Zingg's (1935, p. 53- brown sandy siltstone, "true black shale," green vol­ 55) shape terms. canic sandstone, cherty shale, and tuff, tuff-breccia, and amygdaloidal hornblende andesites which have been GEOLOGIC SETTING extensively albitized and chloritized. The upper Vinini The lower and middle Paleozoic sediments in the is characterized by bedded chert and black organic vicinity of Eureka were deposited in a generally stable shale. Some of the shale and most of the pale-green to miogeosyncline situated between a eugeosynclinal area black chalcedonic chert contain what are probably to the west and a stable shallow shelf to the east. De­ Radiolaria. formation associated with the Antler orogeny began Rocks of the eastern assemblage exposed near Eureka in Late Devonian and disrupted the miogeosynclinal consist of dominant carbonates, shales, and minor pattern of sedimentation; this deformation apparently coarser detrital elastics. Roberts, Hotz Gilluly, and culminated in the low-angle thrusting of eugeosyn­ Ferguson (1958) assigned the lower part of the Mis­ clinal rocks from the west over miogeosynclinal rocks. sissippian section to this assemblage and the upper The upper Paleozoic sediments were deposited, in part, part to the overlap assemblage. Transitional assem­ in basins related to this regional tectonism, and most blage rocks are not exposed in the Eureka area. of the sediments of Mississippian and Permian age are The regional relations of the Mississippian rocks are clearly synorogenic, Uplift preceded deposition of important background for the understanding of the Lower Permian clastic and carbonate rocks, and sev­ present study. Throughout most of east-central Nevada eral thousand feet of Pennsylvanian and Mississip­ the Mississippian consists of three main units: a thin pian strata were locally eroded. Folding, low-angle lower limestone unit with underlying shale; a thick faulting, and uplift followed deposition of the Permian medial black shale unit with varying proportions of sediments and apparently continued intermittently limestone and of coarser material in lenses and throughout the Mesozoic. Pertinent papers concerning tongues; and a thin upper sandstone, shale, and con­ the regional stratigraphic and structural relations in­ glomerate unit. Locally near the western limit of these clude those by Nolan, Merriam, and Williams (1956), three units, as at Diamond Peak, the upper unit is Nolan (1928, 1943), Roberts, Hotz, Gilluly, and Fer- thickened at the expense of the medial unit, and the guson (1958), Roberts and Lehner (1955), Merriam medial unit itself is appreciably coarser than normal. and Anderson (1942), Winterer and Murphy (1960), These regional units are discussed briefly below. and Sharp (1942). The lower unit consists of the Pilot Shale of De­ REGIONAL STRATIGRAPHY vonian and Mississippian age and the overlying Joana Roberts, Hotz, Gilluly, and Ferguson (1958) Limestone of Early Mississippian age. Near Eureka, grouped the Paleozoic rocks of north-central Nevada the upper contact is an erosional unconformity, and in into four tectonostratigraphic units: (1) a western places, the Joana was completely eroded before deposi­ assemblage of lower and middle Paleozoic eugeosyn­ tion of the overlying Chainman Shale. The Joana con­ clinal rocks that have been tectonically transported by sists mainly of dark limestone with minor partings of GEOLOGIC SETTING

dark-gray shale. Although the Joana or its equivalent REGIONAL STRUCTURE lias been recognized over most of Nevada east and The geologic structure around Eureka is char­ south of the Diamond Mountains, it is missing to the acterized by folds and thrusts upon which basin-and- west and north of the southern and central Diamond range-type block faulting is superimposed. The Mountains. Roberts, Hotz, Gilluly, and Ferguson isolated nature of the individual mountain masses end (1958) believe that clastic sediments of the overlap the lack of detailed mapping precludes an exact de­ assemblage were being deposited in the region north lineation of the extensive fold systems. The overall and northwest of Eureka during the time interval picture is one of broad, open, north-south-trending represented by the Joana. folds with apparently near-horizontal axes. The Dia­ The medial unit is the Chainman Shale. The Chain- mond Range is somewhat unusual in that several folds, man is typically a black shale sequence with scattered some of which are overturned, are well exposed. sandstone, minor conglomerate, and limestone lenses. Thrust faults of varying importance and displace­ Many abrupt facies changes are apparent, and the ment are associated with the large-scale folds. The amount of sandstone present differs radically from sec­ best known of these faults is the Roberts Mountains tion to section (Stewart, 1962). The formation is thrust (Merriam and Anderson, 1942; Roberts and known to extend eastward into Utah and possibly ex­ others, 1958; Gilluly, 1960a, b). It is present only a tends southward and sotithwestward for several hun­ few miles to the west of the area studied and is dreds of miles. thought to be the major thrust which brought lov^er The type Chainman occupies a geographic position and middle Paleozoic eugeosynclinal rocks tens of between the synorogenic coarse elastics of the Diamond miles eastward over miogeosynclinal sedimentary Peak Formation to the west and north and the Missis- rocks. The detailed mapping in the Diamond Moun­ sippiaii shelf carbonates some distance to the east and tains demonstrated the presence of still another thrist southeast. In the areas near the Diamond Peak prism fault of possible regional significance (Brew, 1961b). of elastics, the Chainman shows much local variation, The folding in the Eureka quadrangle can be dated and these facies changes are the ones that complicate no closer than post-Permian and pre-Cretaceous. The the Chainman section near Eureka. thrusting in the area studied seems to be of about the The upper unit, the Diamond Peak Formation and same age. These events may be related to the re­ correlative units, is difficult to distinguish from the juvenation of the Late Devonian and Early Missis­ Chainman in many areas because the contact is grada- sippian thrusting of Roberts, Hotz, Gilluly, and Fer­ tional, and the lowermost typically coarser elastics of guson (1958). the Diamond Peak occur at different stratigraphic High-angle faulting has occurred throughout the levels. The rocks here referred to the upper unit are region. Faults which may have originated during mappable intermittently over an area extending from earlier tectonism have, in many places, been obscured the White Pine Range northwestward to beyond the by the later block faulting, and the age relationships vicinity of Carlin. They indicate a significant change are difficult to establish. The block faulting responsive in regimen during Late Mississippian time in this for the general configuration of the mountain ranges general area. The Diamond Peak facies disappears east­ in east-central Nevada is typified by the straight range ward into the Chainman black shales, and at Ely and fronts that are many miles long and by many intra- points to the east no Diamond Peak-type rocks are range high-angle faults. Each block has adjusted inter­ present. nally by means of faults of varying orientations. T" is To the southeast, the stratigraphic interval repre­ faulting probably started in early Tertiary and con­ sented by the Diamond Peak Formation is occupied by tinued intermittently to the present (Nolan, 1943, p. similar, but thinner, clastic units, usually referred to 183). as the Scotty Wash Quartzite. There is some question whether the Scotty Wash was derived from the same STRATIGRAPHIC NOMENCLATURE source as the Diamond Peak and therefore whether it The nomenclature of the Upper Devonian and Mis­ has the same tectonic significance as the Diamond sissippian rocks exposed in the Eureka district is con­ Peak, but the general relationships are the same. troversial, particularly with respect to the application Mississippian rocks have not been recognized to the of the term "White Pine Shale." The area studied in­ west of Eureka in the area considered to be the locus cludes some of the localities to which this name v7as of the Antler orogeny. Synorogenic sediments of the first applied, and a brief discussion of the term is westernmost sequences of the overlap assemblage necessary. (Roberts and others, 1958) are present much farther The nomenclatorial history of the strata formerly west. included in the White Pine Shale and of the overlying Hague (1870) Hague (in Hague and Hague (1880) Hague (1882) Hague (1883; 1892, p. 13) Hague (1892, p. 81) Hague (1892, p. 158) Emmons, 1877)

NEWARK MOUNTAIN NEWARK MOUNTAIN NEWARK MOUNTAIN NEWARK MOUNTAIN WHITE PINE DISTRICT WHITE PINE DISTRICT AND DIAMOND PEAK AND DIAMOND PEAK AND DIAMOND PEAK "PACKER BASIN" DIAMOND PEAK SECTION

Lower Coal Lower Coal Carboniferous Carboniferous Lower Bluish-gray [Lower Measure Measure Coal-measure] Limestone Limestone Limestone Limestone Coal-Measures Limestone 1,500ft 3,800 ft 1,000ft

500ft Ogden Diamond Peak Diamond Peak Dark-gray quartzite, Sandstone Sandstone conglomerate, grit; near Quartzite Quartzite* Quartzite base, narrow belts of limestone 300ft 300ft 3,000 ft 2,500 ft Black argillaceous shale, Sandy Sandy Arenaceous ahale, shaly member member 1,000 ft Black Black longrlomerate argillaceous argillaceous White Pine Shale* White Pine Shale 1,000 ft shale Hard, compact shale Hard, compact 100ft argillaceous argillaceous shale shale member shale member Black s shale 600ft 600ft 400ft 500ft

Gray crinoidal Siliceous Limestone Siliceous Limestone limestone 100ft 100ft 50ft

Calcareous Shale Calcareous Shale

125ft 125ft 300ft 100ft

Nevada Limestone Limestone 250ft Dark-gray, heavily Devonian Limestone Devonian Limestone 1 Limestone Nevada Limestone* bedded, siliceous at Newark Mtn Siliceous limestone pas­ limestone sing: into gray limestone 1,500 ft 1,500 ft 6,000 ft 150ft 3,500 ft 1 On p. 855, in a gen­ Base not exposed eralized stratigraphic column, this unit is called "Nevada Devonian" 8 9 10 11 12 13 14 Lawson (1906, p. 295-297) Spencer (1917, p. 24) Merriam (1938,1940) Easton and others (1953) Nolan, Merriam, and Humphrey (1960) This paper Watson (1939, p. 4) Williams (1956) NEWARK MOUNTAIN ELY DISTRICT ELY DISTRICT AND DIAMOND PEAK EUREKA DISTRICT EUREKA DISTRICT WHITE PINE DISTRICT z z < 9 "Lower Coal z 2 z UPPER NNSYLV/ CO BONIFE JNSYLVA Ely Limestone* z Ely Limestone Measures" z Ely Limestone Ely Limestone Ely Limestone Ely Limestone

CO CO § z 02 z Diamond PeakX^ z CO z LU Alpha Peak LU Diamond Peak Diamond Peak Diamond Peak f? Formation/^1 O member* Formation Formation Formation LLJ w /& lower 3,500 ft 600-1,000 ft M /^>° plate) 0 Black Point &/ W a: P-. § facies ^fj? o +3 Blue-black Q M z a: Hayes Canyon Chainman Shale IPPIAN Z 7 argillaceous Chainman Shale* LU 2 s Chainman Shale White Pine Formation ChainmanJiFormation O Shale* (member) E a. 1 shale O « 1 a. Z W CO CO CO z hH CO ^jy' Water Canyon 3,000 ft E 3 CO CO 1,800-2,000 ft CO 250ft Q Q. CO CO 3y facies a a. H CO a S 2 oa CO i 03 CO Z W Light-gray CO CO Joana Limestone CO Joana Limestone* Crinoidal limestone Joana Limestone Joana Limestone Joana Limestone limestone * 5 8 (member) O PH PH 150ft 100-400 ft Z 0-135 ft 150-250 ft LU W § W 0 H o a a Pilot Shale > Argillaceous shale Pilot Shale* 0! Calcareous shale 15 Pilot Shale Pilot Shale Pilot Shale a (member) a: s 200ft a.UJ 315-425 ft 150-200 ft Z Z Z 3 y Ci zr z oa Dark-gray O o Nevada Limestone z Nevada Limestone Devils Gate Formation 1 Devils Gate Limestone § Nevada Limestone Devils Gate Limestone pj limestone Q a a a a 1,000 ft 4,000 ft fi 675-2,065 ft 1,600 ft FIGURE 3. Nomenclature and correlation chart. Asterisk indicates original description of unit; vertical lines indicate that unit is not present in area; diagonal lines indicate that unit was not specifically noted by the worker cited, but is present at least locally in the area. 8 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Diamond Peak Formation is so similar that both Diamond Peak, the last-mentioned types occurring terms are discussed together. near the top of the unit. His description of the over­ Arnold Hague (1870) described four map units (fig. lying "Lower Coal measure limestone" indicates that 3, col. 1) between his "Devonian Limestone" (which is he included in that unit much of what is now con­ the. Nevada Limestone of Humphrey, 1960) and his sidered part of the Diamond Peak Formation. "Carboniferous Limestone"1 (which is the Ely Lime- Hague (1892) published a monograph on the geol­ si one of current usage) in the White Pine mining ogy of the Eureka district in which he included all the district (fig. 1). Recent mapping (Humphrey, 1960) material contained in the earlier reports, detailed de­ has shown that these units are those called (1) Pilot scriptions of lithostratigraphic units in various parts Shale, (2) Joana Limestone, (3) Chainman Shale, and of the district, and a section on regional correlation. (4) Diamond Peak Formation, in the current Geo­ Hayes Canyon (Tollhouse Canyon on present-day logical Survey nomenclature. Hague and Emmons maps, fig. 4), west of Newark Mountain, was suggested (1877) summarized the work and made minor de­ as the best place to study the White Pine Shale, even scriptive additions (fig. 3, col. 2). though a greater thickness was recognized in the area Hague's mapping in the Eureka mining district east of Sentinel Peak. In Hayes Canyon the Joana started 12 years after completion of the work in the Limestone is almost everywhere missing because of AVhite Pine district. Hague introduced the term "White pre-Chainman erosion. Pine Shale" in the reports dealing with the Eureka Hague described a detailed stratigraphi", section area. from the area east of Sentinel Peak in his 18^2 report In his 1880 Eureka report, Hague described the (fig. 3, col. 6). Comparison of Hague's section with Devonian limestone and the overlying black shales at those of recent workers (Nolan and others, 1956, p. Newark Mountain as being correlative with the rocks 54; Stewart, 1962) shows that Hague included the at AVhite Pine (fig. 3, col. 3). At Newark Mountain Pilot Shale, Joana Limestone, and Chainman Shale the Chainman Shale (current usage) rests unconform- in his AAThite Pine Shale at this locality and also ex­ ably on the Pilot Shale, and it seems that, because cluded all shales from his Nevada Limestone (Hague, of the absence of the normally intervening limestone, 1892, p. 80-81). Hague apparently did not realize that Hague did not recognize the separate shale units he these individual units correlate with those he described had mapped at White Pine. In the same report, Hague from the AAHiite Pine district (1870). In the same re­ referred the overlying "quartzite " to the Ogden port, Hague published a section of the AVhite Pine Quartzite. Shale in Hayes (Tollhouse) Canyon. He excluded all Hague introduced the terms "White Pine Shale"' and shale from his Nevada Limestone at this locality also "Diamond Peak Quartzite" in 1882 (fig. 3, col. 4). He a point which supports the contention that his complete stated clearly (1882, p. 28) that the name of the black AAThite Pine unit included all of the Pilot SI ale. shale unit was taken from the AVhite Pine mining These two sections provided the most detailed de­ district, but did not designate a type section, locality, scriptions of the AVhite Pine Shale given by the geol­ or area. He did note the similarity of the rocks at ogist responsible for the earlier study, description, and Newark Mountain and White Pine and mentioned "a naming of the unit. There is no documented explana­ much greater development" in the Eureka area. In tion for Hague's failure to correlate his original proposing the name "Diamond Peak Quartzite," Hague (Hague, 1870; Hague and Emmons, 1877) units in stated that the unit formed the slopes of Diamond the AAThite Pine district with those described in Packer Peak; from this and almost all subsequent references Basin. R. L. Langenheim, Jr. (1962, 1964), has sug­ it seems that this mountain is the type locality. gested that, based on Hague's comments on correlation In 1883, Hague published detailed descriptions of (1892, p. 193), Hague miscorrelated the Joana Lime­ the AAThite Pine Shale and Diamond Peak Quartzite stone (his unit 3) of the Packer Basin section with a in the Eureka district (fig. 3, col. 5). In describing the limestone lens within the black argillaceous (Chain­ AAliite Pine, Hague noted the outcrops near Newark man) shale in Applegarth Canyon in the AVhite Pine Mountain and those east of Sentinel Peak (now called district. Thus, according to Langenheim's reasoning, the Packer Basin area). He mentioned particularly the AVhite Pine Shale in the AVhite Pine district ex­ the abrupt lateral and vertical changes in lithic type cludes Hague's siliceous limestone (Joana) and cal­ which are well displayed in the Packer Basin section. careous shale (Pilot) units. Hague noted that limestone, conglomerate, "vitreous Hague's 1892 summary of the Diamond Peak Quartz­ quartzite,'" and "thinly laminated green and brown ite repeated the description given in 1883. A combined schists and shales" were common lithic types in the White Pine Shale-Diamond Peak Quartzite section STRATIGRAPHY 9

from the vicinity of Newark Mountain and Bold Bluff Humphrey (1960) redescribed the stratigraphy of (1892, p. 158) is summarized in column 7 of figure 3. the White Pine district and used Spencer's terminology for the lower two units of Hague's White Pine ard Hague's more complete descriptions of the White restricted the term White Pine'' to that part of tl °- Pine Shale in the Eureka district would seem to section correlative with the Chainman Shale. Hum­ establish that area as the type locality, even though the phrey's usage is given in column 13 of figure 3. name was taken from a different place. Certainly, Hague developed his ideas on the White Pine Shale In summary, these descriptions suggest that (1) tl <*< primarily from his study of the unit in the Eureka Eureka district may be interpreted as being the type district. region for the White Pine Shale, even though the name Hague's papers on the Eureka district were not suc­ was taken from a different locality; (2) Arnold Hague ceeded by further descriptions until almost 1940. Dur­ included in his White Pine Shale of the Eureka district ing this time, however, Lawson (1906) and Spencer the units later named Pilot Shale, Joana Limestone, (1917) mapped and described correlative rocks in the and Chainman Shale by Spencer in the Ely district; Ely district, about 75 miles east of Eureka. and (3) the term White Pine has priority. Neverthe­ less, the nomenclature of Nolan, Merriam, and Wil­ Lawson (1906, p. 295-297) extended Hague's Eureka liams (1956) is used in this report. The accepted no­ terminology to the rocks near Ely and concurred with menclature is modified in this report by (1) using tl ^ his age assignments (fig. 3, col. 8). Lawson's strati- term "Chainman Formation" in the Eureka district in graphic column includes three subdivisions within the preference to "Chainman Shale" and (2) using in­ White Pine Shale, corresponding to the Pilot, Joana, formal names for contrasting facies of the Chainman. and Chainman Formations named by Spencer in 1917. The reasons for these modifications are given in tl ^ Lawson recognized the correlation of these subdivisions section of this report dealing with Chainman strati­ with those in the White Pine Shale to the west. graphy. Spencer (1917, p. 24-26) disregarded Lawson's ap­ The name Diamond Peak has been used consistently plication of Hague's prior terminology in the Ely for those rocks which generally overlie the Chainman. district and formally subdivided the White Pine unit into, in ascending order, the Pilot Shale, Joana Lime­ STRATIGRAPHY stone, and Chainman Shale (fig. 3, col. 9). Most, if not all, of the existing naming problems stem from Nolan, Merriam, and Williams summarized th?< this action. results of their stratigraphic investigations in tl^ vicinity of Eureka in 1956. Since that time, Nolan ard Merriam (1938) included in his Devils Gate Forma­ various assistants, including the present author, have tion in the eastern part of the Eureka district rocks now assigned to the Pilot Shale and Joana Limestone. mapped the Silurian, Devonian, and Permian rocks that occur on the west flank of the Diamond Mountains The overlying rocks were included in his Diamond Peak Series. This usage was modified slighly by Wat­ within the Eureka quadrangle. The author alone mapped the Devonian-Mississippian, Mississippian, son (1939) who subdivided the Diamond Peak Series into two members. Merriam and Watson's terminology Pennsylvania!!, and Permian strata in the central part is reproduced in column 10 of figure 3. Merriam for­ of the range. mally proposed the terms in 1940. Although the main purpose of this paper is to pre­ sent new information about the Mississippian rocks, Easton and others (1953) recommended revision of the other strata exposed above and below the Missi^- this part of the Paleozoic section, stating that the con­ sippian part of the section in the study area are also sensus was that the White Pine Shale correlated with discussed briefly. the Pilot Shale, Joana Limestone, and Chainman Shale and proposing the three last-named units as members DEVONIAN SYSTEM of the White Pine Shale. Their suggestion is shown in DEVILS GATE LIMESTONE column 11 of figure 3. They, as did Dott (1955) About 1 mile south of Torre Flat (pi. 1) is a com­ slightly later, considered the term "formation" a better plexly faulted and folded small mass of noncherty designation for the Diamond Peak than "quartzite." medium-light-gray and light-gray very thick bedded Nolan, Merriam, and Williams (1956) in their de­ cavernous limestone. Two small fossil collections from finitive paper on the stratigraphy of the Eureka this outcrop were determined to be Devonian in ag

Oliver, Jr. (written commun., 1961), who reported as shale are predominant. These shales weather gray or follows: grayish brown and are locally contorted. rolln. ES-nS-lOF * * * includes a single specimen of coral The platy-weathering habit of the shales \* distinc­ identified as follows: tive. They commonly break down to form plates a few Alvcolites centimeters across and a few millimeters thick. The genus Alrcnlites is restricted to rocks of Silurian and Devonian age. The contact of the Pilot Shale with the underlying Devils Gate Limestone is sharp and conformable. The The second collection was studied by P. E. Cloud, upper contact with the Joana is also sharp and appears Jr. (written commun., 1961), who reported: conformable; however, Langenheim, Hill, and Waines Colln. ES-58-9F * * *: (1960, p. 69-71) suggest that the contact is «-. regional Thin sections of the rock show stromatoporoids, * * * appar­ ently belonging to the genus Amphipora, which has an almost unconformity. It is therefore possible that some of the cireumglobal distribution in certain dark Devonian limestones thickness variations of the Pilot Shale within the of Givetian and Frasnian age * * *. Diamond Mountains were caused by local pre-Joana Xo thickness could be determined from this one out­ erosion, although it is possible that they are due to crop area. Eight miles to the north, the Devils Gate unrecognized low-angle faulting. Lack of distinctive Limestone is 750 feet thick (Nolan and others, 1956, beds in the upper member of the Pilot maker* recogni­ p. 49). tion of the possible unconformity difficult. In the Eureka quadrangle the thickness of the Pilot DEVONIAN AND MISSISSIPPIAN SYSTEMS Shale varies from about 265 feet (mapped thickness) PILOT SHALE on the slopes of the range above Black Point (fig. 4) The Pilot Shale was named by Spencer (1917, p. 24, to about 425 feet in Water Canyon (pi. 1). Inter­ 26) for Pilot Knob west of Ely. Langenheim, Hill, and mediate thicknesses 360 feet east of the Phillipsburg Waines (1960, p. 68) have restudied the type area, and mine (fig. 4) near the northern edge of the quadrangle they indicate that only the lower part of the whole and 350 feet in Tollhouse Canyon (fig. 4) have also Pilot Shale is present there. At Willow, south of the been measured (Nolan and others, 1956, p. 52). The Ely district, Langenheim, Hill, and Waines consider lower, more calcareous, unit is consistently 120-160 all the formation to be present and have established a feet thick, according to Nolan, Merriam, and Williams reference section. Two members are present in the (1956, p. 52), but it has not been mapped separately. reference section: a lower shaly limestone and calcare­ The detrital material in the fissile rocks of the Pilot ous siltstone member and a black fissile shale upper Shale consists wholly of quartz and clay, vpith some member. Each member is about 190 feet thick. clasts of probably intrabasinal limestone. Organic ma­ In the area covered by the present report, the Pilot terial and pyrite indicate a reducing bottoir environ­ Shale is exposed in a belt extending from Tollhouse ment, whereas the oriented fabric of the clay-size Canyon (Hayes Canyon of Hague) (fig. 4) across the debris suggests slow deposition by flocculation from saddle between Newark Mountain (fig. 4) and Bold slow-moving suspensions. Bluff down into Mining and Water Canyons (pi. 1). The carbon-rich rocks of the lower member of the From Water Canyon the outcrops of Pilot Shale can Pilot Shale have not been studied in detail. be traced northward almost to the mouth of Sadler The paleontologic evidence for the Late Devonian Canyon. Another longer outcrop belt within the Eureka age (prebasal Cassadaga Stage) of the lower unit as quadrangle is located high on the west flank of the reported by W. H. Haas has been given by Nolan, Diamond Mountains and extends from near Black Merriam, and Williams (1956, p. 53). The upper unit Point to beyond the north edge of the quadrangle is considered Early Mississippian in age (this report, (fig. 4). p. 34). The Pilot Shale in the Eureka district (Nolan and others, 1956, p. 52) can be divided into two members MISSISSIPPIAN SYSTEM in areas of good exposures. The lower member consists JOANA LIMESTONE of platy calcareous shale and some thin limestone beds. The Joana Limestone was named by Spender (1917, This member generally weathers from its normal dark p. 24, 26) from exposures near the Joana mine in the gray (N% of Goddard and others, 1948) to various Ely district. Chilingar and Bissell (1957) have sum­ shades of light brown, pale red, and light red brown marized the regional distribution of the formation. that contrast with the medium gray of the underlying Langenheim (1960) reexamined the Joanr. in east- Devils Gate Limestone. The upper member generally central Nevada and proposed detailed reference sec­ is less calcareous, and platy dark-gray shale and silty tions. Langenheim stated that only part of the lower STRATIGRAPHY

EXPLANATION

Ely Limestone

Vc/>

Black Point facies Water Canyon facies of Chainman For­ of Chainman For­ mation mation

Lone Mountain Dolomite

Contact

High-angle fault Dotted where concealed

Low-angle or thrust fault Sawteeth on upper plate 39°30'

3 MILES

FIGURE 4. Generalized geologic map of the eastern part of the Eureka quadrangle, Nevada. Geology by D. A. Brew, except as follows: by T. B. Nolan and D. A. Brew north of 39°40' and east of 115°48'; by T. B. Nolan, A. T. Miesch, .1. B. Stone, and D. A. Brew north of 39°37'30" and west of 115°50'. Rectangle shows area of plate 1. 12 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

of the three members that he has described is present individual beds within the overlying Chainman Forma­ in the type locality. This, according to his interpreta­ tion. tion, is also the situation in the Eureka district; how- Sparse oolitic limestone with very fine grained calcite over, the Joami described by Nolan, Merriam, and Wil­ matrix indicates that some of the carbonate rocks were liams (1956, p. 45, 55) is unlike his basal member. deposited in shallow, but quiet, environments, as was A few thin isolated lenses of Joana Limestone are probably the shale. Limestone with appreciable amounts present in Tollhouse Canyon (fig. 4), where the forma­ of terrigenous debris commonly has more fossil frag­ tion has largely been removed by post-Joana, pre- ments and is cemented with coarse-grained clear sparry Chainman erosion, but the best exposures in the quad­ calcite, indicating, according to Folk (1959), a higher rangle are in an outcrop belt high on the west flank of energy environment and considerable reworking of the the range (fig. 4). This outcrop belt is covered by tree original sediment. Small amounts of pyrite ruggest a growth that marks its position between the Pilot Shale reducing environment after burial of the sediment. and Chainman Formation. Nolan, Merriam, and Williams (1956, p. 55) gave evidence for the Early Mississippian age of the Joana Where exposed in the south-central Diamond Moun­ Limestone. Chilingar and Bissell (1957) presented tains, the Joana Limestone is typically thin- to medium- evidence for a late Kinderhook and early Osage age. bedded dense black and dark-gray (N3) crinoidal lime­ Langenheim (1960, p. 79) reviewed evidence for an stone that weathers light olive gray (5Y 6/1) and other age ranging from Osage through Meramec for the shades of gray. The limestone is commonly fossiliferous middle and upper parts of the Joana Limestone to the but, is locally coarsely crystalline and nonfossiliferous. east and southeast of Eureka. Gordon (p. 36 of this Interbedded with these limestone are thin beds of non- report) assigns a Kinderhook age to the Joana Lime­ fissile very silty dark-gray (/V3) limestone that stone that is preserved in the Diamond Peak area. weathers yellowish gray (5Y 7/2). Some dark gray shale interbeds are also present. Nolan, Merriam, and RELATIONS OF CHAINMAN AND DIAMOND PEAK Williams (1956, p. 55) noted the presence of beds of FORMATIONS black chert in the Joana in Tollhouse Canyon. The close lithogenetic relation of the Chainman The contact of the Joana with the underlying Pilot Formation and the Diamond Peak Formation has made Shale is apparently conformable in the best exposures it difficult to map them separately in some areas. Nolan, available, but, as mentioned above, the possibility of Merriam, and Williams (1956, p. 56) felt that the two an unconformable relation exists. Nolan, Merriam, and formations were not satisfactory map units every­ Williams (1956, p. 52, 55) have cited the similarity of where and cited the extreme lateral variation in lith- the shales mapped within the Joana to those of the ologic character and in thickness and the difFculty of upper part of the Pilot Shale and consider the Pilot- separating the two formations. The present detailed Joana contact to be gradational. The contact with the study, however, proved it possible to map the Diamond overlying Chainman Formation is sharp and, as abrupt Peak Formation separately from the underlying unit lateral variations in thickness of the Joana indicate, in the Diamond Mountains. The contact- is gradational, unconformable. but it can be mapped by (1) walking out individual In most of Tollhouse Canyon and in all the area beds, (2) estimating the change in percent of various covered by plate 1, the Joana Limestone has been lithic types present, and (3) utilizing a particular dis­ completely removed by pre-Chainman erosion, and the continuous conglomerate that contains limestone Chainman Formation rests directly on the upper unit pebbles. As mapped, the contact undoubtedly trans­ of the Pilot Shale. In Tollhouse Canyon, Nolan, Mer­ gresses bedding to some extent and in some places is riam and Williams (1956, p. 55) measured 84 feet of projected laterally with little evidence. Nevertheless, beds assigned to the Joana. However, near the crest it is a significant surface, separating the doTiinantly of the Diamond Range east of the Phillipsburg mine finer elastics below from the overlying interbedded fine (fig. 4) the thickness varies from 115 to 250 feet in and coarse elastics of the Diamond Peak Formation. about 1 mile, whereas 400 feet of Joana is present 3 Stewart (1962) did not differentiate the Chainman miles south in the area east of Black Point. E. E. Lar- and Diamond Peak in his study of two small areas son (written coinmun., 1962) reports about 400 feet of south and southeast of the area of the present study. Joana on the west side of the range not far north of There, the uppermost beds of the Diamond Fa,ak-type the northern boundary of the Eureka quadrangle. That rocks are not exposed, and the section is characterized these variations in thickness are due to post-Joana, by a mixture of fine and coarse clastic units; th^ "pure" pre-Chainman erosion is proved by the mapping of black shale and Diamond Peak lithic typer do not STRATIGRAPHY 13 have a simple relation to one another. It appears that CHAINMAN FORMATION in these and other nearby areas the Diamond Peak The Chainman Shale, as noted previously, was fir^t lithic types intertongue with dominantly finer grained named by Spencer (1917, p. 24, 26). The name was rocks. extended to the Eureka area by Nolan, Merriam, and The problem of differentiating the Chainman and Williams (1956, p. 59) and applied to the upper part Diamond Peak has been confused by previously un- of the rocks mapped by Hague (1882, 1883, 1892) as described structural complications. In short, the White Pine Shale. Because of the abundant nonshaly "typical" Chainman of the Diamond Peak area (herein lithic types mapped in this unit, the term "formation" referred to informally as the "Water Canyon facies"), seems more apt than the term "shale" for the area as exposed in the area around Tollhouse Canyon, New­ covered by this report. ark Summit, and Water Canyon, occurs in a different Within the area of the present study, two facies of thrust plate than does most of the Diamond Peak the Chaiman Formation are present. This situation was Formation exposed on the flanks of Diamond Peak. first noted by Nolan, Merriam, and Williams (1956, p. This "typical" Chainman is in part truncated upward 57) and has been summarized by the present author by the Bold Bluff thrust fault (Brew, 1961b) and is (Brew, 1961b). The informally named Water Canyon elsewhere overlain by a few hundred feet of inter- facies consists mostly of black shale and is exposed in bedded silicified sandstone and siltstone that is mapped the southern and southeastern parts of the mapped as "Diamond Peak Formation of the lower thrust area; it extends from Tollhouse Canyon and Newark plate" but does not closely resemble the Diamond Summit northeastward to beyond the mouth of Sadtar Peak Formation of the upper plate. However, these Canyon (pi. 1.; fig. 4). The informally named Black lower plate Diamond Peak rocks are also truncated by Point facies consists mostly of siltstone and crops out the thrust fault and therefore may not be representa­ on the west side of the range from south of Black tive of all the Diamond Peak originally associated Point northward to beyond the northern boundary of with the "typical" Chainman. the quadrangle. The "Diamond Peak Formation of the upper plate" forms the overwhelming bulk of the Diamond Peak WATER CANYON FACIES exposed in the type locality of the formation. Asso­ The Water Canyon facies of the Chainman Forma­ ciated with it is a different, coarser type of Chainman, tion consists largely of clayrock and clayey siltro?k herein referred to informally as the Black Point facies with minor discontinuous intercalations of sandstone of the Chainman. From these relations it follows that and conglomerate. The informal name is taken from (1) the type Diamond Peak Formation was not origi­ Water Canyon southeast of Diamond Peak where it nally associated with the "black shale" facies of the is well exposed. The finer grained rocks generally are Chainman, but with a coarser grained facies; and (2) medium dark gray (AM), grayish black (A"2.5), or the coarser clastic rocks that originally overlaid the grayish green, and weather to slightly brownish or typical "black shale" facies of the Chainman in this olive shades or even to dark yellowish brown (10!F7? area are incompletely known. This situation is shown 4/2). The weathered rock is not fissile, but forms diagrammatically in figure 5, to which, for purposes distinctive angular pencillike fragments as much as of regional comparison, have been added selected sec­ 20 cm (centimeters) in length and 2.5 cm in diameter. tions from the Carlin area, the northern Diamond The clayrock and siltrock are commonly carbonaceous Range, the White Pine district, the Buck Mountain and pyritiferous and locally contain minor amounts area, the Butte Mountains, and the Ely district (fig. 1). of sand-size quartz grains. Some of the siltrock beds The overall picture shown in figure 5 is that of a are micaceous. Plant-fragment impressions are common. dominantly coarser clastic prism (Tonka Formation of The coarser grained beds intercalated with the silt- Dott, 1955, and Diamond Peak Formation) extending rock and clayrock are in most places less than 10 cm eastward and southeastward into and over the finer thick, but one or two coarse local lenses are more than elastics (Chainman Shale), which also apparently 10 in (meters) thick. The most persistent of these coarsen westward. Numerous irregularly distributed thicker sandstone layers has been traced for slightly coarser clastic lenses occur within the Chainman itself, more than 1 mile. The sandstone is medium light gray and the margin of the dominantly coarser clastic prism to light gray (N5-N6) on fresh surfaces and weathers is undoubtedly marked by intertonguing of the two to brownish and reddish-brown hues. Many of these formations (Hague, 1883, p. 253, 266; 1892, p. 69, 81; layers are pyritiferous, and most are cemented by Nolan and others, 1956, p. 57; Stewart, 1962), but secondary silica. The few beds of chert-pebble con­ more detailed work is needed to establish the exact glomerate and conglomeratic sandstone that occur gra de relationships. laterally into nonpebble-bearing sandstone. MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

2 4 5 CARLIN CANYON EAST OF 3 SOUTH-CENTRAL DIAMOND MOUNTAINS AND TO WEST CARLIN CANYON NORTHERN Dott (1955), Roberts Dott (1955), Roberts DIAMOND MOUNTAINS UPPER PLATE ThiS Paper Dott (1955) and others (1958), and others (1958), SYS­ PROVIN. and J. F. Smith and J. F. Smith SYS­ PROVIN. FORMATION FORMATIONON TEM SERIES (written commun., 1961) (written commun.,1961) TEM SERIES PENNSYL- s Ely SYS­ PROVIN. SYS­ PROVIN. o VANIAN FORMATION FORMATION >f z Moleen1 Lime­ TEM SERIES TEM SERIES co< 1 zz S Formationon stone d z Moleen Moleen 5§ co< 0 Q. Springer Formation |1 0 Formation II z< 0_ Springer Springer % o

o 1 1 z o Diamondd Diamond

^ Joana o g Lime­ i* stone

Joana Lime­ M stone

FEET - 0

-1000

-2000

10 20 MILES _J LOCATION MAP STRATIGRAPHY 15

BUCK MOUNTAIN Rigby (I960) SYS­ PROVIN. FORMATION TEM SERIES WHITE PINE DISTRICT PENNSYL- Moleen Humphrey (I960) 10 VANIAN Formation SYS­ PROVIN. BUTTE MOUNTAINS CENTRAL PART OF FORMATION WARD MOUNTAIN TEM SERIES Douglass (I960) ELY DISTRICT Langenheim and ^z FORMATION Pennebaker(1932) | Ely SYSTEM others (1960, fig. 1) zz ^ Lime­ and Steele (I960) 0 SYS­ PROVIN. stone £z SYS­ PROVIN. FORMATION Diamond Ely FORMATION TEM SERIES >- /> = Peak Zz Lime­ TEM SERIES Formation u 5 stone k- "^ C Ely Diamond ^z Ely III = Joana 5 1 o Lime­ S jjj'I. Lime­ Lower Joana °i-t limestone ill stone stone Lime­ member 1 stone o c Joana 5 Lime­ stone

FIGURE 5. Correlation chart of rocks referred to the Chainman Shale, Diamond Peak Formation, and lithically equiva­ lent units. Datum is base of Diamond Peak or top of the Chainman, where the Diamond Peak is missing.

The Water Canyon facies rests unconformably on Feet Diamond Peak Formation of the lower plate of the Bold the Pilot Shale over most of its outcrop. South of the Bluff thrust fault: mapped area some Joana Limestone is present, as Silicified gray sandstone, some chert-pebble conglom­ mentioned above. The contact is everywhere sharp and erate, interbedded with siltstone. north of Water Canyon may have an angular relation Chainman Formation (Water Canyon facies) : to the underlying Pilot Shale (T. B. Nolan, oral 3. Gray and grayish-black clayrock and siltrock; commun., 1958). To the south in Tollhouse Canyon thin interbeds of gray silicified sandstone be­ coming more common at top of unit 660 (T. B. Nolan, written commun., 1961), the contact may 2. Gray silicified sandstone and chert-pebble con­ be a low-angle fault. glomerate ___ _ 70 The upper contact of the Water Canyon facies of 1. Gray and grayish-black clayrock and siltrock; the Chainman with the interbedded silicified sand­ weathers to pencillike fragments; sparse thin stone, conglomerate, and siltstone of the Diamond interbeds of sandstone ______1,670 Peak Formation of the lower plate is gradational and Total of Chainman Formation 2,400 is well exposed on the southeast side of Bold Bluff. Pilot Shale: The change involves a gradual increase in-the number Gray platy clay shale. of beds of silicified sandstone through about 100 feet Another generalized section of this facies, from the of section. exposures north of the middle part of Water Canyon, The plotted thickness of these exposures of Chain­ is as follows: man is of questionable value because the section may Feet have been thickened (Nolan and others, 1956, p. 57) Diamond Peak Formation of the lower plate of the Bold or thinned by unrecognized faulting or folding. No Bluff thrust fault: Gray silicified sandstone with some chert-pebble con­ repetitions were mapped, and the lack of key beds or glomerate. other similarly useful features make detailed structural Chainman Formation (Water Canyon facies) : analysis impossible. 3. Grayish-green and dark-gray clay shale and silt- A generalized section of this facies of the Chainman rock ; some discontinuous thin silicified sand­ Formation, taken from the exposures in the saddle stone and chert-pebble conglomerate beds; projected position of fossil colln. ES-58-4F between the west side of Newark Mountain and Bold (= U.S. loc. 21269-PC) is about 300 ft be­ Bluff, is as follows: low top ______1,120 16 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Feet collections have been made by C. W. Merriam (written 2. Gray silicifled sandstone and chert-pebble con­ commun., 1958). glomerate ; weathers brown and brownish gray_ 30 1. Grayish-green and gray clayrock and siltrock; thin sandstone beds ______680

Total Chaimnan Formation 1,830 Pilot Shale: Gray clay shale, weathers tan. These section serve to illustrate the consistent nature of the black shale facies in this part of the Diamond Mountains, and the discontinuous nature of the more obvious resistant silicified sandstone and conglomerate layers. Siltrock may be more abundant in the exposures to the northeast than in the vicinity of Newark Sum­ mit, but this cannot be proved with the information available at this time. An estimated 10 percent of the rocks forming the Water Canyon facies of the Chainman Formation are sandstone and chert-pebble conglomerate; the re­ mainder is siltrock and clayrock.

BLACK POINT FACIES The Black Point facies of the Chainman Formation consists of interbedded siltstone, clayrock, sandstone, and conglomerate. The informal name is taken from FIGURE 6. Outcrop area of Black Point facies of the Chainman the prominent topographic feature (fig. 2) that extends Formation showing uniform banded outcrop of the Black from the valley floor almost to the crest of the range Point facies (Mcb) overlain by the Diamond Peak Forma­ on the west side of the Diamond Mountains. The unit tion (Mdp). is well exposed from the Joana Limestone outcrops eastward toward vertical-angle bench mark 9358 (figs. Rocks similar to the dominant types in the Water 4, 6). Canyon facies of the Chainman occur irregularly This facies consists of gray (N5-N7) silicified pyri- throughout the section, but they seem to be more prev­ tiferous sandstone and conglomeratic sandstone; silici­ alent in the lower few hundred feet. Platy and pencil- fied chert- and quartzite-pebble and cobble conglomer­ like weathered fragments occur only on the west side ate; pyritiferous grayish-olive-green (5GY 3/2), of the range about opposite the headwaters of Mau grayish-olive (1QY 4/2), pale-olive (WY 6/2), and Creek (fig. 4). Shale is much less common to the north, dark-gray (A73) siltstone and clayrock, and pale-olive and the average grain size in the section at the north (10]P6/2) conglomeratic siltstone and siltstone-matrix edge of the quadrangle is slightly greater than to the conglomerate. south. The rocks weather to more pronounced olive and The contact of the Black Point facies of the Chain­ brown shades, and many of the sandy beds are distinctly man with the underlying Joana Limestone is every­ brown. Some interbedded silicified sandstone and silt- where sharp, and, as described previously, unconform- stone units are as resistant as the sandstone and con­ able. It is particularly well exposed near the crest of glomerate units; these form steeper slopes than do the the range east of the Phillipsburg mine (fig. 4). The more common interbedded siltstone and clayrock units. contact with the overlying Diamond Peak Formation The more resistant units are also the ones in which is gradational an increase in the number of sandstone discontinuous conglomerate lenses occur. Although the beds marks the lower part of the gradational interval. units locally separable in the Black Point facies of the Lenses of silicified chert- and quartzite-pebble and Chainman are discontinuous in detail and vary both cobble conglomerate and some beds of siltstone-matrix laterally and vertically, several can be mapped in gross conglomerate occur with the sandstone strata. Over­ fashion throughout the whole outcrop belt. lying this zone of interbedded conglomerate, sandstone, Worm trails are present in some of the siltstone and siltstone is the discontinuous silicified sandstone units, and pyrite and crinoid casts are also abundant that has been mapped as the basal part of the Diamond in places. Well-preserved fossils are rare, but some Peak Formation. STRATIGRAPHY 17

The thickness of the Black Point facies ranges from for the few graded thin sandstone beds and perhaps about 3,500 to 4,000 feet in the Eureka quadrangle. also for the very common poorly sorted clay-rich sand­ These thicknesses may be in error because of unrecog­ stone, silty sandstone, and sandy siltstone. Other thin nized faults or folds, although special efforts were beds of sandstone are commonly intercalated with the made to determine their presence. finer grained rocks and may have been deposited by A generalized section of the Black Point facies as low-energy bottom currents; however, their persistence exposed on the upper part of Black Point ridge is may indicate that they are turbidites. given below: The other finer grained rocks in the section appear Feet to have been deposited by slow-moving bottom cur­ Diamond Peak Formation: Gray and brown silicified chert-pebble and cobble rents or from suspension by flocculation. Most of the conglomerate and sandstone with some interbedded clay shales and silt shales have well-oriented fabrics siltstone; some gray limestone cobbles in the con­ that suggest compaction of an originally water-rich glomerate. sediment. Chainman Formation (Black Point facies) : There is no direct evidence of the depth at which 7. Gray siltstone and clayrock with abundant worm trails; also some silicified brown sandstone at these sediments were deposited. The abundance of base; overlain by gray and grayish-green silt- fossil plant debris and crinoid casts suggests that tr^ stone succeeded upwards by interbedded brown environment was not deeper than the neritic zone and sandstone and gray and pale-olive-weathering may have been in part epineritic. The variation in the clayrock and siltrock ______1,160 depositional mechanism probably is an indication of 6. Olive and gray siltstone; some clayrock and lenses of brown-weathering sandstone; forms instability in nearshore areas. The lack of sedimentary steep resistant slopes ______350 structures, other than in the few graded beds noted, 5. Pale-olive, grayish-olive, and gray siltrock and probably excludes the possibility of extensive littoral or clayrock ______400 estuarine deposition. The graded layers are not neces­ 4. Interbedded gray siltstone and clay shale; some sarily indicative of great depth, for similar features pale-olive siltstone ______410 3. Interbedded gray siltstone and clayrock _____ 270 are known to have developed in Pleistocene sediments 2. Interbedded gray and grayish-green siltrock and deposited at depths of less than 100 feet (D. M. Hop- thin-bedded brown sandstone; minor lenses of kins, oral commun., 1961). conglomerate and sandstone; forms resistant Nolan, Merriam, and Williams (1956, p. 58-61) have knobs and slopes ______320 summarized the fossil evidence that supports the Late 1. Interbedded gray and grayish-green siltstone and clayrock; some thin beds of silicified gray sand­ Mississippian (Chester) age assignment of the Chain­ stone; highly fractured locally ______620 man and Diamond Peak rocks exposed near Eureki,. As shown in figure 5, this is a shorter time span than Total Chainman Formation ______3,530 is represented by the lithically correlative rocks in tl °, Joana Limestone: Carlin area. The Chainman Formation in the Diamond Gray crinoidal and dense limestone with minor inter­ calations of gray shale. Peak area is considered to be entirely Meramec in age by Mackenzie Gordon, Jr. (this report, p. 37). The Black Point facies contains on the average, but subject to great local variation, about 2 percent chert - DESCRIPTIVE STRATIGRAPHY OF DIAMOND PEAK and quartzite-pebble and cobble conglomerate, 24 per­ FORMATION cent sandstone, 39 percent siltrock, and 35 percent In the Eureka quadrangle the Diamond Peak Forma­ siltrock and clayrock lithologically similar to the Water tion is exposed in a continuous band that extends from Canyon facies of the Chainman. near Poison Spring on the south to the northern The sediments that now constitute the rocks of the boundary of the quadrangle (pi. 1; fig. 4). At tH Black Point facies of the Chainman Formation were north, the band is relatively narrow, except for tl ^ deposited in many different environments. The abun­ downfaulted blocks that form the hills north ard dance of pyrite and pyrite casts throughout the section south of Strawberry Ranch. At the south, the outcrop indicates that reducing conditions prevailed during belt of the Diamond Peak is broader and is interrupted diagenesis, but the mode of deposition of the original by masses of the overlying Ely Limestone. sediments was varied. Pebble-size detritus with a low As mentioned above, almost all of the Diamord .proportion of matrix may have been transported by Peak exposed in the quadrangle are part of one struc­ strong bottom currents or wave action, whereas similar tural element the upper plate of the Bold Bluff thrust detritus wtih a high proportion of matrix may have fault. The few hundred feet of strata assigned to the been transported by submarine slides or turbidity cur­ Diamond Peak Formation of the lower plate is rents. Turbidity-current transport may also be inferred discussed separately. 18 MISSISSIPPI AN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Hague's original designation of the slopes of Dia­ mond Peak as the type locality of the formation leaves considerable latitude for the selection of a type sec­ tion, for these slopes cover about 15 square miles. De­ tailed mapping showed that a relatively unfaulted sec­ EXPLANATION UNIT APPROXIMATE tion is exposed on the northwestern slope of Diamond THICKNESS IN FEET Peak in sees. T and 18 (misurveyed), T. 20 N., E. 55 E. (between lat 39°36' N. and lat 39°37' N. and between Siltstone long 115°48'30" AY. and long 115°50' W.), and this section is herein designated as the type section. The detailed section is presented on page 67 of this report., 220 Sandstone and its base is plotted on plate 1; the section is sum­ marized in figure 7 and in the discussion of individual 250 members which follows.

Clays tone The 3,525 feet of strata assigned to the Diamond Peak Formation in this section have been divided into eight informal members, all of which have been 315 mapped throughout the type area. It is possible that these conformable and gradational members persist for several tens of miles ; all the members were mapped at 570 the northern boundary of the Eureka quadrangle, Limestone about 10 miles north of the type locality, but there two of the members are thickened relatively at the expense of the intervening member, and a third member differs Cherty in overall lithology. Minor abrupt lateral and vertical 380 limestone variations within members are common, and only a few individual beds persist more than 2 or 3 miles. The type section provides information that supports the conclusions of Dott (1955, p. 2233, 2265-2? -6) and SSillSSl'.' Nolan, Merriam, and Williams (1956, p. 56-31) that HIS-Hill 240 all previous workers had overestimated the amount of coarse clastic material in the Diamond Peak Formation and underestimated the amount of clayrock and silt- Fossil rock. About 13V& percent of the measured section of the collection formation is conglomerate, 20 percent is sandstone, Qy2 percent limestone, 5y2 percent limestone-ph?,noplast

1270 conglomerate, 9^ percent claystone, and 45 percent siltstone, The individual members commonly contain at least three of these six rock types. In the, upper members all six occur together, but in varying pro­ FEET portions (fig. 7). r 0 In another section of this report (p. 38-47) L 100 Mackenzie Gordon, Jr., discusses in detail the bio- stratigraphy and age assignments of the members of the Diamond Peak Formation. He concludes that members A through C are Meramec in age, the 280 ^500 Meramec-Ohester boundary is near the top of member D, and members E through H are Chester in age.

CONTACT OF DIAMOND PEAK AND CHAINMAN FORMATIONS 3525-Total thickness Diamond Peak Formation The contact of the Diamond Peak Formation is FIGXTRE 7. Generalized columnar section of the type section of gradational with the underlying Black Point facies of the Diamond Peak Formation, showing approximate thick­ the Cliainmaii Formation (p. 16). Throughout most ness and dominant lithic types for informal members A-H. of the quadrangle the lowest member of the Diamond STRATIGRAPHY 19

Peak is set off from the Chainman by its characteristic At the type section, member A is about 280 feet silicified thick- or very thick bedded gray-weathering thick and forms prominent ledges. The ledge-forming polymictic pebble and cobble conglomerate that con­ beds are discontinuous in detail (fig. 6) but they have trasts with the dominantly thinner bedded finer grained been traced with some gaps all the way to the northern underlying strata. The occurrence of limestone clasts boundary of the quadrangle. in the conglomerate is diagnostic, as these were not Xear the crest of the range due east of the Phillips- noted elsewhere in the section. In addition, these basal burg mine (fig. 4), this member is about 385 feet thick, conglomerates contain sand- and pebble-size clasts of according to the unpublished notes of C. W. Merriam fine-grained volcanic rock that are readily recogniz­ (written commun., 1958), and includes minor beds of able in thin section, but which are difficult to distin­ gray limestone. A single yellowish-gray-weatherng guish from the siltstone clasts in hand specimen. limestone bed about 1 m thick was mapped in the The increase in the frequency of conglomeratic units member in the headwaters of Man Creek, about 3 miles is not always abrupt, and the contact has been placed north of the type section. These are the only known at the horizon where the coarser grained rocks become occurrences of limestone in this member, although dominant. It is unlikely, therefore, that the mapped limestone mapped as part of member B east of Cotton- contact is everywhere at exactly the same stratigraphic wood Spring could conceivably be incorrectly assigned. level, and its placement may vary vertically more than 100 feet. MEMBER B Locally, the sandstone and conglomerate beds of the The slope-forming rocks of member B consist mainly lowest member of the Diamond Peak Formation seem of siltstone with lesser amounts of interbedded sand­ to be completely missing, either by nondeposition or, stone, clayrock, and minor amounts of lenticular con­ possibly, by faulting. In such localities the contact- glomerate. The siltstone is commonly gray, weathers to between Black Point facies of the Chainman and the light olive gray and pale olive, and forms irregular Diamond Peak has been projected between outcrops fragments and large flakes 1 cm thick and 5-15 cm where member A is present. in diameter. Individual strata are 1-3 cm thick and display casts of former pyrite euhedra, worm trails, MEMBER A and poorly preserved casts of crinoid column^ls, Member A, the lowermost member of the Diamond brachiopods, corals, and plant fragments. Clayrock Peak Formation, is characterized by conglomerate interbedded with the siltstone contains fewer fossil beds, 60 cm to 3 m thick, interbedded with silicified impressions, but otherwise differs only in grain size. sandstone, clayrock, and much siltstone. The conglom­ Thin beds (5-10 cm) of very fine grained to fne- erate is gray and weathers in part to olive gray. It grained gray silicified sandstone are intercalated with consists of pebbles and cobbles of light- and dark-gray the siltstone and clayrock. They weather gray, brown, chert and quartzite, silicified siltstone, gray limestone, and light olive gray, are pyritic, and form resistant and some dark volcanic rocks in a matrix of fine- to "ribs." Several somewhat coarser poorly sorted sand­ medium-grained silicified sandstone. Sparse pyrite stone beds 2.5-10 cm thick are also present. Some of euhedra and poorly preserved casts of fossils are the sandstone contains casts of brachiopods, horn corals, present. The thin-bedded sandstone is gray when fresh, crinoid colunmals, and bryozoans. The few conglomer­ weathers brown, and is fine to medium grained and ates present are of two types a silicified gray-weath­ poorly sorted. Although silicified for the most part, it ering chert and quartzite pebble and cobble variety that contains calcareous cement locally. Some pyrite is also occurs in lenses as much as 7.5 cm thick and several present. The siltstone is gray to black and weathers meters long, and a gray- to light-olive-gray-weathering either grayish brown or olive gray, resembling the variety with a siltstone matrix that locally contains dominant lithic type of the underlying Chainman abundant brachipod and crinoid columnal impressions. Formation. These strata are 5-30 cm thick and contain casts of pyrite cubes, crinoid and bryozoans remains, a At the type section, the member includes 4 percent few scattered thin chert pabble beds, and worm trails. silicified conglomerate, 2i/o percent siltstone-matrix The clayrock is medium gray to medium dark gray and conglomerate and conglomeratic siltstone, 19 percent weathers pale olive and grayish olive. sandstone, 11 percent clayrock, and 63^ percent silt- This member contains, at the type section, about 121^ stone. percent silicified conglomerate, Qy2 percent siltstone- In general, the unit closely resembles the Black Point matrix conglomerate and conglomeratic siltstone, 10 facies of the Chainman Formation. The measured percent sandstone, 4 percent clayrock, and 67 percent thickness of the unit at the type section is about 1,270 siltrock. feet. 20 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

C. W. Merriam's unpublished data (written commun., To the southeast, in the vicinity of Sadler Canyon, 1958) and the present study indicate that the member thick- and very thick bedded conglomerate overlying is lithically similar at the north edge of the quadrangle partial sections of member B has been mapped as mem­ and of similar thickness, namely 1,280 feet. Merriam's ber C. There the situation is complicated by the descriptions suggest that more sandstone may be absence of the finer grained upper part of member C present, than at the type section and also emphasize and the fact that member D in that area consists of the presence of worm trails throughout the member. interbedded conglomerate and limestone.

Merriam noted a 10-foot-thick crinoidal limestone MEMBER D bed close to the top of the member. The limestone resembles those described from the upper part of mem­ Member I) is a resistant cliff- and ledge-forming sequence of thick- and very thick bedded limestones ber C at the type section. As mentioned previously, interstratified with sandstone and minor amounts of limestone was also mapped in member B near the foot of the range due east of Cottonwood Springs, but it clay shale, conglomerate, and siltstone. The limestone may not be in place. is typically gray or blue gray, weathers brownish gray in some places, and is locally very hard and dense. A MEMBER C few of the limestone beds have sets of planar cross- Member C consists of a prominent series of ledge- strata, and others are noticeably pyritic. Almost all forming conglomerates overlain by interbedded silt- are fossiliferous, containing crinoid columnals, colonial stone and clayrock with sparse sandstone and con­ and solitary corals, bryozoans, brachiopodf- and, glomerate. Thin limestone beds occur in increasing locally, foraminifers. Many of the limestone strata numbers in the upper third of the member. The thick- have "stringers"1 and thin beds of' dark chert granules and very thick bedded conglomerates are for the most and pebbles; others contain abundant silt-size quartz part gray, although some brownish-white ledges are and chert grains and grade into limy siltstone. The present in the upper half of the member. These rocks nonlimy siltstone present is olive gray, thin bedded, weather gray and brownish gray and consist of cobbles and occurs also as the matrix of the limestone-pheno- and pebbles of chert and quartzite in a matrix of plast conglomerate of this member. The clay shale silicified medium-grained sandstone. The overlying silt- intercalated with the limestone is gray and fissile, stone and clay stone are gray on fresh exposures and weathers olive gray, and is locally either pyritic or weather to light olive gray. Commonly, the beds are limy. Small brachiopod casts occur in some of the beds. laminated and aggregate 5-10 cm thick. Pyrite casts Light-gray, brown, and light-brown, fairly well sorted, and bryozoan impressions are conspicuous in the silt- fine-grained sandstone in beds 7.5-75 cm thick occurs stone. Parts of the claystones are carbonaceous. The between the limestone beds. Most of the sandstone is few limestone strata in the upper part of the member hard, dense, and moderately well sorted. Some is pyritic are gray and dense, and attain a maximum thickness of and some is conglomeratic. The conglomerates in the 15 cm; interbedded with the limestone in the dominant sequence are gray or brownish white and weather to siltstone and clayrock are sparse thin conglomerate brownish gray and darker brown. Chert and quartzite lenses and very minor amounts of limestone-phenoplast form the rounded pebbles and cobbles, whicl are a conglomerate. maximum of 10 cm in diameter. The chert fragments tend to be the more angular and are red, white, gray, At the type locality the member consists of 38% and black. Some of the conglomerates grade to sand­ percent conglomerate, 29% percent siltstone, 18 per­ stone; others contain relatively little sandstone matrix cent clayrock, 13% percent sandstone, less than % and are cemented with calcite. percent limestone, and perhaps % percent limestone- phenoplast conglomerate. The limestone-pheiioplast conglomerate referred to above is an unusual rock consisting of irregularly The member is about 240 feet thick at the type sec­ shaped nodulelike fragments of gray limestone in a tion. At the northern boundary of the quadrangle the matrix that commonly is mudstone. The nodules range unit consists of about 535 feet of strata (C. W. Mer­ from 0.5 to 10.0 cm in maximum dimension. TT Q- rela­ riam, written commun., 1958), but there, as well as tive proportion of matrix and phenoplasts varies con­ elsewhere north of the type section, the overlying mem­ ber D is not well developed, and siltstone and sand­ siderably both laterally and vertically within any stone occupy the equivalent stratigraphic position. individual bed. The fragments are intraformational in This is illustrated by member D northeast from the origin and are interpreted to have been plastic at the type section; it was found to decrease markedly in time of deposition. Carozzi (1956) has described some­ thickness, whereas the upper part of C increased. what similar rocks from the French Alps. STRATIGRAPHY 21

At the type section, the member consists of 43 per­ silicified matrix of poorly sorted sandstone. Clasts as cent limestone, 20 percent sandstone, 12 percent silt- much as 7.5 cm in diameter were observed. stone, 12 percent clay shale, 11^ percent conglomerate, Slope-forming clayrock is less abundant than con­ 1 percent limestone-phenoplast conglomerate, and one- glomerate. It is gray, weathers olive gray and grayish half of 1 percent siltstone-matrix conglomerate. The green, and in places grades to limestone-phenoplast unit is about 380 feet thick. conglomerate. Some brachiopod casts occur in the clr-y- C. W. Merriam's unpublished field data indicate that stone, and some worm trails are also present. in the northern part of the Eureka quadrangle this The limestone, present as lenses and intercalations limestone member has changed considerably, and the 30-60 cm thick, is generally sandy and in places con­ thick- and very thick bedded limestone is but a minor tains widely scattered chert, pebbles. Some beds con­ part of the unit; the interbedded clay shale and silt- tain crinoid columnals. Other nonfossiliferous beds stone are dominant and are accompanied by minor grade into limestone-phenoplast conglomerate. conglomerate. In this area the unit is about 270 feet Limestone-phenoplast conglomerate occurs in non- thick. resistant beds 30 cm to 1 m thick and consists of ir­ In the area east of Diamond Peak, particularly in regularly shaped fragments of gray limestone in either the vicinity of Sadler Canyon, member D consists of an olive-gray mudstone or very fine-grained sandstone interbedded thick- and very thick bedded conglomerate matrix. and limestone with subordinate amounts of clay shale In the type section, member E consists of about 3?"% and siltrock. To the southeast and south of Diamond percent siltstone, 28^ percent sandstone, 151^ percent Peak, on Diamond Table (which is the ridge between conglomerate, 8y2 percent clayrock, 5 percent lime­ the upper parts of Sadler and Water Canyons (pi. 1)) stone, and 4 percent limestone-phenoplast conglomerate. and Alpha Peak ridge, the member in general includes The member is 570 feet thick at this locality. more conglomerate and finer grained detrital rock. According to the field data of C.W. Merriam (written Where the member underlies Diamond Table, it is commun., 1958), the rocks at the north edge of the mostly conglomerate; but limestone and siltstone are quadrangle assigned by this author to member E are more common on Alpha Peak ridge. about 375 feet thick. Limestone and limestone-pheno­ plast conglomerate were not noted by Merriam, but he MEMBER E did describe the occurrence of minor amounts of very Member E is made up of alternating beds of silt- dark red and dusky-red siltstone like that which is stone, sandstone, conglomerate, clayrock, limestone, diagnostic of the overlying member F. and limestone-phenoplast conglomerate. Limestone and Between the type section and the southern boundary siltstone are more common near the base of the unit, of the area, member E differs from the type section in but diminish upwards, sandstone and conglomerate, the greater amount of silicified chert-pebble con­ interstratified with clayrock and siltstone, form the glomerate present. Although conglomerate is still a upper half of the unit. The member forms steep slopes relatively minor lithic type, several beds were traced with resistant ledges. for more than 1 mile, and one, near the top of the The siltstone is commonly gray or brown and member, occurs discontinuously for perhaps 2 miles. weathers olive gray, grayish green, and, locally, very In this area, member E contains more very dark red dusky purple. In places it grades imperceptibly into and dusky-red siltstone and also more limestone- very fine grained sandstone. The siltstone carries some phenoplast conglomerate than at the type section. brachiopod fragments locally and some limonite pseudomorphs after pyrite. Individual beds are as MEMBER F much as 2 m thick, but 1 m is more common. Member F is characterized by purple, green, and The sandstone is brown, gray, and grayish green gray limestone-phenoplast conglomerate, alternating and weathers to brownish shades of the original colors. purple and green siltstone and clayrock, pale-green Although it is generally fine- and very fine-grained silicified sandstone, and conglomerate. It is this mem­ silicified sandstone, some conglomeratic lenses are ber that has been noted by most previous works as present. Pyrite and limonite stains are common; the being widespread in the upper part of the Diamond pyrite-rich beds are very hard and dense. This lithic Peak Formation (Hague, 1882, 1883, 1892; Dott, 1955, type occurs in resistant uniform beds about 1 in thick. p. 2265-2266; Nolan and others, 1956, p. 58). The conglomerate forms ledges 15 cm to 1 m thick The siltstone is typically grayish red purple and and consists of brown- and gray-weathering, gray, very dusky red purple or pale or blue green, with white, and pale-green cobbles and pebbles of quartzite abrupt color changes; most, but not all, of which are and chert, dark-gray chert, and light-green chert in a grossly controlled by the bedding. From place to place 22 SIISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA the ratio of purple to green varies considerably. In C. W. Merriam's data (written commun., 1958) on the vicinity of Diamond Peak the purple to green the section at the northern boundary of the quadrangle ratio is perhaps 2 to 1, but elsewhere the situation may indicate that about 475 feet of strata can be assigned be reversed. The purple siltstone grades into clay- to member F in that area, and that lithically the unit stone and limestone-phenoplast conglomerate, and the is about the same, except for the absence of limestone- green in places grades into very fine grained sand­ phenoplast conglomerate. This rock type is also miss­ stone. Individual layers are from less than 1 to more ing in the exposures of member F on the east side of than 5 cm thick, and a persistently purple or green Alpha Peak ridge and on the steep slopes above Water section may be as much as 3 m thick. Canyon, but it is present northward from these local­ Limestone-phenoplast conglomerate is best developed ities, both on the east and on the west flanks of Diamond in this member of the Diamond Peak Formation. The Peak. irregularly shaped phenoplasts of limestone are a3 MEMBER G much as 10 cm in diameter and are mostly gray, al­ Member G consists of thick-bedded conglomerate though locally, where they occur in purple claystone, interstratified with siltstone, silicified sandstone, and some are brownish red. The matrix is variable in limestone-phenoplast conglomerate in the resistant, texture and color and includes all varieties of clay- ledge-forming lower half. The conglomerate beds are stone and siltstone that occur in the member. These noticeably thicker than those of the underlying mem­ limestone-phenoplast conglomerate rocks grade into ber, and the chert cobbles and pebbles are darker than siltstone and claystone and, rarely, into limestone. the consistently light-colored clasts of the conglomerate The clayrock is fairly consistently grayish red of member F. The upper half of the member is poorly purple and very dusky red purple, but a minor exposed and probably consists mainly of siltstone. amount is pale green. It grades locally into siltstone The generally gray conglomerate strata weather and into limestone-phenoplast conglomerate and dark gray and brownish gray, and the cobbles and typically has an argillitic appearance. pebbles of light- and dark-gray or very pale grr°,n chert, Some of the silicified very fine-grained sandstone is and light-gray quartzite are generally approximately brown, but most is pale green or greenish gray. It equant and well rounded. Cobbles as much as 13 cm in grades into siltstone and also into conglomeratic sand­ maximum diameter occur in a matrix of silicif ed sand­ stone containing white chert pebbles. The sandstone stone that in places shows abundant limonite stain. The commonly occurs in beds 30 cm to 1.5 m thick and is matrix is not always silicified, and limestone pheno- intercalated with purple siltstone and claystone. clasts similar to those in the limestone-phQ.noplast The white and pale-green conglomerate beds of this conglomerate occur with the siliceous clasts. Inter­ member contrast strongly with the surrounding darker, calated with the conglomerates are gray and brown finer grained rocks. They are composed of subrounded moderately well-sorted silicified sandstone beds as or subangular white and very pale-green chert and much as 1 m thick. The siltstone is usually gray and white quartizite pebbles and cobbles as much as 7.5 weathers grayish green, brown, or olive gray, but some cm is maximum diameter in a silicified matrix of dusky-red-weathering siltstone is also present. The poorly sorted sandstone. siltstone grades locally to very fine grained or fine­ The 315 feet of strata that are assigned to member grained sandstone and also to limestone-pi °,noplast F at the type section include about 37 percent silt- conglomerate. Pyrite is present in a few beds, as are stone (most of which is the purple variety), 30i/£ per­ sparse "worm trails." In general, casts of brs chiopods cent limestone-phenoplast conglomerate, 14 percent are only poorly preserved, but two horizons have sandstone, 10i/k percent clayrock (.much of which is yielded fair collections. also purple), and 8 percent conglomerate. Sandstone in this unit is commonly gray, brown, or The distribution of the distinctive purple coloration grayish green and weathers to brownish shades of in this member is difficult to explain. Although the gray. The sandstone is very fine to medium grained, member can be mapped throughout the quadrangle on and individual beds are well sorted or moderr tely well the basis of color, the local changes are abrupt and sorted; locally, the sandstone is pebbly. A few beds make detailed tracing of any individual stratum diffi­ contain clasts of limestone like those in the limestone- cult. At the type section, part of this member is re­ phenoplast conglomerate. Much of the sandstone is peated, owing to high-angle faulting; but the local silicified, but local areas of calcite cement aro present. vagaries of the color distribution made recognition Pyrite occurs locally, as do poorly preserved casts of of the repetition difficult. fossils. Some of the sandstone is cross stratified. STRATIGRAPHY 23

The limestone-phenoplast conglomerate of this mem­ 2). White, brown, and light-gray varieties occurs, and ber is marked by a relatively small proportion of silt- pebbles of white and light-gray quartzite and light- stone matrix with a commensurate increase in the gray chert are the most common clasts. Also present amount of limestone. The limestone clasts are gray or are pebbles of pale-red, very pale green, and dark- bluish gray, and the siltstone matrix is also gray, gray chert. The largest pebble noted measured 6.25 cm weathering olive gray. A few chert pebbles and poorly in diameter. The pebbles occur in sandstone matrices preserved fossils occur in this lithic type. One 60-cm cemented by either silica or calcite. The conglomerate bed of the conglomerate grades laterally into silty beds are as much as 1.7 m thick and are usually inter­ limestone, and another bed 5 m thick exhibits a pro­ bedded with thin layers of siltstone, limy sandstone, gressive vertical decrease in the phenoclasts, ranging or sandy limestone. from a limestone-phenoplast conglomerate with rela­ The siltstone is gray and dark gray and weathers tively little matrix at the base to a limestone-free silt- olive gray or greenish gray in most places. Some beds stone at the top. grade into very fine grained sandstone; others contain About 250 feet of strata are assigned to member G limestone clasts less than 2 cm in diameter and grade at the type locality. The member consists of about 42 into limestone-phenoplast conglomerate. The limestone- percent siltstone, 19 percent sandstone, IT1/^ percent phenoplast conglomerate in this member of the Dia­ conglomerate, 17 percent limestone-phenoplast con­ mond Peak Formation commonly consists of gray lime­ glomerate, and ±1/2 percent clayrock. stone nodules 2-5 cm in diameter in an olive-gray- From Merriam's field data (written commun., 1958), weathering, gray siltstone matrix. Locally the matrix it seems that northwest of Strawberry Ranch about 430 is very fine grained sandstone or silty sandstone. feet of strata should be considered as constituting mem­ The uppermost 6 feet of this member consists of bers G and H. It may be that member G thins some­ siltstone, which underlies the interbedded gray and what to the north. bluish-gray fossiliferous limestone, green and very

MEMBER H dark-red fossiliferous siltstone, and other noncarbonate rocks that have been mapped as the lower part of the Member H is a transitional unit between member G Ely Limestone. This uppermost siltstone of the Dia­ of the Diamond Peak Formation and the overlying mond Peak Formation has a local disconformity at Ely Limestone of Mississippian and Pennsylvanian its base and fills scours (as much as 1 ft deep) cut into age. It is transitional to the lowermost unit of the Ely, the underlying conglomerate and sandstone. which contains beds of the typical Diamond Peak lithic types. The transition is represented by the alter­ nation of thick-bedded gray and bluish-gray noncherty limestone beds, as much as 1.2 m thick, with silicified sandstone and limestone-phenoplast conglomerate beds and with conglomerate and siltstone layers. The limestone is gray and bluish gray and weathers to slightly lighter shades of gray. Locally, it is sandy or silty. Brachiopods and horn corals are abundant in some of the strata. The limestone commonly occurs interbedded with gray or brown limy sandstone and gray and olive-gray-weathering siltstone and lime­ stone-phenoplast conglomerate. The sandstone varies in color from brown to greenish gray and gray and is generally fine or very fine grained and moderately well sorted, but some poorly sorted, fine- to coarse-grained beds are present. Locally, the sandstone grades into pebbly sandstones as much as 30 cm thick or into siltstone. Both silica and calcite FIGURE 8. Diamond Peak and cliff-forming member H (Mdph) occur as cement, and a few beds are stained slightly of the Diamond Peak Formation. Overlying lower mem­ with limonite. Sandstone commonly occurs in beds 30 ber (PMel) of the Ely Limestone in middleground. Diamond cm to 1 m thick interbedded with limestone or con­ Peak in right background; ridge extending from Diamond glomerate. Peak north consists wholly of the upper member (Peu) of the Ely Limestone. Saddle to north of member H is formed by the The conglomerate of this member contributes sig­ upper half of member G. In foreground are siltstones and sand­ nificantly to its overall resistance to erosion (figs. 8, stones of member F. 24 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

At the type section about 220 feet of strata was The problem of placing a contact within a transi­ measured in member H. The member consists of about tional sequence of rock is difficult, and it can be effec­ 31 percent sandstone, 20 percent limestone, 18y2 per­ tively argued that, in the case at hand, the contact cent conglomerate, 15~y2 percent limestone-phenoplast would be better placed at the base of the transition conglomerate, and 15 percent siltstone. unit, or above it. The important feature is the change The section measured by Riva (1957) about 3 miles in regimen from the deposition of dominant siliceous north of the quadrangle assigns about 240 feet of elastics to the deposition of carbonate rocks. As pres­ strata to the lower unit of his Moleen Formation. As ently placed, the contact marks approximately where he has mapped it, the unit probably includes part of this change occurs, and its position can be readily member H, as here discussed and part of what has determined in the field. The detailed measured section been mapped as the lower member of the Ely Lime­ across the Diamond Peak-Ely contact is given on pages stone in the vicinity of Diamond Peak. 68-70. South of the type section, member H is well exposed It should be emphasized that the placement of the in the cliffs on the east side of Diamond Peak and on formational contact is somewhat arbitrary and that it the west flank of the Alpha Peak ridge. There, it is could be placed either higher or lower in the section. about the same thickness as at the type section. Nolan (written commun., 1966) has pointed out that the contact was placed higher perhaps as high as CONTACT OF DIAMOND PEAK FORMATION AND ELY LIMESTONE the upper part of the lower member of the Ely Lime­ stone in some of the areas discussed by Nolan, Mer- The contact of the Diamond Peak Formation and riam, and Williams (1956). the Ely Limestone has been placed within the sequence of rocks that represents the transition between the DIAMOND PEAK FORMATION OF LOWER PLATE terrigenous clastic strata of the Diamond Peak and OF BOLD BLUFF THRUST FAULT the carbonate strata of the Ely. The rocks of the Diamond Peak Formation below As noted above, significant amounts of limestone are the Bold Bluff thrust are exposed in and near the present in member H of the Diamond Peak the lower upper parts of Water and Mining Canyons (pi. 1). part of the transitional sequence. The abrupt increase The distribution of lithic types is not as well known at the formational contact in the amount of carbonate as in the Diamond Peak Formation of the upper plate rock present is illustrated in the following tabulation, because of poorer exposures and a smaller outcrop which compares the percentages of lithic types in area. Greenish-gray siltstone and clayrock with inter- member H of the Diamond Peak Formation with those bedded gray silicified sandstone that weathers brownish in the lower member of the Ely Limestone: gray are most common. The stratigraphic sequence

Lithic type Member H, Diamond Lower member, where best exposed consists of interbedded medium- Peak Formation Ely Limestone bedded brown-weathering silicified sandstone and gray (percent) (percent) siltstone at the base, succeeded upwards by thick- and Siltrock ______15.0 13.5 Sandstone ______31.0 26.5 very thick-bedded silicified conglomerate and sand­ Conglomerate ______18.5 8.0 stone layers with increasing amounts of siltstone and Clayrock ______.0 1.0 clayrock. Near the top of the sequence are prominent Limestone ______20.0 46.5 silicified conglomerate and sandstone layers together Limestone-phenoplast with a thick-bedded gray fossiliferous limestone. At conglomerate _____ 15.5 4.5 one place near the base, gray "pencillike" clayrock About 110 feet above the Diamond Peak-Ely con­ similar to that of the underlying Water Canyon facies tact is a distinctive mottled yellowish-gray- and light- of the Chainman Formation is intercalated with the olive-brown-weathering cherty limy sandstone or sandy silicified sandstone and siltstone. This stratigraphic limestone that has been recognized almost everywhere sequence is not exactly correlative with any part of in the south-central Diamond Mountains. This key the type section, and there is no polymictic conglom­ bed has been used in mapping the contact in areas erate near the lower contact. However, it resembles where the upper part of the Diamond Peak Formation members A-C in general variation and proportion of is obscured by colluvium. The lowest occurrence of any lithic types and in overall thickness. cherty limestone in the transitional sequence is about The thicknesses exposed range to a maximum of 40 feet above the contact in areas of good exposures; about 1,600 feet in the highly faulted ridge extending this cherty limestone horizon has also been used in from the middle of Alpha Peak ridge eastward to the mapping less well-exposed areas. bottom of Water Canyon. At Bold Bluff about 450 STRATIGRAPHY 25 feet of strata is assigned to the Diamond Peak of the SANDSTONE lower plate. Sandstone is the second most abundant rock in the Diamond Peak Formation. The common sandstone in DEPOS1TIONAL ENVIRONMENTS the type section is a poorly sorted pyritiferous gray The different rocks in the Diamond Peak Formation variety that weathers to olive and olive-gray hues and record a variety of depositional environments as well is composed of particles of quartz, chert, and lithic as changes in the provenance terrane. Figure 9 illus­ fragments in varying proportions. The less common trates the variation in amounts of the more important type is compositionally similar to the first, except for lithic types throughout the type section. a smaller "clay" material content and more common silica cement; but it is texturally dissimilar, being Only the major features of the general depositional moderately well sorted and in general somewhat environment of each of the important rock types are coarser grained. The second type tends to weather to summarized below; conclusions based on textures and composition are presented in greater detail in another brownish shades. Large-scale crossbedding has been reported from report that is in preparation. the Diamond Peak Formation at Buck Mountain, SlLTROCK across Newark Valley to the east (C. M. Wentworfii, Siltrock is the most abundant rock type in the Jr., oral cominim., 1960), but no cross-stratification was Diamond Peak Formation, and almost all gradations noted in the Diamond Mountains. from clayey siltstone to sandy siltstone have been noted. A few of the poorly sorted thin sandstone beds The poorly sorted clayey varieties are the most com­ exhibit poorly developed graded bedding, suggesting mon. Two important subclasses of clayey siltstone are that turbidity currents deposited some of the sand­ present. The more abundant of the two is the olive- stone layers (Kuenen and Migliorini, 1950). Stewart gray-weathering pyritiferous type that is particularly (1962, p. C58) found evidence of turbidite deposition characteristic of members A and B and which is con­ in his undifferentiated Chainman and Diamond Peak sistently gray where fresh. The other type, prevalent Formations. in member F, is characterized by its grayish green or CONGLOMERATE very dusky-red-purple and very dusky-red shades on Conglomerate is the third most abundant rock in both weathered and fresh surfaces and its lack of the Diamond Peak Formation. The most common pyrite, or limonite formed from pyrite. This type variety is the lenticular silica-cemented chert and commonly grades into clayrock. Both types of silt- quartzite-pebble and cobble conglomerate that form" a stone occur in members E and G. conspicuous part of members A, C, G, and H and in­ cludes the polymictic subvariety that is characteristic The evidence suggests that many of these rocks were of member A. A second variety is present in important deposited below the limit of effective wave action by amounts only in members A and B and consists of some type of bottom current. The locally abundant olive-weathering siltstone-matrix conglomerate with pyrite is, according to Williams, Turner, and Gilbert between 30 and 50 percent chert and quartzite granules (195-4, p. 262), indicative of a reducing bottom environ­ and small pebbles. This type commonly grades into ment at depths of less than 100 fathoms; that is, with­ conglomeratic sandstone. in the neritic zone. In places, numerous casts of The most common conglomerate occurs in lenticular brachiopods, gastropods, and disarticulated crinoid layers that probably resulted from the coalescing of columnals indicate the former presence of bottom com­ bodies of coarse detritus brought to the depositional munities. The preservation of worm trails indicates site by closely spaced steep-gradient streams and re­ deposition below wave base and rapid burial. The distributed in the marine environment. The presence abundance of poorly preserved plant fragments sug­ of diagenetic pyrite in some of the conglomerate units gests that land was not far away. indicates deposition under reducing conditions. Tex­ The green and purple siltstone and clayrock in the tures indicate that the conglomerate may have b^en deposited below the limit of effective wave action for upper part of the formation contain the few examples the most part and that submarine slides may have of ripple marks noted. This evidence of wave action, played a part in the transport. Alternatively, the poor plus the association of the siltstone with the apparently sorting may be due to the introduction of sand-size shallow water deposits of limestone-plenoplast con­ material into a lag deposit. The association of some of glomerate, suggests a shallower depositional environ­ these rocks with limestone units whose textures indicate ment for these rocks than for the silt rocks lower in quiet environments supports the hypothesis that they the section. were deposited below the wave zone. 26 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

o> O Lower 295 ft of ^"S upper member 111 0) _____ E Lower member -I______

H

EXPLANATION Limestone Limestone-phenoplast conglomerate Clayrock Siltstone Sandstone Conglomerate Siltstone-matrix conglomerate

c ' O§ E £

.* (0 0) CL

O C O E \ <0 N

Black Point facies of Chainman Formation, upper 1075 ft

10 20 30 40 50 60 70 80 90 100 PERCENT OF LITHIC TYPE IN UNIT

FIGURE 9. Variation and proportion of major lithic types in members of the Diamond Peak Formation at the type section. Comparable values for the lower part of the Ely Limestone and for the upper part of the Black Point facies of the Chainman Formation are also shown. STRATIGRAPHY 27

These conglomerate units do not seem to fill channels with the sparry calcite-cemented limestones in contrast eroded into the subjacent strata; the coarse units grade to their absence in the micrite-cemented one supports laterally into sandstone or siltrock in all places where Folk's hypothesis that the micrite type accumulates in such relations were observed. a lower energy environment than the sparite type. The The siltstone-matrix conglomerate, is everywhere fragmented fossil debris indicates that a higher energy associated with conglomeratic and nonconglomeratic environment existed before accumulation and suggests poorly sorted pyritiferous sandstone and siltstone, and that the sparry calcite-micrite relationship indicates in origin it is probably more closely tied to those rocks only the amount of reworking that took place during than to the conglomerate discussed above. The high a latter stage of the depositional process. In otherwise proportion of matrix, the resulting disrupted frame­ similar limestones this may measure the rate of sub­ work, and the abundance of silt-size material suggest sidence, the micrite types having subsided below the that these rocks may have been deposited from sub­ agitated zone immediately after initial fragmentation marine mudslides or perhaps turbidity flows (Petti- and the sparite types having remained for a longer john, 1957, p. 254). time in the wave-agitated zone. CLAYROCK The sum of the evidence indicates that these lime­ The fourth most abundant rock in the type section stones were deposited in the neritic zone of an inter­ of the Diamond Peak Formation is clayrock, much of mittently subsiding basin. which is clay shale. The clayrock is consistently LIMESTONE-PHENOPLAST CONGLOMERATE medium to dark gray on fresh surfaces and typically This unusual rock occurs only in the upper part of weathers to olive shades. Pyrite euhedra are common. the Diamond Peak Formation and is particularly im­ It is characteristically gradational into the clayey silt- portant in member F. Its inferred origin and some of stone discussed previously, and in many places contains its characteristics have been discussed briefly above and many clasts of silt-size material either scattered or in and are enlarged upon below. lenses a few millimeters thick and a few centimeters The limestone-phenoplast conglomerate is made up long. of gray nodules of fine-crystalline calcite, ranging in Some of the clay shale has numerous worm trails on diameter from a few millimeters to about 20 cm, set bedding surfaces, but other fossils are absent. Plant in a matrix of siltstone, claystone, or, more typically, fragments occur locally in the clay shale, and brown clayey siltstone. The clasts are mostly spheroidal to organic material is abundant in some thin sections, blade shaped in general form (Zingg, 1935), although indicating that these clay shales are similar to the the surfaces are highly irregular in detail with many shales of both the Water Canyon and the Black Point reentrants of several millimeters in depth. Some flat­ facies of the Chaimnan Formation. tened disks are also present. The abundance of th^se LIMESTONE clasts differs laterally and vertically within a single Limestone occurs in significant amounts only in the stratum; all gradations between widely scattered in­ upper part of member C, and in members I), E, and H. dividuals that make up less than 10 percent of the In member D the limestone is associated with con­ rock to closely spaced groups of clasts that make up glomerate and other detrital rocks both as lateral gra­ more than 80 percent of the rock, have been observed. dations and as intercalations; the carbonate rocks The common clayey siltstone matrix of the lime­ seems to have formed where terrigenous debris was stone-phenoplast conglomerate is of two types: a dusky- scarce. red and very dusky red-purple hematitic variety and The most important varieties of limestone are bio- a grayish-green nonhematitic type. In general, each micrite and biosparite (Folk, 1959). Less common are stratum appears to have either one type of matrix or intrasparite, oosparite, intramicrite, and intraspar- the other, but in detail the color boundaries cross the rudite. Terrigenous material is present in some of the stratification surfaces at steep angles and show many limestone types. minor irregularities. The control of these color differ­ The locally fragmented fossil debris in the bio- ences is not clear, and their general distribution does micrite and biosparite consists of endothyroid fora- not provide any clue. minifers, bryozoans, crinoid columnals, and brachiopod Carozzi (1956) described a peculiar thin intra- pieces. In most specimens studied the cement is micro- formational conglomerate from which he was able to crystalline calcite, which Folk (1959) considers to have reconstruct a history involving carbonate sedimenta­ been derived from undisturbed chemically precipitated tion followed by varying degrees of vigorous wave ooze originally present between the biogenic clastic activity. Preserved in this conglomerate are relatively particles. The association of terrigenous clastic grains undisturbed limestone layers as well as all gradations 28 MISSISSIPPI AN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

from the undisturbed through wholly clastic, com­ west of Strawberry Ranch), where only par4-, of the pletely reworked layers in which the limestone clasts same structure is present. The third belt consists of are enclosed in a siltstone matrix. Various arrested three separate outcrop areas (pi. 1) : the area that stages of this process show clearly that the carbonate forms the summit and uppermost slopes of Diamond was plastic during reworking and redeposition. The Peak, a downfaulted portion of the same mass in the limestone phenoplast conglomerate of the Diamond area north of Adobe Canyon, and the narrow generally Peak Formation is probably similar in origin, but the fault-bounded strip extending from Newark Summit intermediate stages of disruption and redeposition northward along Alpha Peak ridge and then along the have not been preserved. The limestone nodules have west side of the range (pi. 1; fig. 4). the size and shapes of clasts, and their lack of internal The original contact, of the Ely with the overlying texture and the irregularity of their shape suggest Carbon Ridge Formation of Permian age is not ex­ plasticity during disruption and incorporation in the posed in the area mapped, and, consequently, the total silt that entered the depositional site during rework­ thickness of the Ely Limestone is not knowr. About ing. It is for this reason that the term "phenoplast" 1,500 feet is present just south of the area, according (Hatch and Rastall, 1950, p. 59) has been used. to Xolan, Merriam, and Williams (1956, p. 63). About SUMMARY 1,400 feet of strata assigned to the Ely is present in The overall distribution and character of the rocks the large downfaulted block just north of Adobe of the Black Point fades of the Chainman Formation Canyon. and the Diamond Peak Formation in the Diamond The Ely Limestone has been subdivided into two Peak area indicate that material derived from a nearby informal members. They were mapped only locally, tectonically active provenance terrane wras transported however, and the subdivision is not shown on the map short, distances, probably by closely spaced steep- (pl.l). gradient streams, and deposited as a series of coalescing LOWER MEMBER steep-fronted deltas in a basin that subsided rapidly The lower member of the Ely Limestone consists of enough to prevent extensive regression of the sea. strata transitional between the mixed carborate and terrigenous clastic rocks of member H of the Diamond MISSISSIPPIAN AND PENNSYLVANIAN SYSTEMS Peak Formation and the wholly carbonate rochs of the DESCRIPTIVE STRATIGRAPHY OF ELY LIMESTONE upper member of the Ely Limestone. It is best ex­ The Ely Limestone is latest Mississippian and Early posed on Diamond Peak. Pennsylvania!! in age in the Diamond Mountains. The contact of the lower member with member H of The formation was first named by Lawson (1906, the Diamond Peak Formation is considered to be at p. 295) from exposures in the Robinson mining district the horizon where the amount of carbonate reck pres­ near Ely. It had been described earlier as the "Lower ent increases abruptly (p. 24). All the rock types Coal Measure Limestone" by Hague (1870, 1882, 1883, common in the upper Diamond Peak occur interbedded 1892) in reports dealing with the White Pine and with the cherty and noncherty gray limestones of the Eureka districts. Nolan, Merriam, and Williams (1956, lower member. The limestones are platy and are less p. 61-62) have summarized the most important of resistant than the interbeds of white-weathering chert these early descriptions. Equivalent strata in the and quartzite-pebble conglomerate, sandstone, and northern part of the Diamond Mountains have been massive dark-greenish-gray siltstone; as a result, the named the Moleen and Tomera Formations by Dott member forms a series of steep steps and narrow (1955, p. 2234-2248). benches. The amount of terrigenous clastic rocks de­ The Ely forms three outcrop belts in the Eureka creases upwards in the section, and the limestone beds quadrangle, but only one of the belts is within the increase in thickness. The amount of replacement chert area covered by this report. The northwesternmost in nodules and irregular layers (fig. 10) increases up­ belt in the quadrangle consists of a discontinuous wards through about the lower third of the unit and series of outcrops along the western base of the range then decreases. south of Pedrioli Creek (fig. 4). All these outcrop The noncarbonate rocks of the lower member of the areas are small and are associated with local fan- Ely are lithically the same as the sandstone, siltstone, glomerates of Tertiary(?) age. The second belt is on conglomerate, limestone-phenoplast conglomerate, and the east side of the range (fig. 4) and extends from the clayrock of the underlying member of the Diamond north edge of the quadrangle, where the Ely occurs Peak Formation. The carbonate rocks are thin to thick on the western overturned limb of a syncline, south­ bedded and consist of silty biomicrite; some oosparite ward to Cedar Mountain (which is about 2 miles south­ and intrasparite are also present. Almost all the lime- STRATIGRAPHY 29

of the summit of Diamond Peak the bed is slightly thicker and is mostly a medium-grained calcareous light-gray sandstone that weathers light olive gray and contains irregular nodules and lenses of medium- gray chert as much as 15 cm long in the calcite-rich parts of the sandstone. Above the type section of the Diamond Peak, the lower member of the Ely Limestone is about 137 feet thick. Nolan, Merriam, and Williams (1956, p. 62) assigned 42.5 feet of transitional interbedded lime­ stone, shale, and sandstone exposed on the southwest ridge of Diamond Peak to the Ely Limestone. The author consistently mapped the formational contact there lower than did Nolan, Merriam, and Williams and considers the Ely part of the whole transitional sequence to be between 150 and 200 feet thick. As noted above, this lower member of the Ely appears to correlate with the upper part of the lower FIGUKE 10. Nodular and lenticular chert, limestone, and sandy member of Dott's Moleen Formation. Mackenzie or silty limestone in lower member of the Ely Limestone. Note Gordon, Jr.'s studies of numerous megafossils (collec­ displacement of limestone layers around chert masses. Ham­ tions from this lower member of the Ely Limestone, mer is about 31 cm long. p. 50-51 of this report) indicate that the lower 80- stone contains at least, 5 percent terrigenous silt- and odd feet is Late Mississippian (posttype-Chester, but sand-size quartz and chert grains, and much of the pretype-Morrow) and that the upper part of the mem­ biomicrite contains more than 10 percent. Replace­ ber is Early Pennsylvanian (Morrow).

ment chert is generally very minor and consistently UPPER MEMBER contains relict clasts of quartz or chert. All the lime­ Above the mixed carbonate and terrigenous clastic stone is dark bluish gray or greenish gray to medium rocks of the lower member is a rather monotonous light gray and weathers to slightly lighter shades of section of gray cherty and noncherty limestone. The gray and, in some places, very pale orange. uniform aspect is interrupted locally by minor pinkish- The upper boundary of the lower member has been gray platy layers, by thin pebbly beds, and by dis­ placed at the top of the highest chert pebble and cobble continuous thin greenish-gray- and olive-weathering conglomerate bed. The discontinuity of these con­ clayrock lenses. The detrital elastics are more common glomerate beds means that the upper boundary is at near the base of the member. A complete section is not different stratigraphic levels from place to place, but present in the mapped area, because the depositional this variation is only about 50 feet. Dott (1955, p. contact with the overlying rocks is nowhere exposed. 2237) placed the upper contact of the lower member Not far to the south, Permian rocks rest with erosional of his Moleen Formation in the Carlin area, using the unconformity on the member (Nolan and others, 1956), same criterion, but apparently did not note this specific and a similar situation just north of the Eureka quad­ lithic type where he observed the contact on Diamond rangle has been mapped and described by Riva (1957). Peak (1955, p. 2268). The limestone of the upper member of the Ely is Near the top of the member is a distinctive gray mostly thin- to very thick bedded medium-dark-gray and yellowish-gray mottled bed like those noted by biomicrite that weathers to medium-light-gray shades. Dott (1955, p. 2237). This mottled bed is at some The beds are composed of broken bryozoans, fusulinid places a sandy cherty biosparite and elsewhere a cherty fragments, and other allochems in a matrix of micro- calcareous sandstone. The changes in the relative crystalline calcite ooze. Many of these limestones are amounts of chert, limestone, and sandstone present pyritiferous and most contain a few percent of silt- are abrupt. Where exposed at the north end of the Ely and sand-size quartz grains. Locally, conglomerate outcrops on Diamond Peak, the bed is about 8.5 feet biomicrite occurs in lenses less than 10 cm thick and thick. Its dominant limestone part is medium dark as much as several meters long. The lenses probably gray, weathering to medium light gray with super­ make up less than 1 percent of the unit. Some oosparites imposed mottling caused by irregular patches of gray­ were studied in thin section and found to contain as ish-orange sandy limestone and gray chert. To the east much as 10 percent silt-size quartz and chert grains. 30 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

They difi'er from the dominant lithic type in that their Little terrigenous debris is present in the upper mem­ fresh surfaces are yellowish gray and their weathered ber. Following deposition of the upper member the surfaces are light olive gray. trough stabilized completely and became the site of Cyclic patterns of the type described by Dott (^1958) carbonate deposition only. were not noted. The composition as well as the contained fossils of Interbedded with the carbonate rock are a few thin, the Ely Limestone indicates that extensive microfaunas beds of medium-light-gray calcareous quartz siltstone and megafaimas existed in the stable basin. The allo- that weathers to distinctive pale-yellowish-brown platy chems consist largely of broken and comminuted fossil fragments. These beds are commonly pyritiferous, and debris, although micritic intraclasts and oolites occur the cement is sparry calcite. locally. These latter indicate intrabasinal erosion of Concentrically banded chert layers occur locally lithiriecl micrite material and local chemical precipita­ near the base of this member. The chert is medium tion of calcite (Diinbar and Eodgers, 1957, p. 234), gray on fresh fracture and weathers dark gray. The respectively. The microcrystalline calcite matrix of concentric surfaces form very flattened spheroids with most of the limestone suggests only limited reworking least axes as much as 5 cm long. The least axes are of the allochems after breaking and before final lithi- oriented approximately perpendicular to the bedding iication. The scattered subrounded sand- and silt-size surfaces. More common in the member are decimeter- quartz and chert grains apparently were introduced size nodules and irregularly shaped lenses of dark re­ from distant sources and transported singly among placement chert that typically contain sand-size quartz the allochems, although scattered lenses of sandy or grains and sparse dolomite rhombs. even conglomeratic limestone indicate sporadic minor This member probably correlates with all of Dott's influxes of terrigenous elastics into the basin. middle and upper members of his Moleen Formation Local concentrations of authigenic pyrite in the and part of his Tomera Formation (Dott, 1955, p. carbonate layers indicate that in some places a reduc­ 2269-2271). ing environment existed during and after deposition. The upper member of the Ely Limestone is Early PERMIAN SYSTEM Pennsylvanian (Morrow) in age, according to the fossil determinations made by Mackenzie Gordon, Jr. Nolan, Merriam, and Williams (1956, p. 64-67) (p. 51). assigned the Permian rocks of the Diamond Mountains to the Carbon Ridge Formation the type area of DEPOSITIONAL ENVIRONMENT which is at Carbon Ridge, about 10 miles southwest of The uniform character of the Ely Limestone indi­ the study area. Nolan and his coworkers noted the cates a more stable and persistent depositional environ­ presence of two f acies in the Carbon Ridge Formation; ment than that under which the rocks of the Chainman the relatively carbonate-rich facies in the Diamond and Diamond Peak Formations were deposited. Mountains and a carbonate-rich facies at the type The mixed carbonate and noncarbonate rocks of the locality. A third, more westerly, facies exposed in the lower member of the Ely were deposited in a variety Sulphur Spring Range west of Diamond Valley was of environments, as were their counterparts in the assigned to the Garden Valley Formation. Nolan, Diamond Peak. The conglomerate, sandstone, and silt- Merriam, and Williams (1956, p. 64) have summarized stone indicate higher energy environments than gen­ Hague's original description of these and younger erally persisted during the deposition of the limestone, rocks and have pointed out the discrepanices and in­ but contrast mainly in the much higher proportion of adequacies which made their thorough revision neces­ terrigenous clastic material. The biosparite and bio- sary. micrite of the Ely have textures like sandstone and The Carbon Ridge Formation is exposed in three siltstone, but consist almost wholly of intrabasinal separate localities in the Eureka quadrangle. The detritus. northernmost is between the alluvium of Diamond The typical alternation of terrigenous clastic rocks Valley and the major fault that bounds the west side and limestone in the lower member is a continuation of of the range near the northern boundary of the quad­ the pattern established in member H of the Diamond rangle (fig. 4). Farther south, on the same side of the Peak Formation, but the noncarbonate rocks become less range but at about the latitude of Cottonwood Spring, common upwards in the section and those present tend is the north end of a band of discontinuous outcrops to have calcareous matrices. Just below the contact of that extend southward to beyond the limits of the the lower and upper members of the Ely, the amount present mapping (pi. 1). The third locality is in the of terrigenous material decreases markedly, and only downfaulted blocks that form foothills on the east thin lenses of conglomerate and siltstone are present. side of the range north of Circle Ranch (pi. 1). STRATIGRAPHY 31

Both the upper and lower contacts of the Carbon mond Mountains describes a locality where E. R. Lar- Ridge Formation are erosional unconformities, and son considers flat-lying Permian rocks to overlie any thickness figures are therefore of limited signifi­ steeply dipping Diamond Peak conglomerate. This cance. In the mapped area, structural complications locality and the rest of the area west of the m?in precluded thickness estimates. Nolan, Merriam, and range have been mapped by T. B. Nolan and the Williams (1956, p. 65) considered the Carbon Ridge authors, and the relation is actually that of an angular Formation to be about 1,500 feet thick along the New- unconformity between overlying Tertiary (?) mono- ark Canyon Road, just to the south of the mapped lithologic megabreccia containing only Permian clasts area. Riva (1957) studied and mapped six units of and underlying upturned conglomerate of Cretaceous Permian and younger age in the area just north of the age, northern boundary of the quadrangle and stated that There are only minor differences between the Per­ the units are bounded by remarkable unconformities, mian rocks exposed west of Alpha Peak ridge and those which cause a variation in aggregate thickness from in the downfaulted blocks north-northwest of Circle about 1,600 feet to more than 6,200 feet. (The upper­ Ranch (pi. 1). At both localities the Carbon Ric'ge most unit that Riva included in his Permian probably Formation includes calcareous sandstone, limestone, is actually correlative with the Newark Canyon For­ mudstone, and conglomerate. West of Alpha Peak mation of Cretaceous age.) Lithologically and litho- ridge, gray, locally sandy, medium-bedded fusulinid- genetically, all of Riva's members are similar, but the bearing limestone is the commonest lithic type; reddish- upper third of the complicated section contains no and yellowish-brown fine- to coarse-grain thin- to fossils. Dott (1955, p. 2271) reported 800-1,000 feet medium-bedded calcareous sandstone (some containing of Permian siltstone, limestone, and chert in the fusulinids), both limestone-matrix and sandstone- northern Diamond Mountains and stated that the matrix chert-pebble conglomerate, and calcareous silt- unit thickened southward. stone are also present. In this particular area the sand­ The relations of the three separate facies of the stone, conglomerate, and siltstone are practically iden­ Permian discussed by Nolan, Merriam, and Williams tical with corresponding lithic types in the overlying (1956, p. 64) to the Permian in the northern Diamond Newark Canyon Formation of Cretaceous age; only Mountains are not known. The westernmost of the the presence of intercalated fusulinid-bearing strata three facies the Garden Valley Formation is simi­ allows consistent separation of the units. In the dovTn- lar to the section described by Riva (1957), but the faulted blocks north-northwest of Circle Ranch, apparent widespread instability during sedimentation reddish-brown and yellowish-brown thin-bedded cal­ that is suggested by the studies of Riva and Dott makes careous sandstone is characteristically interbedded the interpretation of possible facies relationships with gray and pinkish-gray fusulinid-bearing lime­ difficult. Dott (1958, p. 3) suggests that local facies stone, much of which is sandy and some of which is changes are more than adequate to explain the observed mnoidal. Less common rock types are gray and dark- differences; certainly, more information is needed. bluish-gray cherty limestone, fine-grained silicified sandstone (some of which is crossbedded), limestone- CARBON RIDGE FORMATION matrix conglomerate, and gray shale. Rocks of Permian age occur in the area only in fault- The limestone is mostly fusulinid biosparite r,nd bounded blocks overlapped by Quaternary alluvium, biosparrudite and almost all contains at least a few and the original contacts are nowhere exposed. Not percent coarse silt- to medium- sand-size quartz, chert, far to the south, however, the Carbon Ridge Forma­ and rare lithic grains. Local replacement chert occurs tion rests with angular unconformity on the Ely Lime­ in some beds as nodules and nodular beds of limited stone (Nolan and others, 1956, p. 6-i) and is, in turn, extent. The allochems are fragmented and unfr^.g- unconformably overlain by the Newark Canyon For­ mented fusulinid, bryozoans, and crinoid debris. Seme mation of Cretaceous age. Just north of the Eureka brachiopod fragments were also noted. Sparry calcite quadrangle, Riva (1957) mapped basal Permian rest­ cement is most common, but some of the more poorly ing unconformably on the Moleen (= lower Ely sorted limestone have micritic cements. Limestone) Formation of Dott (1955). As mentioned Poorly to moderately sorted sandstone and siltstone above, Riva's youngest Permian member rests un­ with sparry calcite and brown organic-rich clay cements conformably on all the older members and is lithically are also present. The clasts in these rocks consist of similar to the Newark Canyon Formation as described irregularly shaped subangular fragments of quartz, by Nolan, Merriam, and Williams (1956). Dott (1955, chert, and calcite; the latter clasts tending to be more p. 2273), in his discussion of the Permian in the Dia­ rounded than the siliceous ones. Also noted were zircon, 32 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA muscovite, oligoclase or andesine, chlorite, microcline, This sample is similar to the above in fauna and age signif­ and tourmaline grains. Some specimens contain about icance. * * * f21921 <=ES-57-14F) White Pine County, Nev. 1 percent diagenetic euliedral pyrite. With an increase 1,450' N. 69° W. of ele. 6,798 northwest of Newark Valley in the amount of clastic and cementing calcite, the School, west of sec. 15, T. 20 N., R. 55 E., Eureka quad­ sandstone and siltstone grade into the common sandy rangle. limestone. This sample is dominated by bryozoa of ramose and fenes- The composition, texture, and stratification of these trate forms. It also contains scattered abraded fusulirid Fora- minfera and other fossil debris. The fusulinids are of the genus varied rocks of the Carbon Ridge Formation indicate Schwagerina and do not appear to be too different fr->m those that they were deposited in agitated shallow waters in sample f21917-ES-57-12F. * * * into which a considerable volume of terrigenous clastic f21919 ( ES-57-12F) White Pine County, Nev. debris was introduced. The less disturbed calcareous 6,400' S. 83%° W. of BM. 5,874, south of DeBernardi Ranch, rocks alternate with well-sorted sandstone and minor near center of sec. 9, T. 20 N., R. 44 E., EureVa quad­ rangle. conglomerate. Some poorly sorted biomicrudite indi­ This sample is very similar to f21916. * * * cates possible rapid removal of the sediment to below f21920 (=ES-57-13F) White Pine County, Nev. the limit of effective wave action, either by subsidence 7,300' S. 74° W. of BM. 5,874 south of DeBernarli Ranch or submarine sliding. The evidence indicates mixed in SW% sec. 9, T. 20 N., R. 55 E., Eureka quadrangle. sedimentation in a shallow unstable basin. The fusulinids are of a form which has been variously called Pscudofusiilina or Schwagerina. The form in this sample is The rocks of the Carbon Ridge Formation correlate relatively advanced and suggests an age which, although still with the Garden Valley Formation in the Sulphur Early Permian, is probably younger than the other sfmples in Springs Range to the northwest, with the Strathearn this shipment. and younger Permian formations of Dott (1955) in In summary: the Elko region to the north, and perhaps with several All these samples suggest Early Permian age with afnities to formations to the east. the Carbon Ridge Formation insofar as had been determined. Previous fossil collections from the Carbon Ridge These collections are all apparently from tH zones Formation indicated a Wolfcamp age for most of the recognized earlier (Nolan and others, 1956, p. 65-66), formation, although there is the unlikely possibility but they did not contain diagnostic forms and were that some older strata might be included at the base therefore not assigned to the zones. All these co1 lections and some slightly younger beds at the top (Nolan and are from the same few hundred feet of section. others, 1956, p. 65-66). Riva (1957) concluded that the The collection of Permian forms obtained from prob­ several Permian units he mapped were dominantly able fanglomerate was reported on by R. C. Douglass late Wolfcamp and Leonard but noted that no collec­ as follows (written commun., 1961) : tions were obtained from about the upper third of the f21918 (=ES-57-ll) Eureka County, Nev. section. Elev 7,887 (prominent hill) north-northeast of Ccttonwood Five new collections were made from rocks of Spring in SE% sec. 12, T. 20 N., R. 54 E., Eureka quad­ Permian age during the mapping. All were from the rangle. * * * Only fragments of fusulinids were recognized ar

Canyon rocks are included on plate 1 and in figure 4 formations, that is, the Carbon Ridge For­ because the main mass of the formation lies west of the mation or the Ely Limestone. faults that are the approximate western limit of the 4. A total thickness of more than 300 feet is locally mapping. present. Within the area shown on plate 1, the rocks mapped Fanglomerate unit: as Newark Canyon Formation consist of polymictic 1. Individual layers, as much as 50 feet thick, are conglomerate and lithic sandstone interbedded with traceable for only a few hundred feet at the siltstone. The dense fresh-water limestone that is most. typical of the Newark Canyon nearby does not occur 2. Layers are composed of angular to subround°d in the area mapped. The conglomerate and sandstone fragments from silt size up through blocks units are much more resistant that the finer grained as much as several meters long. elastics and form prominent ridges. Angular clasts of 3. Within most layers the clasts are derived limestone (some with Devonian fossils), chert, and mostly from either the Ely Limestone or the quartz are important components of the conglomeratic Carbon Ridge Formation, but the overall units, and similar lithic types occur in the sandstone. composition is more heterogenous than that These terrigenous clastic rocks are generally poorly of the megabreccia unit layers. sorted, and the compositional and textural evidence 4. A total thickness of more than 300 feet is locally indicate a strictly local source and rapid deposition. present. The unit is hard to differentiate from the unconform- The combined fanglomerate and megabreccia unit ably overlying Tertiary (?) f anglomerates unless the is overlain by thin Quaternary colluvium and alluvium angular relationship is exposed. Where the limestone in the mapped area. The unit appears to overlie, at clasts are lacking, it is difficult to separate Newark various places, rocks belonging to the Ely, Carbon Canyon rocks from the locally underlying Diamond Ridge, and Newark Canyon Formations. The un- Peak rocks. The Diamond Peak and Carbon Ridge conformable relationship over the Newark Canyon Formations probably were the source of most of the Formation is well exposed at several places west of the coarse detritus in this Cretaceous unit, but all the area of the map; inasmuch as the megabreccia unit older formations apparently contributed some material. dips less than 20° to the west and the Newark Canyon TERTIARY SYSTEM rocks are within 20° of vertical, the relationship is an The rocks of inferred Tertiary age include extensive impressive one. The origin of the megabreccia unit is not well under­ megabreccias and dissected fanglomerates on the west stood. The present distribution suggests a genetic re­ side of the Diamond Mountains (pi. 1; fig. 4) and two lationship with the higher structural blocks, and the dikes. breccia probably formed as slide masses from the crest FANGLOMERATE AND MEGABRECCIA of the range. The occurrence of rock types derived A megabreccia unit and a fanglomerate unit are from but one formation in each layer indicates that exposed over large areas along the west flank of the the Ely and Carbon Ridge Formations were at different- range. The two units are considered together here, even times singly available as source material. The fan­ though they are different in origin. The best exposures glomerates appear to be more local in origin and occnr are found in the vicinity of Palmer Ranch, Bank only high on the flanks of the range. Both the mega- Ranch, and in the canyons heading in the area west of breccias and fanglomerates include fragments of ques­ Alpha Peak ridge; these localities are west of the tionable Cretaceous rocks. mapped area. Those exposures shown on the map, how­ T. B. Nolan (oral commun., 1956-59) believes that ever, exhibit most of the characteristic features of both the megabreccias are probably Cretaceous in age. It units, as follows: seems more likely to the author that the breccias Megabreccia unit: formed during the final uplift of the range and hence 1. Individual layers are as much as 100 feet thick, predate the erosion that gave the range its present lensing out abruptly within less than 2 miles. form, including the erosion which results in the fan- 2. Layers are composed of angular fragments glomerate. The degree of dissection of the megabreccias ranging from silt size up through blocks as is considerably greater than that of the Quaternary (?) much as several tens of meters in maximum alluvial fans that predate the Pleistocene lakes. More­ horizontal dimension. over, the sequence of megabreccias has been extensively 3. Within most layers the clasts are derived from faulted. The megabreccias therefore are probably old^.r only one of the two most common source than fanglomerates and the alluvial fans. The possible MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA relation of the megabreccia unit and the fanglomerate LAKE DEPOSITS unit to the volcanic rocks outside the mapped area is Deposits formed in the extensive lakes that filled the discussed on page 62. large intermontane valleys during the Pleistocene Epoch constitute part of the valley fill. The only lake IGNEOUS ROCKS deposits examined are terraces, bars, and spits which The only igneous rocks in the area studied are two are younger than the major alluvial fans and pedi­ lamprophyric dikes of unknown age one cutting the ments. Ely Limestone on the northeast side of Diamond Peak about 4,SOO feet north of the summit, and the other BIOSTRATIGRAPHY AND AGE OF THE intruding the Black Point facies of the Chainman CARBONIFEROUS FORMATIONS Formation low on the west side of the range south of the head of Pedrioli Creek (fig. -4). By MACKENZIE GORDON, JR. The dike on Diamond Peak is exposed for about 280 vertical feet in a shallow gully extending eastward INTRODUCTION from the crest of the summit ridge. The rock is a The Carboniferous formations of the Diamond Peak iiepheline-bearing kersantite that is rich in diopsidic area include, in ascending order, the Joana Limestone, augite. Chainman Formation (as defined by D. A. Brew in The other dike was studied by J. H. Wallace (written this report), Diamond Peak Formation, and the Ely commim., 1961) who reports that the rock is a camp- Limestone. This sequence ranges from Early Missis- tonite. sippian (Kinderhook) to Middle Pennsylvanian (Atoka) in age. The uppermost beds of the Pilot Shale QUATERNARY DEPOSITS in the north-central part of the Pancake Pange, as Quaternary deposits of various types have been indicated by conodonts of the Kiplwnodella zore, identi­ mapped together as one unit. Little attention was fied by J. "W. Huddle (written commun., 1968), are given these deposits in the field, other than to map also Kinderhook in age, but this age has yet to be their contact with the bedrock. demonstrated in the Diamond Peak area. There highest Pilot beds seem to be missing on the east side of the ALLUVIUM Diamond Mountains because of erosion before deposi­ Four main types of alluvium were noted during the tion of the Chainman Formation. They are probably mapping. The first consists of younger deposits of sand present on the west side of the range beneath the Joana and gravel along the stream courses that have been Limestone, but fossils have not been collected from cut into the mountains. The second consists of isolated them in that area. patches of apparently formerly widespread older The author's interest in this sequence of Carbonifer­ gravels that may have been dissected as a result of ous rocks began in 1957, when he and D. A. Brew made recent uplift and westward-tilting of the Newark several fossil collections on the east slope of Diamond Mountain-Alpha Peak ridge structural block. The Peak. Studies of these collections, Brew's numerous third type is the pediment gravel in the topographic collections, fossils collected from the area by T. B. embayments on the east side of the range. A fourth Nolan and J. S. Williams (made available b^ Nolan), type consists of great thicknesses of fanglomerate and and one large collection taken by G. H. Girty in the other deposits that fill Diamond and Newark Valleys. area constitute the basis for this report. In addition, Unpublished seismic work in both valleys and deep a restudy of C. D. Walcott's fossils from Conical Hill exploratory drilling in Diamond Valley indicate the (fig. 1) and other localities in the Pinto Summit quad­ presence of several thousand feet of deposits on both rangle (now in the U.S. National Museum collection) sides of the range. has been made to provide a firm basis for identifying and interpreting the faunas from the type Diamond COLLUVIUM Peak section. The author is indebted to U.S. Geologi­ A veneer of rock fragments covers most of the un- cal Survey colleagues Helen Duncan for identification fcrested slopes of the range. At places this layer of of the corals, E. L. Yochelson, the gastropods, and I. mechanically derived weathered material is thick G. Sohn, the ostracodes. Six collections of calcareous enough to obscure all the bedrock. Landslide deposits foraminifers from members C and D of the Diamond are not common, although one or two partially dis­ Peak Formation were studied by Betty A. SHpp. sected probable landslides are located high on the east Relationships between the Joana Limestone, Chain­ flank of the range. man Shale, and Diamond Peak Formation are rather *-" CD B"1 P § K O .ft o pa 3 ^2 O u O p MISSISSIPPIAN SYSTEM I1 ! ff ^ " P"' CO* P t3 *H- M H" PROVINCIAL ct- ** gs O CHESTER KINDERHOOK OSAGE MERAMEC SERIES sf s S^ ^ J« i i CD g. 3 P o TO Cfl 3 Cfl Joana Limestone

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JOANA LIMESTONE AND ITS REGIONAL RELATIONS facies of the Joana Limestone contains beds only of In the Diamond Peak area the Joana Limestone is late Kinderhook age. These beds are present in Toll­ somewhat different lithologically, and represents a house Canyon in the southern part of the Eureka shorter time span than in typical exposures in its type quadrangle, just south of the Diamond Peak area. A area in the Ely district. The type locality of this for­ list of fossils identified by Merriam (in Nolan and mation is in Eobinson Canyon in the Egan Eange, 2 others, 1956, p. 55) from the basal limestone bed of miles northwest of Ely, Nev. As the exposure lies in the Joana includes the Kiuderhook brachiopod Shu- a rather highly mineralized area, the limestone is mardeUa cf. 8. missonriensis (Shumard). altered and little of its original lithic character and North of Tollhouse Canyon and on the east side of faunal content has been preserved. the Diamond Mountains, no outcrops of Jo^na are Outcrops on the west flank of Ward Mountain, known. The Joana is truncated beneath the Cl ainman roughly 9 miles south-southwest of the type locality, Shale, which rests unconformably on the Pilot Shale are typical of the Joana Limestone over much of east- in the more northerly sections on the east slop*- of the central Nevada. Here, the two-fold division of the Diamond Eange. The Joana is present, however, along formation into a lower massive crinoidal limestone the west side of the range in the northern part of the member and an upper slabby fossiliferous limestone Eureka quadrangle. Conodonts collected by Nolan member of roughly equal thickness is well exposed. At from that band of exposure in the upper repches of the base of the formation, but commonly concealed by Phillipsburg Canyon, include Siphonodetta, according talus and slope wash, is a zone of relatively thin shaly to J. W. Huddle (written commun., 1968), and are nodular limestone. The massive crinoidal unit, in­ Kinderhook in age. cluding the basal shaly beds, and the overlying slabby fossiliferous limestone unit are indicated on the cor­ CHAINMAN FORMATION relation chart (fig. 11) as L and U (lower and upper) In the area covered by Brew's map, the CHinman subdivisions, respectively. Both units can be recognized Formation is restricted to that part of the section in the mountain ranges east of the Pancake Eange. which lies beneath the Diamond Peak Formation and The age of the lower unit in the type region is Early above the Joana Limestone. Where the Joana is absent, Mississippian (Kinderhook). J. W. Huddle (written because of an erosional unconformity, and Chainman commun., 1968) recognized the tfiphonodeUa conodont rests directly upon the Pilot Shale. The mapped Chain­ zone in a collection from the top of the crinoidal mem­ man does not include any of the similar shale beds that ber on Ward Mountain. The upper thin-bedded lime­ iiitertongue with clastic beds of the Diamond Peak stone unit contains corals and brachiopods of the Formation. These intertongued shales have be°Ji map­ HomalophyUites-VesiculophyHum zone throughout. ped by Brew as part of the Diamond Peak. As the This zone is Early Mississippian (Osage) in age, ac­ earliest Diamond Peak beds datable by their fossil cording to Helen Duncan (written commun., 1965). content are Meramec in age and the highest beds of Corals typical of the. upper limestone unit in the Ely the Joana in this region are Kinderhook in age, a district are given in the U.S. Geological Survey Pro­ fairly sizable time span could be assigned to th°> Chain- fessional Paper 276 (in Nolan and others, 1956, p. 56). man Formation, but much of this time is instead prob­ Both subdivisions of the Joana Limestone can be ably represented in the unconformity at the base of the recognized in the various mountain ranges from the Chainman. Confusion Eange westward to the White Pine Eange. The lowest collection stratigraphically (UfGS loc. In the north-central part of the Pancake Eange, how­ 21269-PC) was made by Brew from the Water Canyon ever, only the crinoidal lower unit is present, and the facies of the Chainman Formation on the east slope of shaly and nodular limestone beds at its base contain the Diamond Bange, about 300 feet below the base brachiopods of late Kinderhook age. of the Diamond Peak Formation. The collection con­ West and north of the Pancake Eange exposure, the sists of a single impression of an ammonoid, th

tocanites, the fact remains that this shell from the This collection, were it Osage in age, would be the Water Canyon facies cannot be identified as to genus. only one of that age found in the Eureka and Pinto Shells of this shape range well up into the Mississip- Summit quadrangles. Occurring as it does almost pian, even as high as Chester. at the top of the Chainman Formation, there is little likelihood that it is earlier than Late Mississippian A second collection, also from the Water Canyon facies, was made by J. S. Williams in 1938 in a section (Meramec) in age. that he and Nolan measured up the southeast slope of As to the age of the lower part of the Chainman, no Bold Bluff. A plot of the section shows that the col­ paleontologic evidence has been found in the Diamond lection came from a dark-gray limestone lens 227 feet Peak area. The nearest available evidence conies from below the base of the Diamond Peak Formation. The near the southeast corner of the Pinto Summit quad­ following fossils were recognized (USGS loc. 14690- rangle in the section shown by Stewart (1962, p. C?9) PC): as undifferentiated Chainman-Diamond Peak. In this part of the Pancake Range the basal unit of the Chain­ Cystodictya sp. Quadratia hirsutifornris (Walcott) man Shale is a dark-grayish-brown platy hard siliceous Atiloprotonia sp. shale, which is devoid of fossils and is slightly more LeiorhyncJitts car'boniferum Girty than 200 feet thick. Tylothyris sp. The basal shale unit is overlain by several hundred This faunule is Late Mississippian (Meramec) in age. feet of dark-gray soft shale containing sideritic and As the mapping shows Chainman Formation at this clay-ironstone nodules. In this second unit the autl or locality, places the Chainmaii-Diamond Peak contact and F. G. Poole collected specimens of Rayonnoceras, approximately at the same horizon, and recognizes 110 a nautiloid genus known elsewhere in the United States faults between the fossil bed and the top of the Chain­ in beds of Late Mississippian (late Meramec through man where this section was measured, it seems safe Chester) age. These fossils came from near the e^.st to regard it as a ~bona fide collection from the Chain­ edge of SEi/4 sec. 27 (unsurveyed), T. 17 N., R. 55 E. man Formation. They were estimated to occur between 250 and 300 feet above the base of the Chainman Shale. Conodonts hr.ve A third collection was made by Brew, 20 feet below been searched for in these lower beds of the Chainman the top of the Black Point facies of the Chainman by Huddle and the author, but none has, as yet, been Formation on the west side of the range. The follow­ found. ing fossils occur as molds in fine-grained sandstone These basal units of the Chainman Shale can be (USGS loc. 21277-PC) : recognized farther north in the Pinto Summit quad­ Fenestella sp. rangle, in Secret Canyon and the Packer Basin. THy Cystodiotya"! sp. do not, however, seem to be present in sections on the Crinoid columnals Schisophoria sp. slopes of Diamond Peak. Strophomenoid brachiopod, gen. and sp. indet. The faunal evidence discussed above, though meager, Cleiothyridina cf. C. incrassata (Hall) points to a Meramec age for the Chainman Shale in Naticopsis"! sp. indet. the Diamond Peak area. This agrees with the Late In the southern part of the Mississippi Valley region, Mississippian age suggested for this formation in the Cleiothyridina. incrassata and a closely related species Eureka district by Nolan, Merriam, and Williams are characteristic late Osage forms and do not occur (1956, p. 60). in the Meramec Series. The temptation to regard this An idea of the extent of the hiatus represented by Nevada assemblages as Osage in age, however, gives the unconformity at the base of the Chainman can be way to the more sober reflection that perhaps so far gained by the realization that no fossils positively away from the Mississippi Valley Cleiothyridinas of identifiable as Osage or early Meramec in age hr.ve this sort might not have the same stratigraphic range. been found in the Eureka and Pinto Summit qurd- Like Spirifer brazerianux Girty and DimegaJasma raiigles. Locally, the Chainman rests directly upon the eurekensis Linz and Lohr, the large Cleiothyridina Upper Devonian part of the Pilot Shale. from the Diamond Range might be a Late Mississip­ pian version of a closely related but different and DIAMOND PEAK FORMATION earlier species in the American Midcontinent. We The Diamond Peak Formation, unlike the Chain- simply lack sufficient knowledge at present to employ man Shale beneath it, is abundantly fossiliferous at in the American West a rule of thumb based upon many localities. The most profusely fossiliferous bels, relations in a depositional basin so remote from it. in numbers of species present, are limestones inter- 38 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA calated with the dominantly clastic sequence. Many MEMBER B calcareous pebbly sandstones abound with limy fossils, Twelve collections, most of them small, were studied however, and various finer grained sandstones and from rocks assigned by Brew, either definitely or coarse-grained siltstones bear mold faunas. The shale tentatively, to member B. Four collections are from the units are relatively unfossiliferous, except in sparsely measured type section of the Diamond Peak Forma­ distributed lenses of dark-gray limestone. tion. The fossil content of all 12 collections is given in The subdivision by Brew of the Diamond Peak into table 1. eight members for mapping has been extremely help­ The fauna of member B is similar to fninas of ful in delineating the faunal succession. His collections Meramec age, such as that of the Moore field Formation from the measured type section on the relatively un­ of Arkansas and Oklahoma. It is similar also to the disturbed northwest slope of Diamond Peak have con­ fauna of the Diamond Peak beds at Conical Hill, near tributed greatly to our knowledge of the biostrati- Eureka, Nev. (tig. 1), which is considered to be late graphy of the formation. Brew's material also has Meramec in age. However, as members C and D have enhanced our ability to correlate the formation with greater percentages of species in common with the other Upper Mississippian sections in the American Conical Hill fauna, member B is believed to be slightly West, older than the beds at Conical Hill. Identifications of fossils from the 59 Diamond Peak Of -48 species recognized in member B, 20 species Formation collections are given in tables 1-4. These (42 percent) occur also at Conical Hill (table 1). include calcareous foraminifers from member D of Distinctive species common to member B and Conical the Diamond Peak Formation, studied by Betty A. Hill include SehellwieneUa n. sp., Neochonetes sp. A, Skipp. Foraminifers from member C are listed in the Iiifatia sp. B, Moorefielddla eurekensis (TTalcott), text. About 210 species of invertebrates have been tfpirifer aff. X. arkanscmus Girty, and Tylothyris n. sp. recognized in this formation in the Diamond Peak Apparently restricted to member B and not recurring area. The faunas are discussed below, member by at Conical Hill are AnopJiopsis sp., Brachythyris sp. member. A, and Echhwcorlia sp.; all three of these genera are The location of the Meramec-Chester boundary as it represented by similar forms in the Moorefnld For­ relates to the formation is also discussed. As nearly as mation and its stratigraphic equivalents. The Moore- can be determined, this boundary is located near the field fauna also has many genera represented ty closely top of member D. The Mississippian (Chester)-Penn- related species in the Conical Hill fauna of the Dia­ sylvanian (Morrow) boundary is not believed to occur mond Peak Formation. within the Diamond Peak Formation. Few, if any, species of the Conical Hill faima occur in the Ferdelford beds at, or near, the base of the MEMBER A Diamond Peak in the Carlin region, although several No fossils have been found in member A, which, of the same genera are present. Moreover, none of the therefore, must be dated by interpolation based upon Ferdelford species appears to be present in member B. its stratigraphic position. Having argued for the The fauna of member B therefore has a closer relation Meramec age of the Chainman Shale, based principally with late Meramec than with early Meramec species, upon the collection of that age from the upper part of and the member is believed to be middle- to late the Chainman at Bold Bluff, the author obviously Meramec in age. believes that member A also is Meramec in age. MEMBER C One piece of negative evidence for this belief is Six collections of megafossils made by Br°,w from the absence in the Diamond Peak area, in fact in the member C, three of them from the measured type sec­ entire Eureka district, of the late Osage to early tion, have been studied by the author (taWe 1). In Meramec fauna that occurs at, or near, the base of the addition to these collections, foraminifers from a lime­ Diamond Peak Formation at Ferdelford Creek and at stone in the type section were studied by Betty A. other localities in the Carlin quadrangle (Gordon and Skipp. The megafossils came mostly from calcareous Duncan, 1962). The most likely explanation for this shales and coarse siltstones or fine sandstones; the is that the same span of geologic time represented by fossils, relatively few in number of species, occur as the Ferdelford beds falls within the hiatus at the base molds. The preliminary study of this fauna indicates of the Chainman Shale in the Diamond Peak area. that of a total of 30 megafossils, 17 (55 percent) are But the possibility that the Ferdelford fauna is absent represented also in the fauna from Conical Hill. One because of faeies differences cannot be ruled out at of the most striking species is Dirnegalasma eurekensis present. Linz and Lohr, a large spiriferoid brachiopod, which BIOSTRAT1GRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS 39

TABLE 1. Fauna from members R-D of the Diamond Peak Formation, Diamond Peak area, Nevada and from Conical Hill, Eureka district, Nevada

[See register for descriptions of fossil localities]

Member B 1 Member C Member D Collecting localities

Fauna o O ConicalHill O O O O O o O o fe 0 V 0 O o o F14-59-ES 5608-PC *t P^ & P^ P^ Hi 1278-PC PH 1280-PC CH kA PH 1283-PC 1285-PC 1286-PC 1288-PC 1289-PC V t- n ^ ^ ^ j-t * 3 % CO o> CO kA o O5 rH 01 01 01 t t~ o 00 00 00 00 00 t- t^ 00 kA I- t- t- 00 00 t- 00 o 0 0 o « to 01 Cl 01 Cl 01 01 01 01 01 01 01 0) 01 Cl 01 01 K 01 01 01 01 01 01 01 01 01 01 01 01 01

Corals :

V

V X X X Bryozoans : v Fenestella sp. indet _ . X X X X X X v Archimedes sp. indet _ . Cystodictya sp X X v * Encrusting forms, indet Pelmatozoans : Pelmatozoan debris v Crinoid columnals X X X X . X X X X V X X X X * Echinoid plates and spines v * Brachiopods : Rhipidomella sp _ 9 Schizophoria sp. indet V SchellwieneUa n. sp _ . v * Orthotetes cf. 0. kaskaskiensis (McChesney) _ _ __ _ v ? * Strophomenoid, gen. and sp. indet _ . X X Neochonetes sp. A v X X * Neochonetes sp. B X X * Anopliopsis cf. A. subcarinatu (Girty) v Quadratia hirsutifonnis (Walcott) ? Krotovia sp v _ ? Inflatia sp. B v v v * Echinoconchus cf. E. alternatus (Norwood and Pratten) X * Echinoconchus aff. E. biseriatits (Hall) * Auloprotonia sp v X X * Ovatia cf. 0. latior (Snider) _ _ v X V X * Ovatiat V v v * Rhynchopora sp X * Anthracospirifer aff. Anthracospirifer pellaensis (Weller) ? X .__ X .__ X ._- * 9 ? * V X X Tylothyris n. sp ______v * 7'fi't*j/'M i'ff^f* QTI i n fl At" X X V X v X __ ? Compositaf sp. indet ______v Reticulariina aff. R. spinosa (Meek and TVorthen ) * Dimeffalasma eurekensis Linz and Lohr v * * V * Dielasma aff. D. bisinuatum (Weller) X Pelecypods : * * X ) - X Aviculonecten eurekensis Walcott y * 40 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

TABLE 1. Fauna from members B-D of the Diamond Peak Formation, Diamond Peak- area, Nevada and from Conical Hill, Eureka district, Nevada Continued

Member B Member C Member D Collecting localities

Fauna 0 0 ConicalHill 0 0 0 o o O O 0 O 0 PLH o 0 O 0 O 270-PC 279-PC 1283-PC 1286-PC 1288-PC 1289-PC 1290-PC F14-59-ES 1 1 1 1 W i 00 rH CO 10 00 O rH rH Ol CO 1O O 00 00 CO 00 00 00 00 1O 00 00 00 00 to to to to to Ol 01 01 Ol 01 01 01 01 01 w 01 IN IN 0) 01 01 01 01 01 01 IN IN Ol

Pelecypods Continued Limipecten sp X X * Streblopteria similis Walcott? X * Pectenoid, gen. and sp. indet V Posidonia becheri Bronn * Caneyella, cf. C. richardsoni Girty Myalina sp. indet Leptodesma protoformc (Walcott)? Schizodus sp X * Sphenotiis sp X X Cypricardinia cf. C. moorefleldana Girty ) * Edmondia? sp Gastropods :

Glabrocinguhiml sp. indet V Neilsonia sp ______V Cephalopods : Tylonautilus gratiosus (Girty) ? _ _ . v * Trilobites : > Kaskia sp _ _ _ X V Ostracode : "Paraparchites" sp _

was found at USGS locality 21271-PC. This collection The stratigraphic position of these fossils irdicates was not from the measured section, but is believed to to the author that zone 15 is represented here, rather have come from member C. than zone 16i. No evidence for the presence of the Betty A. Skipp (written commun., 1963) identified Lower Posidonia (Pi) zone below member D has been the following foraminifers from a limestone bed 161 found, and, as foraminiferal zone 15 includes thQ, lower feet above the base of member C (USGS foraminiferal part of that zone (Mamet and Skipp, 1970), the base loc. f21922) : of zone 16i probably lies within member D. C Endothyra tantaU (D. Zeller) 1953 Both megafaimal and microfaunal evidence irdicates C. Endothyra ex gr. E. bowmani Brady 1876, emend a late Meramec age for member C. Foraminiferal zone CIZN 1965 15, according to Mamet and Skipp (1970), occurs C Cornuspira sp. also in the Ste. Genevieve Limestone in the Mississippi C Brunsia spp. Valley region and does not extend downward to the C Earlandia spp. base of that formation. It seems reasonable, therefore, C Calispheara sp. to ascribe to member C an equivalence to at least part B Archaediscus ex gr. A. moelleri Bauzer-Chernoussova of the Ste. Genevieve. 1948 MEMBER D B. Glomospiral sp. C = common, R = rare, CIZN = Commission Internationale de la Eight collections of megafossils collected by Brew, Nomenclature Zoologique. seven from the measured type section on the northwest slope of Diamond Peak, are given in table 1. An addi­ She commented on the collection as follows: tional six collections from the east slope of t!N°s Dia­ This fauna belongs to zone 15 or 16, but does not contain the mond Range, one made by Girty, three by No] an and distinguishing elements of either. It is thought to be younger Williams, and two by Brew and the author, ar*- given than 14, based on the common occurrence of Cornuspira. in table 2. These collections have been recorded in a BIOSTRATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS

TABLE 2. Fossils from beds assigned to member D of the Diamond Peak Formation, on the east slope of the Diamond Range and at Conical Hill, Eureka district, Nevada [See register for descriptions of collecting localities]

USGS locality USGS locality

ConicalHill ConicalHill u o u y o 0 o U CM OH CM OH U

Corals : Pelecypods Continued X X X * Bryozoans : V V * Modiomorpnal pintoensis Walcott? ______X Fistuliporoid, gen. and sp. indet xxxx X * * Stenoporoid, encrusting form, indet X X * Sphenotus salteri (Walcott) ______X ramose form, indet y * sp. A X X X Anisotrypa sp * sp. B _ _ _ _ _ V FenesteJla sp * X X X X X Polyporal sp X X * sp. B _ _ * Cystodictya sp _ _ ) * sp. C X X X X Solenomorpha sp X * Echinoderms : Crinoid columnals X X X * * X X X * Echinoid spines _ _ X Y aff. O. striata (Walcott) Cypricardinia aff. C. moorefieldana Girty X X ~ * Brachiopods : V * Orbiculoidea aff. O. moorefieldana (Girty) _ X * * RMpidomella n. sp V * Schizophoria sp V X * Schuchertella sp _ > Scaphopods : * Orthotetes cf. O. kaskaskiensis (McChesney X ' Dent ali um sp _ _ _ X Neochonetes sp. A X V V * sp. C X Quadratia hirsutiformis (Walcott) V V * Krotovia sp _ _ * Gastropods : * Straparolltis (Euomphalus) sp. A X X * sp. B _ _ _ * (Euomphalus) sp. B _ _ X * * Belleropfion sp _ ? * X * X * Knightites (Retispira) sp Y sp. B V * Euphenites sp. indet _ V * Rhineodermal sp. indet V aff. E. biseriatus (Hall) _ _ __ . * Trepospira ? sp. indet X Banleal sp. indet X X X X X * X * X X X - * X * Lunulagona sp V x . * Pleurotomariacean aff. Caliendrum sp X V * Moorefieldella eurekensis (Walcott) __ _ X X - V * G-labrocingulum neradenae (Walcott) ____ ? X * sp V Leiorhynchus carboniferum polupletirum Girty _ X y Pleurotomariacean aff. Nielsonia sp V Wort henia ? sp X X X * X * Gosseletina ? sp. B _ X sp X Pleurotomariacean gen. indet. A X Anthracospirifer cf. A. Wfitrcatus (Hall) X X * Y X X * sp. B X * Platt/ceras (OrthonycJiia) sp _ V * Naticopsis (Naticopsis) sp. A X * (Naticopsis) ? sp. B _ _ V * (Jedria) sp _ ____ V * Gen. indet. cf. Platyzona. sp X X * "Lofonema" bella Walcott V X X * Stegocoelia sp. A V X X :: X * sp. B V Dimegalasma eurekense Linz and Lohr __ X X \ * V * InntJiinopsis sp _ _ V * Beecheria sp ? * Cranaenat sp Cephalopods : Pelecypods : Nuculopsis levattformis (Walcott) X X y * V X X X X X X * V Yoldia sp * V Paleoneilo sp. A * sp. B _ _ _ Trilobites : Paleoneilo"! sp _ Y > * Parallelodon aff. P. truncatus (Walcott). X * Pterinopecten spio Walcott _ Ostracodes : Aviculopecten a finis Walcott X X ? X * eurekensis Walcott X X * "Paraparchites" n. sp. aff. "P." cyclopeus ? * Girty. 1910 _ _ V cf. "P." nickelsi Ulrich, 1891 V GrrapJiiodactyllis sp X * SansabeUa"! sp__ Y * X Pernopecten sp X * Posidonia becheri Bronn X X * Fish : Posidonia ? sp x . 42 MISSISSIPPI AN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA separate table so as not to prejudice the faimal evidence occurrence of P. becheri should be assigned to the from the measured type section. Assignments to a spe­ Lower Posidonia (Pi) zone. cific member generally are less certain on the east side Posidonia becheri is present in two other collections of the range, owing to faulting, than on the less dis­ (USGS Iocs. 14694-PC, 14695-PC) from the e,<\st slope turbed western side. Nevertheless, the author feels rea­ of the Diamond Range (table 2), all believed refer- sonably certain of the correct assignment of these col­ rable to member 1). A small crushed indeterminate lections to member D. Foraminifers found in five rock goniatite~ from USGS collection 14694-PC was said specimens collected for petrographic examination were by the author (Gordon, in Nolan and others, 1956, p. studied by Betty A. Skipp. 61) to have surface sculpture that suggested the genus Member D is the most highly fossiliferous unit of Crarenoceratoides of the Upper Eumorphoceras (E2) the Diamond Peak Formation. The Conical Hill fauna zone. Although nothing is intrinsically wrong with this reaches its most prolific development in this member. comment as stated, it is nevertheless misleading. The Species that occur in the beds at Conical Hill and in statement was made without the author's having seen member I) on the east slope of the Diamond range are the rest of the collection. The presence in the collection given in table 2. The fauna is varied. Several cal­ of such forms as Quad rat ia, hirsutiformis (Yralcott), careous sandstone beds in this member contain as many Leiorliynchus carbonifentni polypleurum Girty, and as 25 species of megafossils, but the limestone beds P. beeheri Bronn shows that it cannot be younger than are by far the most highly fossiliferous, in both num­ Posidonia zone. A general similarity exists between bers of individuals and species. A dark-gray lime­ the Diamond Peak collections that contain P. becheri. stone at Bold Bluff (USGS loc. 6567-PC) yielded 121 and the fauna of the Moorefield Formation of Arkansas species of fossils. Particularly striking is the number as restricted by the author (1948), in the upper beds of mollusks in this part of the section. The member D of which P. becheri is found. megafauna in our collections aggregates 142 species In Brew's measured type section of the Diamond subdivided as follows: 3 corals, 7 bryozoans, 2 echino- Peak Formation, 100 feet above the bed that contains derms, 44 brachiopods, 42 pelecypods, 2 scaphopods, Posidonia becheri. a sandy limestone bed (USGS loc. 34 gastropods, 6 cephalopods, 1 trilobite, and 1 fish. 21289-PC) is crowded with shells of a terebratuloid Of these 142 species, 85 (60 percent) are present also brachiopod identified as Dielasma aff. D. bisinuatum in the beds at Conical Hill. In addition, the microfauna (Weller). This shell is distinctive in having a median includes at least 32 foraminiferal and 5 ostracode fold in the pedicle valve and a corresponding median species. sulcus in the brachial valve. It appears to be fairly similar to Weller's species from the St. Louis Lime­ MEGAFAUNAL EVIDENCE stone. The base of member D in the type section is marked No particularly diagnostic megafossils ar? known by a bed that contains (Helen Duncan, written com- from the upper half of member D in the type section, inun., 1963) the colonial coral Siphonodendron, but microfossil evidence partly fills the gap. represented by an undescribed species having a rather strong columella, associated with the brachiopod MICROFAUNAL EVIDENCE Auloprotonia (USGS loc. 21285-PC). Float specimens Foraminifers studied by Betty A. Skipp indicate of the same coral (USGS Iocs. 21273-PC, 21286-PC) that zones 16i and 16s of Mamet and Skipp (1970) are were regarded by Brew as derived from this bed. present in the upper 150 feet of member D. Zone 16i fliphonodendron is generally regarded as restricted to contains foraminifers that are found also in the upper the Meramec Series in the United States. part of the Lower Posidonia (Pa ) zone of th? British About 90 feet above the base of member D, a small Carboniferous section; zone 16s contains forrminifers collection (USGS loc. 21287-PC) contains Posidonia commonly found associated with ammonoids of the becheri Bronn. This pelecypod is particularly char­ Upper Posidonia (P2 ) or Goniatites granoms zone. acteristic of the Lower Posidonia (Px) zone of the Both ammonoid zones are late Visean in age. The British Carboniferous section and equivalent rocks at foraminiferal collections are given in table 3. many localities in the Northern Hemisphere. P. becheri Because of the questioned identification of Neo- ranges upward and is found sparingly in the Upper archaediscus sp. in USGS collection f21923 (table 3), Posidonia (P2 ) zone at a few scattered localities but 246 feet above the base of the member, Skipp (written has not thus far been found in that zone in the east- commun., 1968) was not positive whether zone 15 or central Nevada. Foraminiferal evidence from beds zone 16i is represented. The stratigraphic position of higher in member D indicates that the Diamond Peak the collection, however, 156 feet stratigraphically BIOSTRATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS

TABLE 3. Calcareous foraminifers from member D of Hie Mountains region of Oklahoma, in the upper par*; of Diamond Peak Formation, Diamond Peak area, Nevada. the Moorefield in northern Arkansas, and in the Ste. [Identifications by Betty A. Skipp. See register for description of collective localities. R, rare; x, occurrence; C, common] Gene vie ve Limestone on the east side of the Missis­ USGS foraminiferal sippi River in Illinois and Kentucky. collection Precisely where the limits of the Pi zone occur in the eo * w to t- Diamond Peak section is not certain, but the rone C-l M c > X in the Upper Posidonia. (P2 ) zone of late Visean age, C X X C X X X - which is also known as the Goniatites granosus zone. Palaeotextularia ex. gr. P. consobrina Lipina 1Qii.fi C X Climacammina ex. gr. C. prisca Lipina 1948 _. C X MERAMEC-CHESTER BOUNDARY R X spp - The combination of macrofaimal and microfaunal R evidence in member D of the Diamond Peak Formation X pandorae (D. Zeller) 1958 V focuses attention on a divergence of criteria for the phrissa (D. Zeller) 1953 X ex. gr. E. boicmani Bradv 1876 emend. precise location of the Meramec-Chester boundary. It CIZN 1965 *_ __ _. c X excellens (D. Zeller) 1953 <" has been customary for U.S. Geological Survey bio- tantala (D. Zeller) 1953 X ex. gr. E. ? priaca Rauzpr-Ohprnoussova and stratigraphers in the Western United States to place Reitlinger) 1936 V C R the base of the Chester Series equivalents just above X X X compressus (Rauzer-Chernoussova and the top of the Faberophyllum coral zone in dominantly Reitlinger) 1936 _ _ R R limestone fades where such corals are present and just ArcTiaediscus krestovnikovi Ranzer- V below the Goniatites granosus (P2 ) ammonoid rone ex. gr. A. krestovniJcovi Rauzer-Chernoussova v ex. gr. A. moeUeri Rauzer-Chernoussova in fine-grained clastic facies where corals are normally 1948 _ _ _- r X X qn X X absent. Recent foraminiferal studies by Mamet m R c X R (written commun., 1968) have indicated that the top c X X X Eostaffella (ParamillereUa) tortilla (D. Zeller) of the Faberophyllum zone corresponds approximately 1953 _ _ V X X Pseudoendotliyra sp _ . R with the top of foraminiferal zone 15, and the bas? of Cornuspira sp _ c X X Calcispheara sp _ _ _ the Goniatites granosus zone with the base of zone 16s. Hedraitest sp X This relation implies that the intervening zone 16i would be referred to the Chester in limestone sect:ons above a bed containing Posidonia becheri, indicates where corals are present, and to the Meramec in sec­ that assignment to zone 16i is preferrable. USGS col­ tions composed mainly of fine-grained clastic rocks lection f21924, 265 feet above the base of the member, where goniatite assemblages are present. contains a typical zone 16i fauna, according to Skipp. The problem is complicated by the fact that in the A small collection (TTSGS f21925), 325 feet above type region of the Meramec Series in Missouri, the the base of the member, belongs in zone 16, but it does Upper Mississippian section is incomplete. Erosion not contain sufficient diagnostic species to assign it has removed part of the Ste. Genevieve Limestone, the either to zone 16i or 16s. uppermost formation included in the Meramec Series. Two collections (USGS f21926, f21927) from a lime­ West of the Mississippi River, in the type sectior of stone bed 6 feet belo\v the top of the member are the the Ste. Genevieve Limestone, the upper part of rone lowest that contain a microfauna definitely assignable 14 and only the lower part of zone 15 are present to zone 16s, according to Skipp. Common Neoarcliae- (Mamet and Skipp, 1970). East of the Mississippi River, the Ste. Genevieve includes the upper part of di-scus and Eostaffella are the diagnostic foraminifers. zone 14 and all of zones 15 and 16i (Mamet and Skipp, CORRELATION 1970). The type sections of the Aux Vases Sandstone Combined macrofaimal and microfaunal evidence in Missouri and of the Renault Formation in soutl ?rn indicates that a large part of member D, from 90 to Illinois are referred to zone 16i by Mamet and SHpp 265 feet above its base, can be assigned with confidence (1970). Thus, they regard zone 16i as the basal rone to the Lower Posidonia (Pi) zone of late Visean age. of the Chester Series in the Mississippi Valley. Rocks of similar age containing megafaunas assign­ The author considers the brachiopod fauna of the able to this zone are present in the Chainman Shale on beds on Conical Hill as very*f late Meramec in age.o both sides of the Nevada-Utah State line, in the lower Just below these beds near the top of the Chainman part of the Caney Shale in the northern Arbuckle Shale at Conical Hill, as mapped by Nolan (1962r pi. 44 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

1), some of the same brachiopods occur is association feet of member D and as G. gi'tmosus has beer recog­ with a primitive species of FaberophyHum, identified nized somewhere near the top of member E, it would by Helen Duncan (in Xolan and others, 1956, p. 60), seem safe to refer this member in its entirety to the P2 indicating a fairly late Meramec age. zone, The author (Gordon, in Nolan and others, 1956, It is not yet known whether the Conical Hill p. 61), reporting on the presence of the nautiloid brachiopod fauna occurs in association with zone 16i Tylonautihis sp. in the type Diamond Peak section foraminifers. As far as is now evident, both the posi­ (USGS loc. 14698-PC), pointed out that in Europe tively and tentatively identified 16i collections occur Tylonautihis is generally restricted to the Upper in member D above the abundantly fossiliferous beds Enmorphocerax (E2) zone. Subsequent study of the bearing the Conical Hill megafossils. Almost no mega- Diamond Peak fossils and their stratigraphic occur­ fossils are known from the upper 150 feet of the mem­ rence have shown that most of the specimens cf Tylo- ber and no microfossils have been found in the member vautilus in the Diamond Peak Formation have come below that. from the PI and P2 zones. Member E is early Chester The Renault Formation in Illinois, of early Chester in age. age, carries a megafauna more like that of member E MEMBER F of the Diamond Peak Formation than of members Only two collections are available from member F. B-D. Both were made by Brew and the author on tl °, slope Obviously, further studies are needed of the Late southeast of Diamond Peak. The presence of Dia- Mississippian megafaunas and microfaunas of both phragmus cf. D. c-estriensis (Worthen) in one collec­ the Great Basin and the Mississippi Valley regions to tion (USGS loc. 17178-PC) suggests an ewly to resolve this area of uncertainty. The author regards middle Chester age, as does the occurrence of Inflatia the bulk of member D, including all those beds that cf. /. ~btiobata Sadlick in the other collection (USGS contain the typical Conical Hill megafauna, as late loc. 17179-PC). Meramec in age. He concurs with Skipp in regarding Absence of recognizable corals and ammoroids in the top few feet of member D, with its zone 16s fora- member F and overlying members of the Diamond miniferal fauna, as Chester in age but wishes to reserve Peak Formation, as well as the present lack of fora­ judgment on the relationship of the Meramec-Chester miniferal evidence, precludes precise correlation of boundary to the 16i foraminiferal zone. The rather this part of the formation with other Missifsippian incomplete foraminiferal evidence would place the sections in the United States or with well-documented Meramec-Chester boundary somewhat lower, probably Carboniferous sections in Europe. For example, evi­ at least 135 feet below the top of the member. dence is not available to indicate accurately th?/ posi­ MEMBER E tion of the Visean-Namurian boundary of the- north­ west European section; however, as this boundary is Six collections were made in this member, four from based on goniatites, it must lie somewhere above the Brew's measured type section and two from rocks highest bed containing the ammonoid fauna of the outside the line of section (table 4). The lowest of Goniatites granosus zone, near the top of member E. Brew's collections (USGS loc. 21291-PC), 280 feet Presumably, therefore, most of member F is Nrmurian above the base of the member, contains species typical in age. Whether member F is late early Chester or of the Chester Series, such as Diaphragtnus cf. D. early middle Chester in age cannot yet be determined. cestt'iensis (Wortlien), and Anthracospirifer aff. A. increbescens (Hall). The same forms also occur in a FAUNAL HIATUS collection 110 feet higher stratigraphically (USGS In a large part of the Cordilleran region of the loc. 21293-PC). American West, including the Great Basin, the middle An imprint of Goniatites rhoctawensis Shumard in part of the beds of Chester age is recognized in sec­ siltstone (USGS loc. 21275-PC) in a small fault block tions combining limestone and shale by the presence on the southeast side of Diamond Peak possibly be­ of the coral zone of Caninia excentnca Mee-k (and longs stratigraphically between the two collections allied species), commonly known as the Caninia zone; mentioned above. Another collection from the same this is the K zone of Dutro and Sando (1963). In the general area (USGS loc. 21274-PC), which includes Great Basin these corals are commonly associated with imprints of Goniatites granosus Portlock, is believed an as yet undescribed species of the productoid brachi­ by Brew to have come from near the top of member E. opod Antiquatonia, which is abundant at some local­ As foraminifers typical of the Goniatites granosus ities. This brachiopod, which superficially resembles or Upper Posidonia (P2 ) zone occur in the top few the undescribed species of Auloprotonia in th°i lower BIOSTRATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS

TABLE 4. Fauna from members E-H of the Diamond Peak Formation, Diamond Peak area, Nevada [See register for descriptions of collecting localities] Mem­ ber Member E F Member G Member H USGS fossil collections

Fauna a 5-59-BS 1< PH PH PH J93-PC L78-PC L79-PC J76-PC PS PH >96-PC 298-PC 299-PC PL s 1 ? * in Cl ?b- l» * el t- ! i ! i^ ! © 0 C" Cl c: IN IN « M 01 M M

Corals : Zaphrentoid coral y Horn Coral Bryozoans : Fistuliporoid, gen. and sp. indet v v v Fenestella sp X X X NX y - X X V Pelmatozoans : X v NX v Brachiopods : OrWculoidea sp X X X X X X X X X X V v X X X V X X X X X Inflatia n. sp v X X X X X Inflatia sp. indet _ ____ v Kozlowskia n. sp X Flexaria aff. F. arkansana (Girtv) X X X X X X ? x~ Flexariat sp. indet . X V - X X X X V ? X X X X X X X X X X X X X X1 X X X X X X X X X Eumetrial sp. indet _ X X X Pelecypods : Poli devcia sp Paleoyoldia sp _ V X Aviculopecten spp _ _ ' Pterinopecten spio Walcott X X StreWopteria similis Walcott X X Posidonia sp Pteronites sp CaneyeUa cf. G. richardsoni Girtv NX Promytilusl sp X X X X X X X X X Conocardium sp w X X v v X X X Gastropods : v X X^ X v CoJeolus sp ______X 46 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

TABLE 4. Fauna from members E-H of the Diamond Peak Formation, Diamond Peak area, Nevada Continued

Mem­ ber Member E F Member G Member H USGS fossil collections

Fauna O2 O O O O O O o o O o o o 0 a O H O a o O O CM CM CM CM CM CM CM CM CM Cu fc PM V CM PM 7" CM 1 1 I 7 ^ T t 1 7 * l-f 7 10 iH o on ± t- i 1O 50 t- <^ <& o IN S!b* O5 X O5 t- t~ t- OS O5 OS t- K O5 O5 OS A f <& o 0 O w w M M Cl 10 iH TH iH M w W W W N lH IN 05 05 05 w w N W Cl iH iH iH ^ M w w w W N N iH W IN W IN

Cephalopoda :

V _ X

Trilobite : v >

part of the Diamond Peak Formation, is present at one of the most abundant, is a Diaphragimts-V&e, pro­ some localities where the corals are absent. Near the ductoid brachiopod identified in table 4 a^ "Dia- south end of Buck Mountains, 11 miles east-northeast p/it-agmus" aft'. "D." pJnlUpsi (Norwood and Flatten), of Diamond Peak, this Antiquatoma is fairly common which has compound diaphragms that form a series in calcareous shale and fine-grained sandstone beds of frills 011 the brachial valve. In the measured section in the lower 150 feet of the exposed section of the this species was common in two beds of drrk-gray Diamond Peak Formation. This species has not been platy shale, 27 and 97 feet above the base of the mem­ recognized in the section at Diamond Peak. ber \USGS Iocs. 21296-PC, 21298-PC). The species Were the Canhiia zone beds present in the Diamond also was recognized in a bed at the crest of the range, Peak section, they should be represented somewhere roughly 120 feet above the base of the member (USGS in the upper part of member F, or near the base of loc. 21276-PC). member G. The productoicl identified in member F Forms similar to, or identical with, this species occur (table 4) as Diaphragmus cf. D. eestnensis (Worthen) in the Chaimnan Shale in the Burbank Hills in west­ is common below the Ca>nitia zone in other sections ern Utah, beginning near the top of the Cravenocems where this zone is present. The productoid identified lienpenum animonoid zone and extending upward ap­ from the lower part of member G (USGS loc. 17177- proximately to the base of the Ely Limestone. Rhipi- PC) as "Diaphragmus" atl'. "/>/' phUUpsi (Norwood domella ueradeHxix (Meek) is also common in this and Pratten) is very common above the Caninla zone part of the section in western Utah. In member G in in other Great Basin sections. These two collections the Diamond Peak area, ti. necadensis was recognized were made on a spur on the east slope of Diamond only at USGS locality 17177-PC in the lower part of Peak and are about 250 feet apart stratigraphically. the member. Whether an unconformity is present between these Those two brachiopod species indicate that member two collecting localities or whether the absence of the G is late Chester in age. The observed stratigraphic Caninia zone fauna is due to a lateral facies change position of these brachiopods in relation to am monoids accompanied by thinning is not presently known. The in western Utah sections indicates that par4; of the possibility of cutout due to faulting also exists, but it Eiimorphoceras bisulcatum (E2 ) zone of Namurian A seems less likely because even in the measured type age is represented by member G. section, apparently undisturbed by faulting, this part of the beds of Chester age seems rather thin in com­ MEMBER H parison with other Great Basin sections. Five collections from member H have been studied, of which four are from the measured type section. The MEMBER G lowest collection, 19 feet stratigraphically above the Eight collections from member G were studied by base of the member (USGS loc. 21299-PC), i? from a the author, including six from the measured type sec­ gray-black limestone bed; it contains the long-ranging tion (table 4). The most characteristic species, and Leiorhynchus carbonifemm Girty in some abundance. BIOSTRATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS 47

The next collection, 97 feet above the base of the mem­ REGIONAL RELATIONS OF THE DIAMOND PEAK ber (USGS loc. 21300-PC), contains "DiapJiragmw" FORMATION AND THE CHAINMAN SHALE aff. "Z>." phUUpsi (Norwood and Pratten). As in the Perhaps by now the reader who has followed the Confusion Range section in western Utah, the strati- discussion finds himself wondering how the Chainman graphically higher forms of this distinctive Dia- Shale can underlie the Diamond Peak Formation in phragmus-like shell are somewhat more finely cost ate the Diamond Peak area and yet be in part equivalent than the stratigraphically lower specimens. elsewhere in age to the highest beds of the type Dia­ Seven feet stratigraphically above the last collec­ mond Peak. The correlation chart (fig. 11) was pre­ tion, one bed (USGS loc. 21301-PC) contains abundant pared primarily to explain this situation. RhipidomeUa nevadensis. Roughly 75 feet higher than The type section of the Chainman Shale is in Rotin- this bed, and 42.5 feet below the base of the Ely Lime­ son Canyon in the Egan Range, 2 miles west of Ely, stone, another bed (USGS loc. 21302-PC) contains Xev. Although the Chainman is less affected by altera­ a more varied fauna, including Kozloirskia n. sp. This tion than the nearby type exposure of the Joana Lime­ Mississippian Kozlowskia is locally abundant at the stone, its type section is sparsely fossiliferous and may top of the Chainman Shale in the Confusion and be incomplete. RhipidomeUa nevadensis (Meek), how­ Conger Ranges in western Utah. ever, occurs near the top of the Chainman. In the Member H, therefore, carries about the same fauna, Egan Range and in the Schell Creek Range, which lies to the east, the Chainman Shale is Late Missis­ though in less abundance, as the uppermost part of the sippian (Chester) in age. Ammonoids of the Goniat- Chainman Shale in the mountain ranges that flank the Nevada-Utah border east of Ely. The age of member ites granoxns zone ( = Upper Posidonia, or P2 zone) H is very late Chester. occur near the base, and brachiopods of the Rhipi- domeUa nevadensis zone occur near the top of the DIAMOND PEAK FORMATION OF THE LOWER PLATE shale. The Chainman Shale in its type region, there­ OF THE BOLD BLUFF THRUST FAULT fore, is approximately equivalent in age to members E through H of the type section of the Diamond PT,ak One collection was made from rocks assigned by Formation. No beds of Meramec age have been recog­ Brew to the Diamond Peak Formation of the lower nized in the Chainman Shale in the Egan and Schell plate of the Bold Bluff thrust fault. The collection Creek Ranges. (USGS loc, 17173-PC) contains the following fauna: Farther east, in the Snake and Confusion Ranges Horn corals, gen. and sp. indet. along the Nevada-Utah State line, the Chainman SI ale Fistuliporoid bryozoan, massive form Fistulioporoid bryozoan, ramose form has approximately the same upper limit as in the Ely Stenoporoid bryozoan, gen. and sp. indet. region, being overlain by the Ely Limestone. The lower Fene stclla sp. part of the formation, however, includes beds of Polypora sp. Meramec age, identified by their ammonoid-faunas Crinoid columnals content. These stratigraphically lower beds of the SchisopJioria sp. Neochonetes sp. A Chainman Shale are equivalent, at least in part, to Inflatia sp. A members C and D of the type Diamond Peak sect: on, Buxtonia sp. and unfossiliferous beds beneath the ammonoid-bear- Echinoconchus aff. E. bitseriatus (Hall) ing beds may correlate with even lower parts of the Auloprotonia n. sp. Diamond Peak section. Ovatin cf. O. latior (Snider) Striatifera n. sp. Beds of Meramec age are also present in the lower Moore fieldella eurckcnsc (Walcott)? part of the Chainman Shale west of Ely, in the WMte Anthracospirifer aff. A. pellaensis (Weller) Tylothyris n. sp. Pine and Pancake Ranges, but in that region tongues Pseudosyrinx desiderata (Walcott)? of Diamond Peak type clastic rocks extend eastward Hustedia sp. into the upper part of the Chainman. Where the Dia­ BeeeJieria? sp. indet. mond Peak facies is well developed, the top of the Avictilopecten haguei Walcott V Chainman Shale locally lies at different levels. Never­ This collection is typical of the Conical Hill fauna of theless, in parts of the "White Pine Range, beds of the Diamond Peak Formation and could belong in dominantly Chainman lithology contain all the major either member C or D. According to Brew, the material ammonoid assemblages of late Meramec and Chester is from rocks that may be approximately equivalent to age and locally extend upward to the base of the Ely the upper part of member C. Limestone. 48 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Some geologists have used the term "Illipah Forma­ Nolan and others (1956, p. 60) This report (table 2) tion" (Christiansen, 1951, p. 76; Bissell, 1960, p. 1427, Rhipidomella ncvadensis (Meek) Rhipidomella n. sp. 1433-1435) to designate coarse-grained clastic sedi­ Chonctes cf. C. oklahomensis Neochonetes sp. A mentary rocks at the top of the Chainman Shale in Snider the White Pine Range and in areas to the east. Others Dictyoclostus n. sp. Auloprotonia n. sp. have suggested dropping the name "Illipah" because Linoproductus "ovatus" (Hall) Ovatia cf. O. latior (Snider) they regard it as synonymous to the Scotty Wash Quartzite of the Pioche district (Steele, 1960, p. 99) Spirifer mortonananus Miller Spirifer aff. 8. hay^^nianus or to the Diamond Peak Formation (Sadlick, 1960, Girty p. 81-84). In the western part of the White Pine Brachythyris sp. Brachythyris sp. Range and in the Pancake Range, most coarse-grained Dimcgalasma cf. D. neglectum Dimegalasma eurekense clastic beds are lenses and tongues of Diamond Peak (Hall) Linz and Lohr rocks. In much of eastern Nevada, however, quartzites In the opinion of the author, all the fossils from and some limestone beds are fairly commonly inter­ both the Chainman Shale and the Diamond Peak calated with the upper part of the Chainman Shale. Formation in the immediate vicinity of Conical Hill Usage of the name "Illipah" for a stratigraphic occur in beds considered stratigraphically equivalent unit of Carboniferous age has never been properly to member D and perhaps to the uppermost part of formalized by designation of a type section and iden­ member C of the type Diamond Peak section, a few tification of the delimiting strata. Christiansen's orig­ miles to the north. The presence of Fdberophyllum in inal usage of the term "Illipah Formation"' was merely beds mapped as Chainman, recognized by Helen Dun- passing mention in a guidebook article. The same name, can (Nolan and others, 1956, p. 60), indicates thr.t these however, has been formalized for an Eocene formation beds are rather late Meramec in age. in northeast Nevada (Eakin, 1960, p. 26; Humphrey, True RhlpidomeUa nevadensis (Meek) is restricted 1960, p. 41-42, pi. 1). The name should therefore not to members G and H of the Diamond Peak Formation, be used for any part of the Carboniferous. its uppermost subdivisions, and to the lower Hds of In the Pancake Range the Upper Mississippian sec­ the Ely Limestone. This species, associated with a late tions exhibit a general merging of Chainman and Dia­ Chester fauna, has been found in typical Chainman mond Peak lithologies. Stewart (1962, p. C59) found Shale lithology on the east slope of the Diamond it impossible to differentiate the two formations in the Mountains north of Pinto Creek Ranch. Thus, age north-central part of the range, but divided the undif- determinations and biostratigraphic relations based ferentiated sequence into four informal units. Fossils upon contained fossils indicate that in some p^.rts of collected by Stewart during his study and by the writer the Eureka district the base of the Diamond Peak subsequently show that Stewart's lower two units, and Formation lies at considerably different levels and that at least the lower part of the third, are Meramec in tongues of Chainman-like shale interfinger with coarse­ grained clastic rocks of the Diamond Peak Formation almost as high as the base of the Ely Limestone. In the Eureka district the Chainman Shale, in the North of the Diamond Peak area, in the Pinyon two areas where it can be differentiated, is considered Range in the Pine Valley and Carlin quadrangles, as to underlie the Diamond Peak Formation (Nolan and mapped by Smith and Ketner (1968, p. 112-113), the others, 1956), but an intertonguing relationship exists Chainman Shale is of Early Mississippian age. On the between the upper beds of the Chainman and the bulk west slope of the range in the Pine Valley quadrangle, of the Diamond Peak Formation as represented by its where the so-called Chainman is locally overlain un- type section, in the Diamond Mountains and also near conformably by rocks of Late Permian age, it consists Eureka. Near Eureka, bodies of Chainman Shale have of a clominantly shale, siltstone, and sandstone sequence been mapped beneath the Diamond Peak Formation in that contains the ammonoid genus Protocanites in the the vicinity of Conical Hill in Windfall Canyon lower part, indicating late Kinderhook age, and a coral-brachiopod assemblage (including Trochophyl- (Nolan, 1962, p. 11, pi. 1). The stratigraphic equiva­ luni} in the upper part, indicating early Osage age lence of these beds to part of the type Diamond Peak (Gordon and Duncan, 1962, p. C233). Ely Limestone section is indicated by fossils from the Chainman caps the main ridge of the range. The so-called Chain- Shale listed by Nolan and others (1956, p. 60). These man Shale in this area is a temporal equivalent of fossils are relisted below, as originally identified and roughly the upper two-thirds of the Joana Limestone as given in table 2 of the present report: of the Ely district. BIOSTKATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS

In the Carlin quadrangle, including the northern part tion, beds that contain abundant brachiopods consti­ of the Pinyon Range, the Mississippian section prob­ tuting a fauna of late Chester age are probably equiva­ ably is without a stratigraphic break of any con­ lent to member H or to the upper part of member G. sequence. The upper part of the co-called Chainman The uppermost beds of the Diamond Peak Formation Shale includes beds of late Osage age. In the lower in Carlin Canyon are Early Pennsylvanian in age and part of the overlying Diamond Peak Formation, a carry a very early Morrow fauna; they are therefore yellow siltstone contains a fauna that can be placed equivalent in age to part of the Ely Limestone of the at, or near, the Osage-Meramec boundary. The upper Diamond Mountains and other areas (see fig. 1). part which contains the colonial corals ftiphonodendron Deposition of the Diamond Peak Formation in the (not the Diamond Peak species) and Diphyphyllum, Carlin region therefore began earlier and ended Inter is Meramec in age (Gordon and Duncan, 1962, p. than in the type region (Smith and Ketner, 1968 p. C234). The lower part of the Diamond Peak Forma­ 113). None of the faunas recorded from the so-called tion contains species of genera that cross the Osage- Chainman Shale and the basal part of the Diamond Meramec boundary such as the bryozoan Worthe- Peak Formation of the Carlin region has been found nopora and the brachiopods, Leptagonia, Setigerites, in the Diamond Peak area, or anywhere else in the Spirifei\ Clewthyridina, Composite, and Dimegalasma, Eureka district. which may belong in either series. These forms are associated, however, with ostracodes that, according ELY LIMESTONE to I. G. Sohn (written commun., 1962), are more The study of 18 fossil collections (table 5) made by typical of Late than of Early Mississippian age. Brew from the Ely Limestone demonstrates that the Higher in the Diamond Peak Formation of the Mississippian-Pennsylvanian boundary lies within the Carlin region, limestone beds contain the coral Fa- lower member of this formation, a little more than 80 berophyllum associated with the productoid brachiopod feet above its base. Only the lower part of the Ely Striatifera; just beneath these beds, dark-gray shales Limestone is exposed in that part of the Diamond contain brachiopods that occur also in the Moorefield Formation of Arkansas such as Quad ratio, hirsuti- Peak area where Brew's section was measured. No beds formis (Walcott), Leiorhynchus carbonifemm Girty, later than Early Pennsylvanian in age were recognized ^Spirifer^ maftiiniformis Girty, and EcJiinocoelia cf. in the section. Elsewhere in the Eureka quadrangle, E. pilosa (Girty). These beds are very late Meramec however, along the southwest edge of the mapped area, in age and roughly equivalent to member D of the Ely Limestone beds of Middle Pennsylvanian (AtoVa) type Diamond Peak section. Even higher in the sec­ age have been reported (Nolan and others, 1956, p. C3).

TABLE 5. Fauna of the Ely Limestone, Diamond Peak area, Nevada. [See register for descriptions of collecting localities] Upper Mississippian Lower Pennsylvanian Lower member I Upper member USGS collecting localities Fauna o 0 O O O O 0 O 0 O O 0 fc 1303-PC b 1305-PC L306-PC 04 1308-PC A A °T CU 176-PC 1

Rhipidomella nevadensis assemblage : Corals : AmpleseizapJirentisI sp _ _

Bryozoans : Stenoporoid, gen. and sp. indet Pelmatozoans : Crinoid columnals ______Brachiopods : Rhipidomella nevadensis (Meek) _ _ _ _ X X X X X Schteophoria cf. 8. texana Girtv X X Krotoviat sp v Inflatia sp EchinoconcJius sp _ ^ Buxtonia aff B subcircularis Sutton and Wagner Diaphragmus t sp X X Cvatia sp. B _ _ _ _ V y 50 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

TABLE 5. Fauna of the Ely Limestone, Diamond Peak area, Nevada Continued Upper Mississippian Lower Pennsylvaniin Lower member Upper member USGS collecting localities Fauna 0 O O O O O O O O O O fe CM L318-PC U76-PC & L304-PC & 2 L308-PC L309-PC & PH V ? * * -* * t- 05 10 to ti i rH N 05 IA o 0 5 J 0? OS 05 05 05 CO 05 05 CO ? § 05 05 OS rH 04 ei m « 04 04 N N 04 M M w O4 N W O4 H

Brachiopods Continued X X X X v ^ v X X x X X X X . y X v Pelecypods : v V v Sphenotus"! sp. indet _ _ _ _ v

Fish: V Rugoclostus n. sp. assemblage : Corals : Caninoid, pen. and sp. indet X Zaphrentoid, gen. and sp. iudet _ __ X X Bryozoans : Stenoporoid, gen. and sp. indet _ X X Stenoporoid, gen. and sp. indet (ramose) X X Fenestella sp Rhomboporoid, gen. and sp. indet _ _ X Pelmatozoans : Crinoid columnals v X Bchinoid spines _ _ ^ Brachiopods : Orbiculoidea sp _ _ V Strophomenoid, gen. and sp. indet __ Schizophoria cf. 8. texana Girtv X Neochonetes sp _ _ _ _ v Rugoclostus n. sp Flexaria sp _ V Antiguatonia sp Linoproductus sp X X Dictyoclostid, gen. and sp. indet V WellereUa sp Anthracospirifer occiduus (Sadlick) v Anthracospirifer opimus (Hall) X X Anthracospirifer rockymontanus (Marcou) X X v Neospirifer cf. N. cameratus (Morton) Cleiothyridina cf. C. orbicularis (McChesnev) _ Cleiothyridina sp X V Composita sp X X X X .__ Punctospirifer trans versus (McChesnev) X Reticulariina campestris (White) v V V Hustedia cf. H. miseri Mather V Beecheria sp. indet __ Pelecypods : Pelecypod indet _ _ _ _

LOWER MEMBER member. Torynifer cf. T. setiger (Hall), a character­ The fauna of the lower part of this member is a istic Mississippian form, was found from 31 to 55 feet continuation of the fauna of member H of the Dia­ above the base. mond Peak Formation. The uppermost Mississippian The fauna takes on a Pennsylvanian aspect 90 feet fauna contains abundant Rhipidoniella nevadensis above the base of the member, where productoid (Meek). This species is present in collections from brachiopods referrable to Rugoclostus and spirifers levels 2, 31, 36, 46, and 81 feet above the base of the identifiable as Anthracospirifer occiduus (Sadlick) BIOSTRATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS 51 appear. Although the two collections from the upper CORRELATION WITH HOMOCERAS ZONE part of the lower member are meager, the fossils in In the Confusion and Schell Creek Ranges a distirc- them are similar to those from the upper member; tive and, as yet, undescribed species of DiapJiragmus Rhipidoniella nevadensis was not found in these higher has been recognized in this Mississippian interval at beds. the base of the Ely Limestone. From beds containing

CRITERIA FOR RECOGNIZING THE MISSISSIPPIAN-PENNSYLVANIA this species on the east slope of the Schell Creek Range, BOUNDARY near Majors Place at the Junction of U.S. Highways In most of the Great Basin it is possible to recognize 6-50 and 93 (fig. 1), Mamet (written commun., 196°) the Mississippian-Pennsylvanian boundary within a has recognized his foraminiferal zone 19 fauna in one, few feet, or at worst, within a few tens of feet, by and probably a second, of four specimens provided by means of the brachiopod faunas. The author places the the author. This is the first record of zone 19 fora- boundary above the beds with a predominance of minifers in the Great Basin. Mamet has previously RhipidomeHa nevadensis (Meek) and below the first recognized this fauna in Idaho ("W. J. Sando, written appearance of the productoids of the Rugoclostus commun., 1698). A suite of specimens from the same assemblage. RhipidomeUa nevadensis has been found interval on Diamond Peak failed to yield any fora- locally in the Rugoclostus beds but is always rare. minifers. Characteristic of very Late Mississippian beds in the Zone 19 foraminifers occur in the northwest Euro­ Great Basin is a proliferation of medium-sized pro­ pean Carboniferous section in the Homoceras (IT) ductoids particularly of the genera Inflatia, Flexaria, zone. The ammonoid genus Homoceras has not be^n Ovatia, and related forms along with Torynifer. recognized in the United States. The Homoceras (P) These forms are succeeded in the basal Pennsylvanian zone in northwest Europe is suceeded by the Lower rocks by generally larger productoids of the genera Reticidoceras (Ri) zone, which also can be recognized Rugoclostus, Flexarial, Echinoconchus, Antiqiiatonia, in the lower part of the type section of the Morrow and Linoproductus. The location of the boundary by Series in northwest Arkansas. these criteria seems to agree rather closely with where Zone 20 foraminifers are fairly widespread in lower Girty placed the same boundary, as recorded in various Morrow deposits, according to Mamet (written com­ earlier U.S. Geological Survey publications on the mun., 1968). Zone 18 foraminifers occur in the type Great Basin. sections of the Clore and Kinkaid Limestones in Illinois Some geologists have recommended locating the (Mamet and Skipp 1970). Zone 19 seems to correspond base of the Pennsylvanian at the first appearance of in the American midcontinent to a hiatus at the Missis­ RhipidomeUa nevadensis, but this would introduce sippian-Pennsylvanian (Chester-Morrow) boundary numerous difficulties. For one thing, there is no obvious in the type areas of both series. faunal break at that level among the rest of the The beds at the base of the Ely Limestone, therefore, brachiopods. Also, as R. nevadensis in the Conger are post-type-Chester and pre-type-Morrow in age. As Range, Utah, has been found about 20 feet below a the fauna of this interval is overwhelmingly similar to bed containing the ammonoid Cravenoceras merriami fauna those of the Mississippian beds below, we r.re Youngquist, part of the Upper Eumorphoceras (E2 ) including these beds in the Mississippian. zone would have to be included in the Pennsylvanian. This step is not likely to be recommended by any UPPER MEMBER ammonoid specialist. Nine collections were studied from the upper mem­ REGIONAL DISTRIBUTION OF THE MISSISSIPPIAN ber of the Ely Limestone; eight are from the measured PART OF THE ELY LIMESTONE section (table 5). Characteristic of these higher cherty The Mississippian beds at the base of the Ely have limestone beds of the Ely are Rugoclostus n. gp., been recognized also in the Confusion, Schell Creek, Antiquatonia sp., Anthracospirifer occiduus (Sadlick), A. opimus (Hall), and Hustedia cf. H. miseri (Mather). and Egan Ranges. This part of the section has not As in other parts of the Great Basin, the Chester been studied in detail in the Snake, White Pine, and spiriferinids Punctospirifer transversus (McChesney) Pancake Ranges. Normally, the thickness of these beds and Reticidariina campestms (White) range upward is nearer to 50 feet than to the 80-odd feet measured in through beds of Early Pennsylvanian age. As far as the section 011 Diamond Peak. This thickness is con­ could be determined, no beds of Middle Pennsylvanian sistent with the greater overall thickness of the Tipper (Atoka) age occur in the measured section on Diamond Mississippian section in the Diamond Mountains. Peak. 52 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

CONCLUSIONS Piny on Range (north) area of the Carlin quad­ The author's biostratigraphic studies in the west- rangle are Early Pennsylvanian in age. central part of the Great Basin, and particularly in 13. The Mississippian-Pemisylvanian boundary lies the Eureka district, permit the following conclusions within the lower part of the Ely Limestone in to be drawn regarding the age and correlation of the the Eureka district, as well as in the Ely district Carboniferous formations. These conclusions have al­ and the Confusion Range. ready been supported in this discussion and are briefly 14. The uppermost beds of the Ely Limestone in the summarized here. Diamond Peak area are Early Pennsylvanian, but elsewhere in the Eureka area the formation 1. The earliest Mississippian (Kinderhook) beds in includes beds as young as Middle Pennsylvania!! the Eureka district occur in the upper part of (Atoka). the Pilot Shale. 2. The Joana Limestone in its type area in the Ely REGISTER OF FOSSIL COLLECTING LOCALIT] ES IN district is late Kinderhook and Osage in age. THE DIAMOND PEAK AREA, NEVADA 3. In the Eureka district, including the Diamond U8G8 locality Description and collectors Peak area, the Joana Limestone contains no 6567-PC Eureka 15-min quadrangle, White Pin^ County. beds of Osage age. Apparently just west of Bold Bluff and just 4. The Cliainman Shale in its type area in the Ely east of fault south of Diamond Peik. Lime­ district is Chester in age. stone occurring in black shale in lower part of Diamond Peak Formation. Seemingly the one 5. In the Confusion Range of Utah and the White mentioned (Walcott, 1884) as 200 ft above the Pine Range of Nevada the Chainman is late base. G. H. Girty and H. G. Fergu^on, June Meramec and Chester in age. 1928. 6. In parts of the White Pine and Pancake Ranges 14690-PC Eureka 15-min quadrangle, Wliite Pine County. the upper part of the Chaiaiman Shale and the Highest zone of black shale on east slope of Diamond Peak Formation intertongue. Bold Bluff, in the SW^ sec. 6, T. 19 N., R 55 E. f White Pine [now Chainman] Shale, from a 7. In the Pancake Range, the undifferentiated Chain- lenticular siliceous limestone near the top bed man-Diamond Peak sequence of Stewart (1962) 24 of Bold Bluff section. ,T. S. Williams, July

is late Meramec and Chester in age.~ 17, 1938. 8. In the Eureka district, including the Diamond 14693-PC Eureka 15-min quadrangle, White Pin? County. Peak area, the Chainman Shale, which is over­ Section up ridge trending southward from east lain by, or intertongues with, the lower part of end of Diamond Table, well below top. [Prob­ the Diamond Formation, is Meramec in age. ably in SW^NW^i sec. 32 (unsurveyed), T. 20 N., R. 55 E.] Diamond Peak Formrtion bed 9. In the Carlin region the rocks called Chainman 11 of measured section. J. S. Williams, T. B. Shale are very late Kinderhook and Osage in Nolan, and T. A. Broderick, July 14, 1938. age and are temporally equivalent to the Joana 14694-PC Eureka 15-min quadrangle, White Pin? County. Limestone. About 800 ft below top on southeast side of 10. The Diamond Peak Formation at its type locality Diamond Table Peak. Diamond Peak Forma­ is Meramec (mostly late Meramec) and Chester tion, from float below a quartzite which is the in age. upper part of bed 13 of measured section. J. S. Williams and others, July 14, 1938. 11. Within the type Diamond Peak Formation: a. The Meramec-Chester boundary is located 14695-PC Eureka 15-min quadrangle, White Pin-1 County. Top of second massive ledge of quartzite below within and near the top of member D; top of southeastern part of Diamond Table. b. The Visean-Namurian boundary probably Diamond Peak Formation fossils from olive- occurs near the contact between members brown siltstone bed 17 of measured section. E and F; and J. S. Williams and others, July 15, 1938. c. A faunal hiatus that represents much of 16680-PC Eureka 15-min quadrangle, White Pin? County. middle Chester time probably occurs at On east slope of Diamond Mountains not far or near the contact between members F below main crest, 3,900 ft S. 33° E. of VABM and G. 9358 above Black Point. Diamond Perk Forma­ tion, member B. D. A. Brew, 1956. 12. No beds of Pennsylvania!! age are present in the 16681-PC Eureka 15-min quadrangle. White Pin? County. Diamond Peak Formation of the type area, but A little higher on slope than last, 3-900 ft S. the uppermost beds of the formation in the 28Y2 ° E. of VABM 9358 above Black Point. BIOSTRATIGRAPHY AND AGE OF THE CARBONIFEROUS FORMATIONS 53

U8G-8 USGS locality Description and collectors locality Description and collectors Diamond Peak Formation, member B. D. A. crest, at a point 3,200 ft S. 8° E. of summit of Brew, 1956. Diamond Peak, in SE%NEi4 sec. 30 (un­ surveyed), T. 20 N., R. 55 E.; at elev of about 16682-PC Eureka 15-min quadrangle, White Pine County. 9,900 ft. Diamond Peak Formation; Diaphraff- On main crest, 4,250 ft S. 22%° E. of VABM mus bed in upper p rt. Mackenzie Gordon, Jr., 9358 above Black Point. Diamond Peak Forma­ and D. A. Brew, July 16, 1957. tion, member B. D. A. Brew, 1956. 17178-PC Eureka 15-min quadrangle, White Pine County. 16683-PC Eureka 15-min quadrangle, White Pine County. On same ridge as USGS loc. 17177-PC Int High on east slope of Diamond Mountains, about 1,000 ft to south-southeast, at about elev 6,100 ft S. 27° E. of VABM 9358 above Black 9,800 ft, and roughly 250 ft lower in section. Point. Diamond Peak Formation, member B. Diamond Peak Formation, upper part. Mac­ D. A. Brew, 1956. kenzie Gordon, Jr., and D. A. Brew, July 16, 16684-PC Eureka 15-min quadrangle, White Pine County. 1957. Near top of main ridge directly upslope from 17179-PC Eureka 15-min quadrangle, WThite Pine County. USGS loc. 16683-PC, 5,950 ft S. 16° E. of Same general locality as USGS loc. 17177-F^, VABM 9358 above Black Point. Diamond Peak but about 100 yd to northeast and 70 ft lower Formation, member B. D. A. Brew, 1956. stratigraphically. Mackenzie Gordon, Jr., and 16685-PC Eureka 15-min quadrangle, White Pine County. D. A. Brew, July 16, 1957. On top of main ridge, 10,700 ft S. 8%° E. of 18590-PC Eureka 15-min quadrangle. Eureka County. With­ VABM 9358 above Black Point Diamond Peak in Diamond Peak measured section. (See p. 67 Formation, member B. D. A. Brew, 1956. for details). Diamond Peak Formation, mem­ Eureka 15-min quadrangle. White Pine County. ber E; 2,559 ft above base of formation and Limestone blocks in minor drainage on slope at 967 ft below base of Ely Limestone. D. A. Brew, about 8,400 ft elev, about one-eighth mile due July 6, 1959. (Appears to be same level as north of Bold Bluff in the NW^SWH sec. 6, USGS loc. 21293-PC.) T. 19 N., R. 55 E. Diamond Peak Formation. 21269-PC Eureka 15-min quadrangle, White Pine County. Mackenzie Gordon, Jr., and D. A. Brew, July On ridge at south side of Sadler Canyon, 7,100 15, 1957. ft N. 77^° W. of B.M. 5927, in NW^NW^ 17173-PC Eureka 15-min quadrangle. White Pine County. sec. 34 (unsurveyed), T. 20 N., R. 55 E. Chain- On crest of ridge that extends in general south- man Shale deformed here, but best estimate southeast direction from main divide of Dia­ places collection 300 ft below base of Diamond mond Mountains to Water Canyon, between two Peak Formation. D. A. Brew, June 29, 1958. west tributaries of Water Canyon, in NEVt SW*4 sec. 31 (unsurveyed), T. 20 N., R. 55 E.; 21270-PC Eureka 15-min quadrangle, Eureka County. 4,7^0 approximate elev 7,950 ft. Diamond Peak For­ ft N. 18° W. of summit shown as elev 10,3~5 mation, limestone and calcareous shale, 50 ft on topographic map, on crest of range, north of thick, above fourth massive conglomerate on Diamond Peak. Diamond Peak Formation, ridge, perhaps 1,000 ft above base of forma­ probably member B: perhaps 390 ft above ba«e tion. Mackenzie Gordon, Jr., and D. A. Brew, of formation and 3,136 ft below base of Ely July 15, 1957. Limestone. D. A. Brew, August 15, 1957. 17174-PC Eureka 15-min quadrangle, White Pine County. 21271-PC Eureka 15-min quadrangle, White Pine County. East slope of Diamond Mountains, about 70 ft On ridge trending eastward from southeast end below top of main ridge, near middle of NE^ of Diamond Table, 9,600 ft N. 78° E. of B.I*. NE*4 sec. 36, T. 20 N., R. 54 E. Diamond Peak 5927, in NE% sec. 34 (unsurveyed), T. 20 I T., Formation; Rhipidomella nevadensis bed in R. 55 E. Diamond Peak Formation, perhaps upper part. Mackenzie Gordon, Jr., and D. A. from member C. about 1,000 above base of Brew, July 15, 1957. formation. D. A. Brew, June 29, 1958. 17176-PC Eureka 15-min quadrangle, on Eureka-White Pine 21272-PC Eureka 15-min quadrangle. White Pine County. County line. Fossils in shaly nodular limestone On slope above (west of) Robinson Springs; on main ridge directly upslope from USGS loc. rubble pile, 4,000 ft N. 87° E. of elev 9,271 17174-PC, in NE^NE^ sec. 36, T. 20 N., R. 54 shown on topographic map on crest of ran.Te E. Ely Limestone, 7 to 10 feet above base of south of Minoletti Creek. Diamond Peak For­ formation. Mackenzie Gordon, Jr., and D. A. mation, probably from member C, about 1,550- Brew, July 16, 1957. 1,650 ft above base of formation and 1,87^- 1,976 ft below base of Ely Limestone, although 17177-PC Eureka 15-min quadrangle, White Pine County. member assignment is very questionable. M. K. On top of ridge that extends southeastward Hubbert and D. A. Brew, July 29, 1957. from south shoulder of Diamond Peak, the fairly level part of which ridge is known as 21273-PC Eureka 15-min quadrangle, White Pine County. Diamond Table; at local base of slope on ridge- On crest of range south of Minoletti Creel"; 54 MISSISSIPPI AN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

uses VSGS locality Description and collectors locality Description and collectors 3,580 ft S. 22V2 ° E. of elev 9,271. Diamond 21278-PC Diamond Peak Formation, member B; 317.5 ft Peak Formation, member D; about 1,788 ft above base of formation and 3.208.5 ft below above base of formation and 1.738 ft below base base of Ely Limestone. D. A. Brew, June 29, of Ely Limestone. From same unit as USGS 1959. colln. 21285-PC. D. A. Brew. July 25, 1957. 21279-PC Diamond Peak Formation, member B; 403 ft 21274-PC Eureka 15-min quadrangle, White Pine County. above base of formation and 3,123 ft below On southeast-trending ridge between Adobe and base of Ely Limestone. D. A. Brew, June 29, Sadler Canyons: 3.370 ft S. 77° E. of summit of 1959. Diamond Peak. Diamond Peak Formation, mem­ 21280-PC Diamond Peak Formation, member B; 410.5 ft ber E(?). probably 1,400-1.550 ft below base above base of formation and 3,115.5 ft below of Ely Limestone and 1,980-2,126 ft above base base of Ely Limestone. D. A. Brew, June 30, of formation. D. A. Brew, June 20, 1958. 1959. 21275-PC Eureka 15-min quadrangle, Wbite Pine County. 21281-PC Diamond Peak Formation, member B; 567.5 ft On east-trending ridge just north of Adobe above base of formation and 2,958.5 ft below Canyon, in fault-bounded block 3,800 ft S. base of Ely Limestone. D. A. Brew, June 30, 88y2 0 E. of elev 10,365 on main ridge north 1959. of Diamond Peak. Diamond Peak Formation, member E ( ?), stratigraphie position thought 212S2-PC Diamond Peak Formation, member C; 1,673 ft to be similar to that of VSGS loc. 21274-PC. above base of formation and 1,853 ft b-^low base D. A. Brew, June 25, 1958. of Ely Limestone. D. A. Brew, July 1. 1959. 21276-PC Eureka 15-min quadrangle, White Pine County. 21283-PC Diamond Peak Formation, member . C; same Almost on crest of range at head of intermit­ horizon as USGS loc. 21282-PC. D. A. Brew, tent drainage that descends eastward to New­ July 1, 1959. ark Valley School. 700 ft S. 4V2 0 E. of elev 212S4-PC Diamond Peak Formation, member C; 1,736 ft 9,951 on main ridge west of Circle Ranch. above base of formation and 1,790 ft below Diamond Peak Formation, member G ; 3,152.5 base of Ely Limestone. D. A. Brew, July 1, ft above base of formation and 373.5 ft below 1959. base of Ely Limestone, from same unit as Diamond Peak Formation, member D; 1,788 ft USGS Iocs. 21297-PC and 21298-PC. D. A. 21285-PC above base of formation and 1,738 ft below Brew, Aug. 22, 1957. base of Ely Limestone. D. A. Brew, Aug. 14, 1959. COLLECTIONS FROM DIAMOND PEAK 212S6-PC Diamond Peak Formation, member D; probably MEASURED SECTION same horizon as USGS loc. 21285-PC but found loose on member C, 1,663.5 ft above bpse of for­ Eureka 15-minute quadrangle, Eureka County, Nevada mation and 1,862.5 ft below base of Ely Lime­ The section was measured by D. A. Brew in the sum­ stone. D. A. Brew, July 1, 1959. mer of 1959 on the northwest slopes of Diamond Peak; 212S7-PC Diamond Peak Formation, member D; 1,880 ft it is the type locality of Diamond Peak Formation. above base of formation and 1,646 ft below base of Ely Limestone. D. A. Brew, July 3, The section includes 1,077 feet of Chainmaii Forma­ 1959. tion, 3,526 feet of Diamond Peak Formation, and 432 212SJS-PC Diamond Peak Formation, member D; 1,889 ft feet of Ely Limestone. The base of the section is a above base of formation and 1,637 ft below point 3,940 feet N. 39°40' E. of the conical hill shown base of Ely Limestone. D. A. Brew, July 3, on the topographic map with elevation 7,887 feet, 1959. three-quarters of a mile north-northeast of Cotton- 212-S9-PC Diamond Peak Formation, member D; 1,980.5 ft wood Spring. (This hill is in SWi/4SEV4 sec. 12, T. above base of formation and 1,545.5 ft below 20 N., R. 54 E.) The top of the section is at an eleva­ base of Ely Limestone. D. A. Brew, July 4, tion 10,000 feet on the northward-extending summit 1959. ridge of Diamond Peak, at a point about 5,550 feet N. 21290-PC Diamond Peak Formation, member D; 2,031 ft above base of formation and 1,495 ft below 12° E. of the summit of Diamond Peak. The section base of Ely Limestone. D. A. Brew, July 4, includes USGS fossil localities 18590-PC, 21277-PC 1959. through 21318-PC, and f21922 through f21927 (fora- 21291-PC Diamond Peak Formation, member B; 2,449.5 ft miniferal collections). above base of formation and 1,076.5 ft below base of Ely Limestone. D. A. Brew, July 6, USGS locality Description and collectors 1959. 21277-PC Black Point facies of Chaimnan Formation, 20 Diamond Peak Formation, member B; 2,500 ft ft below top. D. A. Brew, June 29, 1959. above base of formation and 1,026 ft below STRUCTURE 55

USGS locality Description and collectors locality Description and collectors base of Ely Limestone. D. A. Brew, July 6, 21312-PC Ely Limestone, upper member: 144.5 ft above Vase 1959. of formation. D. A. Brew. July 19, 1959. 21293-PC Diamond Peak Formation, member E: 2,559 ft 21313-PC Ely Limestone, upper member; 150.5 ft atove above base of formation and 967 ft belo\v base base of formation, D. A. Brew, July 20, 1959. of Ely Limestone. D. A. Brew, July 6, 1959. 21314-PC Ely Limestone, upper member; 166.5 ft above 21294-PC Diamond Peak Formation, member G: [float] base of formation, D. A. Brew, July 20, 1959. 3,095.5 ft above base of formation and 430.5 ft 21315-PC Ely Limestone, upper member; 169 ft al ove below base of Ely Limestone. D. A. Brew, July base of formation, D. A. Brew, July 20, 1959. 13, 1959. 21316-FC Ely Limestone, upper member; 176.5 ft atove 21295-PC Diamond Peak Formation, member G; 3,101.5 ft base of formation, D. A. Brew, July 20, 1959. above base of formation and 424.5 ft below 21317-PC Ely Limestone, upper member; 252.5 ft above base of Ely Limestone. D. A. Brew, July 13, base of formation. D. A. Brew, July 20 and 23, 1959. 1959. 21296-PC Diamond Peak Formation, member G: from same 21318-PC Ely Limestone, upper member; 432 ft above tase unit as USGS loc. 21295-PC? D. A. Brew, July 11, 1959. of formation. D. A. Brew, July 23, 1959. 21297-PC Diamond Peak Formation, member G; 3,152.5 ft FORAMINIFERAL COLLECTIONS above base of formation and 373.5 ft below base of Ely Limestone. D. A. Brew, July 13, All the following collections are from the Diamond 1959. Peak measured section (see p. 67 for details). 21298-PC Diamond Peak Formation, member G: same f21022 Diamond Peak Formation, member C; 1,713 ft horizon as USGS loc. 21297-PC. D. A. Brew, above base of formation and 1,815 ft below July 13, 1959. base of Ely Limestone. D. A. Brew, 1959. 21299-PC Diamond Peak Formation, member H; 3,325 ft f21923 Diamond Peak Formation, member D; 2.03C ft above base of formation and 201 ft below base above base of formation and 1,490 ft below of Ely Limestone. D. A. Brew, July 17, 1959. base of Ely Limestone. D. A. Brew, 1959. 21300-PC Diamond Peak Formation, member H; 3,403 ft f21924 Diamond Peak Formation, member D; 2,05F ft above base of formation and 123 ft below base above base of formation and 1,473 ft below of Ely Limestone. D. A. Brew, July 17, 1995. base of Ely Limestone. D. A. Brew, 1959. 21301-PC Diamond Peak Formation, member H; 3,410 ft f21925 Diamond Peak Formation, member D; 2,11? ft above base of formation and 116 ft below base above base of formation and 1,411 ft below of Ely Limestone. D. A. Brew, July 17, 1959. base of Ely Limestone. D. A. Brew, 1959. 21302-PC Diamond Peak Formation, member H; 3,483.5 ft f21926 Diamond Peak Formation, member D; 2,164 ft above base of formation and 42.5 ft below base above base of formation and 1,362 ft below of Ely Limestone. D. A. Brew, July 17, 1959. base of Ely Limestone. D. A. Brew, 1959. 21303-PC Ely Limestone, lower member; 2 ft above base. f21927 Diamond Peak Formation, same locality and D. A. Brew, July 18, 1959. horizon as USGS loc. f21926. D. A. Brew, 1959. 21304-PC Ely Limestone, lower member; 31 ft above base. D. A. Brew, July 18, 1959. STRUCTURE 21305-PC Ely Limestone, lower member; 36 ft above base. The rocks of the Diamond Mountains have been de­ D. A. Brew, July 18, 1959. formed by folding and faulting. The folds consist of 21306-PC Ely Limestone, lower member; 45.5 ft above base. a series of north-trending gently plunging anticlines D. A. Brew, July 18, 1959. and synclines of probably latest Paleozoic or Mesozoic 21307-PC Ely Limestone, lower member; 52.5 ft above base. age. They have been overturned to the east and tightly D. A. Brew, July 18, 1959. appressed in the northern part of the Eureka quad­ 21308-PC Ely Limestone, lower member; 80.5 ft above base. rangle and the southern part of the Diamond Springs D. A. Brew, July 19, 1959. quadrangle to the north (Larson and Riva, 1963). In 21309-PC Ely Limestone, lower member; 90 ft above base. addition to these major folds, warps of lesser magni­ D. A. Brew, July 19, 1959. tude occur; some of the warps are the same age as the 21310-PC Ely Limestone, lower member; 106.5 ft above base. major folds, and some are probably Tertiary in a*?e. D. A. Brew, July 19, 1959. Near Diamond Peak the folded rocks are cut by a low- 21311-PC Ely Limestone, upper member; 138 ft above base angle thrust that is interpreted to be slightly younger of formation. D. A. Brew, July 19, 1959. than the folds. It is probable that more thrusts are 56 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA present in the range than were mapped. Younger high major episode of folding postdated the deposition of angle faults, largely, if not all normal, have displaced the Permian rocks. The youngest bedrock unit mapped the axial surfaces of .he major folds, defined the pres­ and described by Riva (1957) and Larson and Riva ent north-trending boundaries of the mountain range, (1963) is unconformable over all the older rocks and and caused adjustments between different blocks of the probably is correlative with the Newark Canyon For­ range proper. These faults are Tertiary in age. mation of Early Cretaceous age (p. 31). This unit is Structures pertinent to the deciphering of the strati- definitely younger than the folding that formed the graphic relations near Diamond Peak are shown on major north-trending folds of the range. On this basis plate 1 and are discussed in the following section. The the folding of the Cold Creek syncline can b?< dated structures in the area covered by figure 4 have already as post-Permian (post-Leonard) and pre-Early Creta­ been described in detail by Brew (1963). ceous.

FOLDS LESSER FOLDS AND GENTLE WARPS The folds of the south-central Diamond Mountains A minor anticlinal axis can be traced from the edge can be classified in three groups: (1) major folds, (2) of bedrock on the west side of the range not far north lesser open folds and warps, most of which may be of the divide at the head of Man Creek (fig. 4) south­ associated with differential movement within indi­ eastward through that divide and then southwestward vidual fault blocks, and (3) very small flexures occur­ and southward almost as far as Cottonwood Spring. ring near, and related to, thrust planes. The first group The limbs dip as much as 35°, but generally about 20°. is represented only by the Cold Creek syncline, the The southern extent of the axis lies entirely within second group by numerous gentle warps in the vicinity partially concealed dominantly fine-grained rocks of Diamond Peak and elsewhere, and the third group assigned to the Black Point facies of the Chainman by very small folds mapped in two localities near the Formation, so that the position of the axis is known base of the upper plate of the Bold Bluff thrust fault. only approximately. Not far to the southeast of these anticlinal folds is COLD CREEK SYNCLINE the open syncline that has been previously suggested as a possible southern extension of the Cold Creek The major fold of the Eureka quadrangle is a syn­ syncline. The dips of its limbs average about 20°, but cline belonging to the series of north-trending folds local variations are common. The fold plunges very that characterizes the northern and central parts of the gently to the northeast, east of the crest of the range, Diamond Mountains. In the northern part of the area and is horizontal on the west side. of figure 4 all formations up to, and including, the Ely To the south and southeast of this syncline are Limestone are folded about a gently north-plunging several open folds whose axes can be traced for not axis; the axial surface dips steeply to the west. This more than 2 miles. Perhaps the most significant of structure is here called the Cold Creek syncline. these is a west-dipping anticlinal bend of the monocline The western overturned limb of the Cold Creek syn­ that occurs on the east side of Alpha Peak ridge-, on the cline is traceable as far south as the latitude of Black east limb of the syncline discussed above. This axis Point (fig. 4). South of that latitude the western limb has been purposely omitted from plate 1 and figure 4. is upright (except locally), and the dips lessen. About The beds east of the axis dip an average of 25° to the 2i£ miles west-northwest of Circle Kanch (pi. 1) a west, and those to the west, dip an average of 50° in southwest-trending open syncline is exposed on the the same direction. Section B-B of plate 1 shows this north slope of Diamond Peak; it extends to the west steepening and also shows the apparent similar con­ flank of the range south of Cottonwood Spring. This figuration of the Bold Bluff thrust fault; the similarity gently plunging open structure is interpreted to be suggests that the folding may have deformed the the southern continuation of the Cold Creek syncline thrust. beyond the limits of its overturned segment. In the area east of Diamond Peak there are several The precise age of the deformation that produced the gentle warps, all but one of which occur in the down- Cold Creek syncline is not known. Riva (1957) and faulted blocks that adjoin the high part of the range. Larson and Kiva (1963) did not describe or depict any These slightly sinuous warps are difficult to trace extreme structural discordance between the rocks of and die out abruptly. Their lack of continuity, the Pennsylvaniaii age and those of Permian, although flatness of their limbs, and their tendencies to converge local angular unconformities and considerable local all suggest formation not as a result of regional relief is present, It therefore seems likely that the stresses, but rather from differential tilting along very STRUCTURE 57

minor faults during the downfaulting of the blocks on Structural features associated with it include slicken- the flanks of the range. sides, minor thrusts and folds which are described briefly below, and local areas of large irregular compe­ FAULTS tent blocks "swimming" in finer grained rock. The LOW-ANGLE FAULTS available evidence indicates that the upper plate moved The only significant low-angle faults recognized southeastward relative to the lower plate. occur south and southeast of Diamond Peak, where the RELATED MINOR THRUSTS AND FOLDS Bold Bluff and associated thrust faults have been mapped, and on the lower slopes of Black Point (fig. In the vicinity of Diamond Table, which is just north 4). Only the Bold Bluff thrust fault is critical to the of Water Canyon (pi. 1), two areas of relatively small- stratigraphic interpretation of the Diamond Peak area. scale folds and associated minor thrusts were mapped in the upper plate of the Bold Bluff thrust fault, not BOLD BLUFF THRUST FAULT far above the thrust plane. The faults are too small to The Bold Bluff thrust fault (pi. 1) has already been show on plate 1, but the small folds are shown. described briefly in relation to the contrasting facies of A complexly thrusted and folded small overturned the Chainman Formation in its upper and lower plates anticline with a horizontal axis was mapped on the (Brew, 1961b). It has been mapped for about 6 miles southwest side of Diamond Table. It is related to the in a generally northeasterly direction from Poison presence of a resistant 10-foot-long wedge of silicified Spring to the base of the range at a point about 1 conglomerate that acted as a rigid mass along an mile north of the mouth of Sadler Canyon. The thrust auxiliary thrust plane. The conglomerate was not only surface has been displaced by later high-angle normal an active element, but a separate small lens some 50 faulting. Structure contours and three-point solutions feet to the northwest of the fold acted as a dam against on the surface show that it dips about 10° W. along which the less competent beds were piled up and, in Alpha Peak ridge from its high point in the head­ part, underthrust along high-angle surfaces. The direc­ waters of Water Canyon; to the east of this area the tion of movement inferred from these features is north­ surface is about horizontal (fig. 12), and then to the west to southeast. north and northeast the generalized dip is about 15° N. An anticline and reverse-faulted complementary syn- The thrust surface is delineated by the truncation of cline were mapped at the east end of Diamond Table, lithologic units within both plates (pi. 1). It is also south of Sadler Canyon. The horizontal anticlinal axis marked by several springs in the Water Canyon area. trends about northeast, and the eastern limb is appreci­ ably steeper than the western. These folds could not be seen lower on the hill and appeared to die out within a few tens of feet along strike.

EXTENT AND SIGNIFICANCE Although the Bold Bluff thrust fault has not been recognized in the Diamond Range north of the area of plate 1, there is one enigmatic locality just southeast of Pedrioli Creek (fig. 4) where an exceptionally large apparent thickness of Chainman rocks has been inter­ preted to be due to high-angle faulting. Some of the poorly exposed Chainman there consists of "pencil- weathering" black clayrock, and it is conceivable that a fenster exposing the lower plate Chainman occurs in this area. The questionable exposures are bounded on the northwest by the vertical Pedrioli Creek fault and are obscured by colluvium to the east and south. In the Diamond Mountains north of the Eureka FIGURE 12. South side of Diamond Table, showing nearly quadrangle (Dott, 1955; Riva, 1957; Larson and Riva, horizontal bedding in very thick conglomerates of Diamond Peak Formation above the Bold Bluff thrust fault. The 1963), the Bold Bluff thrust fault is apparently not thrust surface is located about 100 feet below the base of exposed. As a purely speculative regional hypothesis the prominent cliff in the middle of the picture. it is tempting to extend the fault beneath Newark 58 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Valley (fig. 1) to join the thrust fault in the southern vides an essential clue to the understanding of the Ruby Mountains which Sharp (194:2) mapped as sepa­ stratigraphy of the southern Diamond Range because rating several thousand feet of clastic Carboniferous contrasting facies of Mississippian rocks have been rocks from underlying older Paleozoic strata. Willden, juxtaposed along it. These relations have been sum­ Thomas, and Stern (1967) have established that the marized previously (Brew, 1961b), and also elsewhere age of this thrusting is Oligocene or younger. One can in this report. infer connections of these faults with the thrusts Figure 13 shows the generalized thickness and char­ mapped in the area north of Buck Mountain and south acter of the rocks in the upper and lower plates of the of Overland Pass by Rigby (1960). Dott (1955, p. Bold Bluff thrust fault. In addition to the contrasting 2266) has suggested generally similar connections, Mississippian stratigraphy in the two plates, there are primarily on the basis of facies contrasts in the Dia­ also minor differences in thickness and lithologic char­ mond Peak and overlying rocks on the opposite sides acter of the other formations. The most significant of of Newark Valley. these are the lithologic and thickness differences in the The recognition of the Bold Bluff thrust fault pro­ Devils Gate Limestone (Nolan and others, 1956, p. 49).

l'/2 MILES EAST NORTH, EAST, AND SOUTHEAST NEWARK MOUNTAIN EXPLANATION OF PHILLIPSBURG MINE OF BLACK POINT BOLD BLUFF FEET pyl^ =,=,=,=,= -^___^ Ely Limestone ^^ ^m

Diamond Peak 3750 Formaton *¥»

000 .....

00000

a« Conglomerate Cherty limestone r=_^r=Jj- -^______^ 000 000 o o o *>"o o

^-- - Sandy limestone

: ;. ;--: Vn-rrTTTT 4000 Chainman Formation FEET 0 ~^/~~~^~^ Chainman Formation

2500 (Maximum, due to tectonic thickening)

115- :ifrfTTTT 250 Joana Limestone i i i i 360 Pilot Shale ~i i r i i 675 i i Devils Gate Limestone Devils Gate 1 1 1 Limestone 1 ^7 ^ 7 / / / Bay State Dolomite s / / _/" / Member jS ; / / s 7 / 7 7 7 220 - S- ~ Woodpecker Lime- 1 1 1 1 Nevada 450 £ Sentinel Mountain Formation - <° Dolomite Member 450 u Dxyoke Canyon

^ 0 ', r >~ 7- 940 7/7 Beacon Peak 7 7 Dolomite Member '; '/ / '""" "'"'

FIGURE 13. Generalized thickness and lithologic character of rocks in the upper and lower plates of the Bold Bluff thrust fault. Modified in part from Nolan, Merriam, and Williams, 1956. STRUCTURE 59

HIGH-ANGLE NORMAL FAULTS Where the Ely Limestone has been dropped against High-angle normal faults occur on both sides of the the Black Point facies the throw is estimated to be as Diamond Mountains and within the range itself. A much as 8,000 feet. Farther to the south, not far from third group, comprising faults that are in part boun­ Cottonwood Spring, the minimum total stratigraphic dary and hi part internal, is also present. Faults be­ throw on the main branch of the fault is 3,500 feet. The longing to all these categories are discussed briefly throw probably decreases steadily to the south and below; more detailed descriptions were given by Brew some is taken up on the northern continuation of the in 1963. Newark fault, but the steep attitudes of the units on both sides of the fault make any estimate highly BOUNDARY FAULTS suspect. The term "boundary fault," as used, refers to a fault The map pattern indicates that the Alpha fault dips (either inferred or mapped) along which movement or in general moderately, but locally very steeply, to the erosion has at least, in part, defined a portion of the west. Three-point solutions show that due west of present boundaries of the range (pi. 1; fig. 4). Tri­ Alpha Peak the fault dips about 55° W. and at the angular facets characteristically truncate the spurs on latitude of Cottonwood Spring 62° W. both sides of the elevated central block; on the west NEWARK VALLEY FAULT side of the range there is evidence for several thousand feet of stratigraphic throw on the boundary fault. The Newark Valley fault, is inferred to border all About 2 miles southeast of the summit of Newark the various subblocks of the Diamond Mountains on Mountain, downdropped blocks of Devonian limestone the east side (pi. 1; fig. 4). It is entirely concealed by establish the existence of about 2,500 feet of strati- alluvium, and the evidence for its existence consists of graphic throw on one of the boundary faults on the the steep east-faring scarps of Rattlesnake and Cedar east side of the range. E. R. Larson (in Dott, 1955, p. Mountains (north and south of Strawberry Ranch, 2261 ; Larson and Riva, 1963) has suggested that most respectively, fig. 4) and the very steep triangular- of the boundary faults on the west side of the Diamond faceted scarp which extends from Circle Ranch south Mountains north of the Eureka quadrangle are of the along the face of Newark Mountain. A branch of the reverse type. The evidence from the Eureka quadrangle fault is exposed at the foot of Newark Mountain south does not directly refute this interpretation, but the of the area mapped. There it separates Lower Devonian configuration of the inferred folds and the shape of the rocks from a downdropped block made up of Upper scarp suggest that a normal origin is more likely. Devonian rocks. At this latter locality the apparent stratigraphic ALPHA FAULT throw on the branch fault is about 2,500 feet, and the The Alpha fault was named by Hague (1892, p. 28) cumulative throw of the fault system is correspond­ in the area clue west of Alpha Peak (pi. 1). The name ingly greater. No direct evidence of the dip of the fault is extended to cover the northward continuation of is available. The faceted spurs in the area between that fault to its inferred juncture with the Pedrioli Mining Canyon and Adobe Canyon dip between 28° Creek fault. It forms the western boundary of the and 40°, but they have been considerably modified by mapped area of plate 1. erosion and their steepness represents only the mini­ In its northern exposure (fig. 4) the fault separates mum limit of dip. the Black Point facies of the Chainman Formation from similar downdropped rocks and from several FAULTS WITHIN THE RANGE (INTERNAL FAULTS) large masses of Ely Limestone. To the south, near Internal faults are defined as those which occur CottonwTood Spring, the downdropped block includes within the main block of the range and whose topo­ rocks o'f the ^Newark Canyon Formation and Ter­ graphic significance is much less than that of the tiary (?) fanglomerates. Near the south edge of the boundary faults. mapped area, vertically dipping rocks of the Carbon The block-to-block adjustments along these faults Ridge Formation make up the western block, and within the range indicate the complicated nature of the steeply west-dipping Ely Limestone, the eastern block. high-angle faulting. All the internal adjustments are The stratigraphic throw on the Alpha fault at its probably related to the main mid-Tertiary episode of .north end is difficult to estimate because key horizons Basin and Range block faulting, but they could con­ are not exposed, and the rocks on both sides belong to ceivably be in part earlier. T. B. Nolan (oral commun., the Black Point facies of the Chainman Formation. 1957) has suggested that some of the faulting may be 60 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Pliocene or even younger on the basis of the faulted Newark Valley high-angle fault; the Water Canyon, remnants of gravel deposits which overlie various older Sadler Canyon, and Sadler Ridge faults, which are units near Newark Summit. described here; and the Adobe Canyon fault, which is described on page 61. NEWARK FAULT The Water Canyon fault (pi. 1) has been mapped The Newark fault was named by Hague (1892, atlas, from near the summit of Diamond Peak south through sheet XIII) in Tollhouse Canyon, just south of the the saddle where Diamond Table joins the main ridge mapped area, where it separates the Ely Limestone on of Diamond Peak and down into Water Canyon. The the west from Water Canyon facies of the Chainman east side is upfaulted about 200-300 feet. The fault dips and underlying Mississippian units on the east. The about 70° E. at its north end and is about vertical south name is here extended to cover the northern continua­ of Diamond Table. tion of the fault west of Alpha Peak and along Alpha The vertical Sadler Canyon fault (pi. 1) has been Peak ridge as well as the related faulting on Alpha mapped for about 2,500 feet in the main branch of Peak ridge due east of Torre Flat (pi. 1). This Sadler Canyon. It is entirely covered by alluvium, but Newark fault system is closely related to the Alpha its existence is demonstrated by the presence of the fault, and the two systems actually merge about 1 mile Water Canyon facies of the Chainman on the south­ northeast of Torre Flat. west side of the fault and downfaulted member D of The Newark fault truncates the Bold Bluff thrust the Diamond Peak Formation in the upper plate of fault, the Chainman and Diamond Peak Formations of the Bold Bluff thrust fault on the northeast side. The the lower plate, and members of the Diamond Peak of throw on the fault is estimated, only approximately, the upper plate near Poison Spring (pi. 1) and in the as 500 feet, area west of Alpha Peak (pi. 1, section C-C/). The The Sadler Ridge fault (pi. 1; fig, 14) follows a downfaulted block consists of steeply dipping Ely ridge of highly fractured rock from the edge of New­ Limestone. The fault dies out to the north on Alpha ark Valley into the steep cliffs of member D of the Peak ridge in a locality where high-angle cross faults Diamond Peak Formation near the head of Sadler are predominant. Canyon. The fault is for the most part vertical through­ The stratigraphic throw near Poison Spring must be out its length and has the Diamond Peak of the upper at least 2,000 feet and it decreases northward. Near plate of the Bold Bluff thrust fault and the Chainman altitude 8,966 northwest of Alpha Peak the Newark of the lower plate on both sides. In the southeastern fault dips 45° W., as determined by three-point solu­ half of its extent the southwest side has been down- tion. faulted about 400 feet, and the northwest half the same Farther to the north along Alpha Ridge, near alti­ side has been raised a few hundred feet relative to the tude 9,345 due east of Torre Flat, are faults which can north side. also be considered part of the Newark fault system The greater part of the Adobe Canyon fault is (pi. 1, section B-B'). In this area a downdropped discussed below, but because of its importance in the wedge of Ely Limestone is adjacent to the also down- Sadler Canyon complex, the southern part is discussed faulted western block made up of Diamond Peak mem­ here. On the south and east sides of Diamond Table the bers G and H and the Ely Limestone. Member F makes up the eastern block, and the overall stratigraphic throw is about 300-400 feet. The throw on the Ely wedge may be 600-800 feet. These faults strike north­ west to join the Alpha fault about 1 mile west-south­ west of the summit of Diamond Peak and dip in gen­ eral about 50°-60° W., as determined by three-point solutions.

SADLER CANYON FAULT COMPLEX High-angle faulting in the upper part of Sadler Canyon and on to the south on Diamond Table has resulted in differential elevation and depression of several fault-bounded blocks (pi. 1, section A-A", B- FIGURE 14. Generalized fault map of the Sadler Canyon- B'; fig. 14). Among the faults involved in the mosaic Water Canyon area, showing movement on principal faults. are the previously described Bold Bluff thrust and Circled letters indicate blocks referred to in text. STRUCTURE 61

Adobe Canyon fault dips steeply to the east (pi. 1, sec­ Springs it parallels the front of the range, and then it tion B-B') and the throw, as indicated by the position enters the range about 2% miles northwest of Circle of the Bold Bluff thrust in both blocks, is about 280 Ranch (pi. 1) and swings south westward toward the feet with the southeast side down. This relatively crest. Near the crest it splits into two branches, both of simple relationship continues northward into the south which have their northwestern sides downfaulted, as branch of Sadler Canyon. does the main fault. Between the south branch of Sadler Canyon and the The fault dips steeply west for most of its length, Sadler Ridge fault the Adobe Canyon fault dips as but it is vertical near the range crest. The stratigraphic much as 70° W., as shown by three-point solution, and throw is estimated at about 200 feet near the range the sense of movement is reverse. North of the Sadler front Avhere abruptly overturned dips and apparent Ridge fault the dip is again moderate to the east and tight folding make structural interpertation difficult. the movement sense normal. This local change in at­ Farther to the south the throw is perhaps slightly titude is enigmatic. greater, and the northern branch of the fault shows The sequence of movements on this complex of faults 340 feet of throw. The southern branch may have 200 has been interpreted from the observed throw on each feet where it intersects the Ely Limestone. Everywhere fault; the principal blocks and the movement senses else the Diamond Peak Formation occurs on both sides are shown on plate 1 and in figure 14. Block A is up of the fault. relative to B, C, D, and E. Block B is up relative ADOBE CANYON FAULT to C, D, and E and down to A. Block C is up rela­ tive to D and E and down to A and B. Block D The Adobe Canyon fault (pi. 1, section A-A') ex­ is up relative to E and down to A, B, and C. Block E tends from Robinson Springs due south for more than is down relative to A, B, C, and D. 3 miles to the Sadler Canyon fault complex. Its role The sequence of movements, as shown by these rela­ in the complex has been described previously. tions,-is as follows: (1) Movement on the Bold Bluff The Adobe Canyon fault dips moderately to the east, thrust fault; (2) C, D, and E down with respect to A and three-point solutions at three different places gave and B by movement on the whole Adobe Canyon fault; 42°-45° dips. Near altitude 9,045 the Ely Limestone (3) B and C down relative to A, D, aiid E by move­ has been faulted against members E and F of the Dia­ ment on the Sadler Ridge fault; (4) D and E down mond Peak Formation (fig. 15), and the stratigraphic relative to A, B, and C by movement on parts of the throw is about 2,800 feet. South of altitude 9,045 the Adobe Canyon and Sadler Ridge faults; and (5) E Ely is faulted out against a subsidiary fault in the down with respect to the rest of the blocks by move­ bottom of the north fork of Adobe Canyon, and the ment on the Sadler Canyon and parts of the Adobe throw on the southward continuation of the fault is Canyon and Sadler Ridge fault. The movement of the much less. Exact determination of the amount is not Newark Valley fault could either follow this sequence or occur anywhere within it. Likewise, the movement on the Water Canyon fault could have occurred at any time after (2). This sequence is not of great importance, except that it illustrates that fault-bounded blocks were dif­ ferentially jostled during the main faulting episodes.

COMBINATION BOUNDARY AND INTERNAL FAULTS The term "combination boundary and internal faults" is used to denote faults that are located in part along the edge of the main mountain block and in part within the range. As far as is known, most of the valley-side blocks are downfaulted, and in this way they are more closely related to the boundary faults than to the more complicated internal faults. * ROBINSON SPRINGS FAULT FIGURE 15. Ely Limestone downfaulted against the Diamond The Robinson Springs fault branches off the south­ Peak Formation along Adobe Canyon fault. Cliffs in center ern continuation of a large fault to the north near Man are part of member F of the Diamond Peak, and slopes at Creek (fig. 4). For a short distance south of Robinson upper right are the Ely Limestone. 62 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA possible because of lack of marker beds in member D yon Formation of Early Cretaceous age, thus establish­ through which the fault passes, but about 400 feet ing the maximum age of the unit. At this same locality seems probable. This figure is similar to that deter­ the fanglomerate and megabreccia have been locally mined for the Adobe Canyon fault in the Sadler Can­ displaced along a system of high-angle faults that yon fault complex. The remainder of the throw at strike south-southwest toward Richmond Mountain present at hill 9,045 is taken up on the subsidiary fault (just northeast of the town of Eureka) where the cap­ in the north fork of Adobe Canyon. This fault could ping andesite and basalt of probable late Tertiary age not be traced very far to the southeast. (Xolan, 1962, p. 17) are faulted (T. B. Nolan, written An associated fault extends from Robinson Springs commun., 1968). to near the Newark Valley School site and has dropped The tenuous minimum age of pre-Pleistocene is in the Ely Limestone of Mississippian and Pennsylvanian accord with the evidence from the alluvial fans and age and the Carbon Ridge Formation of Permian age pediments on the east side of the range. The Pleistocene against members E and F of the Diamond Peak For­ lakes postdated the extensive fan deposits and caused mation (pi. 1). This fault dips in general very steeply much reworking of their materials, as in the area near to the northeast. The maximum stratigraphic throw Circle Ranch. Inasmuch as the fans formed after the represented must be 5,000-6,000 feet. This throw is major uplift of the mountain block, a pre-Pleistocene divided between two branches of the fault near altitude minimum age is indicated. 7,815, northwest of the Circle ranch. The southeastern terminus of this fault is an abrupt GEOLOGIC HISTORY right-angle corner not far from the edge of the range. The purpose of this section is to present a general The northeast-striking fault that terminates the main outline of the sedimentation and subsequent deforma­ fault could not be traced more than a couple of hun­ tion of the upper Paleozoic and younger rocks in the dred feet southwest of the corner. Eureka quadrangle. The Chainman, Diamond Peak, and Ely Formations are treated at somewhat greater SUMMARY length than are the older and younger formations. The boundary, internal, and combination faults de­ scribed above are (in addition to the Cold Creek syn- LATE DEVONIAN AND EARLY MISSISSIPPIAN cline and the Bold Bluff thrust fault) the main struc­ SEDIMENTATION tural features of the Diamond Mountains in the Eureka The youngest Devonian and oldest Mississippian quadrangle. As presently interpreted, the overall effect rocks exposed in the south-central Diamond Mountains of the faulting has been to elevate the main block of are calcareous and noncalcareous dark clayrock and the range relative to the valley blocks. In areas where minor siltrock assigned to the Pilot Shale. Deposition good stratigraphic control is available, however, the of these shaly strata followed a long period during overall result is seen to have involved differential move­ which dominantly carbonate sediments were deposited ments on and within various blocks of the fault mosaic. (fig. 16.4). These shaly strata were laid down under The highest standing block in the southern part of the quiet conditions and the silt-size clasts are wholly area is the one that includes Diamond Table (pi. 1) quartz, suggesting that, although the Antler orogeny and the area on the east side of Diamond Peak. may have already been affecting areas to the west, no The age of the main episode of this faulting cannot chert clasts were contributed from the rocks involved be more accurately determined than post-Early Cre­ in that orogeny. In contrast, similar fine-grained rocks taceous and pre-Pleistocene. However, weak evidence of the Water Canyon fades of the Chainman. Forma­ points to an early, middle, and possible late Tertiary tion contain appreciable amounts of chert that are age. This evidence is based primarily on the relation of inferred to have been derived from rocks in the orogenic the Tertiary (?) megabreccia unit to the main blocks of belt. the mountain range. The megabreccia unit dips uni­ Deposition of calcareous sediments of the Joana formly away from the range and its distribution along Limestone followed the deposition of fine-grained sedi­ the flank implies a close genetic relation to the range, ments of the Pilot Shale, apparently without any inter­ as do the compositional and textural features of the ruption, in the Eureka quadrangle. The textures of the unit (p. 83-34); the uplift of the range must have Joana suggest much more reworking than for the predated the deposition of this unit. To the west of the Pilot, caused, perhaps, by shoaling. Chert grains are mapped area, in and around Palmer Ranch, the mega­ present, indicating that the provenance terrane that breccia unit unconformably overlies vertically dipping furnished the great volume of the Chainman and Dia­ conglomerate, sandstone, and shale of the Newark Can­ mond Peak sediments had already been tapped. GEOLOGIC HISTORY 63

Diamond Mountains "° » ° o :.o .f^^r i _| -f- -r1 "^ u p:_i-i ! i ! i j_ i i ' | Joana Limeston'e ^ ' -L~ ' 1 ' 1 1 -IT Y H i i "-T , ' ' i . i . ' H

Tonka Formation _ZZT" _ ^^ __L ~ . 1 III ./i/I 1 ' 1 1 1 L

Joana Limestone Diamond Mountains

Tomera and Moleen Formations of Dott (1955). Diamond Mountains

Tonka Fb'rmatior of Dott (1§55). -

Joana Limestone

Diamond Mountains

Tomera and Moleeru Formations of Dott (1955)

Joana Limestone

FIGURE 16. Inferred evolution of part of the western edge of the Chainman-Diamond Peak depositionai basin. A, After deposition of the Lower Mississippian Joana Limestone; B, After uplift and erosion of the Joana Limestone; C, After deposition of the Chainman, Diamond Peak, and Ely Formations; and D, After deposition of the Carbon Ridge Formation of Permian age. Vertical scale greatly exaggerated and horizontal relations diagrammatic. 64 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

EARLY MISSISSIPPIAN DEFORMATION terrane for both facies to the west of the D'amond Uplift, probably minor tilting, and erosion followed Mountains. The regional evidence suggests tliat the the deposition of the Joana Limestone, causing it to be formation is thinner to the east and south (fig. 5). The completely removed in some parts of the Eureka quad­ available evidence indicates that the greatest accumula­ rangle (fig. 165). Lack of key beds in the Joana and tion of sediment in the Chainman basin formed the the Pilot prevent a more exact estimate of the amount rocks now exposed in the Diamond Mountains, but this removed, but a few hundred feet of relief existed on interpretation may be disproved by detailed study of the surface before the deposition of the lower part of adjacent areas. the Chainman Formation. There is no evidence that Into this subsiding basin (the part represented by folding accompanied the uplift. the Black Point facies) were transported large volumes This phase of deformation (probably within the of poorly sorted silt-, clay-, and sand-size detritus Early Mississippian Kinderhook and Osage) is the derived from a provenance terrane to the west which only one clearly recorded in the Mississippian of the apparently was elevated as the basin subsided (fig. Eureka quadrangle. If other unconformities are present 16^'). Periods of shallow-water conditions w°.re ap­ they are obscured by the local variations in lithic types parently short lived and gave way to continued sub­ that are common in the Diamond Peak. This deforma­ sidence and continued rapid deposition. Farther from tion is considered part of the Antler erogenic episode the provenance terrane the sediments consisted only as defined by Roberts, Hotz, Gilluly, and Ferguson. of fine material carried beyond the area of maximum (1958, p. 2817, 2820) even though it was perhaps only accumulation plus a few scattered tongues and lenses local and far removed from the main part of the of the coarser Black Point facies. Increases in the erogenic belt. amount of pebble- and cobble-size debris, which prob­ ably resulted from intensified tectonic activity in the

LATE MISSISSIPPIAN THROUGH MIDDLE PENNSYLVANIAN Antler erogenic belt, presaged the greater influxes of SEDIMENTATION pebble-size debris which differentiate the Diamond Peak Formation from the Chainman Formation. Most of the rocks considered in detail in this report were deposited in the interval bounded by the post- DIAMOND PEAK FORMATION Joana and the pre-Carbon Ridge unconformities, and the changes in depositional environment and in the In the area of maximum accumulation, the sediments provenance terrane during that time can be traced from of the Diamond Peak Formation began accumulating the relatively quiet sedimentation during early Chain­ sometime in the Meramec. The sediments of the lower man time through the period of most rapid sedimenta­ part of the Diamond Peak were deposited in virtually tion and subsidence into the abruptly unstable and the same environment as was the Black Point facies of changeable conditions that persisted until the proven­ the Chainman Formation. The formations differ only ance terrane practically ceased to provide terrigenous in the greater frequency of conglomeratic and sandy debris. At that time the generally slow and continuous strata in the Diamond Peak. The provenance terrane subsidence characterizing the deposition of the Ely was about the same for both, and the depcsitional Limestone platform sediments began. This subsidence basin continued to subside. Not much is known of the continued until uplift and deformation occurred in Late geometry of the Diamond Peak deposits, but the evi­ Pennsylvania!! time. Realizing the continuity of the dence at hand indicates that they form a prism with its whole sequence, it is still convenient to discuss it for­ long axis oriented about north-south. In profile the mation by formation, as possible facies relationships prism was originally a nearly triangular lens, with its are thereby emphasized. longest side forming the upper surface of the deposit and the oblique apex located near the western edge of CHAINMAN FORMATION the basin (fig. 16<7). The relationships of the Water Canyon and Black As interpreted here, the coarsed sediments which Point facies of the Chainman Formation are inter­ characterize the Diamond Peak interfinger v^ith the preted to indicate that the Black Point facies, which Black Point facies and perhaps with the Water Can­ occurs in the upper plate of the Bold Bluff thrust yon facies of the Chainman Formation. As pointed out fault, probably is a sourceward equivalent of the in the section on "Stratigraphy," the Diamord Peak typical Chainman Shale, of which the Water Canyon has been defined by the relatively greater proportion facies is a part. This interpretation, together with the of coarse elastics it contains. The fact that it is classi­ evidence regarding the later thrusting, puts the source fied as a separate formation should not obscure its GEOLOGIC HISTORY 65 lithogenetlc ties with the finer grained rocks that are fossiliferous marine limestone apparently was intro­ also parts of the same tectonic and depositional pattern. duced to a locale of carbonate sedimentation wl°,re It should also be emphasized that there are many marine organisms existed and the conglomerate debris details of the Chainman and Diamond Peak strati­ must have been moved by strong marine bottom cur­ graphy which have not yet been studied. rents of some type. The influxes of coarser debris are considered to be The overall pattern of sedimentation in the upper the result of intensified orogenic activity in the Antler part of the Diamond Peak indicates general shallowing orogenic belt to the west. R. J. Roberts (oral commun., of the trough, longer periods during which agitation of 1963) has suggested that the orogeny involved move­ the bottom took place and ripple marks formed, and ment of the upper plate of the Roberts Mountains possibly even temporarily emergent episodes. Domi- thrust toward the Chainman-Diamond Peak trough. nantly unreworked terrigenous clastic sediments con­ The present report and the petrographic data (Brew, tinued to be deposited, but interspersed with tHse 1963) support the orogeny as the cause of the influx of phases occurred times when little terrigenous debris detritus, and it is likely, from petrologic evidence, that reached the depositional site and carbonate deposits the provenance terrane was not more than a few tens accumulated. This trend increased, and the terrigenous of miles away. The Roberts Mountains thrust probably elastics of the Diamond Peak gradually gave way to was the mechanism by which the provenance terrane the limestone of the Ely. was brought to the edge of the trough, and the terrigen­ ous elastics were probably derived from the upper plate ELY LIMESTONE during or after its movement. There is no clear evi­ The deposition of the lower member of the Ely Lime­ dence in the Diamond Mountains that the Roberts stone followed the trend indicated by the uppermost Mountains thrust actually overrode its own debris as member of the Diamond Peak Formation. About at an erosion thrust. the Mississippian-Pennsylvanian, systemic boundary The bedding and textures of the interbedded sand­ the amount of terrigenous debris reaching the deposi­ stone and siltrock in the Diamond Peak suggest that tional site began to drop off markedly, and deposition turbidity currents may have carried much of the sand- of slightly to moderately reworked limestone becrme size material well out into the basin. dominant. Thereafter, only very minor amounts of The transportation of the gravel-size material far pebble- through silt-size terrigenous debris were trans­ out into the basin is more difficult to explain. Some ported from the quiescent orogenic belt eastward into may have been dislodged from coalescing deltas at the edge of the basin and carried into deeper water by the slowly subsiding basin. subaqueous slides. The absence of crossbedding, definite The evidence from the Eureka quadrangle shows channeling, or small-scale scours makes river transport, only that the edge of the Ely depositional basin was unlikely, although these features could have been somewhere to the west. In the northern Diamond Me Tin- destroyed when the sea transgressed fluvial deposits. tains and the Elko area Dott (1955, 1958) found that Their sorting characteristics, however, appear to pre­ the provenance terrane continued to shed clastic debris clude such extensive reworking. into the basin during much of Early Pennsylvanian time; those areas must have still been close to the edge The problem of transporting gravel-size debris into of the active source area (fig. 16(7). To the east, the the basin is even more apparent when the sedimenta­ carbonate deposition extended well into what is row tion history of the upper members of the Diamond Utah, and the whole area was apparently a stable, but Peak is considered. During their deposition a pattern slowly subsiding, shelf. The fossil record in the north­ of small-scale fluctuation in sediment influx and shoal­ ern Diamond Mountains (Dott, 1955) and elsewhere ing replaced the pattern of more constant deposition near Eureka (Nolan and others, 1956) indicates that evident in the lower part of the section. In the upper this situation persisted until the Late Pennsylvanian. members, which range from early to late Chester in age, the conglomerate is closely associated with fossili- ferous marine limestone in some places and with fossili- POST-MIDDLE PENNSYLVANIAN DEFORMATION ferous clay rock and siltrock in others. In still a third No direct evidence of post-Ely Limestone deforma­ situation (that typified by member F) the conglomerate tion occurs in the part of the Eureka quadrangle con­ occurs with sediments which were apparently deposited sidered in this report. Although both the Ely and the very near the lower limit of effective wave action in younger Carbon Ridge Formation are exposed in the what seems to have been a very abruptly fluctuating area, their original contact is not exposed. West of environment. The conglomerate associated with the Newark Summit the Carbon Ridge unconformably 66 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA overlies 1,500 feet of Ely Limestone on a surface with when coarse elastics from the upper plate were shed slight relief (Nolan and others, 1956, p. 62). Here, at into the Diamond Peak trough, but that it did not then least, post-Ely uplift and erosion was slight to moder­ reach the longitude of the Diamond Mountains, nor ate. According to Kiva (1957) and Dott (1955), the did any associated folding. Long after, following situation in the northern Diamond Range is similar; deposition of the Permian elastics derived f~*om the as much as several hundred feet of their Tomera and rejuvenated Antler provenance terrane, the orogenic Moleen Formations were eroded before deposition of belt migrated eastward and the renewed stresses caused the Permian strata. The Ely Limestone was completely the overturned folds and thrusts in the LN 'amond eroded in the vicinity of Secret Canyon before Permian Mountains. There is still no proof that the Roberts time (Nolan and others, 1956, p. 64-65). Mountains thrust ever extended to the Diamond Moun­ Nowhere in the area noted above is there evidence of tains. tight folding during the deformation that caused the EARLY CRETACEOUS SEDIMENTATION uplift and erosion. The continental deposits of the Newark Canyon EARLY PERMIAN SEDIMENTATION Formation were laid down unconformably across many of the older rock units. These sandstones, corglomer- During the Early Permian the coarse elastics, mud- ates, and shales appear to have been derived from whol­ stone, limy sandstones, and fossiliferous limestones of ly local source areas and deposited in an intermittently the Carbon Ridge Formation were deposited through­ subsiding environment that Nolan (1962, p. 2P) inter­ out the area. These rocks are lithogenetically similar prets to be part of the final stages of a deformational to the Diamond Peak Formation and are inferred to episode that was most intense at the beginning of have been deposited in an actively subsiding trough Early Cretaceous time. The regional distribution of adjacent to the rejuvenated Antler orogenic belt. The these rocks is at present poorly known. alternations of lithic types indicate many minor fluctu­ The presence of abundant locally derived lithic ations in detritus and in the water depth. Riva (1957) clasts and textures resulting from rapid erosion, trans­ discovered several unconformities within the Permian port, and deposition indicates that they may h<* ve been section just north of the Eureka quadrangle, suggest­ deposited in separate local troughs. This may, in part, ing that the depositional trough was apparently even explain their spotty distribution. more unstable than was the Diamond Peak trough (fig. LATER EVENTS POST-EARLY PERMIAN DEFORMATION The Newark Canyon Formation was in mor^t places Permian and underlying strata near the mapped area only gently folded by later structural events. In the were folded and faulted together before the uplift and area south of Black Point and west of the msin block erosion which formed the surface upon which the New­ of the Diamond Mountains, the Newark Canyon was ark Canyon Formation of Early Cretaceous age was strongly folded and truncated by erosion before the unconformably deposited (Nolan and others, 1956, p. formation of the fanglomerates and megrbreccias 65). Inasmuch as the Cretaceous rocks are not known which rim the west side of the mountain range. The to be involved in any thrusting in the Eureka area, it outcrop pattern indicates that the fold axes probably is likely that all thrust faulting occurred during this trend about north or northeast parallel to the range latest Paleozoic pre-Cretaceous interval (Nolan, 1962, front and to the high-angle boundary faults. T. B. p. 28). It likewise seems apparent from reinterpret a- Nolan has suggested (oral commun., 1958) that the tion of Riva's mapping (Riva, 1957) that the main deformation may have resulted from gravity sliding folding of the rocks in the Diamond Mountains pre­ into a graben created by an early episode of high-angle dated the deposition of the Newark Canyon rocks. faulting. This folding cannot be dated more exactly The forces that caused the folding and low-angle than post-Early Cretaceous and prefanglomerate and faulting in the Diamond Mountains were in an east- megabreccia unit. west direction and tectonic transport by both folding Erosion truncated the folded Cretaceous strata be­ and faulting was to the east or southeast. It seems un­ fore the megabreccias were deposited, and since the likely that these forces were related to the original megabreccias probably either accompanied or post­ movement of the Roberts Mountains thrust sheet, be­ dated the main high-angle faulting, the relation of the cause they occurred much later than the thrust's first erosion and the faulting is not known. The generally activity in Mississippian time. A reasonable interpreta­ even nature of the erosion surface suggest? that it tion is that the Roberts Mountains thrust was active might have been either part of a pediment formed STRATIGRAPHIC SECTION 67 adjacent to the fault block mountain range or part of later part of the Mississippian the provenance terrane a larger pediplane. The former possibility seems more spasmodically provided significant volumes of con­ likely in view of its apparent limited extent; if so, glomeratic debris which were transported into the the major high-angle faulting interpreted to have marine environment. As the abrupt movements typical given the mountain range its present general form of the latest part of the Mississippian diminished and must have predated the truncation of the upturned gradual subsidence took over in the Pennsylvanian, Cretaceous strata. more and more of the sediments were reworked befcre Accompanying and following the high-angle fault­ burial. ing, the fanglomerate and megabreccias formed along The rocks of Paleozoic age were folded about north- the west base of the range. Their present absence on trending axes, and eastward-directed thrusting occurred the east side is perhaps due to more recent faulting and after deposition of another prism of synorogeric resultant erosion in that area. These deposits were elastics during the Early Permian. This deformation subsequently modified and dissected by erosion that produced overturned folds in part of the Diamond may have been caused by changes in base level related Range, but less shortening took place elsewhere and to younger minor faulting. The high-angle faulting the folds produced there are upright and open. During continued at reduced intensity throughout most of the the Tertiary, high-angle faulting outlined the main Tertiary and perhaps into the Holocene. block of the mountain range and caused differential The well-developed alluvial fans on the east side of movement of individual fault-bounded blocks within the range have no counterpart where the megabreccia the range. and fanglomerate are exposed on the west side, and the time relations of the two are not known, although it STRATIGRAPHIC SECTION OF THE UPPEE PART OF THE BLACK POINT FACIES OF THE is likely that the fans are younger. Beach deposits CHAINMAN FORMATION, THE TYPE SECTIC N formed at the edges of Pleistocene lakes modified the OF THE DIAMOND PEAK FORMATION, AND fans to a certain extent and also affected the alluvial THE LOWER PART OF THE ELY LIMESTONE 1 debris that mantles the pediment near Robinson Eureka la-minute quadrangle, Nevada: Base of section (alt 8,130) is 3,9^0 ft N. S9°40' E. of conical hill alt 7,887 in sec. 12, T. 20 N., Springs. R. 5!f E. (% mile north-northeast of Cottonwood Spring); section extends about 3,500 ft 8. 56° 30' E. up spur to crest of range at alt 9,780, then south along crest ending 5,550 ft N. 12 E. of Diamond Peak CONCLUSIONS summit; section is in sees. 7 and 18 (unsurveyed), T. 20 N., R. 55 E. The Mississippian rocks of this part of the Basin and Top of measured section; alt about 10,000 ft Range province were deposited along the tectonically Ely Limestone: active western edge of an extensive marine basin. The Upper member: Feet older Mississippian strata exposed are in part black 29. Limestone, medium-gray (weathering shales interpreted to have been deposited in the off­ light-bluish-gray), chert nodules, very shore parts of the basin, but correlative rocks deposited fossiliferous locally; interbedded sand­ west of the black shales show intertonguing of that stone (ES-59-165: calcareous quartz arenite), gray (weathering brown), facies with a more sandy, shoreward facies. This fine-grained, poorly sorted; unit is synorogenic shoreward facies includes interbedded medium bedded. Fossil colln. F45-59- sandstone, siltrock, minor clayrock, and coarse pebble ES ( USGS loc. 21318-PG) at top and cobble conglomerate, all of which were derived of section ______Tl.O from older eugeosynclinal sedimentary rocks of the 28. Limestone, gray (weathering brownish- Antler orogenic belt. These older rocks are inferred to gray), sandy, poorly exposed; inter­ have been moved into the provenance terrane as the bedded limy brown-weathering sand­ stone ; unit forms low saddle 12.0 upper plate of the Roberts Mountains thrust fault. At about, the end of the Mississippian the source area 27. Limestone, dark-gray (weathering bluish- gray), poorly exposed, local "fossil ceased to shed coarse elastics into the elongate trough hash," scattered chert nodules near and limestones were deposited over a large area in a base, more chert at top than at base; slowly subsiding basin. unit is a medium-bedded slope-former; The Mississippian sediments deposited closest to the sparse beds contain clastic chert orogenic belt were at first "poured'" into the trough and pebbles ______3^.5 few well-sorted strata are present. The younger sedi­ 2G. Limestone (ES-59-164: biomicrite), me­ dium-gray (weathering light-bluish- ments were deposited under virtually similar condi­ gray), abundant "fossil hash" locally. tions, but reworking became intermittently greater be­ 1 Petrographic classifications of rocks are given in parentheses with cause of fluctuations in the subsidence. During this specimen numbers (see Brew, 1963, for details of classification). 68 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Ely Limestone Continued Ely Limestone Continued

Upper member Continued Feet Upper member Continued peet sparse chert beds as much as 15 cm 16. Limestone (ES-59-154: biomicrite), thick; unit is thick bedded at base, be­ dark-gray (weathering bluish-gray), comes medium bedded and platy locally fossiliferous, local nodules of weathering at top ______14.5 dark chert as much as 10 cm in maxi- 25. Limestone, medium-gray (weathering inium dimension, spare chert pebbles; unit is medium to thick bedded. Fossil lighter bluish-gray than unit 24), colln. F40-59-ES (=USGS loc. 21313- sparsely fossiliferous, abundant tan- PC) (7.0 ft above base) ______19.0 weathering chert in 15-cin beds and nodules, latter having "bullseye" form 15. Limestone (ES-59-152: cherty sandy in some cases; unit is medium bedded 15.5 biosparite, and ES-59-153: biosparite or biosparrudite), dark-gray (weather­ 24. Limestone, dark-gray (weathering bluish- ing bluish-gray), cherty, fossiliferous; gray), abundant dark chert in nodules unit is medium to very thick bedded; and 0.1- to 0.5-ft beds (weathering lower 0.5 ft is platy and weathers "honey" color), very abundant crinoi- yellowish gray. Fossil colln. F38-59- dal and brachiopod debris; unit is me­ ES (=USGS loc. 21311-PC) (0.5 ft dium to thick bedded, forms cliff ____ 15.5 above base) and F39-59-ES (= USGS 23. Limestone, poorly exposed, unit is prob­ loc. 21312-PC) (7 ft above base) __ 9.0 ably thin bedded and similar to unit Total upper member ______295.5 22; forms debris-covered slope ______31.0 Lower member: peet 22. Limestone, medium-gray (weathering light-gray and pinkish-gray), abundant 14. Sandstone, weathering brownish-gray chert in irregular masses as much as and brown, fine-grained,.scattered 1-cm 0.4 ft thick, abundant brachiopods and chert pebbles throughout; grades up­ corals; unit is thin to medium bedded, ward to conglomerate, calcareous forms saddle. Fossil colln. F44-59-ES matrix (ES-59-150: calcareous lithic (=USGS loc. 21317-PC) ______3.5 chert conglomerate), with chert clasts as much as 5 cm in maximum dimen­ 21. Limestone, medium-gray (weathering sion in matrix of calcareous sandstone, bluish-gray), chert abundant in ir­ fine-grained, moderately sorted 3.5 regular masses and beds as much as 13. Conglomerate (ES-59-148: calcareous 0.5 ft thick, fossiliferous towards top; silicified lithic chert-quartz conglomer­ unit is medium bedded; gradational ate), gray clasts of chert as much as 5 with unit 20 ______9.0 cm in maximum dimension in matrix 20. Limestone (ES-59-159: biomicrite), me­ of sandstone, medium-grained, moder­ dium-gray (weathering medium-gray), ately sorted 5.5 sparsely fossiliferous (brachiopods), 12. Sandstone (ES-59-147: calcareous silici­ locally cherty; unit is medium bedded 5.0 fied quartz-chert conglomerate), gray, 19. Siltstone, gray (weathering light-brown), clasts of chert as much as 5 cm in calcareous ; interbedded limestone, gray maximum dimension in matrix of sand­ (weathering mottled-brown and gray), stone, medium-grained, moderately few fossils, local chert nodules; unit sorted ______8.5 is thin bedded ______1.0 11. Limestone (ES-59-146: cherty recrystal- 18. Limestone (ES-59-157: biomicrite), lized silty limestone), gray and yellow dark-gray (weathering bluish-gray), (weathering light-yellowish-brown and some beds coarser grained, locally gray), locally fossiliferous; distinctive fossiliferous, chert nodules and beds mottled appearance, very cherty 8.5 as much as 12 cm thick irregularly dis­ 10. Limestone (ES-59-145: sandy biomic­ tributed and locally abundant; unit is rite), gray (weathering brownish- thin to thick bedded (most medium gray), becoming bluish gray upwards, bedded). Fossil colln. F42-59-ES ( = pyritiferous, scattered chert pebbles USGS loc. 21315-PC) (2.0 ft above and granules, fossiliferous; grades base) and F43-59-ES (=USGS loc. into limy sandstone. Fossil colln. F37b- 21316-PC) (8.5 ft above base) ______47.5 59-ES (rzUSGS loc. 21310-PC) from 17. Siltstone, gray (weathering light-olive- middle of unit ______8.0 gray), fossiliferous, calcareous, some 9. Conglomerate (ES-59-144: silicified pyrite; grades into unit 18. Fossil lithic chert conglomerate), white colln. F41-59-ES (=USGS loc. 21314- (weathering light-brown and pale- PC) ______2.5 green), clasts as much as 1.8 cm in STRATIGRAPHIC SECTION 69

Ely Limestone Continued Ely Limestone Continued Lower member Continued Lower member Continued Feet maximum dimension, possible bioniodal siliferous. Fossil colln. F32-59-ES sorting, firmly cemented with silica; (=USGS loc. 21304-PC) at top of unit 9.0 contact with unit 8 is irregular, prob­ 1. Limestone (ES-59-135: silty biomicrite, ably a scour surface ______3.5 and ES-59-136: biomicrite), gray 8. Claystone-matrix limestone-phenoplast (weathering greenish-gray and gray), conglomerate (ES-59-143: hema- fossiliferous (mainly crinoidal debris), titic(?) silty claystone-matrix dismi- platy-weathering; interbedded silt- crite nodule rock), gray (weathering stone, weathering light-brown; and olive-gray and dark-greenish-gray) ; minor sandstone, brown, very fine grades upward into siltstone similar to grained. Fossil colln. F31-59-ES the matrix ______4.5 (=USGS loc. 21303-PC) about 2.0 ft above base 22.5 7. Limestone, dark-gray (weathering dark- Total lower member _ 137.0 bluish-gray), chert beds as much as 15 cm thick show minor contortions, some Total Ely Limestone 4f2.5 "fossil hash" ______3.5 6. Limestone, gray (weathering yellowish- Diamond Peak Formation: gray) ; interbedded sandstone, weather­ ing brown and yellowish-brown, cal­ Member H: careous ; limestone-matrix limestone- 104. Siltstone, dark-gray (weathering dark- phenoplast conglomerate (ES-59-141) ; grayish-green with purplish hue), silty micrite-matrix dismicrite nodule sandy at base; interbedded with sand­ rock), and minor shale, weathering stone light-gray (weathering light- dark-green, fossiliferous. Fossil colln. greenish-gray), very fine grained; and F36-59-ES (=USGS loc. 21308-PC) claystone with sparse limestone clasts (7.0 ft above base) and F37a-59-ES [ES-59-134: ferruginous limestone (=USGS loc. 21309-PC) (13.0 ft nodule-bearing silty (quartz-chert) above base) ______18.0 claystone], weathering dark-purplish- gray. Contact with unit 103 is a dia­ 5. Claystone (ES-59-140: chloritized silty stem, with minor scours about 1 ft (lithic quartz-chert) claystone), gray deep ______6.0 (weathering dark - greenish - gray), lightens in color upwards; grades into 103. Conglomerate (ES-59-132: silicified siltstone of same aspect; gradational lithic chert conglomerate), weather­ with unit 6 ______3.0 ing white and pale-green, clasts of white and pale-green chert as much as 4. Limestone (ES-59-139: intrasparite), 2 cm in maximum dimension in matrix gray (weathering yellowish-gray) ; and of sandstone, medium-grained, poorly subequal amount of sandstone, weather­ sorted; interbedded subequal amount ing brown and yellowish-brown, cal­ of conglomeratic sandstone (ES-59- careous, at base. Contact with unit 3 is 133 : calcareous silicified conglomeratic irregular, probably a diastem ______9.5 quartz-chert arenite), gray (weather­ 3. Limestone (ES-59-138: cherty oospa- ing olive-gray) ______27.5 rite), bluish-gray (weathering gray), 102. Sandstone, light-gray (weathering light- fossiliferous (mostly crinoid stems and grayish-green), very fine grained, brachiopods), platy-weathering, some dense; interbedded subequal amounts nodules of gray chert near top; inter- of siltstone. weathering dark-grayish- bedded sandy siltstone and sandstone, green, like unit 100. with scattered 2- weathering brown and olive-gray, near om limestone clasts; and siltst one- base. Fossil colln. F33-59-ES (=USGS matrix limestone-phenoplast conglom­ loc. 21305-PC) (5.5 ft above base), erate, gray (weathering olive-gray), F34-59-ES (=USGS loc. 21306-PC) near middle of unit. Fossil eollu. F30- (14.5 ft above base), and F35-59-ES 59-ES (=USGS loc. 21302-PC) (22.0 (=USGS loc. 21307-PC) (21.0 ft above ft above base) ______39.5 base) ______29.5 101. Siltstone-matrix limestone-phenoplast 2. Siltstone, dark-purple (weathering conglomerate, like unit 100, but lime­ dusky-red-purple) ; grades upwards in­ stone clasts are larger (greater than to limestone, weathering purplish-gray 2 cm) ; grades upward into limestone, (ES-59-137: silty intramicrite), fos- gray, nonfossiliferous ______4.0 70 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Diamond Peak Formation Continued Diamond Peak Formation Continued

Member H Continued Feet Member G Continued Feet 100. Siltstone-matrix liniestone-phenoplast (weathering dark-gray), clasts of light conglomerate (ES-59-131: chloritized and dark chert as much as 3.5 cm in limestone nodule-bearing clayey maximum dimension in matrix of quartz-chert siltstone), davk-gray poorly sorted fine-grained sandstone; (weathering dark - greenish - gray), iuterbedded sandstone of two types: scattered nodules less than 2 cm in (ES-59-123: silicified lithic chert- maximum dimension; grades into silt- quartz arenite), greenish-gray, fine­ stone like the matrix; and sandstone, grained, poorly sorted; and (ES-59- light-gray (weathering light-greenish- 124: calcareous silicified lithic quartz- gray), very fine grained, flrnily chert arenite), brown, fine-grained, cemented with silica ______30.5 moderately sorted 29.0 99. Conglomerate (ES-59-130: silicified 92. Siltstone. gray (weathering olive-gray lithic chert conglomerate), light-gray and brown), sparse worm trails, abun­ (weathering white) ; clasts of light- dant pyritef?) casts, poorly preserved gray chert and quartzite as much as brachiopods; grades upwards into sub- 6.5 cm in maximum dimension in equal amount of limestone-pheiioplast matrix of sandstone, flue- to medium- conglomerate: grades locally into ATery grained, poorly sorted ______5.0 fine grained sandstone; and shale (ES- 59-121: calcareous clay shale) near 98. Limestone (ES-59-129: silty intra- top: minor faults. Fossil colln. F25- sparrudite), gray, abundant brachi- 59-ES (13.5 ft above base), and F26- opods. horn corals; interbedded equal 59-ES (=USGS loc. 21297-PC) (25.5 amounts of siltstone. gray (weather­ ft above base), also approximate loca­ ing olive-gray), fossiliferous; and silt- tion of colln. F21-59-ES (=FSGS loc. stone-matrix Ihnestone-phenoplast con­ 21296-PC) and F22-59-ES ( TJSGS glomerate, gray (weathering olive- loc. 21298-PC) from fault-duplicated gray). Fossil colln. F28-59-ES part of section _ 30.5 (=FSGS loc. 21300-PC) <9.:> ft above 91. Conglomerate (ES-59-120: silicified base) and F29-59-ES (=USGS loc. lithic chert-quartz conglomerate), 21301-PC) (17.5 ft above base) _____ 21.5 light-gray (weathering light-gray) ; 97. Conglomerate, white, pebbles of light- clasts of pale-green, light- and dark- gray chert as much as 5 cm in maxi­ gray chert as much as 12.5 cm in maxi­ mum dimension in matrix of sand­ mum dimension in matrix of silicified stone, calcareous: grades upward to sandstone ; some Fe stain _ 27.5 conglomeratic sandstone ______3.0 90. Sandstone (ES-59-119: calcareous 96. Limestone (ES-59-128: sandy biospa- quartz-chert arenite), light-brown rite ( V)), gray (weathering medium- (weathering brown), fine-grained, gray) ; interbedded equal amount of poorly sorted, calcareous cement at conglomerate (ES-59-127 : calcareous base, local silica cement higher; fossili­ lithic chert conglomerate), gray, flue- ferous locally. Fossil colln. F24-59- grained, calcareous ______39.0 ES (=USGS loc. 21295-PC) (1.0 ft above base) __-____ _ 17.5 95. Limestone ( ES-59-125 : intrasparrudite), dark-gray (weathering medium-gray), 89. Shale (ES-59-118: gypsiferous silty clay fossiliferous, dense, thick-bedded; shale), gray (weathering olive-gray), interbedded sandstone (ES-59-126: locally pyritiferous and poorly fossili­ sideritic quartz-chert arenite), dark- ferous, worm trails. Fossil colln. F23- gray (weathering brown), fine- to 59-ES (=USGS loc. 21294-PC) (froir medium-grained. well-sorted; limy float) ______10.0 cement, Fe stain, thick-bedded. Fossil 88. Limestone (ES-59-117: sandy intramic- colln. F27-59-ES ( FSGS loc. 21299- rudite), gray (weathering gray and PC) (near middle of unit) ______45.0 light-olive-gray) ; resembles limestone- phenoplast conglomerate which it prob­ Total member H 221.0 ably grades into laterally; sparse chert pebbles locally ______13.0 Member G: 87. Sandstone (ES-59-116: calcareous silici­ 94. Covered, probably mostly siltstone, some fied quartz-chert arenite), light-browr fossiliferous float; forms saddle _____ 117.5 (weathering light-brown), fine-grained, 93. Conglomerate (ES-59-123: calcareous poorly sorted, some Fe stain ______6.0 lithic chert conglomerate), gray Total member G ______251.0 STRATIGRAPHIC SECTION 71

Diamond Peak Formation Continued Diamond Peak Formation Continued

Member F: Feet Member F Continued Feet 86. Siltstone, purple and grayish-green: white chert pebbles, firmly cemented grades into sandstone and interbedded with silica 3.0 subequal amounts of siltstone-matrix 78. Conglomerate, like unit 76. but slightly limestone-phenoplast conglomerate coarser 12.5 (ES-59-102: silty claystone-matrix 77. Siltstone, weathering red-purple and dismieriteC ?) nodule rock, purple); grayish-green; interbedded sandstone, and sandstone chert arenite, purple weathering greenish-gray and purple and greenish-gray very fine grained, siltstone-matrix limestone-phenoplast with sparse pebbles, silicifled; and conglomerate ______20.5 sandstone (ES-59-101: barite-bearing calcareous silicifled quartz-chert are­ 76. Conglomerate ( ES-59-93 : silicifled lithic nite), fine-grained, moderately to well- chert-quartz conglomerate), weathering sorted, thick-bedded ______85.0 white and pale-green, clasts of light- gray and pale-green chert as much as 85. Siltstone-matrix lirnestone-phenoplast 7.5 cm in maximum dimension in conglomerate, weathering greenish- matrix of sandstone, flne-grained, gray (becoming dusky purple up­ poorly to moderately sorted ______11.0 wards), limestone nodules as much as Siltstone (ES-59-92: chloritized clayey 20 cm in maximum dimension _ ___ 26.0 quartz-chert siltstone). weathering 84. Siltstone- and claystone-matrix lime­ dusky-red-purple, color more intense stone-phenoplast conglomerate, like at top, and grayish-green; grades into unit 82; interbedded siltstone, as in minor claystone; gradational from matrix, dusky-purple, some green; and unit 74 ______18.5 sandstone (ES-59-99: chloritized 74. Siltstone-matrix limestone-phenoplast clayey lithic quartz-chert arenite). conglomerate [ES-59-91a (matrix) : dark-gray (weathering greenish-gray). chloritized clayey chert-quartz silt- fine-grained, poorly sorted, some cross- stone, and ES-59-91b (nodule) : mic­ bedding ______-______- rite] ; interbedded siltstone, like the 83. Conglomerate, light-gray (weathering matrix, weathering red-purple and white and pale-green), pebbles sub- light-green, and claystone ; color bound­ aries irregular ______25.0 angular, like units 76 and 78 ______1.5 73. Siltstone (ES-59-90: clayey quartz- 82. Siltstone, weathering greenish-gray: chert siltstone), weathering dusky-red- interbedded sandstone, weathering purple and green; less clayey parts greenish-gray, very fine grained, firmly tend to be green; grades into clay- cemented with silica; clayrock, stone ______9.0 weathering purple; siltstone-matrix limestone-phenoplast conglomerate, Total member F 317.5 weathering green; and minor chert- pebble conglomerate (ES-59-98: sili­ Member E: cifled lithic chert-quartz conglomer­ 72. Conglomerate (ES-59-88: chloritized ate) ______23.0 silicifled lithic chert-quartz conglom­ 81. Claystone-matrix limestone-phenoplast erate), weathering white and pale- conglomerate [ES-59-95: claystone- green, clasts of pale-green and light- matrix micrite nodule rock; ES-59- gray chert as much as 6.5 cm in maxi­ 96: silty (quartz-chert) claystone, mum dimension in matrix of sand­ matrix micrite nodule rock, and ES- stone, medium-grained, poorly sorted; 59-97: clayey lithic quartz-chert silt grades upward into sandstone (ES- shale], weathering dusky-purple and 59-89: chloritized silicifled lithic green ; irregular color boundary ___ 4.5 quartz-chert arenite), weathering light- green, flne-grained, poorly sorted 13.0 80. Siltstone, weathering dusky-purple, grades to claystone; near middle of 71. Sandstone (ES-59-87: clayey lithic unit a very thick claystone-matrix chert-quartz arenite), dark-greenish- limestone-phenoplast conglomerate gray (weathering dark-greenish-gray), (ES-59-94: chloritized silty claystone flne-grained, poorly sorted, pyritifer- ous; interbedded siltstone of same matrix micrite nodule rock) bed __ 18.5 aspect; and 1 thin bed of siltstone- 79. Sandstone, gray (weathering greenish- matrix limestone-phenoplast conglom­ gray), like that of unit 71, scattered erate 63.0 72 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Diamond Peak Formation Continued Diamond Peak Formation Continued

Member E Continued Feet Member E Continued 70. Sandstone (ES-59-83: silicified(?) 62. Mudstone-matrix limestone-phenoplast clayey chert-quartz arenite), weather­ conglomerate (ES-59-75: silty clay- ing brownish-green, very fine grained, stone-matrix dismicrite nodule rock), poorly sorted; grades into siltstone and matrix medium-gray, weathering me- upwards into clay shale with worm dium-greenish-gray, nonresistant 3.5 trails, and minor siltstone-matrix lime- 61. Siltstone, gray (weathering olive-gray) ; stone-phenoplast conglomerate ______45.5 grades to clay rock and minor sand­ 69. Conglomerate (ES-59-82: calcareous stone; siltstone-matrix limestone- lithic chert-quartz conglomerate), gray phenoplast conglomerate, medium- (weathering white), chert and quartzite bedded, near middle 3.5 clasts as much as 10 cm in maximum 60. Sandstone (ES-59-74: calcareous con­ dimension in moderately to poorly glomeratic quartz-chert arenite), gray sorted medium-grained matrix; inter- (weathering brown), medium-grained, bedded subequal amount of sand­ poorly sorted, firmly cemented, abun­ stone, gray (weathering white), firmly dant Fe stain _ 5.5 cemented; forms ledge ______16.0 59. Siltstoue, gray (weathering light-olive- 68. Sandstone (ES-59-81: clayey lithic gray), abundant worm trails, some chert-quartz arenite) gray (weather­ brachiopods ; interbedded shale (ES- ing brown), medium-grained, poorly 59-73: silty clay shale), gray, also sorted; grades upward into siltstone, fossiliferous, and minor sandstone, gray (weathering dark-greenish-gray) 15.0 very fine grained, and silstone-matrir 67. Conglomerate, light-gray (weathering limestone-phenoplast conglomerate, white) ; fine pebbles, well-sorted, abun­ thick-bedded. Fossil colln. F17-59-EF dant Mn stain; interbedded subequal (=USGS loc. 21291-PC) (4.0 ft above amount of sandstone (ES-59-80: silici- base) ______21.5 fied conglomeratic quartz arenite), 58. Limestone (ES-59-72: silty biomicrite), weathering white, fine-grained, well- gray, nonfossiliferous at base, scat­ sorted ______3.0 tered chert granules ; grades upward 66. Siltstone (ES-59-78: clayey quartz-chert to siltstone-matrix limestone-pheno­ siltstone), gray (weathering light- plast conglomerate with sparse cri- olive-gray), fossiliferous, some pyrite; noidal debris and back to limestone 7.5 grades into sandstone (ES-59-79: 57. Siltstone (ES-59-71: silicified chert- clayey lithic quartz-chert arenite), quartz siltstone), gray (weathering very fine grained, poorly sorted, and olive-gray), grades into very fin? clay rock locally; at base, siltstone- grained sandstone 6.5 matrix limestone-phenoplast conglom­ erate, thick-bedded. Fossil colln. F19- 56. Siltstone, gray, locally fossiliferous ; interbedded minor clayrock and silt- 59-ES (=USGS loc. 21293-PC) (18.5 ft above base) and F20-59-ES stone-matrix limestone-phenoplast con­ glomerate ; nonresistant slope-forme" 49.0 (=USGS loc. 18590-PC) (same) __ 38.0 65. Siltstone (ES-59-77: silicified( ?) clayey 55. Sandstone (ES-59-70: silicified chert- quartz-chert siltstone), gray (weather­ quartz arentite), gray (weathering ing greenish-gray) ; grades into sand­ brown), fine-grained, poorly sortec1, stone, very flne grained; interbedded locally conglomeratic, firmly cemented minor shale ______14.5 with silica, some pyrite; forms resist­ 2.5 64. Conglomerate (ES-59-76: silicifled lithic ant ledge chert-quartz conglomerate), gray 54. Sandstone (ES-59-69: clayey quartr- (weathering brownish-gray), poorly to chert areuite), gray (weathering olive- moderately sorted, light-colored quartz­ gray and dark-greenish-gray), fine­ ite and chert pebbles and cobbles with grained, poorly sorted; forms resistant maximum dimension of 7.5 cm in ledges ; interbedded siltstone, gray matrix of medium-grained sandstone; (weathering dark-greenish-gray an-* interbedded sandstone, brown ______15.5 dusky -purple ), and minor mediunr- 63. Shale, gray (weathering olive-gray), bedded limestone, conglomerate, an^ fossiliferous, nouresistant; grades into moderately sorted silicified brown subequal amount of siltstone of similar sandstone ____ - 15.5 aspect. Fossil colln. F18-59-ES 53. Limestone (ES-59-68: clayey biospr- (=USGS loc. 21292-PC) is from float 32.5 rite), gray, thick-bedded lens 2.0 STRATIGRAPHIC SECTION 73

Diamond Peak Formation Continued Diamond Peak Formation Continued

Member E Continued Feet Member D Continued fjet 52. Sandstone (ES-59-67: calcareous silici- 44. Limestone (ES-59-60: foraminiferal fied chert-quartz arenite), gray biomicrite, =USGS loc. f21924), dark- (weathering brown), fine-grained, gray (weathering medium-gray), fos- moderately to poorly sorted, dense, siliferous; interbedded minor conglom­ firmly cemented with silica ( ?) ; inter- eratic sandstone, weathering brown, bedded subequal amount of conglom­ dense ______F3.0 erate, and minor gray limestone, and 43. Shale (ES-59-59: calcareous clay shale), minor siltstone-matrix limestone- gray (weathering brown), some phenoclast conglomerate; unit is me­ pyrite : interbedded with lesser amount dium bedded ______16.5 of limestone, gray, fossiliferous. Fossil 51. Siltstone, medium-gray (weathering colln. F15-59-ES (=USGS loc. 21290- brown), sandy, thick- to very thick PC) from middle of unit ______3.5 bedded; interbedded conglomerate, 42. Limestone (ES-59-58: foraminiferal bio­ gray, firmly cemented with silica, sparite, =USGS loc. f21923), gray, thick-bedded, and sandstone, gray fossiliferous, contact with unit 41 is (weathering brown), very fine grained, irregular and could be a diastem; very limestone (ES-59-66: sandy intra- minor shale interbeds; forms promi­ sparite), gray, crinoidal debris, and nent cliff. Fossil colln. F14-59-ES near minor siltstone-matrix limestone-pheno- middle of unit ______15.5 clast conglomerate. Unit forms slope 181.0 41. Siltstone, like unit 38, at base; grades Total member E 570.5 upward into conglomeratic sandstone (ES-59-57: calcareous conglomeratic Member D: quartz-chert arenite), weathering brown, medium-grained, moderately 50. Limestone (ES-59-65: sandy biomicrite, to poorly sorted, chert pebbles as much =TJSGS loc. f 21926), gray, chert clast as 1 cm in maximum dimension; and content increases upwards; grades to sandstone ______8.5 unit 51 ______5.0 40. Limestone, gray, abundant chert pebbles; 49. Siltstone, gray (weathering olive-gray), a 0.5-ft siltstone bed like unit 38 near some chert pebbles, otherwise similar base ______3.5 to siltstone of unit 48 __ _ __ 7.0 39. Conglomerate (ES-59-56: calcareous lithic chert conglomerate), weather­ 48. Limestone, gray, crinoidal debris, some ing brownish-white, pebbles of chert crossbedding; sparse chert pebbles; and quartzite as much as 2.1 cm in interbedded minor siltstone, gray maximum dimension; moderately to (weathering light-olive-gray) _____ 19.5 poorly sorted, becomes silty upwards 47. Conglomerate (ES-59-64: silicified lithic (like unit 38) and grades into unit 40 3.5 chert-quartz conglomerate), weather­ 38. Siltstone (ES-59-55: calcareous silici­ ing brown, chert clasts as much as 1.5 fied quartz-chert siltstone), light- cm, in maximum dimension poorly brown (weathering light-olive-gray), sorted, firmly cemented with silica: dense ______7.0 interbedded lesser amount of silt shale (ES-59-63: quartz-chert silt shale), 37. Limestone, gray, crossbedded, crinoids gray (weathering olive-gray) ______17.5 and brachiopods; interbedded with minor pebble beds and sandstone, gray 46. Limestone (ES-59-62: silty biosparite, (weathering olive-gray) ______4.0 =USGS loc. f21925), gray, crinoidal debris; interbedded subequal amount 36. Sandstone, light-brown (weathering of siltstone, gray (weathering olive- light-olive-gray), dense ______2.0 gray) ; and minor siltstone-matrix 35. Limestone (ES-59-54: sandy intra- limestone-phenoclast conglomerate _ 20.0 sparite), gray (weathering gray), al­ 45. Conglomerate (ES-59-61: silicified lithic most 5 percent chert pebbles, brachio- chert-quartz conglomerate), gray pod fragments. Fossil colln. F13-59-ES (weathering brown), angular chert (=USGS loc. 21289-PC) (near middle and quartzite clasts as much as 10 cm unit) ______7.0 in maximum dimension, poorly sorted; 34. Shale (ES-59-53: clay shale), gray lowest 0.5 ft is brown-weathering sand­ (weathering light-olive), calcareous in stone ______9.0 part, some pyrite cubes ______5.5 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Diamond Peak Formation Continued Diamond Peak Formation Continued

Member D Continued Feet Member 1)- Continued Feet 33. Limestone, dark-gray (weathering blue- 26. Limestone (ES-59-40: cherty biomi- gray ). some crinoidal debris: grades crite). medium-gray (weathering me­ upward into minor conglomeratic and dium- to light-gray), medium- to thick- sandy beds (ES-59-52: sandy intra- bedded, fossiliferous: horn corals, cri- micrite). gray, very thin bedded to noid fragments, bryozoans. and thin-bedded; interbedded with very brachiopod fragments; interbedded minor clay shale, gray (weathering with siltstone (ES-59-42: quartz-cher4- light-olive-gray) : local lenses pinch siltstone). gray (weathering olive- and swell, some are thick bedded __ 28.0 gray), and minor limestone nodule rock with matrix of silty limestone, 32. Conglomerate (ES-59-51: calcareous which grades upward into silty lime­ lithic chert conglomerate), variegated, stone (ES-59-41: silty bryozoan biomi- moderately to poorly sorted: red, gray, crite). Fossil ES-57-6F and colln. black, and white chert clasts as much (original position of) F6-59-EF as 7.5 cm in maximum dimension; 85 (=USGS loc. 21286-PC) are from 1.0 percent pebbles and cobbles ______3.0 ft above base and F10-59-ES (=FSGP 31. Conglomeratic sandstone (ES-59-50: loc. 212S5-PC) is from middle of unit 22.5 calcareous conglomeratic lithic chert- quartz arenite). coarse-grained, poorly Total member D 379.5 sorted; grades into minor conglom­ erate; less resistant than unit 30 __ 17.5 Member C: 30. Conglomerate, gray, rounded chert (some 25. Siltstone ( ES-59-39: clayey quartz-chert red) and quartzite clasts as much as siltstone), gray (weathering lighte^ 7.5 cm in maximum dimension, firmly gray), pyrite casts, thin-bedded: inter­ cemented with silica : interbedded with bedded with gradational very fin° lesser amount of sandstone (ES-59- grained sandstone: and clayrock, gray 49: silicified conglomeratic quartz- (weathering olive-gray). Possibly som? chert arenite). gray (weathering limy nodules in siltstone at base of unit 19.5 brown), medium-grained, moderately 24. Conglomerate (ES-59-38: silicified sorted; forms resistant ledge ______12.0 lithic chert-quartz conglomerate), 29. Shale (ES-59-48: silty clay shale), gray light-gray (weathering white and (weathering light-olive-gray), abun­ light-brown), clasts of chert and dant small brachiopods: becomes quartzite with maximum dimension of sandy in upper 5 ft with sparse chert 7.5 cm in matrix of silicified poorly pebbles. Fossil collu. F11-59-ES sorted sandstone __ __ 6.5 (=FSGS Inc. 21287-PC) (15.5 ft 23. Siltstone (ES-59-37: chert-quartz silt above base) and F12-59-ES (=FSGS shale), dark-gray (weathering gray loc. 2128S-PC) (24.5 ft above hase)__ 49.0 and olive-gray), carbonaceous, fossili­ ferous ; grades into snbequal amount 28. Sandstone (ES-59-47 : silieified conglom­ of clay shale. Fossil colln. F9-59-E? eratic quartz-chert arenite), gray (r=FSGS loc. 21284-PC) is from float (weathering brown), fine-grained, near middle of unit __ 49.0 moderately sorted, some pebbly layers, firmly cemented with silica ______9.0 22. Limestone (ES-59-36: foraminiferal bio­ sparite, =FSGS loc. f21922), dark-gray 27. Sandstone (ES-59-43 : calcareous quartz- (weathering medium-gray), dense, chert arenite), gray (weathering fossiliferous ___ .5 brownish-gray), fine-grained, moder­ ately sorted to well-sorted, very dense, 21. Siltstone, dark-gray (weathering light- abundant pyrite cubes; interbedded olive-gray), abundant bryozoan casts ; with lesser amount of limestone (ES- grades into sandstone (ES-59-34: 59-44: sandy biosparite), gray clayey chert-quartz arenite), gray (weathering gray), very dense, some (weathering light-olive-gray), very pyrite cubes; and siltstone (ES-59- fine grained, moderately to poorly 45: calcareous chert-quartz siltstone) sorted: iuterbedded with minor clay- like that in unit 26; near top some rock ( ES-59-35 : silty claystone) gray sandstone (ES-59-46: silicified quartz- (weathering olive-gray), with abur- chert arenite). gray, very fine grained, dant bryozoan casts. Fossil colln. F6- moderately to poorly sorted; tightly 59-ES (i=USGS loc. 21286-PC) (floet cemented with silica ______47.5 10.0 ft above base and is from unit STRATIGRAPHIC SECTION 75

Diamond Peak Formation Continued Diamond Peak Formation Continued

Member C Continued Feet Member B Continued peet 26), F7-59-ES (=USGS loc. 21282- ing olive-gray), some pyrite: and shale PC) (17.5 ft above base), and F8-59- (ES-59-27: silty clay shale), dark- ES (=USGS loc. 21283-PC) (same gray (weathering light-olive-gray), level as F7, but float) ______abundant pyrite ____ _ 44-.5 20. Conglomerate (ES-59-32: silicifled lithic 13. Siltstone. gray (weathering olive-gray), quartz-chert conglomerate), gray some pyrite (?) casts, sparse worm (weathering brownish-gray and gray), trails and concretions: interbedded chert, quartzite, and other lithic clasts with lesser amount of sandstone, gray, as much as 15 cm in maximum dimen­ very fine grained to medium-grained, sion in matrix of poorly sorted sand­ poorly sorted, medium-bedded: and stone, firmly cemented with silica; minor clayrock; and minor sandstone interbedded with lesser amount of (ES-59-25: silicified quartz-chert aren­ sandstone (ES-59-33 : silicified quartz- ite), gray, fine- to medium-grained, chert arenite) gray, fine-grained, mod­ moderately sorted, firmly cemented erately sorted, firmly cemented with with silica, thick-bedded ______25? 5 silica, sparse chert pebbles; unit forms 12. Conglomeratic sandstone (ES-59-24: prominent ledge ______106.5 conglomeratic lithic chert-quartz aren­ Total member C 237.0 ite), gray (weathering olive-gray) ; maximum pebble size 3.5 cm in maxi­ Member B: mum dimension in matrix of silty sandstone: interbedded with siltstone 19. Covered; float is mostly sandstone like (weathering olive-gray), some fossil "that of unit 18 ______176.5 casts; and conglomerate, gray, cobbles IS. Sandstone (ES-59-31: silicified chert- and pebbles of chert in silicified quartz arenite, and ES-59-29: clayey matrix, forms resistant ledges ____ 44.5 lithic quartz-chert arenite), gray (weathering gray and olive-gray), in­ 11. Siltstone (ES-59-23: chert-quartz silt- dividual beds very fine grained to stone), gray (weathering olive-gray), coarse-grained, poorly sorted; silica thin-bedded, hematite cubes after cement; thin-bedded, abundant pyrite, pyrite (?), local concentrations of brachiopods, horn corals, crinoid sparse (more near top) worm trails; interbedded with lesser amount of con­ columnals, and bryozoans, sparse con­ glomerate and conglomeratic sandstone cretions ; interbedded with sandstone (ES-59-22: lithic quartz-chert aren­ (ES-59-30: silicified conglomeratic lithic chert-quartz arenite), gray, chert ite), gray, very fine grained to me­ dium-grained, moderately to poorly clasts as much as 3 cm in maximum sorted, thin-bedded, forms resistant diameter in matrix of poorly sorted ledges; and clayrock. gray. Fossil sandstone, silica cement. Unit forms colln. F5-59-ES (=USGS loc. 21281- ledges ______19.0 PC) (42.0 ft above base) ______6?.0 17. Covered; probably similar to unit 16 _ 339.0 10. Siltstone (ES-59-21: quartz-chert silt 16. Siltstone, gray (weathering light-olive- shale), gray (weathering olive-gray), gray), partially covered; interbedded abundant worm trails and pyrite casts with sandstone, weathering olive-gray, and hematite cubes after pyrite, thin-bedded ______74.0 weathers to 1-crn thick fragments 5-10 15. Conglomerate (ES-59-28: silicified lithic cm across, some carbonaceous debris chert conglomerate), gray (weather­ and wood, crinoid, brachiopod, and ing gray), pebbles of quartzite and coral casts; interbedded with clay- chert as much as 5 cm in maximum di­ rock, gray (weathering olive-gray) ; mension in matrix of poorly sorted and sandstone (ES-59-20: clayey sandstone, firmly cemented with silica ; lithic chert-quartz arenite) weather­ a local lens ______3.0 ing olive-gray, very fine grained, thin- bedded, abundant pyrite casts. Fossil 14. Sandstone (ES-59-26: silicified quartz- colln. F2-59-ES (=USGS loc. 21278- chert arenite), gray (weathering olive- PC) (39.0 ft above base), F3-59-ES gray to brown), very fine grained, mod­ <=USGS loc. 21279-PC) (115.0 ft erately to poorly sorted, very thick above base), and F4-59-ES (=USGS bedded, cemented with silica, some loc. 21280-PC) (130.0 ft above base) 245.0 pyrite; interbedded with subequal amount of siltstone, gray (weather- Total member B ______1,2 9.0 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

Diamond Peak Formation Continued Diamond Peak Formation Continued

Member A: Feet Member A Continued Feet 9. Conglomerate (ES-59-19: silicified lithic ments,, most are disk shaped; inter­ chert-quartz conglomerate), gray, bedded with thin beds of siltstore clasts of chert and limestone and weathering olive-gray _ _ 9.0 quartzite as much as 10 cm in maxi­ Total member A ______280.5 mum dimension, some pyrite, firmly Total Diamond Peak Formation 3,526.0 cemented with silica; interbedded with lesser subequal amounts of siltstone like unit 8 (ES-59-18: chert-quartz Chainman Formation: silt-shale), but contorted and dis­ Black Point f acies : Feet rupted, and clay shale, gray (weather­ ing olive-gray) ; minor sandstone also 44.0 21. Conglomeratic sandstone (ES-59-11: conglomeratic clayey lithic cher*- 8. Siltstone and shale (ES-59-17: sandy quartz arenite), chert pebbles in clay shale), grayish-black (weather­ matrix of sandstone, weathering oliv?- ing grayish-brown), thin- to medium- gray and brown, very fine grained to bedded; some pyrite, "slaty" appear­ medium-grained, some casts of crino?d ance ______8.5 columnals and bryozoans; grades u*> 12.0 7. Conglomeratic sandstone (ES-59-16: wards into siltstone ______conglomeratic lithic chert-quartz aren- 20. Siltstone, gray (weathering olive-gray), ite), clasts as much as 10 cm in maxi­ poor casts of crinoids, bryozoans, ar«l mum dimension, thick-bedded; inter- brachiopods; interbedded with lesser bedded with sandstone, gray, medium- amount of conglomerate, gray, pebbles grained, poorly sorted, firmly cemented of chert in matrix of sandstone, gray with silica, some pyrite; suggestion of (weathering olive-gray), very fine grading ______6.0 grained to fine-grained; some worm trails. Fossil colln. F1-59-ES (=TJSGS 6. Covered; probably mostly siltstone in­ loc. 21277-PC) near middle of unit, terbedded with thin sandstone beds 151.5 mostly float ___-_ _ - ____ 15.5 5. Conglomeratic sandstone (ES-59-15: 19. Covered; float is lithic conglomerate conglomeratic clayey lithic chert- from upslope ____ _ - ____ 94.0 quartz arenite), weathering olive-gray, fine- to medium-grained, poorly sorted, 18. Conglomerate (ES-59-9: lithic chert chert and quartzite pebbles as much as conglomerate), gray, maximum pebtTe 5 cm in maximum dimension in matrix size about 1 cm in maximum dimen­ of sandstone ; some pyrite ( ?) and poor sion, matrix is sandstone, fine- to coarse-grained, poorly sorted, pebbles fossil casts ______9.5 are chert and quartzite, casts of

Chainman Formation Continued Chainman Formation Continued

Black Point facies Continued Feet Black Point facies Continued peet bedded (some beds are graded), abun­ 2. Sandstone (ES-59-2: quartz arenite), dant pyrite (?) casts and crinoid gray (weathering brown), very fine columnal casts, sparse carbonaceous grained to medium-grained, moderately (woody) debris: interbedded with sub- to poorly sorted; abundant pyrite in equal amount of siltstone, grayish- coarser parts; probably a local lens 7.5 black (weathering olive-gray), worm 1. Siltstone (ES-59-1: quartz siltstone), trails ______32.0 dark-gray and black (weathering olive- 12. Covered; probably similar to unit 11, gray) ; pencil weathering in part, con­ but float is mostly brown-weathering tains "worm trails" and cubic casts sandstone ______159.0 of pyrite(?) 1^5 11. Siltstone, dark-gray (weathering olive- Total Black Point facies of Chain­ gray and grayish-brown) ; interbedded man Formation _ _ 1,077.0 with subequal amount of clay shale Base of section; not base of exposure. (ES-59-7: silty clay shale), dark- gray ; and minor sandstone, very fine grained, medium-bedded; grades from REFERENCES CITED unit 10, worm trails and pyrite (?) casts throughout; weathers to 5- to 15- Bissell, H. J., 1960, Eastern Great Basin Permo-Pennsylvaniin cm-diameter plates ______69.0 strata Preliminary statement: Am. Assoc. Petrolerm 10. Siltstone, gray (weathering olive-gray) ; Geologists Bull., v. 44, no. 8, p. 1424-1435, incl. sketch interbedded with lesser amount of gray maps, chert, section and fence diagrams. clay shale; grades from unit 9; Brew, D. A., 1961a, Lithologic character of the Diamond Peak weathers to 2- to 5-cm-diameter flakes; Formation (Mississippian) at the type locality, EureVa worm trails and sparse cubic pyrite( ?) and White Pine Counties, Nevada, in Geological Survey casts; coarsens upwards ______155.5 research 1961: U.S. Geol. Survey Prof. Paper 424-C, p. 9. Siltstone (ES-59-5: quartz-chert silt- C110-C112. stone) dark-gray (weathering olive- ___ 1961b, Relation of Chainman Shale to Bold Bluff thrrst gray) ; interbedded with sandstone, fault, southern Diamond Mountains, Eureka and White medium-gray (weathering brown), Pine Counties, Nevada, in Geological Survey research very fine grained to fine-grained; sand­ 1961: U.S. Geol. Survey Prof. Paper 424-C, p. C113-C115. stone beds irregularly spaced, medium- ___ 1963, Synorogenic sedimentation of Mississippian age, to thick-bedded, form resistant ledges; Eureka quadrangle, Nevada: Stanford Univ., Stanford, abundant worm trails and pyrite(?) Calif., Ph.D. dissert., 360 p.; U.S. Geol. Survey open-file casts in siltstone and sandstone. At report, Jan. 9, 1964, 296 p. 56.0 above base a 35-cm bed of sand­ stone (ES-59-6: chert-quartz aren- Carozzi, Albert, 1956, An intraformational conglomerate by ite), medium-grained, moderately mixed sedimentation in the upper Cretaceous of the Roc- sorted; noticeable lithic fragments _ 81.5 de-Chere, autochthonous chains of High Savoy, France: Jour. Sed. Petrology, v. 26, no. 3, p. 253-257. 8. Siltstone, same as unit 6, grades up­ ward into unit 9 ______21.5 Chilingar, G. V., and Bissell, H. J., 1957, Mississippian Joana limestone of Cordilleran miogeosycline and use of Ca/I-Tg 7. Covered; probably siltstone, same as ratio in correlation [Nevada-Utah] : Am. Assoc. Petroleum unit 4 ______82.5 Geologists Bull., v. 41, no. 10, p. 2257-2274. 6. Siltstone, same as unit 4; not so highly Christiansen, F. W., 1951, A summary of the structural history fractured, sparse cubic pyrite(?) casts of the Great Basin province in Utah and eastern Nevada and worm trails in upper part ______26.5 in Intermountain Assoc. Petroleum Geologists, Geology of 5. Covered, probably siltstone, same as the Canyon, House and Confusion Ranges, Millard County, unit 4 ______13.0 Utah: [Utah Geol. Soc.], Guidebook 6, p. 68-80, figs. 16-18. 4. Siltstone (ES-59-4: clayey quartz-silt- Dott, R. H., Jr., 1955, Pennsylvanian stratigraphy of Elko and stone), grayish-black (weathering northern Diamond Ranges, northeastern Nevada: Am. olive-gray) ; weathering and fracture Assoc. Petroleum Geologists Bull., v. 39, no. 11, p. 2211- cleavage about 1 ft deep ______7.0 2305. 3. Sandstone (ES-59-3: quartz arenite), ___ 1958, Cyclic patterns in mechanically deposited Penn­ gray (weathering brown), fine-grained, sylvanian limestones of northeastern Nevada: Jour. S?d. well-sorted, sparse pyrite; interbedded with similar sandstone, medium- to Petrology, v. 28, no. 1, p. 3-14. coarse-grained, friable, abundant Douglass, W. B., Jr., 1960, Geology of the southern Butte pyrite; some quartz veinlets ______6.5 Mountains, White Pine County, Nevada, in Guidebook to 78 MISSISSIPPIAN STRATIGRAPHY OF THE DIAMOND PEAK AREA, EUREKA COUNTY, NEVADA

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America Bull., v. 64, no. 4, p. 381-38r, Geol. Survey Mon. 20, 419 p. (with atlas). Merriam, C. WT., 1938, Devonian strata on east margin of the Hague, Arnold, and Enimous. S. P., 1877, Descriptive geology: Eureka district, Nevada [abs.] : Geol. Soc. America Bull., U.S. Geol. Explor. 40th Parallel (King), v. 2, 890 p. v. 49, no. 12, pt. 2, p. 1917. Hatch. F. H., and Rastall, R. H., 1950, The petrology of the Merriam, C. W.. 1940, Devonian stratigraphy and paleontology sedimentary rocks, revised by Black. Maurice [3d ed.] : of the Roberts Mountains region, Nevada: Geol. Soc. London, George Alien & Unwin, Ltd., 383 p. America Spec. Paper 25, 114 p. REFERENCES CITED 79

Merriam, C. W., and Anderson, C. A., 1942, Reconnaissance Sadlick, Walter, 1960, Some preliminary aspects of Chainman survey of the Roberts Mountains, Nevada: Geol. Soc. stratigraphy in Guidebook to the geology of east central America Bull. v. 53, no. 12, pt. 1, p. 1675-1727. Nevada : Intermountain Assoc. Petroleum Geologists and Eastern Nevada Geol. Soc., llth Ann. Field Conf., Nevada, Nolan, T. B., 1928, A late Paleozoic positive area in Nevada : 1960. p. 81-90. Am. Jour. Sci., 5th ser., v. 16, no. 92, p. 153-161. Sharp. R. P., 1942. Stratigraphy and structure of the southern ____ 1943, The Basin and Range province in Utah, Nevada, Ruby Mountains, Nevada: Geol. Soc. America Bull., v. 53, and California: U.S. Geol. Survey Prof. Paper 197-D, p. no. 5, p. 647-690. 141-196. Smith. J. F.. and Ketner. K. B.. 1968. Devonian and Missis- ____ 1962, The Eureka mining district, Nevada: U.S. Geol. sippian rocks and the date of the Roberts Mountains thrrst Survey Prof. Paper 406, 78 p. in the Carlin-Pinon Range Area. Nevada: U.S. Geol. Nolan, T. B., Merriam, C. W.. and Williams. J. S., 1956. The Survey Bull. 1251-1. p. 11-118. 4 figs. stratigraphic section in the vicinity of Eureka, Nevada : Spencer. A. C.. 1917, The geology and ore deposits of E'", U.S. Geol. Survey Prof. Paper 276, 77 p. Nevada : U.S. Geol. Survey Prof. Paper 96, 189 p. Nolan, T. B., Merriam, C. W., and Brew D. A., 1970, Geologic Steele. Grant. 1960. Pennsylvanian-Permain stratigraphy of map of the Eureka quadrangle, Nevada : U.S. Geol. Survey east-central Nevada and adjacent Utah, in Guidebook to map. 1-612 (in press). the geology of east central Nevada : Intermountain Ass?c. Pennebaker, E. N., 1932, Geology of the Robinson (Ely) mining Petroleum Geologists and Eastern Nevada Geol. Soc., llth district in Nevada; a preliminary report on the primary Ann. Field Conf.. Nevada, 1960. p. 91-113. monzonite prophyry intrusive ore bodies and how they Stewart. J. H.. 1962. Variable facies of the Chainman and are formed: Mining and Metallurgy, v. 13, no. 304, p. Diamond Peak Formations in western White Pine County, 163-168. Nevada, in Geological Survey research 1962: U.S. Geol. Survey Prof. Paper 450-C. p. C57-C60. Pettijohn, F. J., 1957, Sedimentary rocks [2cl ed.] : New York, Harper & Bros., 718 p. Walcott. C. D., 1884, Paleontology of the Eureka district, Nevada : U.S. Geol. Survey Mon. 8. 298 p. Powers, M. C., 1953, A new roundness scale for sedimentary particles: Jour. Sed. Petrology, v. 23. no. 2, p. 117-119. Watson, J. G.. 1939, The lower carboniferous of the Diamond Peak area, Nevada: Ithaca, N.Y., Cornell Univ., M.S. Rigby, J. K., 1960, Geology of the Buck Mountain-Bald Moun­ thesis, 40 p. tain area, southern Ruby Mountains, White Pine County, Nevada, in Guidebook to the geology of east central Willden. Ronald, Thomas, H. H.. and Stern, T. W., 1967, Nevada: Intermountain Assoc. Petroleum Geologists and Migocene or younger thrust faulting in the Ruby Moun­ Eastern Nevada Geol. Soc., llth Ann. Field Conf., 1960, tains, northeastern Nevada: Geol. Soc. America Bull., p. 173-180. v. 78, p. 1345-1358. Williams, Howel, Turner, F. J., and Gilbert, C. M., 1954, Riva, J. F., 1957, Geology of a portion of the Diamond Range, Petrography an introduction to the study of rocks in White Pine County, Nevada : Reno, Univ. of Nevada, M.S. thin sections: San Francisco, Calif., W. H. Freeman & thesis, 50 p. Co., 406 p.; repr. 1958. Roberts, R. J., Hotz, P. E., Gilluly, James, and Ferguson, H. G., Winterer, E. L., and Murphy. M. A., 1960, Silurian reef com­ 1958, Paleozoic rocks of north-central Nevada : Am. Assoc. plex and associated facies. central Nevada: Jour. Geology, Petroleum Geologists Bull., v. 42, no. 12, p. 2813-2857. v. 68. no. 2, p. 117-139. Roberts, R. J., and Lehner, R. E., 1955, Additional data on the Zingg, Theodor, 1935, Beitrag zur Schotteranalyse; Die age and extent of the Roberts Mountain[s] thrust fault, Schotteranalyse und ihre Anwendung auf die Glattal- north-central Nevada [abs.] : Geol. Soc. America Bull., schotter : Schweizer: Mineralog. u. Petrog. Mitt., v. 15, v. 66, no. 12, pt. 2, p. 1661. no. 1, p. 39-140.

INDEX

[Italic page numbers indicate major references]

Page Page Pfge Chainman Formation Continued Diamond Mountains ___ 3,12, 48, 55, 56, age ______37 57, 59, 62, 64, 65, 66 Black Point facies ____./3, 16, 37, 56, Diamond Peak ____ 24, 28, 29, 54, 55, 56 Acknowledgments ______2, 34 59, 64,76 Diamond Peak-Ely contact, measured Adobe Canyon ______59, 61 fossils ______16 section across ___ 24 Age, megabreccias ______33 stratigraphic section _____ 17 Diamond Peak Formation ___ 5, 8, 12, 16, monolithologic ______33 33, 52, 61, 62, 64, 65 Water Canyon facies ___ 13,16,24, Alluvial fans ______67 clayrock 27 36, 60, 62, 64 Alluvium ______34 conglomerate ___ 25 Alpha Peak ______24, 60 stratigraphic sections ____ 15 crossbedding 25 Alpha Peak ridge _____ 24, 56, 57, 60 Chainman Shale ______5, 8, 9, 13, 43, 46, depositional environments 25 Alpha Ridge ______60 52, 64 descriptive stratigraphy 17 Angular unconformity. Tertiary (?) fossils ______-- 48 fossiliferous beds 37 monolithologic megabreccia over type section ___ 47 fossils ______-- 25,27 conglomerate of Cretaceous age _ 31, 33 Chester age ______37,44, 46, 47, 52 informal members 18 Antler erogenic belt ______65, 66, 67 Chester-Morrow boundary __ _ 38, 51 limestone _ 27 Antler orogeny ______4, 5, 62, 64 Chester Series ______- 43, 44 lirnestone-phenoplast Arbuckle Mountain ______43 Chilingar, G. V., cited ______10, 12 conglomerate 27 Area of field study ______3 Christiansen F. W., cited _____ 48 lower plate of Bold Bluff thrust Atoka age ______34, 49 51 Clayrock, Diamond Peak Formation __ 27 fault ______24 Aux Vases Sandstone ______43 Clore Limestone ______51 Cloud, P. E., quoted ______10 age _ __ 47 Cold Creek syncline ______56,62 fossil collection 47 Collectors of fossils ______52, 54 measured section, foraminiferal Colluvium ______34 collections __ , 55 Basin and Range block faulting ____ 59 Confusion Range ______35, 36, 47, 51, 52 fossil collections 54 Basin and Range province ______67 section ______47 member A ______19, 25, 38, 76 Beach desposits ______67 Conger Range, Utah" ______51 fossils ______19 Biomicrite ______27, 28, 29, 30 Conglomerate, Diamond Peak member B ______19, 25, 38, 75 Biomicrudite ______32 Formation ______25 age ______38 Biosparite ______27, 30, 31 Conical Hill ______38, 42, 43, 44, 47, 48 fossils ______- 19 Biosparudite ______31 fauna of Diamond Peak beds ___ 38 member C ______20, 25, 27, 38, 74 Biostratigraphy and age of Contact, Black Point facies of the age _ 40 Carboniferous formations _____ 34 Chainman Formation with Joan member D ___20, 25, 27, 38, 40, 60, 73 Bissell, H. J., cited ______10, 12, 48 Limestone ______--- 16 age 44 Black Point ______56, 57 Diamond Peak and Chainman foraminiferal zones ______44 Black Point facies of Chainman Formations ______18 fossils ______20 Formation ___ 13, 16, 37, 56, 59, 64, 76 Diamond Peak Formation and Ely member E __ 21, 25, 27, 44, 61, 62, 71 stratigraphic section ______17 Limestone ______-4 age 44 Bold Bluff ______15, 24, 37, 42 Ely Limestone with Carbon Ridge fossils ______2J Brew, D. C., cited ____ 13, 56, 57, 58, 59 Formation ______28 member F ___ 2/, 25, 27, 44, 60, 61, Buck Mountain area ______13 Cordilleran region ______44 62, 71 Buck Mountains ______46, 58 Correlation of Mississippian and age _ 46 Burbank Hills ______46 earliest Pennsylvanian formations faunal hiatus 44,52 Butte Mountains ______13 of central part of Great Basin, Utah member G ____ 22, 25, 46, 60, 70 and Nevada ______35 age _ 46 Cretaceous System ______32 fossils _____ 22 Criteria for recognizing the member H ____ 23,24,25, Mississippian-Pennsylvania 27, 28, 30, 46, 50, 60, 69 Camptonite ______34 boundary ______51 age 38, 47 Caney Shale ______43 Crossbpdding, Diamond Peak fossils ____ 23 Carbon Ridge Formation ___ 28, 30, 31,33, Formation ______25 members B-D, fossil collections 38 59, 62, 65, 66 members E-H, fossil collections 45 fossil collections ______32 D Meramec-Chester boundary _ 52 fossils ______31 Deformation, Early Mississippian __ 64 sandstone 25 Carboniferous formations, post-Early Permian ______66 siltrock ______25 biostratigraphy and age ______34 post-Middle Pennsylvanian 65 stratigraphic section 67 fossil collections ______3b Depositional environment, Black Visean-Namurian boundary 52 Carlin area ______13 Point facies of Chainman Diamond Peak Quartzite _ 8 Carlin Canyon ______49 Formation ______17 Diamond Peak Series ______9 Carlin quadrangle ______38, 48, 49, 52 Ely Formation ______30 Diamond Peak trough _____ 66 Carlin region ______52 Devils Gate Formation ______9 Diamond Range ____ 5, 13, 36, 58, 66, 67 Carozzi, Albert, cited ______27 Devils Gate Limestone _____^____ 9, 58 Diamond Table ______21, 57, 60, 62 Chainman Formation ___9, 12, 36, 54, 57, Devonian and Mississippian Systems 10 Differentiation of Chainman and 62, 64 Devonian System ______9 Diamond Peak Formations _ 13

81 82 INDEX

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Dikes, lampropliyric __-_-___ 34 Fossil Collections Continued Fossils Continued Dott, R. H., Jr., cited ______13, 18, 21, Diamond Peak Formation Continued Diamond Peak Formation Continued 29, 30, 31. 57. 59, 65, 66 members E-H ______45 member H ______23 Douglass, R. C., cited ______32 measured section ______54 Diaphragmiis ______4«, 47, 51, 53 Duncan, H. M., cited ____ 36, 38, 42, 44. Ely Limestone ______49, 55 cestriensis ______44,46 48, 49 Jotiua Limestone ______36 phiUipsi ______46, 47 fossils identified by ____ 39,41, 45 Fossil localites, Diamond Peak area 52 Dictyoclostus ______48 Fossil plant debris ____ 17 Dielasma bisinuatutn ______42 nimegalasma ______49 Fossil zones : E eurekensis ______37, 38, 48 Ganinia ______44,46 neglectvm ______48 Eakin, E. E., cited ______48 Crarenoeeras hesperium Diphypliylhtm ______49 Easton, W. H., cited ______9 ammonoid ______46 Earlandia spp ______40 Egan Range __ _ 51 Ely Limestone, lower member, Echinocoelia pilosa ______49 Ely district ______13,36,52 correlation with Homoceras sp ______38 Ely Formation ______62 zone ______51 Eclrinoconchus ______51 Ely Limestone ____ 33, 48, 49, 54, 55, 59, lower member, foraminiferal biseriatus _ 47 60, 61, 62, 64, 65, 66 zones _ 51 Ely Limestone 30 fossil collections ______49, 55 Eumorplioceras bisuJcatum (E.) __ 46 Endotliy bowtnani _ 40 fossils ______30 FaberophiiUum coral ______43 tantala ______40 lower member ______28,50,68 Goniatites granosun zone of late Eostaffella ______43 age ______51 Visean age ______42,43,47 Eumorphoceras ______42, 44, 51 upper member ______2.9, 5J, 52,67 Homatopliyllites-Yesiculophyllum _ 36 bisulcatum 46 age ______51 K zone of Dutro and Sando ____ 44 FaberopJujllum ______43, 44, 48, 49 Eureka district ______52 Lower Posidonia (Pi) of British Fenestella sp ______37, 47 Enreak mining district ______2,3,8 Carboniferous section _____ 42 Fistuliporoid bryozoan 47 Lower Posidonia (Pi) of late Flexaria ______51 Visean age 43 Glomospira sp _____ 40 F Lower Reticuloceras (Ri) _ _ 51 Goniatites clioctawensis ___ 44 SipJionodella zone ______34, 36 granosus ______42, 43, 44, 47 Fangloinerate ______- 33, 62, 66, 67 Upper Eumorphoceras Homoceras ___ _ 51 Tertiary(?) ______32,59 (En) ______42,44,51 horn corals 47 Faulting, age ___ 61 Upper Posidonia (Pi-) of late Hustedia miseri ______51 block ______5 Visean age ______42,43,44,47 sp ____ 47 Basin and Range __-___ 59 Fossils : Inflatia ______51 high-angle ______5,66,67 AlevoUtes ______10 bttobata ______44 Faults : Amphipora ______10 sp. A ______47 Adobe Canyon _ 60, 61 Anopliopsis sp ______38 sp. B ______38 Alpha ______59 AntJtracospirifer occiduus _____ 50, 51 KozlowsJcia ___ 47 boundary ______59 opimus ______51 Leiorhynchus carboniferum _ 37, 46,49 combination boundary and increbescens ______44 carboniferum poJypIeurnm 42 internal ______61 peUaensis ______47 Leptagonia ______49 high-angle ______5, 62 Antiquatonia ______44, 46, 51 Linopi'odtictus ______51 normal __ _ _--_._ - 56, 59 sp ______51 ovatus ______48 internal ______59 Archaedisciis moelleri ______40 MoorefieldeUa eurekensis ___ 38,47 low-angle ______15, 55, 57 Atiloprotonia ______42. 44, 47, 48 Naticopsis sp ______37 Bold Bluff thrust ___ 13, 17, 24, sp ______37 Neoarcltaediscus sp ______42, 43 56, 57, 58. 80, 61, 62, 64 Ariculopecten liagnei ______47 Neochonetes sp. A ______38, 47, 48 extent and significance ___ 57 Becclitria ______47 Ovatia ______51 Newark ______60 Black Point faeies of Chainman latior ______47 Newark Valley ______59 Formation ______16 Polypora sp ______47 Pedroll Creek ______57, 59 Brachythyris sp ______48 Posidonia ______42, 43, 44, 47 Roberts Mountains thrust ____ 5, 67 sp. A ______38 becneri ______42,43 Robinson Springs ______61 Brnnsia sp ______40 Protocanites ______37,48 Sadley Canyon ______60, 61 BiiJTtonia sp ______47 Pseitdofusulina ______32 thrust ______5 Calispheara sp ______40 Pseudosyrinx desiderata ______47 Water Canyon ______60 Caninia ______44. 46 Punctospirifer transversus ____ 51 Fauna of Diamond Peak beds at ejccentrica ______44 Qiiadratia hirsutiformis __ 37, 42, 49 Conical Hill ______38 Carbon Ridge Formation _____ 31 Rayonnoceras ______37 Faunal hiatus. Diamond Peak Chainman Shale ______48 Reticulariina campestris ______51 Formation, member F ___ 44, 52 Chonetes oklahomensits ______48 ReticuJoceras ______51 Ferdelford Creek ______38 Cleiotliyridina ______37, 49 RhipiodomeUa ______48 Ferguson, H. G.. cited __ _ 64 incrassata ______37 neradensis ______46,47,48, Field work ______2 Composita ______49 50, 51, 53 Folding in Eureka quadrangle _ 5 Cornuitpira ______40 Rugoclostits ______50, 51 Folds ______5.55^56.57 sp ______40 Schellwienella sp ______38 Folk, R. L., cited ______4, 12, 27 Crarenoceras nesperium ___ _ 46 Schizophoria sp ______37, 47 Foraminiferal collections, from merriami ______51 ScJtwagerina ______32 Diamond Peak Formation Craretioceratoides ______42 Setigerites ______49 measured section ______55 crinoid columnals ______37, 47 ShumardeUa ______36 Fossil collections ______._____ 9 Cystodictya sp ______37 missotiriensis ______36 Carbon Ridge Formation ___ _ 32 Diamond Peak Formation __ 25, 27 Kiplionodella ______34, 36 Carboniferous formations _____ 34 member A ______19 Siphonodendron ______42, 49 Diamond Peak Formation, member B ______19 Spirifer ______49 lower plate of Bold Bluff member D ______20 arkansanus ______38 thrust fault ______4? member E ______21 brazerianus ______37 members B-D ______38 member G ______22 martiniiformis ______49 INDEX 83

Page Page Fossils Continued Lower part of Ely Limestone, R Spirifcr stratigraphlc sections ____ 61 mortonnnnnus ______48 Rastall, R. H., cited _ 28 stenoporoid bryozoan 47 M Regional distribution of the Strattfera ______47,4!) Mississippian part of the strophomenoid braehiopod ______'.'7 Mamet, Bernhard, cited ___ 40, 42, 43, 51 Ely Limestone __ SI Torynifer ______51 Man Creek ______56, 61 Regional relations of setigtr ___ _ - 50 Megabreccia ______33, 66, 67 Diamond Peak Formation and Trochophiillum ______4s Megabreeeia unit, Tertiary (?) _____ 62 Chainman Shale __ 47 Tylonautilus sp ______44 Meramec age ______36, 37, 38, 44, 47, Register of fossil collecting Tylothyris ______38. 47 48, 49, 52, 64 localities in Diamond Peak area, Tl/lothyris sp __ 37 Meramec-Chester boundary ______38 Nevada _ 52 Worthetiopora ______49 Diamond Peak Formation ______52 See also Tables 1, 2, :\, 4, 5. location ______43 Related faults, low-angle, Bold Bluff minor thrusts and folds 57 French Alps ______20 Meramec Series ______43 Merriam, C. W., cited ___ 9, 10, 12, 12,13, Renault Formation _ 43, 44 G 17, 18, 19, 20, 21, 22, Results of study 1 23, 28, 29, 30, 31, 32, Richmond Mountain 62 Garden Valley Formation _____ SO, HI, 32 36, 37, 44, 48, 49, 58, Rigby, J. K.. cited __ 58 Geography ______$ 65,66 Riva, J. F.. cited ____ 24, 31, 32, 55, 56, Geologic history __ ___ 62 Migliorini, C. L. cited ______25 57, 59, 66 Geologic setting ______4 Mining Canyon ______24, 59 Roberts, R. J.. cited ______64, 65 Glrty, G. II., cited ______40 Mississippian and Pennsylvania!! Roberts Mountains thrust, Gordon, Mackenzie, Jr., cited __ 12, 18, 29, Systems. Ely Limestone, relations to sedimentation k, 65 30, 38, 48, 49 descriptive stratigraphy _ ___ 28 Roberts Mountains thrust sheet 66 Great Basin ______44, 4fi, 51, 52 Mlssissippian-lVnnsylvanian Gulluly, James, cited ______64 Robinson Canyon in Egan Range _ 36, 47 boundary ______49, 65 Robinson Springs __ 67 Mississippian-Pennsylvanian H Chester-Morrow boundary ___ 51 Hague, Arnold, cited ___ 8, 9, 13, 18, 21, Mississippian rocks, regional relations _ 4 s 28,59 Mississippian System ______10 Moleen Formation __ 24, 28. 29, 30, 31, 66 Hatch, F. II.. cited ______28 Sadler Canyon ______21, 57, 60 Moorefleld Formation ______38,43,49 Hayes Canyon ______8 Sadler Canyon fault complex 60 Morrow age ______49 Hill, J. D., cited ______10 Sadlick, Walter, cited ______48 Morrow Series, northwest Arkansas ___ 51 Hopkins, I), M., oral commun _____ 17 Sando, W. J. ______51 Hots, P. E.. cited ______64 N Sandstone, Diamond Peak Formation _ 25 Huddle, J. W., cited ______34, 36 Schell Creek Range ______47, 51 Humphrey, F. L., cited ______9, 48 Nepheline-bearing kersantite _ 34 Scotty Wash Qnartzite ______5 Newark Canyon Formation __ SI, 32, 56, Secret Canyon ______37 59, 62, 66 Sedimentation, Early Cretaceous ___ 66 Early Permian ______66 Igneous rocks ______3% Newark Mountain __ 8, 59 Late Devonian and Illipah Formation ______48 Newark Valley __ __- 57 Early Mississippian ______62 Intramicrite ______27 Nolan, T. B.. cited ___ 5, 9, 10, 12, 13, 15, Late Mississippian through Intnisparite ______27, 28 17, 18, 21, 24, 2.S, 2!l, Middle Pennsylvanian ______64 Intrasparrndito ______27 30, 31, 32, 33, 36, 37, Sentinel Peak ______8 Introduction ______1 40, 43, 44, 48, 49, 58, 59, 62, 65, 66 Sharp, R. P., cited ______58 Nomenclature, stratigraphic 5 Silica-cemented chert ______25 Siltrock, Diamond Peak Formation __ 25 Joana Limestone ___ 4.8,9,78,15,16,52, O Slltstone-matrix conglomerate ___ 25, 27 62, 64 Sklpp, B. A., fossils studied by __ 38,40, ago ______36 Ogdon Qnartzite ______8 42, 43, 51 fossil collections ______36 Oliver. W. A.. Jr., quoted ______10 Smith. J. F., cited ______48, 49 its regional relations ______36 Oosparite ______27, 28, 29 Snake Range ______47, 51 Osage age ______36. 37. 48, 49, 52, 64 Sohn. I. G.. cited ______49 K Osage-Meramee boundary 49 fossils identified by ______40, 41 Osage Series ______35 Spencer, A. C., cited ______9, 10, 13 Ketncr, K. B., cited ______48. 49 Overland Pass ______58 St. Louis Limestone ______42 Kinderhook age ______.'54.48.52,64 Ste. Genevieve Limestone ______43 Kinderhook beds ______52 P. Mississippi Valley region _____ 40 Klnkaid Limestone ______51 Steele, Grant, cited ______48 Kuenen. P. II., cited ______25 Packer Basin _ _ 37 Stern. T. W., cited ______58 Packer Basin area _ ___ 8 Stewart, J. H.. cited __ 12, 13, 25, 37, 48, 52 Pancake Kange ______36,48.51,52 Strathearn Formation ______32 Lake deposits ______.14 Permian System _ 30 Stratigraphic sections, Black Point Langenheim. K. L.. Jr.. cited _____ S, 10 Pilot Shale ______4, 8, 9, 10, 52, 62 facies of the Chainman Formation _ 17 Larson. E. K.. cited ___ 12. 55. 56. 57. .19 age ______-__-___ - *4 Diamond Peak Formation ______67 Lawsoii. A. C.. cited ______!». US Pine Valley quadrangle ___ 48 lower part of Ely Limestone ___ 67 Limestone. Diamond I'eak Formation __ 27 Pinto Summit quadrangle 37 upper part of Black Point facies Limestone-phenoplast conglomerate __ 20, Pinyon Range ______36, 48, 49 of Chainman Formation _____ 67 ii/, 32. £3 Previous work ______3 Water Canyon facies Chainman Diamond I'eak Formation ______'? Pyrite _____ 12. 16. 17. 19. 21, 25, 27, 30 Formation ______15 Limestones, classiflcation ______4 Stratigraphy ______9 Litliogenetic relations of Cliaiiunan Qnartssite-pebble and cobble regional ______4, 34 and Diamond I'eak Formation ___ 12 conglomerate __ 25 Structural block, Newark Location of area ______3 Quaternary deposits _ ___ _ 34 Mountain-Alpha Peak ridge _____ 34 1N1>EX

Page Page Page Structure ______55 U, V Wentworth, C. M., cited ______25 regional ______5,3^ White Pine district ______8, 13 Sulphur Spring Range ______30 Upper part of Klack Point facies White Pine Range ____ 36, 47, 48, 51, 52 «f Chaimnan Formation, White Pine Shale ______- 5, 8, 9, 13 stratigraphie sections ______

& U.S. GOVERNMENT PRINTING OFFICE: 1971 O-386-523