Coralliferous Carbonate Shelves of 

Mississippian Age, West Side of 

Antler Orogen, Central Nevada

U.S. GEOLOGICAL SURVEY BULLETIN 1988-F
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STENNIS SPACE CENTER, Mississippi-Bldg. 3101
Coralliferous Carbonate Shelves of 

Mississippian Age, West Side of 

Antler Orogen, Central Nevada

By WILLIAM J. SANDO

EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN 

HARRY E. COOK and CHRISTOPHER J. POTTER, Project Coordinators

U.S. GEOLOGICAL SURVEY BULLETIN 1988-F

A multidisciplinary approach to research studies of sedimentary 

rocks and their constituents and the evolution of 

sedimentary basins, both ancient and modem

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1993
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

For sale by

USGS Map Distribution

Box 25286, Building 810

Denver Federal Center

Denver, CO 80225

Any use of trade, product, or firm names in this publication is for descriptive purposes only and 

does not imply endorsement by the U.S. Government.

Library of Congress Cataloging-in-Publication Data

Sando, William Jasper

Coralliferous carbonate shelves of Mississippian age, west side of Antler orogen, central Nevada / by 

William J. Sando.

p. cm. (U.S. Geological Survey bulletin ; 1988) 

(Evolution of sedimentary basins Eastern Great Basin ; ch. F)

Includes bibliographical references.

Supt. of Docs, no.: 128.3:1988-F

1. Geology, Stratigraphic Mississippian. 2. Coral reefs and islands Nevada. 3. Geology Nevada. 

I. Title. II. Series. III. Series: Evolution of sedimentary basins Eastern Great Basin ; ch. F. 

QE75.B9 1988-F 

[QE672]

557.3 s dc20 93-17177 

[551.7'51'09793] CIP
CONTENTS

Abstract................................................................................................................................. Fl

Introduction........................................................................................................................... 1

Geology of Coral Occurrences............................................................................................. 3

South-Central Nevada................................................................................................. 7

Areas 1 and 2........................................................................................................ 8

Areas 3-5.............................................................................................................. 9

Interpretive Summary........................................................................................... 10

North-Central Nevada................................................................................................. 10

Area 6.................................................................................................................... 10

Area7................................................................._^ 11

Interpretive Summary for Area 7.................................................................. 12

AreaS.................................................................................................................... 13

Summary of Geologic History.................................................................................... 14

Paleogeographic Significance of Coral Occurrences ........................................................... 14

Taxonomic Composition of Coral Faunas.................................................................. 14

Biogeographic Affinities of Coral Faunas.................................................................. 15

Paleogeographic Analysis........................................................................................... 15

Paleogeographic History....................................................................................................... 17

Coral Zone IIB (Osagean, late Tournaisian)............................................................... 17

Coral Zone HID (middle to late Meramecian, middle Vise"an).................................. 17

Coral Zone IV (latest Meramecian, late Vise"an)........................................................ 19

Post-Coral Zone IV (Chesterian, latest Vise"an and early Namurian)......................... 19

Locality Register................................................................................................................... 22

Area 1 Candelaria Hills, Esmeralda County............................................................ 22

Area 2 Monte Cristo Range, Esmeralda County..................................................... 23

Area 3 South San Antonio Mountains, Nye County................................................ 23

Area 4 North San Antonio Mountains, Nye County................................................ 24

Area 5 Toiyabe Range, Nye County........................................................................ 24

Area 6 East Range, Pershing County....................................................................... 24

Area 7 Osgood Mountains, Humboldt County........................................................ 24

Area 8 Mountain City District, Elko County........................................................... 25

Note.............................................................................................................^ 25

References Cited................................................................................................................... 26

Appendix Foraminifera and Algae, by B.L. Mamet.......................................................... 28

Candelaria Hills (area 1)............................................................................................. 28

South San Antonio Mountains (area 3)...................................................................... 28

Toiyabe Range (area 5)............................................................................................... 29

Osgood Mountains (area 7)........................................................................................ 29

General Comment on the Ecology and Biogeography of the Microfossils................ 29

PLATES

[Plates follow appendix]

1-4. Representative corals from central Nevada:

1. Coral Zone IIB.

2. Coral Zone HID.

3. Coral Zone HID.

4. Coral Zone IV

m
IV CONTENTS

FIGURES

1. Map showing Mississippian paleotectonic units and locations of coralliferous areas, Nevada and

adjacent States ................................................................. F2

2. Biostratigraphic correlation of Mississippian sedimentary sequences in coralliferous areas on west side of

Antler orogen.............................................................................................................................................................. 4

3-6. Nonpalinspastic Mississippian paleogeographic maps of Nevada and adjacent States:

3. Showing evidence bearing on locations of postulated straits across Antler orogen............................................ 16

4. During Coral Zone IIB (Osagean, late Tournaisian) time................................................................................... 18

5. During Coral Zone HID (middle to late Meramecian, middle Vise'an) time....................................................... 20

6. During Coral Zone IV (latest Meramecian, late Vise'an) time............................................................................. 21

7. Diagram showing quantitative variations in various aspects of shallow-water coral distribution and

environmental factors that affected these corals in the Western Interior basin of the United States during the 

Carboniferous............................................................................................................................................................. 22

TABLES

1-3. Distribution of corals in collections from areas of central Nevada:

1. Zone IIB (Osagean, late Tournaisian).................................................................................................................. F3

2. Zone HID (middle to late Meramecian, middle Vise'an)..................................................................................... 6

3. Zone IV (latest Meramecian, late Vise'an)........................................................................................................... 7

4. Shallow-water habitat index (SWHI) of coral assemblages in coral zones and areas of central Nevada................... 8

5. Approximate distances and times for coral migrations from eastern sources on Cordilleran platform and

Antler foreland basin to western Antler coralliferous ............................................................................................... 19
CORALLIFEROUS CARBONATE SHELVES OF

MISSISSIPPIAN AGE, WEST SIDE OF 

ANTLER OROGEN, CENTRAL NEVADA

By William J. Sando

ABSTRACT INTRODUCTION

Mississippian coral faunas collected from eight areas 

along the west side of the Antler orogen in central Nevada 

contain elements of three Western Interior coral zones. 

The oldest fauna, which represents Coral Zone IIB (Osagean, late Tournaisian), is present in deep-water carbonate 

gravity-flow deposits in one area in south-central Nevada 

and in another area in north-central Nevada. A more diversified younger fauna, present in all eight areas, represents 

Coral Zone HID (middle to late Meramecian, middle 

Vise"an) and lived on nearshore and offshore shelves that 

were distributed along the entire west side of the orogen. 

A third fauna, present in three areas, represents Coral Zone 

IV (latest Meramecian, late Visdan) and lived on two small 

shelves on the west side of the orogen in the southern part 

of the study area.

Close similarities between the Antler coral faunas and 

endemic faunas of the Antler foreland basin and Cordilleran platform east of the orogen and the absence of similar 

coral faunas west of the orogen indicate that the Antler 

corals were derived by westward migrations from eastern 

sources through straits that separated islands in an island 

chain that extended across central Nevada from south to 

north. Probable locations for these straits are inferred from 

distributions of similar coral faunas on both sides of the 

Antler island chain, locations of areas on the orogen where 

Mississippian sediments were never deposited, locations of 

siliciclastic submarine fan systems in the Antler foreland 

basin, and postulated paleocurrent circulation patterns in 

the foreland basin.

The Mississippian coralliferous sequences in seven 

areas on the west side of the Antler orogen are parts of a 

western overlap sequence on the Roberts Mountains allochthon and are truncated either by pre-Permian erosion or by 

the Triassic Golconda thrust. In the eighth area, a similar 

coralliferous sequence is in the Golconda allochthon.

The Antler orogen is a linear positive area in central 

Nevada produced by Late Devonian to Early Mississippian 

plate collision (Roberts, 1951; Roberts and others, 1958; 

Poole and others, 1967; Burchfiel and Davis, 1972; Poole, 

1974; Poole and Sandberg, 1977, 1991) or plate convergence (Burchfiel and Royden, 1991). During Mississippian 

time, this positive area separated the Havallah oceanic 

inner arc basin in western Nevada from the Antler foreland 

basin, an area of flysch and molasse deposition in eastern 

Nevada (fig. 1). In the eastern part of the orogen, highly 

deformed sedimentary rocks of Cambrian through Devonian age are overlain unconformably by less deformed 

Pennsylvania and younger sedimentary rocks, and there is 

no credible evidence that Mississippian sediments were 

ever deposited (area 7, fig. 1, is an exception resulting 

from thrust transport). The western part of the orogen contains scattered, small areas of carbonate, terrigenous, and 

volcanic rocks of Mississippian age that are overlain 

unconformably by Permian and younger sedimentary rocks 

or are truncated by sedimentary rocks of Mississippian to 

Permian age moved eastward on thrust faults. Although the 

western boundary of the eastern Antler area coincides with 

the 0.706-initial-strontium isopleth that marks the eastern 

limit of inferred Paleozoic oceanic crust, the restored western margin of the Paleozoic continent probably coincides 

with the western limit of the Antler orogen (Poole and 

Sandberg, 1991, p. 108, 109). Most Mississippian paleogeographic maps depict the Antler orogenic highland as a 

continuous land area (Poole, 1974, fig. 1; Poole and Sandberg, 1977, fig. 1, 1991, fig. 8; Little, 1987, fig. 5).

Although corals of Mississippian age have been 

known from carbonate rocks on the west side of the Antler 

orogen for about 70 years, their paleogeographic significance has never been thoroughly investigated. These corals 

were used for dating some of the western Antler rocks as 

Mississippian by H.M. Duncan (in Roberts and others,

Fl
F2 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

118° 116° 114°

~^~ Banner 

Limestone

-/,______ Coughs Canyon 

.. Formation :-: :

' ill/

:LT^~^^_-_-Lr-L.-L--1 nskip ; 

 i-j^rir_~Lrt_r^ Formation

CORDILLERAN

36°-

Figure 1 (above and facing column). Mississippian paleotectonic units and locations of coralliferous areas described in text (solid 

circles), Nevada and adjacent States. Areal extent of Mississippian rocks beneath Golconda allochthon and younger rocks on west side of 

Antler orogen restored from distribution of isolated outcrops. Modified from Poole and Sandberg (1977,1991).
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F3

EXPLANATION

Oceanic sedimentary rocks 

Carbonate, clastic, and volcanic rocks 

Mississippian rocks absent 

Flysch and molasse 

Shelf carbonate rocks

 Contact

 " Fault Arrows show direction of movement

 ^ ^ Thrust fault Sawteeth mark upper plate 

X Pre-thrusting position of area 7

1958, p. 2847; in Hotz and Willden, 1964, p. 26-28) and 

by Sando (in Poole and Sandberg, 1977, p. 79, 1991, p. 

131; in Little, 1987, p. 58, Appendix A). Some western 

Antler Mississippian coral localities were located and 

listed by Sando (in Sando and Bamber, 1985, p. 41, fig. 2), 

and these localities formed the basis for Sando's (1989, 

figs. 3C, F, G) paleogeographic interpretations of the Antler orogen during Mississippian time; however, none of 

these published works discusses the paleogeographic 

implications of the corals.

The purpose of this paper is to present evidence bearing on the origin of the western Antler corals and how 

these corals got to their present locations. A new hypothesis on the paleogeography of the Antler orogen is built on 

this evidence. An earlier version of these ideas is in an 

abstract by Sando (1992).

Acknowledgments. I am particularly indebted to 

F.G. Poole for sharing with me much unpublished data on 

south-central Nevada and for several enlightening discussions on the geology of the Antler orogen (Poole does not 

agree with all of my interpretations). I am also grateful to 

K.B. Ketner and to M.B. and L.B. McCollum (Eastern 

Washington University) for unpublished information 

derived from their recent studies in north-central Nevada 

(my interpretations do not always coincide with the ideas 

of these colleagues). I thank L.B. McCollum for coral collections from the Coughs Canyon Formation and A.G. 

Harris for conodont data on collections made by E.L. 

Miller, A.E. Jones, and D.H. Whitebread in north-central 

Nevada. I also thank Poole, Ketner, M.B. McCollum, J.T. 

Dutro, Jr., N.J. Silberling, and M.E. Taylor for their helpful reviews of the manuscript. I am especially grateful to 

B.L. Mamet for his analysis of foraminifer and algal 

assemblages from the study area (see appendix).

GEOLOGY OF CORAL OCCURRENCES

In this part of the report, I present data on the 

geologic age, habitat, and preservation of the coral assemblages and on the petrography of the rocks in which the

corals occur. These data, together with published and 

unpublished information on the coral occurrences, are then 

used to interpret the geologic history of the sedimentary 

sequences in which the corals are found. I have not made 

any field observations in the study area but have relied 

heavily on material and information given me by other 

geologists. Geologic ages and usages of formal stratigraphic units in discussions of the stratigraphy are those of 

the writers cited as references and do not necessarily coincide with ages and usages currently recognized by the U.S. 

Geological Survey (USGS).

Geologic ages for the coral assemblages are given in 

terms of the Western Interior coral zones of Sando and 

Bamber (1985) and correlative North American and western European series and stages (Sando, 1985)(see also 

time scale on fig. 2). Coral assemblages are listed for each 

of the coral zones recognized, along with USGS Upper 

Paleozoic locality numbers and geographic areas, for all 

collections studied (tables 1-3).

The shallow-water habitat index (SWHI) is a measure 

of the probability that the living habitat of a given coral 

genus was in shallow water (<100 m, <300 ft) versus deep 

water (>100m, >300 ft) based on distribution data from 

the Western Interior (Sando, 1980). Genera having 

SWHI=50-100 are more probably shallow-water forms 

than genera having SWHI=0-50. In this study, mean 

SWHI for each collection and grand mean SWHI for each 

zone in each area were calculated (table 4). SWHI values, 

together with petrographic data, are used to interpret the 

environments in which the corals lived.

The corals are in sedimentary sequences exposed in 

five areas in south-central Nevada and three areas in 

north-central Nevada (figs. 1, 2). A total of 51 collections

Table 1. Distribution of Zone Iffi (Osagean, late Tournaisian) 

corals in collections from areas of central Nevada. 

[See text for descriptions of areas. Collection numbers refer to USGS 

Upper Paleozoic locality file (-PC). Superscript T indicates collection 

from which thin sections were made; superscript plus (+) indicates species 

similar to Western Interior Province species]

Area/collection

Coral taxa

Nondissepimented solitary rugosans

Amplexizaphrentis sp.+ - 14026T 

Cyathaxonia sp.+ 25581 14026 

Sychnoelasma cf. S. ulrichanum (Girty)+ 25579 -

25581T

Rotiphylloid corals, undet.+ - 14026 

Lophophylluml sp.+ 25581 14026T 

Ufimia sp.___________________-_____14026? 

Dissepimented solitary rugosan

Vesiculophyllum sp.H 25581

Tabulate

Michelinicft sp. 14026T 

19808
F4 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

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unicornis

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altusGnathodus 

glrtyl

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Cavusgnathus

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penescltulus

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varlans

_/ Scaliognathus \_

anchorallaDollognathus latus

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typlcus

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isostichaUpperS. crenulata

U

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S. duplicate \^

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CORAL BIZONES

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20 

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17 

16 

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HILLS 

T. 3 N., R. 36 E. 

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T. 6 N., R. 42 E. 

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(M-P)

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EXPLANATION 

LITHOLOGY

Siltstone

Quartzite, graywacke, or 

sandstone 

Conglomerate

^7-rvr

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v/%/V?^

Unnam

VfVX^

ed ~rl

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Pillow lavas 

Basaltic flows

Figure 2 (above and facing page). Biostratigraphic correlation of Mississippian sedimentary sequences in coralliferous areas on west 

side of Antler orogen. Locations of areas shown by numbers in figure 1. Time scale modified from Sando (1985). See text for sources 

of lithic and paleontologic data for columns 1-8.
MISSISSIPPIANCORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F5

5 

TOIYABE 

RANGE 

T. 1 4 N., R. 42 E 

NYE 

COUNTY

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Relations 

unknown

6 

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RANGE 

T. 31 N., R. 36 E. 

PERSHING 

COUNTY

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T. 38 N., R. 41 E. 

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BIOZONES

OTHER ZONES 

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noduliferus

Rachlstognathus primus

Adefognafhus 

unicornfs

Cauusgnatftus 

a/tusGnathodus 

girtyf

Cauusgnatfius afiusHindeodus crisiu/us

Cauusgnathus 

a/tusHindeodus 

penescitu/us

u

L

Taphrognathus 

varians

anchoralisDoliognathus lotus

Gnathodus 

typicus

Siphonodella 

isostichaUpperS. crenulata

L S. crenulata

S. sandbergi

^ S. duplicata

S. su/cato

BIOZONES FORAMINIFER 

20

(FT-)

19

18 

17

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1 

1

1

16

5 

4

3

12 

11

10 

9

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RADIOMETRICTIME SCALE

(Ma)

320

*

ooc

*

-330 

*

-335 

-340

-345

-#350

occ

360

*

SYSTEMS EUROPEAN 

AND SERIES

fe

CARBONIFEROUS (1UPPER 

LOWER CARBONIFEROUS

SUBJACENT STRATA (ORDOVICIAN)

FORMATION 

CONTACTS

^^-x~~-^~^ Discor 

^^^/^ Thrust

rmable 

iformable 

GAPS IN SEQUENCE

OCCURRENCES 

OF FOSSILS

Depositional hiatus Nondeposition | 

or removal of strata by erosion A 

Structural hiatus Strata 0 

obscured or removed by 

faulting *

Corals 

Conodonts 

Brachiopods 

Foraminifers
F6 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

Table 2. Distribution of Zone HID (middle to late Meramecian, middle Visean) corals in collections from areas of central Nevada. 

[See text for descriptions of areas. Collection numbers refer to USGS Upper Paleozoic locality file (-PC). Superscript T indicates collection from which thin 

sections were made; asterisk (*) indicates genus endemic to Western Interior Province; superscript plus (+) indicates species similar to Western Interior 

Province species]

Coral taxa 1 23456

Area/collection

7 8

Nondissepimented solitary rugosans

Amplexizaphrentis7 sp. (may be young 

Canadiphyllurri)

*Canadiphyllwn sp.+

Cyathaxonia sp.

Hapsiphyllum? sp.

24772? 

26250

5165 

25007

25585

26250

-

-

-

-

-

5165

 

14214 26248T 25580? 16459 

14215 -

14216 -

24451

26252? -

26253? -

-----

26254? -

_____

_____

14027T 

38082

12108 

14027T

19807

38080

38081

38083

38084

-

14029

_

15384? 

16093?

17659

17662

19526

19527

21588

22813

-

_

Dissepimented solitary rugosans

*Ekvasophyllum sp.+

Koninckophyllum? sp.

Large horn coral aff. Faberophyllwn

5165 

26250

-

25007 

25583T

26250

-----

_____

-----

28067 14216 - 

26254 -

_____

19807 

38082

-

-

_

16093 

17662?

19527?

22813

-

_

Colonial rugosans

Acrocyathus sp. (cerioid)+

Sciophyllum sp.

Siphonodendron cf. S. sinuosum (Warren)+

Siphonodendron cf. S. whitneyi of Meek+

Siphonodendron cf. S. whitneyi of Meek 

(diphymorph)+

-

25584T

25007 

24772T

25584T

-

-

26250 

25583

-

-

-

25007

26253T -

-----

19778? 26248 

24944 -

26252 -

_____

26253 -

19778? 26248 

24944 -

26252 -

-----

26253 -

14216 26249 - 16459T 

24450T - 

26254T -

-

-

14029

-

-

-

14029

-

-

-

-

21588

-

15384T 

19527

19528

21588

22813

15384T 

19527

19528

21588

22813

-

"Dorlodotia" of Sando & Bamber (1985), 

aff. 5. whitneyi of Meek+

Stelechophylluntf sp.

22813

17662
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F7

Table 2. Distribution of Zone HID (middle to late Meramecian, middle Visean) corals in collections from areas of central 

Nevada Continued.

[See text for descriptions of areas. Collection numbers refer to USGS Upper Paleozoic locality file (-PC). Superscript T indicates collection from which thin 

sections were made; asterisk (*) indicates genus endemic to Western Interior Province; superscript plus (+) indicates species similar to Western Interior 

Province species]

Area/collection

Coral taxa 1

Tabulates

Cladochonus sp. 

Multithecoporal sp. (cerioid)

Multithecopora morphogroup A 

ofSando(1984b)?+

Pleurosiphonella morphogroup A 

ofSando(1984b)+

Syringopora morphogroup G 

ofSando(1984b)+

5165 

25007T

26253 26248

24944T

28067?T 14215? 26248? 

24450?? 

26252 

26254T

16459

22813

21588T

25580T

14029T

Table 3. Distribution of Coral Zone IV (latest Meramecian, 

late Visean) corals in collections from areas of central Nevada. 

[See text for descriptions of areas. Collection numbers refer to USGS 

Upper Paleozoic locality file (-PC). Superscript T indicates collection 

from which thin sections were made; asterisk (*) indicates genus endemic 

to Western Interior Province; superscript plus (+) indicates species similar 

to Western Interior Province species]

Area/collection

Coral taxa

Dissepimented solitary rugosans

*Canadiphyllum sp.H 14666

26256

*Faberophyllum sp.+ 28065 

28066T

14666T 

26255 

26256

2625 IT

Colonial rugosans

Siphenodondron cf. 5. whitneyi 

of Meek+ -

14666 

26255 

26256T

-

Acrocyathus sp. (cerioid)4 26256?

Tabulates

Pleurosiphonella morphogroup - 

AofSando(1984b)+

Cladochonus sp.

14666? 26251

26255?

26256?T

14666?

of corals, 29 from south-central Nevada and 22 from 

north-central Nevada (locality register, p. F22; tables 1-3), 

were studied for this report.

SOUTH-CENTRAL NEVADA 

(AREAS 1-5, FIGS. 1,2)

Paleozoic rocks crop out in isolated mountain ranges 

surrounded by Mesozoic and Tertiary sediments in Esmeralda and Nye Counties, where F.G. Poole recognized an 

unnamed Mississippian carbonate unit in his mapping of 

selected areas in several mountain ranges in the early 

1960's and 1970's (Poole in Poole and Sandberg, 1977, p. 

79; in Speed and others, 1977, p. 302). The unnamed carbonate unit was included previously in the Permian Diablo 

Formation (dolomite facies) and in a Devonian limestone 

unit mapped by H.G. Ferguson and his colleagues in the 

old Hawthorne and Tonopah 1° quadrangles (Ferguson 

and Muller, 1949; Ferguson, 1952; Ferguson and others, 

1953, 1954), where age determinations were based on 

studies of a few collections of fossils by G.H. Girty (Permian) and Edwin Kirk (Devonian) in the 1920's (see 

locality register for details). Subsequent restudy of the old 

collections and studies of new collections from several 

localities by H.M. Duncan in the 1950's and 1960's and 

by me in 1970's and 1980's resulted in confirmation of 

the Mississippian age of the unnamed carbonate unit 

mapped by Poole (see locality register for details).

The relationships between the unnamed Mississippian 

carbonate unit and subjacent and superjacent rock units in 

south-central Nevada have been interpreted differently by 

different geologists. Poole (in Poole and Sandberg, 1977,
F8 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

Table 4. Shallow-water habitat index (SWHI) of coral 

assemblages in coral zones and areas of central Nevada 

[See text for descriptions of areas and explanation of SWHI. Collection 

numbers refer to USGS Upper Paleozoic locality file (-PC)]

Shallow-water habitat index ( SWHI)

Area

Collection

number

Collection

range

Collection

mean

Grand

mean

Coral Zone IIB

5

5

7

7

25579

25581

14026

19808

97

18-98

6-86

86

97

72.5

49

86

84.8

67.5

Coral Zone HID

1

1

1

1

1

1

1

2

3

3

3

3

3

3

3

3

3

3

4

4

5

6

7

7

7

7

7

7

7

7

7

8

8

8

8

8

8

8

8

8

5165

24772

25007

25583

25584

25585

26250

28067

14214

14215

14216

19778

24450

24451

24944

26252

26253

26254

26248

26249

25580

16459

12108

14027

14029

19807

38080

38081

38082

38083

38084

15384

16093

17659

17662

19526

19527

19528

21588

22813

66-100

74-100

50-100

50-100

100

66

66-100

50-100

66

66-100

50-100

100

100

66

100

66-100

66-100

50-100

66-100

100

66-100

66-100

66

66-74

39-100

66-95

66

66

74-95

66

66

66-100

66-95

66

66-100

66

66-100

100

66-100

66-100

88.7

87

79

75

100

66

86.2

75

66

83

72

100

100

66

100

88.7

88.7

79

88.7

100

83

90.3

66

70

79.7

80.5

66

66

84.5

66

66

83

80.5

66

87

66

87

100

91.5

90.3

83.1

75

84.3

94.3

83

90.3

71.6

83.5

Coral Zone IV

2

2

3

3

3

28065

28066

14666

26255

26256

96

96

66-100

96-100

66-100

96

96

90.5

98.7

92.4

96

93.9

26251 96-100 98 98

fig. 2a, col. 6) recognized an unconformity between the 

Mississippian unit and the overlying Diablo Formation 

(restricted) in the Candelaria Hills and Monte Cristo Range 

(areas 1 and 2, figs. 1, 2), whereas Speed (1984) decided 

that the Mississippian unit is in a different thrust slice of 

Mesozoic(?) age than that of the Diablo Formation in the 

Candelaria Hills. Moreover, Poole (in Poole and Sandberg, 

1977, fig. 2a, cols. 6-8) recognized an unconformity 

between the Mississippian unit and the underlying Valmy 

Formation (Ordovician) in areas 1-5 (figs. 1, 2), whereas 

Stewart (1979), Bonham and Garside (1979), and Kleinhampl and Ziony (1985) decided that the Mississippian unit 

was in thrust contact on Ordovician rocks in the Candelaria 

Hills (area 1) and South San Antonio Mountains (area 3) 

and in the North San Antonio Mountains (area 4), respectively. I follow Poole's (in Poole and Sandberg, 1977) 

interpretations of the contact relations of the unnamed Mississippian carbonate unit.

Mississippian corals were collected from Poole's 

unnamed carbonate unit in the Candelaria Hills (area 1, 7 

collections) and Monte Cristo Range (area 2, 3 collections) in Esmeralda County and in the South San Antonio 

Mountains (area 3, 13 collections), North San Antonio 

Mountains (area 4, 2 collections), and Toiyabe Range 

(area 5, 4 collections) in Nye County (fig. 1).

AREAS 1 AND 2

In the Candelaria Hills (area 1) and Monte Cristo 

Range (area 2), the unnamed carbonate unit consists of 

dolomite and limestone as much as 400 ft (120 m) thick 

(Ferguson and others, 1954) that rest unconformably on 

the Valmy Formation of Ordovician age and are overlain 

unconformably by the Diablo Formation of Permian age 

(fig. 2, cols. 1, 2)(Poole and Sandberg, 1977). F.G. Poole 

(written commun., 1975) measured a thickness of 325 ft 

(100 m) for the unnamed unit at his Gates Mill locality in 

the Candelaria Hills.

In the Monte Cristo Range, two Western Interior 

coral zones are represented in the collections: Coral Zone 

HID (middle to late Meramecian, middle Vise"an) and 

Coral Zone IV (latest Meramecian, late Vise"an) (tables 2, 

3). Only the older zone is represented in the collections 

from the Candelaria Hills, probably as the result of a 

greater depth of pre-Permian erosion in the latter area, 

although perhaps as the result of poor exposures of the 

rock unit or incomplete collecting of available coral fauna.

The corals are dolomitized and silicified and are in a 

matrix of tan-weathering fossiliferous dolomicrite (wackestone and packstone) in four of the seven collections from 

the Candelaria Hills. In two collections from this area 

from the lower part of the carbonate unit, the corals are 

calcitic and are in a matrix of gray-weathering silty biomicrite (wackestone and packstone), and, in a third collection 

from the upper part of the unit, the matrix is gray crinoidal
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F9

biomicrite (packstone). A few silicified brachiopod fragments are associated with the corals in two of the dolomite 

samples, and one limestone sample contains foraminifers 

and algae of Mamet Foraminifer Zones (MFZ) 13-14 

(Mamet in Mamet and Skipp, 1970) identified by B.L. 

Mamet (see appendix). Corals are dolomitized or silicified 

and are in tan-weathering crinoidal dolobiomicrite (packstone) without other identifiable fossils in all three samples from the Monte Cristo Range.

Shallow-water habitat indices (SWHI)(Sando, 1980) 

for the eight coral collections from Coral Zone HID in 

areas 1 and 2 range from 50 to 100 (grand means 83.1 and 

75, respectivelyXtable 4). The two coral collections from 

Coral Zone IV have SWHI values of 96. The SWHI values 

suggest that the corals in both zones lived in shallow-water 

environments well within the photic zone (about the upper 

100 m (300 ft) of the water column). Lack of appreciable 

abrasion of the solitary corals and good articulation of corallites of the phaceloid corals suggest coral growth in a 

relatively quiet, subtidal environment. The foraminiferalgal assemblage in Coral Zone HID suggests a bathymetry 

of 30-40 m (100-130 ft)(B.L. Mamet, appendix). These 

data, together with the petrography of the rocks, suggest 

that the unnamed carbonate unit represents autochthonous 

accumulation of carbonate sediment on a shallow-water 

carbonate shelf in south-central Nevada during Late Mississippian (middle to latest Meramecian) time.

AREAS 3-5

Although the unnamed carbonate unit extends eastward and northward into Nye County, the lithology and 

structural setting of this unit are somewhat different from 

its occurrences in Esmeralda County. Here the carbonate 

unit again rests unconformably on the Valmy Formation 

(Ordovician), but its top is eroded and locally may be truncated by the Golconda thrust, upon which rocks of the 

Havallah Formation (Mississippian to Permian) were carried over rocks of the Roberts Mountains allochthon (fig. 2, 

cols. 3-5). Although published geologic maps of the South 

San Antonio Mountains show a thrust fault separating the 

unnamed Mississippian carbonate unit from the Ordovician 

Valmy Formation, F.G. Poole (written commun., 1992) 

interpreted the contact as a sheared sedimentary contact. In 

Nye County, the unnamed carbonate unit is mostly limestone, in contrast to its predominantly dolomitic character 

in Esmeralda County. Moreover, the carbonate unit in Nye 

County includes an older sequence of limestone not found 

in Esmeralda County.

In the South San Antonio Mountains (area 3), Coral 

Zones HID and IV (tables 2, 3) are represented in the 

middle part of a limestone sequence 900 ft (275 m) thick 

(F.G. Poole, written commun., 1975); limestone above the 

highest coral level may be of Chesterian age (fig. 2, col. 

3). In the North San Antonio Mountains (area 4), only

Coral Zone HID (table 3) is represented in a limestone 

interval 50 ft (15 m) thick (F.G. Poole, written commun., 

1975). In the Toiyabe Range (area 5), Coral Zones HID 

and IV (tables 2, 3) are represented in a limestone interval 

200 ft (60 m) thick (F.G. Poole, written commun., 1975), 

and Coral Zone IIB (Osagean)(table 1) is represented in 

limestone of undetermined thickness and uncertain structural relations to the younger limestone beds (F.G. Poole, 

written commun., 1975). Foraminifers and algae in collections from areas 3-5 were determined by B.L. Mamet 

(appendix) as Coral Zone IIB=Osagean, Coral Zone 

IIID=MFZ 13-14, Coral Zone IV=MFZ 15 or younger. I 

have not verified reports of early Meramecian (MFZ 10- 

12) foraminifers (B.A. Skipp in Bonham and Garside, 

1979, p. 17) and uppermost Osagean foraminifers (B.A. 

Skipp in Kleinhampl and Ziony, 1985, p. 86) from the 

South San Antonio Mountains.

Rock samples from Coral Zones HID and IV in the 

South and North San Antonio Mountains are all lightgray-weathering crinoidal biomicrite (wackestone and 

packstone). Most samples are strongly sheared and veined 

with calcite. The corals are silicified or calcitic, and they 

are associated with rare brachiopods. SWHI values for 

coral collections from Coral Zone HID from areas 3 and 4 

range from 50 to 100 (grand means 84.3 and 94.3, respectively), and those from Coral Zone IV in area 3 range 

from 66 to 100 (grand mean 93.9)(table 4). The corals are 

minimally abraded or disarticulated. The foraminifer-algal 

assemblages from Zones HID and IV suggest a bathymetry of 30-40 m (100-130 ft) (B.L. Mamet, appendix) 

These data support an autochthonous shallow-water carbonate shelf environment for both zones, similar to that 

suggested for areas 1 and 2 in Esmeralda County.

A significantly different environment is postulated for 

the rock samples from Coral Zones IIB, HID, and IV in the 

Toiyabe Range. Rock samples of Coral Zone IIB are darkgray-weathering, very silty biomicrite (packstone) containing abundant foraminifers, crinoid columnals, and bryozoan fragments. Only solitary corals are represented in the 

Zone IIB collections, and these are variably abraded. The 

Zone IIB collections have SWHI values ranging from 18 to 

98 (grand mean 84.8)(table 4). One sample from Zone IIB 

contains a reworked foraminifer-algal assemblage composed of Devonian as well as Osagean forms that B.L. 

Mamet (appendix) regards as a probable gravity-flow 

deposit.

Rock samples of Coral Zone HID and IV are darkgray-weathering, silty, spiculitic, fossiliferous micrite 

(wackestone) containing sparse foraminifers, crinoid 

columnals, and gastropods. The SWHI value for Zone 

HID is 83 and that for Zone IV is 98 (one collection 

each)(table 4). Some corals are strongly abraded. These 

data suggest that the collections from all three coral zones 

represent allochthonous sediments derived from a nearby 

shallow-water carbonate shelf and deposited in deeper 

water on the foreslope of the shelf. Microfossil
F10 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

assemblages from the Toiyabe Range are impoverished 

and indicate Zone IIID= MFZ 13-14 and Zone IV=MFZ 

15 (B.L. Mamet, appendix).

INTERPRETIVE SUMMARY

I regard the scattered outcrops of Mississippian rocks 

in south-central Nevada as evidence of a formerly extensive 

sheet of Mississippian carbonate sediments deposited on 

eroded lower Paleozoic rocks belonging to the Roberts 

Mountains allochthon along the west side of the Antler orogen. My interpretation of these rocks coincides essentially 

with that of Poole and Sandberg (1977, p. 79,1991, p. 131), 

who characterized the rocks as "autochthonous to parautochthonous" with respect to their structural setting.

The sedimentary textures and the taxonomic composition of corals, foraminifers, and algae in the Mississippian 

rocks are consistent with shallow-shelf environments having a bathymetry of about 100 m (300 ft) or less, except 

for the rocks in the Toiyabe Range, where the Mississippian sequence probably represents a carbonate gravity flow 

that came to rest in deeper water (>100 m, >300 ft) on the 

foreslope of the shelf. In situ shelf-rock localities probably 

represent outer shelf locations because the microfauna and 

microflora suggest deeper (30-40 m, 100-130 ft) or cooler 

waters than normally indicated by Cordilleran microfossils 

of the same age (B.L. Mamet, appendix).

The probable overlap relationship of these Mississippian rocks on the west side of the Antler orogen suggests 

similarity to the Pennsylvanian and Permian rocks of the 

Antler overlap sequence of Roberts and others (1958) on 

the east side of the orogen. Miller and others (1984, fig. 5) 

recognized an older overlap sequence of Chesterian age on 

the continental shelf in north-central Nevada. Little (1987, 

p. 5, 9) placed the Mississippian sequence of the Mountain 

City area (area 8, figs. 1, 2) in his "Upper Mississippian 

Antler overlap sequence" and extended this sequence concept southward to include the Mississippian rocks of southcentral Nevada (Little, 1987, fig. 5). Little (1987, p. 9) 

interpreted this overlap sequence as a result of rifting along 

the continental margin associated with "extensional or 

borderlands-style tectonics."

The precise structural position of the Upper Mississippian Antler overlap sequence in south-central Nevada is 

still uncertain. The Mississippian rocks are overlain unconformably by the Permian Diablo Formation in the Candelaria Hills and Monte Cristo Range, but a thrust fault 

separates them from rocks of the overlying Havallah Formation (Mississippian to Permian) in the San Antonio 

Mountains and Toiyabe Range (F.G. Poole, oral commun., 

1992). Thus, the structural unit overlying the Mississippian 

rocks probably is the Triassic Golconda allochthon, as 

shown on geologic maps of Nevada by Miller and others 

(1984, fig. 1) and Little (1987, fig. 1).

NORTH-CENTRAL NEVADA 

(AREAS 6-8, FIG. 2)

Occurrences of Mississippian corals in north-central 

Nevada are in limestone beds in complexly deformed, 

predominantly terrigenous and volcanic sequences whose 

structural and stratigraphic relationships are poorly known 

and controversial. These rocks are being studied by K.B. 

Ketner and by M.B. and L.B. McCollum. The Mississippian rocks have been interpreted variously as an autochthonous part of the Antler overlap sequence on the Roberts 

Mountains allochthon (Banner Formation: Little, 1987), as 

an allochthonous unit within the Golconda allochthon 

(Inskip and Goughs Canyon Formations: Roberts and 

others, 1958; Hotz and Willden, 1964), and as a part of an 

accreted terrane that originated in an oceanic setting west 

of the Antler orogen (Goughs Canyon Formation: McCollum and McCollum, 1989, 1991; Jones, 1991). Corals were 

collected from the Inskip Formation in the East Range, 

Pershing County (area 7, 1 collection), the Goughs Canyon 

Formation in the Osgood Mountains, Humboldt County 

(area 8, 11 collections), and the Banner Formation, Mountain City district, Elko County (area 9, 10 collections).

AREA 6

The Inskip Formation consists predominantly of 

graywacke, conglomerate, chert, greenstone, calcareous 

shale, and quartzite and some thin beds of limestone (Ferguson and others, 1951); it may be as much as 9,000 ft 

(3,000 m) thick, but its true thickness is unknown because 

the top is nowhere exposed (K.B. Ketner, written commun., 1992). The Inskip was originally thought to be Permian in age when it was mapped in the Winnemucca and 

Mount Tobin 30' quadrangles (Ferguson and others, 1951; 

Muller and others, 1951). In 1956, however, R.J. Roberts 

found corals in a small limestone lens in the lower part of 

the formation, and these were regarded as probably Mississippian by H.M. Duncan (in Roberts and others, 1958, 

p. 2847; in Silberling and Roberts, 1962, p. 13) The Inskip 

Formation was included in the Golconda allochthon by 

Roberts and others (1958).

When the Inskip was first described, it was thought to 

rest conformably on the Leach Formation, which was 

regarded as Pennsylvanian in age (Ferguson and others, 

1951; Muller and others, 1951). After discovery of Mississippian corals in the Inskip, the Leach Formation was 

regarded as Mississippian or older (Roberts and others, 

1958, p. 2847; Silberling and Roberts, 1962, p. 13). Lithologic similarity of the Leach and the Valmy Formation 

(Ordovician)(Silberling and Roberts, 1962, p. 13) finally 

led to interpretation of the Leach Formation as a synonym 

of the Valmy (Roberts in Langenheim and Larsen, 1973, p. 

26, chart 3, col. 55b). Most recently, conodonts from the 

Leach Formation, identified by I.E. Repetski, confirmed
MISSISSIPPIANCORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA Fll

the Ordovician age of the Leach and its identity with the 

Valmy (Whitebread, 1978). The base of the Inskip, originally thought to be depositional, was reinterpreted as a 

thrust fault by Silberling and Roberts, (1962, p. 14; see 

also Roberts in Langenheim and Larsen, 1973, p. 26, chart 

3), but more recently, Whitebread (1978) and K.B. Ketner 

(written commun., 1992) interpreted the base as a depositional contact. I conclude that the Inskip probably rests 

unconformably on the Valmy Formation, similar to the 

unnamed Mississippian carbonate unit in south-central 

Nevada and to the Grossman and Banner Formations in 

north-central Nevada.

The Inskip Formation was originally thought to lie 

unconformably beneath the Tallman Fanglomerate and 

Koipato Formation of Permian age (Ferguson and others, 

1951; Muller and others, 1951), but later work in its outcrop area resulted in a thrust interpretation for the contact 

between the Inskip and overlying beds (Silberling and 

Roberts, 1962, p. 14; Langenheim and Larsen, 1973, chart 

3, col. 55b; Whitebread, 1978; K.B. Ketner, written commun., 1992). I follow Silberling and Roberts (1962), who 

regarded the overlying beds as Havallah Formation, 

because this interpretation is confirmed by recent studies 

of the East Range by K.B. Ketner. Moreover, this interpretation (fig. 2, col. 6) is consistent with the geology of 

rocks of similar age in areas 3-8. The upper part of the 

Inskip probably is as young as Chesterian, judging from 

the postulated thickness of beds above the level of the 

Mississippian corals in the lower part of the formation. 

The coral fauna from the limestone lens in the lower part 

of the Inskip Formation contains three taxa characteristic 

of Coral Zone HID (table 2), indicating that the lens is the 

same age (middle to late Meramecian) as the lower part of 

the unnamed carbonate unit in south-central Nevada. The 

corals are in a matrix of strongly sheared and veined, darkgray-weathering, silty biomicrite (wackestone) containing 

ostracodes, fragmentary bryozoans, and pelmatozoan 

columnals. The corals are calcitic, mostly recrystallized, 

and strongly deformed. Phaceloid corals are well articulated, and solitary corals may or may not be abraded. 

Although the fauna has an SWHI of 89 (table 4), indicating that the corals lived on a shallow-water carbonate 

shelf, the lens containing them is in a predominantly terrigenous sequence whose lithologies suggest deposition in 

deeper water. These data suggest that the limestone lens is 

a gravity-flow deposit derived from a nearby shallowwater carbonate shelf.

Conodonts collected from limestone beds in a sequence 

of argillite, quartzite, and gritty quartzite in the lower part 

of the Inskip Formation by D.H. Whitebread (1978) in his 

mapping of the Dun Glen 7.5' quadrangle and identified by 

A.G. Harris (report on shipments WMR-80-6) provide 

evidence for older beds of Mississippian age below the coralliferous lens in the Inskip Formation. Harris identified 

conodonts having a possible range from the upper Gnathodus typicus Zone into the Doliognathus latus Zone in USGS 

collection 27593-PC, which formed the basis for an Early 

Mississippian (middle Osagean) age determination. The 

conodont fauna includes Eotaphrus burlingtonensis, which 

is restricted to "well-aerated shallow water of the upper 

foreslope and platform margin" in the bathymetric model of 

Sandberg and Gutschick (1984, p. 150, fig. 14). Hence, the 

lower limestone beds probably had the same allochthonous 

origin as the coralliferous limestone bed above them.

The Inskip Formation is probably an offshore facies 

of the Upper Mississippian Antler overlap sequence of 

Little (1987, p. 5), which rests unconformably on the 

Roberts Mountains allochthon and is structurally beneath 

the Golconda allochthon. Deposition of terrigenous detritus derived from an eastern highland source and deposited 

in shallow (<100 m, <300 ft) to deep (>100 m, >300 ft) 

water offshore probably characterized most of the time 

represented by the formation. The lithology of the limestone lens and limestone beds below it and the occurrence 

of these carbonate rocks in a terrigenous sequence suggest, 

however, that carbonate sediments were transported by 

gravity flow from a nearby shallow-water (<100 m, <300 

ft) carbonate shelf that was present on the west side of the 

Antler land area during times when terrigenous supply 

was diminished. Changes in the directions of currents supplying terrigenous detritus to the area of Inskip deposition 

might also explain the interbedding of terrigenous and carbonate sediments.

AREA?

The Goughs Canyon Formation is a thick sequence of 

predominantly metavolcanic rocks and limestone and 

minor amounts of calcareous sandstone, calcareous shale, 

siliceous shale, and chert (Hotz and Willden, 1961, 1964, 

p. 24, 25). An age range of Early Mississippian (early 

Osagean) to Late Mississippian (Meramecian) was established by H.M. Duncan (corals and bryozoans) and Mackenzie Gordon, Jr. (brachiopods) on collections made from 

limestone beds during mapping of the formation in the 

early 1950's (Hotz and Willden, 1964, p. 26-28). The coralliferous limestones were interpreted by Hotz and Willden (1964, p. 28) as shallow-marine deposits, and the 

associated volcanic rocks were regarded as submarine 

extrusions into shallow water. The formation is bounded 

above and below by thrusts and is covered by Tertiary 

volcanic rocks; its structural position was determined by 

Hotz and Willden (1964) as below the Parrel Canyon 

Formation (Pennsylvanian? and Permian?) and above the 

Valmy Formation (Ordovician) by mapping and by its age 

based on fossils. The anomalous geographic position of 

the Goughs Canyon, east of the 0.706-initial-strontium 

isopleth, as compared to all other sequences of Mississippian carbonate units discussed herein (fig. 1) suggests that 

it was transported technically a greater distance eastward 

than the other sequences previously described.
F12 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

The Goughs Canyon Formation was included in the 

"western sequences of upper Paleozoic rocks" (as 

"unnamed formation of Late Mississippian age") that make 

up the Golconda allochthon by Roberts and others (1958, 

p. 2846). This interpretation was followed by Poole and 

Sandberg (1977, p. 78, 79), who assigned the formation to 

their "inner-arc-basin," which was later called "back-arc 

Havallah basin" by Poole and Sandberg (1991, p. 128) and 

"Schoonover-Havallah basin" by Miller and others (1984, 

fig. 2).

Two recent investigations of the geology of the 

Goughs Canyon Formation in the Osgood Mountains 

(McCollum and McCollum, 1989, 1991; Jones, 1991) 

resulted in interpretations of this sequence as a part of an 

accreted terrane that includes continental-slope to oceanbasin sediments originally deposited west of the Antler 

orogen during the Mississippian. The McCollums recently 

traced the Goughs Canyon Formation northward into the 

Parrel Canyon Formation and found radiolarian cherts typical of the Parrel Canyon interbedded with coralliferous 

limestones typical of the Goughs Canyon (M.B. McCollum, written commun., 1992). Mississippian fossils collected by the McCollums from Parrel Canyon lithologies 

suggest at least partial temporal equivalence with the 

Goughs Canyon. Vesicular pillow basalt interbedded with 

the limestone in the Goughs Canyon was interpreted by 

McCollum and McCollum (1989, 1991) as indicative of 

deep water. According to Jones (1991, p. 788), the 

Goughs Canyon and Parrel Canyon Formations are both 

part of a melange within the Golconda accreted terrane. 

Both the McCollums (1989, p. 244, 1991, p. 737) and 

Jones (1991, p. 784, 785) interpreted the limestone beds in 

the Goughs Canyon as debris flows derived from an atoll 

located on a seamount on the continental slope or continental rise.

Eight conodont collections made by A.E. Jones and 

analyzed by A.G. Harris (reports on shipments 0-90-8, 

0-90-12, and 0-90-19) establish the probable age range 

of the Goughs Canyon Formation as late Kinderhookian 

to late Chesterian. Two coral zones are represented in the 

formation: Coral Zone IIB (Osagean) in two collections 

from the lower part of the formation (table 1) and Coral 

Zone HID (middle to late Meramecian) in nine collections 

from the middle part of the formation (table 2). Stratigraphic positions of the collections are approximate and 

were determined from ages indicated by the fossils. The 

generalized lithic sequence of the Goughs Canyon Formation (fig. 2) is taken from the graphic column presented 

by Little (1987, fig. 3), which is based on description of 

the sequence by Hotz and Willden (1964, p. 24, 25); this 

simplified lithic column will have to be revised after the 

McCollums complete their studies of these rocks. Hotz 

and Willden estimated the thickness of the Goughs 

Canyon as more than 5,000 ft (1,500 m), but McCollum

and McCollum (1991, p. 737) estimated a tectonostratigraphic thickness of approximately 1,000 m (3,300 ft).

Zone IIB corals are present in limestone beds interbedded with basaltic flows. In collection 14026-PC, the 

limestone is dark-gray-weathering ferruginous biomicrite 

(packstone) containing subrounded fragments of brachiopods, bryozoans, and volcanic rock. In collection 19808- 

PC, the limestone is dark-gray-weathering crinoidal biomicrite (packstone). Both collections contain well-preserved 

brachiopods that were dated as early Osagean by Mackenzie Gordon, Jr. (in Hotz and Willden, 1964, p. 27). The 

Zone IIB corals are variably abraded and have a grand 

mean SWHI of 67.5 (table 4). The coral data, petrography 

of the limestone, and absence of deep-water conodont 

assemblages suggest that the limestone was deposited on a 

shallow-water (<100 m, <300 ft)) carbonate shelf.

Zone HID corals are present in limestone interbedded 

with basaltic flows. The limestone weathers light gray to 

yellowish gray and is classified as crinoidal biomicrite 

(packstone). Well-rounded fragments of brachiopods, bryozoans, and clasts of volcanic rock, pellets, and intraclasts 

are abundant. Phaceloid corals are well articulated, and 

solitary corals are variably abraded. The coral assemblages 

have a grand mean SWHI of 71.6 (table 4), suggesting 

that the corals lived in shallow (<100 m, <300 ft) water. 

Foraminifers of Meramecian age (Skipp, 1979, p. 300; 

B.L. Mamet, appendix) are common and show evidence of 

reworking that B.L. Mamet interprets as indicating a possible gravity-flow deposit. Meramecian conodonts were 

recovered from the coralliferous interval by McCollum 

and McCollum (1989, p. 242). Conodonts of late Meramecian to early Chesterian age, collected by A.E. Jones from 

beds presumably above the coral beds, have characteristics 

of high-energy, shallow-water deposition (A.G. Harris, 

written commun., 1990). These data suggest deposition of 

the carbonate sediment on a high-energy, shallow-water 

shelf and transport by gravity flow into deeper water.

INTERPRETIVE SUMMARY FOR AREA 7

The sedimentary textures, taxonomic composition of 

the coral faunas of both Zone IIB and Zone HID, and taxonomic composition of the microfauna and microflora of 

limestone samples from the Goughs Canyon Formation 

examined in this study strongly support an originally shallow water (probably 30-40 m, 100-130 ft) origin for the 

limestone beds. Evidence of reworking of the microfossils 

supports transport of the sediment by gravity flow. The 

presence of basalt clasts in the limestone (and vice versa 

according to M.B. McCollum, written commun., 1992) 

indicates a sedimentary association with vesicular pillow 

lavas that have been determined as deep-water features. 

The intimate association of Goughs Canyon lithologies 

with associated deep-water radiolarian cherts suggests that 

the limestone beds belong with the oceanic suite that is
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F13

present in the Havallah Formation of the Golconda allochthon elsewhere in central Nevada.

The taxonomic composition of the coral faunas 

seems to rule out an atoll environment for their original 

life habitat. These corals are virtually identical to corals 

in rocks interpreted as shallow-shelf deposits in southcentral Nevada, where the rocks are in an overlap 

sequence that unconformably overlies the Roberts Mountains allochthon and are structurally beneath the oceanic 

suite of the Golconda allochthon. Moreover, the corals of 

both Zone IIB and Zone HID in the Goughs Canyon are 

characteristic of shallow-shelf deposits of the Cordilleran 

platform east of the Antler foreland basin, where no reefs 

are known. True atoll corals, such as those of the Akiyoshi Limestone (Carboniferous and Permian) in Japan, 

show skeletal morphologies that reflect adaptation to a 

reef environment as framebuilders, binders, and bafflers 

(Ota, 1968, 1977; Sugiyama and Nagai, 1990, 1991), 

whereas the Goughs Canyon corals show none of these 

features. In fact, there are very few places in the world 

where true coral reefs have been found in the Carboniferous.

A coralliferous island-margin shelf that developed on 

a basaltic seamount on the continental slope of the Havallah basin may well have been the source of carbonate sediment in the gravity-flow deposits of the Goughs Canyon 

Formation. Corals living at the steep edge of such a shelf, 

having no fringing reef, could have been transported into 

deeper water by periodic gravity flow. The paleogeography may have been similar to that of the west side of 

Andros Island in the Bahamas today.

These paleogeographic conclusions favor interpretation of the thrust at the base of the Goughs Canyon Formation as the Golconda thrust and are generally consistent 

with evidence presented by McCollum and McCollum 

(1989, 1991) and by Jones (1991). The anomalous location of the Goughs Canyon outcrop area east of the 0.706- 

initial-strontium isopleth requires moving the area northwestward approximately 25 km in order to restore it to a 

position consonant with the other areas of coeval Mississippian shelf limestone exposed along the west side of the 

Antler orogen (fig. 1). This distance approximates the 

amount of eastward movement on the Golconda thrust.

AREA 8

In its type area, the Banner Formation comprises an 

upper part composed of silty and sandy limestone and a 

lower part composed of siliceous sandstone and polymict 

conglomerate; the formation is approximately 600 ft (190 

m) thick (Coats, 1969, p. A24; Little, 1987, p. 5-8)(fig. 2). 

The formation was first described (as Banner limestone) by 

Granger and others (1957, p. 116), based on an unpublished 

study of the Mountain City mining district by T.B. Nolan in 

1932, and was mapped by Coats (1968, 1971) in the Mountain City 15' and Owyhee 7.5' quadrangles. According to

Coats, the Banner unconformably overlies the Valmy 

(Ordovician) and Grossman (Devonian or Mississippian) 

Formations and grades upward into basaltic lava of the 

Nelson Formation (Late Mississippian). The Nelson is 

succeeded conformably by the Chainman Shale (Late Mississippian) (Little, 1987, p. 8), which was formerly called 

Mountain City Formation by Coats (1969, p. A26). This 

Mississippian sequence is in fault contact with the overlying Reservation Hill sequence (Mississippian?-Permian?), 

which is a Havallah equivalent and is part of the Triassic 

Golconda allochthon (Little, 1987). Thus, according to published studies, the Grossman through Chainman sequence 

represents an overlap sequence resting on the Roberts 

Mountains allochthon.

Recent work in the Mountain City area by K.B. 

Ketner (written commun., 1992) suggests that strata having the lithologic characters of the Banner, Grossman, and 

Nelson Formations are all in conformable relationships 

and that they can be in any order, making the formations 

based on these lithologic distinctions invalid regionally. 

Moreover, Ketner believes that Coats' Mountain City Formation is more appropriate than Chainman for the 

sequence that overlies the Nelson Formation because rocks 

assigned to the Chainman Shale of Little (1987) in the 

Mountain City area include bedded chert and rocks of 

Pennsylvanian and Permian ages that are more properly 

assigned to the Golconda allochthon. Hence, the stratigraphic sequence used in this report (fig. 2, col. 8) is subject to considerable revision when Ketner completes his 

study.

Corals collected from the limestone by Nolan in 

1932 were originally dated as Late Mississippian(?) by 

G.H. Girty in 1932 but were reinterpreted as Permian(?) 

by H.M. Duncan in 1955 (see locality register); the latter 

age determinations formed the basis for the Pennsylvanian to Permian(?) age given by Granger and others 

(1957, p. 116). Duncan revised her previous dating to 

Late Mississippian (Meramecian) in 1960, based on better 

fossils collected by Coats. Sando and Wardlaw (in Little, 

1987, p. 5, 8, Appendix A) restudied collections previously used for dating the Banner and refined the Late 

Mississippian age. Conodonts identified by Wardlaw in 

USGS collection 17662-PC indicate a possible age range 

of middle Meramecian to Chesterian.

Corals in 10 collections from the upper limestone 

beds of the Banner Formation belong to Coral Zone HID 

(middle to late Meramecian, middle Vis6an)(table 2, col. 

8). The coral assemblages have a grand mean SWHI of 

83.5 (table 4). The rock matrix of the coral collections is 

light-gray-weathering crinoidal biomicrite (packstone and 

wackestone) containing well-rounded fragments of brachiopods, bryozoans, and ostracodes. Most samples are 

strongly sheared and recrystallized, and the corals are 

mostly deformed and silicified. Phaceloid corals are articulated, and solitary corals show variable abrasion. These
F14 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

data suggest that the limestone represents an autochthonous accumulation of carbonate sediment deposited on a 

shallow (<100 m, 300 ft) subtidal shelf.

Terrigenous sedimentary rocks that form the lower 

half of the Banner Formation and the underlying Grossman Formation, which also consists of terrigenous rocks, 

have not been dated by fossils. I tentatively assign the 

lower part of the Banner to the early Meramecian and the 

Grossman Formation to the Osagean (fig. 2). Confirmation 

of this age assignment and the age of the overlying rocks 

awaits determination of conodont samples collected by 

K.B. Ketner (written commun., 1992).

The overlying Nelson Formation, which consists of 

volcanic rocks, has not been dated by fossils, but its probable latest Meramecian age is determined by its stratigraphic position between the Banner Formation and the 

overlying Chainman Shale, both of which are dated by 

fossils. A limestone bed near the base of the Chainman 

contains fossils of the Goniatites granosus cephalopod 

zone (Mackenzie Gordon, Jr., in Little, 1987, p. 8), which 

corresponds approximately to Mamet Foraminifer Zone 

16s (early Chesterian)(Gordon in Brew, 1971, p. 43). Fossils from a higher limestone bed in the Chainman, collected from the Mt. Velma 15' quadrangle by Coats (field 

locality 58NC56, shipment MD-58-25), include conodonts corresponding to Mamet Foraminifer Zones 17-19 

(middle to late Chesterian)(B.R. Wardlaw, written commun., 1984); K.B. Ketner (written commun., 1992) 

believes that this locality belongs in the Golconda allochthon.

SUMMARY OF GEOLOGIC HISTORY

Data compiled in this study indicate that most of the 

isolated exposures of Mississippian sedimentary rocks on 

the west side of the Antler orogen rest on the Roberts 

Mountains allochthon and are part of a western overlap 

sequence deposited at the seaward margin of a land area 

during Mississippian time. These rocks were deposited 

unconformably on the Valmy Formation (Ordovician) 

after erogenic uplift in Late Devonian and early Early 

Mississippian time and were truncated by the Triassic 

Golconda thrust, which forms the base of the Golconda 

allochthon. Gravity-flow carbonate deposits of the Goughs 

Canyon Formation in the Osgood Mountains, which are 

part of the Triassic Golconda allochthon, are an exception 

to the rule.

The oldest record of Mississippian sedimentation is in 

the Goughs Canyon Formation in the Osgood Mountains 

(area 7), where shallow (<100 m, <300 ft) subtidal carbonate sedimentation began in Early Mississippian time, at 

least as early as late Kinderhookian (middle Tournaisian), 

on an island-margin shelf that formed on a basaltic seamount on the continental slope. Evidence of slightly later

(Osagean, late Tournaisian) sedimentation is present in 

three areas: (1) the lower part of an unnamed carbonate 

unit in the Toiyabe Range (area 5), where a deep-water 

carbonate gravity-flow deposit betrays the existence of a 

nearby shallow-shelf carbonate production area; (2) the 

lower part of the Inskip Formation in the East Range (area 

6), where allochthonous carbonate derived from a nearby 

shallow-water production area is present in a predominantly deep water (>100 m, >300 ft), offshore terrigenous 

sequence; and (3) in the Grossman Formation in the 

Mountain City area (area 8), where undated fluvial or 

nearshore terrigenous sediments may be of Osagean age. 

The sea may have withdrawn from the Mountain City area 

after deposition of the Grossman Formation and returned 

in Late Mississippian (early Meramecian) time, when a 

second transgression is recorded in shallow-water siliceous 

clastic sediments that form the lower part of the Banner 

Formation, followed by shallow-water shelf carbonate 

deposition in the middle and late Meramecian (based on 

published data). Most of south-central Nevada (areas 1-4) 

remained emergent until Late Mississippian (middle to late 

Meramecian, middle Vis£an) time, when transgression 

produced an extensive shallow-water carbonate shelf.

The total duration of the shallow-water carbonate 

shelf in south-central Nevada cannot be determined 

because the Upper Mississippian sequence there is truncated by a pre-Permian erosion surface (areas 1, 2) or by 

the Triassic Golconda thrust (areas 3-5); biostratigraphic 

evidence suggests that carbonate sedimentation continued 

at least into the early Chesterian (late Vise"an and early 

Namurian). In north-central Nevada, truncation by the 

Golconda thrust also prohibits determination of the total 

duration of deep-water (>100 m, >300 ft) terrigenous sedimentation represented by the Inskip Formation (area 6) 

and by predominantly terrigenous sedimentation and volcanic activity represented by the Nelson Formation and 

Chainman Shale (area 8). Biostratigraphic evidence in the 

north-central Nevada areas suggests that sedimentation 

continued at least into late Chesterian (early Namurian) 

time.

PALEOGEOGRAPHIC SIGNIFICANCE 

OF CORAL OCCURRENCES

TAXONOMIC COMPOSITION OF 

CORAL FAUNAS

The central Nevada Mississippian coral faunas are 

composed of genera and species that belong to the Rugosa 

and Tabulata, the two major divisions of Paleozoic corals 

(tables 1-3). The more common forms in each of the three 

coral zones represented are illustrated in plates 1-4. 

Rugosan species are much more common than tabulate 

species in the western Antler faunas, making up 88 percent
MISSISSIPPIANCORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F15

of Zone IIB, 74 percent of Zone HID, and 67 percent of 

Zone IV. Generic distributions of Mississippian rugosans 

and tabulates are generally more soundly established than 

species distributions because most of the species have not 

been studied adequately. Hence, species are not formally 

defined or described in this study, but similarities to extant 

species are indicated.

Rugosan genera are generally more useful than tabulate genera for biostratigraphic and biogeographic analysis 

in the Mississippian because their more complicated morphologies permit finer taxonomic discrimination. Mississippian rugosan genera are strongly endemic; 41 percent 

of the Mississippian genera are limited to one of the fifteen provinces recognized in the Mississippian, and 25 

percent are restricted to two or three provinces (Sando, 

1990, table 1). This high degree of endemism makes the 

Mississippian rugosans very useful for biogeographic 

fingerprinting.

BIOGEOGRAPHIC AFFINITIES OF 

CORAL FAUNAS

The central Nevada coral faunas (tables 1-3) show 

very strong affinities to corals of the same age in the 

Western Interior Coral Province, which extends from the 

District of Mackenzie in Canada to southeast California 

and southern Arizona and occupies the area between the 

Antler orogen and the Transcontinental arch in the Western United States (Sando and Bamber, 1985, figs. 1, 2). In 

Coral Zones IIB and IV all the genera are Western Interior 

forms, and in Zone HID all the tabulate genera and 75 

percent of the rugosan genera are present in the Western 

Interior. Although none of the Zone IIB genera is unique 

to the Western Interior, two of the twelve Zone HID genera and two of the six Zone IV genera are endemic Western Interior forms. Six of the eight species in Zone IIB are 

similar or identical to Western Interior species, ten of the 

nineteen Zone HID species show the same similarity, and 

five of the six Zone IV species are of Western Interior 

aspect.

The close similarity of the western Antler corals to 

the coral faunas east of the Antler orogen prompted Sando 

and Bamber (1985, fig. 2, explanation; p. 41) to include 

them in the Western Interior Province. Zone HID and IV 

corals in the Milford Group of southwest British Columbia 

(E.W. Bamber, oral commun., 1991) occupy a paleotectonic position analogous to the western Antler corals. The 

only other Mississippian corals known from western North 

America are distinctly different, cosmopolitan faunas in 

the Pacific Coast Province and Alaska Province of Sando 

and others (1975, 1977). More recently, I observed Western Interior corals in collections from Chichagof Island 

(report on shipment A-57-14, 1989), which led me to 

conclude that the southeastern Alaska area, originally

included in the Pacific Coast Coral Province, is actually a 

seaward extension of the Western Interior Coral Province. 

At any rate, the western Antler corals have no logical 

nearby source from the area west of the Antler orogen and 

most certainly were derived from the Western Interior 

basin on the east.

PALEOGEOGRAPHIC ANALYSIS

The biogeographic affinities of the western Antler 

corals require marine connections across the Antler orogen 

so that the corals could migrate westward from the Antler 

foreland basin during the time intervals represented by the 

three Western Interior coral zones. Four lines of evidence 

(fig. 3) are useful for determining the locations of the 

marine connections (straits): (1) locations on the Antler 

orogen where Mississippian rocks were probably never 

deposited, (2) locations of siliciclastic submarine fans 

(Poole and Sandberg, 1991, fig. 11) in the Antler foreland 

basin immediately adjacent to the east side of the Antler 

orogen, (3) locations of coralliferous habitats in the Antler 

foreland basin and Cordilleran platform that may have 

been sources of coral larvae, and (4) probable surface current circulation patterns in the Antler foreland basin controlling migration of coral larvae to the western Antler 

shelves.

Localities in the Roberts Mountains allochthon east 

of the coral localities where Mississippian rocks are missing from the stratigraphic record (Langenheim and others, 

1973, charts 2, 3) were probable highland areas that were 

not submerged during the Mississippian. Post-Mississippian terrigenous rocks of the Antler foreland basin do not 

contain clasts that could be attributed to a pre-existing 

sheet of Mississippian rocks that covered the orogen. 

Moreover, many of the postulated highland areas coincide 

with source areas for the siliciclastic submarine fans 

(Poole and Sandberg, 1991, fig. 11). The locations of 

these siliciclastic fans also serve to constrain probable 

locations for straits across the orogen. The straits must 

have been between the highland areas and between the 

siliciclastic fans. The record of sedimentation in the straits 

was probably removed by post-Mississippian uplift and 

erosion, although some remnants of the Mississippian sedimentary record may be preserved beneath the cover of 

younger sediments.

Coralliferous areas from which coral larvae could 

have migrated during the time intervals represented by 

Zones IIB, HID, and IV are common in the Antler foreland 

basin and on the Cordilleran platform (Sando and Bamber, 

1985, fig. 2, p. 32-42). Corals were living mostly in deepwater environments in the Cordilleran basin during earliest 

Mississippian time (Zone I, Kinderhookian) and became 

abundant in shallow-water habitats later in the Mississippian (Zone II, Osagean)(Sando, 1980, 1989). During Zone
F16 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

118° 116° 114°

CORDILLERAN 

PLATFORM

36°-

Figure 3 (above and facing column). Nonpalinspastic Mississippian paleogeographic map of Nevada and adjacent States showing evidence bearing on locations of postulated straits across Antler orogen. 0, Ordovician strata; P, Pennsylvanian strata; P, Permian strata; T, 

Tertiary strata. See text for sources of data.

IIB time they occupied deep-water environments in the HID and Zone IV times, the Antler foreland basin was the

Antler foreland basin and shallow-water environments on locus of shallow-water molasse sedimentation, and coral

the Cordilleran shelf (Sando, 1989, fig. 3C). During Zone growth was impeded by terrigenous influx; however, some
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F17

EXPLANATION 

CORAL OCCURRENCES 

Zone IV (late Meramecian) 

Zone III D (middle-late Meramecian) 

Zone II B (Osagean)

Area where Mississippian sediments were never deposited

Potential location of strait entrance

SILICICLASTIC SUBMARINE-FAN SYSTEMS 

Molasse basin 

Flysch basin

Transport direction

^^

L CF Y CORIOLIS-FORCE DIAGRAM Paleocurrent circulation 

^-^

corals were living on small carbonate shelves within the 

foreland basin, and corals were abundant on the vast Cordilleran shelf to the east (Sando, 1989, figs. 3F, G).

Migration of corals is accomplished principally in the 

larval stage in surface waters of the sea. Distribution patterns are controlled mainly by currents. The maximum twomonth swimming time of the larval stage permits migration 

over significant distances, particularly if favorable conditions prevail for a long time (Sando, 1984a, p. 439). 

Approximate migration rates of 1,200-7,600 km/m.y. for 

11 groups of Mississippian corals were calculated by Sando 

(1990, p. 180, 181). The approximate amount of time 

needed for the Antler corals to migrate from eastern 

sources to the western Antler shelves can be calculated by 

applying Sando's (1990) range in migration rates to the 

distances between the western Antler shelves and possible 

coral sources (table 5). These calculations range from 0.05 

to 0.55 m.y., which is well within the constraints of zonal 

durations of 2-4.5 m.y. for the three coral zones. The short 

migration times in relation to zonal durations would also 

account for the great similarity between the western Antler 

coral assemblages and Western Interior assemblages from 

which they are presumed to have been derived.

Surface-water circulation patterns are driven in a 

clockwise direction in the Northern Hemisphere by the 

Coriolis force. In a large basin, the general Coriolis pattern is broken up into a number of circulation cells by 

islands and shallow-bottom areas. In the paleogeographic 

reconstructions that follow, hypothetical surface-water circulation patterns, derived from the interaction of Coriolis 

force and topography, are used to test the validity of the 

coral migration hypothesis.

PALEOGEOGRAPHIC HISTORY

Nonpalinspastic paleogeographic maps (figs. 4-6) for 

time intervals corresponding to the three coral zones 

represented on the west side of the Antler orogen are modified from Sando (1989, figs. 3C, F, G) to include new data 

compiled in this study. The three time intervals coincide 

with bursts of coral abundance and diversity throughout 

the Western Interior region of the United States (fig. 7)(see 

also Sando, 1989). Possible migration paths from eastern 

sources to western Antler coral areas can be inferred from 

hypothetical circulation patterns.

CORAL ZONE IIB (OSAGEAN, 

LATE TOURNAISIAN)(FIG. 4)

Coral Zone IIB marks the greatest burst of shallowwater coral abundance and diversity in the Carboniferous 

of the Western Interior United States. A major transgression associated with a rise in regional relative sea level 

expanded optimum coral habitats and facilitated genetic 

change by evolution of indigenous corals and by influx of 

exotic elements (internal and external genetic communication of Sando, 1989). Corals were abundant in shallowwater habitats on an expanded Cordilleran shelf and in 

deep water in the Antler foreland basin.

The Antler orogen was occupied by an island chain 

that formed the continental margin across central Nevada 

into northeastern Nevada and southwestern Idaho. The 

topography of the Antler islands ranged from low hills to 

high mountains. An apron of terrigenous detritus, including 

two submarine siliciclastic fans, around the east side of the 

Antler island chain prohibited carbonate production in that 

area, but a carbonate shelf was developed in shallow water 

along the west side of a large island that occupied much of 

north-central Nevada. A smaller island-margin carbonate 

shelf was developed on a basaltic seamount on the continental slope northwest of the main island, where influx of 

terrigenous detritus, derived from the main island, dominated sedimentation. Surface-water currents carried coral 

larvae from the Cordilleran shelf westward across the Antler foreland basin and through shallow straits separating the 

main Antler island from smaller islands on the north and 

south.

CORAL ZONE IHD (MIDDLE TO

LATE MERAMECIAN, MIDDLE VISEAN)

(FIG. 5)

Coral Zones HID and IV together mark a second 

major burst in abundance and diversity in the Western 

Interior Carboniferous coral succession (fig. 7). In contrast 

to the earlier burst, this phenomenon coincided with a 

lowering of relative regional sea level, reduction in the
F18 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

118° 116° 114°

ut - I T i ; I

-I ,_ -i... -,-,-^.L -..p^. J ,_..,^, ~^__,..

36°-

Figure 4 (above and facing column). Nonpalinspastic paleogeographic map of Nevada and adjacent States during Coral Zone IIB 

(Osagean, late Tournaisian) time showing postulated straits across Antler orogen, inferred paleocurrent circulation, and occurrences of 

corals. Modified from Sando (1989, fig. 3C).
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F19

EXPLANATION (Figs. 4-6)

SEDIMENTOLOGY 

Autochthonous shelf carbonate

Allochthonous basinal carbonate

Fine siliciclastic flysch or molasse

Coarse siliciclastic flysch or molasse (submarine fan system)

Volcaniclastic and siliciclastic oceanic sediment

Deltaic sand (Humbug delta) (shown in figs. 5, 6 only)

LAND 

Mountains 

High hills 

Low hills

X Noncoralliferous control point 

 Coral locality 

 Paleocurrent direction

area of optimum shallow-water coral habitats, increase in 

terrigenous influx, and poorer internal and external genetic 

communication (Sando, 1989). During Zone HID time, the 

mountainous areas on the Antler island chain were 

expanded by uplift, doubling the number of siliciclastic 

submarine fans and flooding the foreland basin with 

molasse, but the carbonate shelf on the west side of the 

main island also expanded, and another shelf was developed along the west side of the northern island. The 

island-margin shelf northwest of the main island continued

to contribute gravity-flow carbonate sediments to the 

deep-water terrigenous sediments of the continental slope. 

Although coral sources in the foreland basin and on the 

Cordilleran shelf were much reduced in number, the main 

surface-water current circulation patterns were maintained, 

and corals were even more successful than before in populating the western Antler shelves.

CORAL ZONE IV (LATEST MERAMECIAN, 

LATE VISEANXFIG. 6)

During Zone IV time, continued uplift in the Antler 

island chain caused expansion of the mountainous areas 

and terrigenous flooding of the northern parts of the marginal carbonate shelf on the west side of the island chain. 

Coral habitats were restricted to two small carbonate 

shelves adjacent to the southern strait that provided a 

migration path for the corals. By this time, a major carbonate factory, containing many coral habitats, had pushed 

into the Antler foreland basin from the north and provided 

a source for coral larvae, and a few small island shelves 

were developed in the southern part of the molasse basin.

POST-CORAL ZONE IV (CHESTERIAN,

LATEST VISEAN AND EARLY NAMURIAN)

(FIG. 2)

The loss of sedimentary record by erosion and structural truncation in the southern part of the Antler island

Table 5. Approximate distances and times for coral migrations from eastern sources on Cordilleran platform and Antler foreland 

basin to western Antler coralliferous areas. 

[See text for sources of data]

Coral Duration of 

zone zone (m.y.)

HE 4.5

mo 2.0

IV 2.5

Antler 

area

4

7

1

2

3

4

5

6

7

8

2

3

5

Distance (km)

Location of eastern source

Western Utah, shelf margin

Southeast Idaho, shelf margin

Southeast Nevada, foreland basin

Southeast Nevada, foreland basin

Southeast Nevada, foreland basin

Southeast Nevada, foreland basin

Southeast Nevada, foreland basin

Western Utah, foreland basin

Western Utah, foreland basin

Western Utah, foreland basin

Southeast Nevada, foreland basin

Southeast Nevada, foreland basin

Southeast Nevada, foreland basin

Uncorrected

240

345

325

300

270

270

330

410

330

220

170

140

200

Corrected

490

595

575

550

520

520

580

660

580

470

420

390

450

Migration time(m.v.)

Minimum

0.07

0.08

0.08

0.07

0.07

0.07

0.08

0.09

0.08

0.06

0.06

0.05

0.06

Maximum

0.41

0.50

0.48

0.46

0.43

0.43

0.48

0.55

0.48

0.39

0.35

0.33

0.38
F20 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

118° 116° 114°

36° 

Figure 5. Nonpalinspastic paleogeographic map of Nevada and adjacent States during Coral Zone HID (middle to late Meramecian, 

middle Vise*an) time. See explanation of figure 4 for additional information. Modified from Sando (1989, fig. 3F).
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA

118° 116° 114° 112°

F21

42'

 \-

-~~~~^

 

Figure 6. Nonpalinspastic paleogeographic map of Nevada and adjacent States during Coral Zone IV (latest Meramecian, late Visdan) 

time. See explanation of figure 4 for additional information. Modified from Sando (1989, fig. 3G).
F22 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

ENVIRONMENTAL FACTORS

A B C 

TOTAL INDIGEN. EXOTIC

Figure 7. Quantitative variations in various aspects of shallow-water coral distribution and environmental factors that affected these 

corals in the Western Interior basin of the United States during the Carboniferous. Shading marks time intervals represented by the western Antler coral occurrences. Modified from Sando (1989, fig. 11).

chain and by structural truncation in the northern part prohibits a complete analysis of Chesterian history. What 

remains of the record in the northern shelves indicates 

that terrigenous sedimentation greatly reduced carbonate 

production and prohibited coral growth in that area during 

the Chesterian and possibly into the Pennsylvania^ 

Although limestone beds are present in the upper part of 

the Goughs Canyon Formation, indicating that the islandmargin shelf still existed in area 7, no corals have been 

found in them. The presence of limestone beds above the 

highest Zone IV corals in area 3 of the southern shelf 

area suggests that carbonate production continued well 

into the Chesterian throughout that area, but no evidence 

has been found for continued coral habitation. A cooler 

climate may have been a factor in the absence of corals.

LOCALITY REGISTER

All collections are located at the USNM Center of 

the Paleontology and Stratigraphy Branch of the U.S. 

Geological Survey, National Museum of Natural History, 

Washington, D.C. Collection numbers refer to the Upper 

Paleozoic locality file (-PC) at the same facility. Internal 

USGS reports on fossils cited are on file with the Paleontology and Stratigraphy Branch. All localities are in 

Nevada. Locations of areas 1-8 are shown on figure 1.

AREA 1 CANDELARIA HILLS, 

ESMERALDA COUNTY

5165: Unnamed carbonate unit, mapped as Permian 

by Ferguson and Muller (1949, pi. 1). Candelaria-Tonopah
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F23

road, near BM 4829, Tonopah 1° quadrangle (probably in 

NMz sec. 8, T. 3 N., R. 36 E., Rock Hill 7.5' quadrangle). 

29 coral specimens in dolomite matrix collected by H.G. 

Ferguson in 1922 and dated Permian by G.H. Girty in 

1923.

24772: Same unit as 5165, mapped as Permian by 

Ferguson and Muller (1949, pi. 1) and as Diablo Formation (Permian) by Ferguson and others (1953). NW»/4 SE»/4 

sec. 8, T. 3 N., R. 36 E., Rock Hill 7.5' quadrangle. 14 

coral specimens in dolomite matrix collected by F.G. 

Poole in 1970 and dated Late Mississippian (Meramecian) 

by Sando in 1972 (report on shipment RMM-72-3)

25007: Same unit and area as 24772 but from 

NWi/t sec. 8, T. 3 N., R. 36 E. 16 coral specimens in 

dolomite matrix collected by F.G. Poole in 1973 and 

dated Late Mississippian (Meramecian) by Sando in 

1975 (report on shipment CMR-74-3).

25583: Same unit as 24772, 125-130 ft (39^0 m) 

above base. East side of ridge 1 mi (1.6 km) north of 

Columbus townsite in SWV4 sec. 7, T. 3 N., R. 36 E., 

Columbus 7.5' quadrangle. 6 coral specimens in limestone 

matrix collected by F.G. Poole in 1974 and dated Late 

Mississippian by Sando in 1975 (report on shipment 

CMR-74-5).

25584: Same unit and location as 25583 but 195- 

205 ft (60-63 m) above base of unit. 8 coral specimens in 

limestone matrix. Collection data same as 25583.

25585: Same unit and location as 25583 but 285- 

290 ft (87-89 m) above base of unit. 2 coral specimens in 

limestone matrix. Collection data same as 25583.

26250: Same unit and area as 24772 but 200-275 ft 

(61-84 m) above base of unit 325 ft (100 m) thick on hill 

about 0.9 mi (1.4 km) north of Gates Mill in NE»/4 sec. 8, 

T. 3 N., R. 36 E. 95 coral specimens in dolomite matrix 

collected by F.G. Poole in 1975 and dated Late Mississippian (Meramecian) by Sando in 1976 (report on shipment 

CMR-76-1).

AREA 2 MONTE CRISTO RANGE, 

ESMERALDA COUNTY

28065: Unnamed carbonate unit, mapped as Permian 

by Ferguson and Muller (1949, pi. 1) and as Diablo Formation (Permian) by Ferguson and others (1953). Lat 

38°ir36" N., long 117°47'48" W., Coaldale NE 7.5' 

quadrangle. 12 coral specimens in dolomite matrix collected by F.G. Poole in 1976 and dated Mississippian (late 

Meramecian) by Sando in 1981 (report on shipment 

CMR-81-8).

28066; Same unit and area as 28065 but from lat 

38°10'02" N., long 117°47'53" W. 46 coral specimens in 

dolomite matrix. Collection data same as 28065.

28067: Same unit and area as 28065 but from lat 

38°06'30" N., long 117°50'47" W. 1 coral specimen in

dolomite matrix collected by F.G. Poole in 1976 and dated 

Mississippian by Sando in 1981 (same shipment as 

28065).

AREA 3 SOUTH SAN ANTONIO 

MOUNTAINS, NYE COUNTY

14214: Unnamed carbonate unit, mapped as Devonian 

by Ferguson and Muller (1949, pi. 1), about 200 ft (60 m) 

above base. Approximately 8 mi (12.8 km) north of 

Tonopah (probably in N'/2 sec. 23 or 24, T. 4 N., R. 42 E.), 

Tonopah 15' quadrangle. 5 coral specimens in limestone 

matrix collected by H.G. Ferguson in 1951 and dated Carboniferous by H.M. Duncan in 1951 (report on shipment 

MD-51-19).

14215: Same unit and area as 14214 but from hill 

2.25 mi (3.6 km) north of USLM 206. 4 coral specimens 

in limestone matrix collected by H.G. Ferguson and dated 

Devonian by Edwin Kirk in 1922 and as probably Mississippian by H.M. Duncan in 1953.

14216: Same unit and area as 14214 but 2.25 mi (3.6 

km) N. 16° W. from USLM 206. 22 coral specimens in 

limestone matrix. Collection data same as 14215.

14666: Same unit and area as 14214 but 8.5 mi 

(13.6 km) north of Tonopah. 21 coral specimens in limestone matrix collected by H.G. Ferguson in 1963 and 

dated early Late Mississippian by H.M. Duncan in 1964 

(report on shipment SW-63-2)(see Bonham and Garside, 

1979, p. 17).

19778: Same unit and area as 14214 but approximately 

10 mi (16 km) north of Tonopah, 34,000 ft N. 39° W. of 

pumping station located 6.5 mi (10.4 km) northeast of 

Tonopah (probably in sec. 13, T. 4 N., R. 42 E.). 5 coral 

specimens in limestone matrix collected by F.J. Kleinhampl 

in 1962 and dated Late Mississippian by H.M. Duncan in 

1963 (report on shipment SW-63-2)(see Bonham and 

Garside, 1979, p. 17).

24450: Same unit and area as 14214 but on prominent ridge approximately 9 mi (14.4 km) north of 

Tonopah, near common boundary for sees. 13, 14, 23, and 

24, T. 4 N., R. 42 E. 5 coral specimens in limestone 

matrix collected by F.G. Poole in 1967 and dated Late 

Mississippian (late Meramecian or Chesterian) by Sando 

in 1971 (report on shipment HM-67-12).

24451: Same unit and location as 24450. 11 coral 

specimens in limestone matrix. Collection data same as 

24450 but dated Late Mississippian(?).

24944: Same unit and area as 14214 but on hill 

between SW»/4 sec. 13 and SE'/4 sec. 14, T. 4 N., R. 42 E. 

2 coral specimens in limestone matrix collected by F.G. 

Poole in 1968 and dated Late Mississippian (Meramecian) 

by Sando in 1972 (report on shipment RMM-69-9).

26252: Same unit and area as 14214 but from lower 

part of unit 900 ft (275 m) thick on south side of ridge
F24 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

about 0.25 mi (0.4 km) east of Rays townsite, lat 

38°11'52" N., long 117°13'50"W., T. 4 N., R. 42 E., 

Tonopah 15' quadrangle. 15 coral specimens in limestone 

matrix collected by F.G. Poole in 1975 and dated Late 

Mississippian by Sando in 1976 (report on shipment 

CMR-76-1).

26253: Same unit and area as 14214 but from float 

almost in place from middle part of unit on south side of 

large hill about 1 mi (1.6 km) east-southeast of Rays 

townsite at lat 38°11'41" N., long 117°13'06" W. 5 coral 

specimens in limestone matrix. Collection data same as 

26252.

26254: Same unit and area as 14214 but from middle 

part of unit at lat 38°1 1'40" N., long 117°13'09" W. 36 coral 

specimens in limestone matrix. Collection data same as 

26252 but dated Late Mississippian or younger.

26255: Same unit and area as 14214 but 410-460 ft 

(125-140 m) above base of unit at lat 38°11'37" N., long 

117°13'H" W. 30 coral specimens in limestone matrix. 

Collection data same as 26252 but dated Late Mississippian (latest Meramecian).

26256: Same unit and area as 14214 but 470-500 ft 

(142-150 m) above base of unit at lat 38°11'36" N., long 

1170 13'16" W. 15 coral specimens in limestone matrix. 

Collection data same as 26255.

AREA 4 NORTH SAN ANTONIO 

MOUNTAINS, NYE COUNTY

26248: Unnamed carbonate unit 50 ft (15 m) thick, 

mapped as Permian by Ferguson and Muller (1949, pi. 1). 

West side of hill 6578, NW'/4 sec. 32, T. 6 N., R. 42 E. 

25 coral specimens in limestone matrix collected by F.G. 

Poole in 1975 and dated Late Mississippian (probably 

Meramecian) by Sando in 1976 (report on shipment 

CMR-76-1)

26249: Same unit and location as 26248. 15 coral 

specimens in limestone matrix. Collection data same as 

26248.

AREA 5 TOIYABE RANGE, NYE COUNTY

25579: Unnamed carbonate unit. Spur extending 

west-northwest from peak 9885 in uppermost part of Tierney Creek drainage in SE'/4 sec. 28, T. 14 N., R. 42 E., 

North Shoshone Peak 15' quadrangle. 9 coral specimens in 

limestone matrix collected by F.G. Poole in 1974 and 

dated Mississippian (probably Early Mississippian) by 

Sando in 1975 (report on shipment CMR-74-5).

25580: Same unit and location as 25579 but from 

lower part of unit. 6 coral specimens in limestone matrix. 

Same collection data as 25579.

25581: Same unit and location as 25579. 11 coral 

specimens in limestone matrix. Same collection data as 

25579.

26251: Same unit and location as 25579 but from 

170-180 ft (52-55 m) above base of unit 200 ft (62 m) 

thick. 40 coral specimens in limestone matrix collected by 

F.G. Poole in 1975 and dated Late Mississippian (late 

Meramecian) by Sando in 1976 (report on shipment 

CMR-76-1).

AREA 6 EAST RANGE, PERSHING COUNTY

16459: Inskip Formation, limestone lens in graywacke and volcanic sequence in lower half of formation. 

Approximately 1 mi (1.6 km) from mouth of Reed Canyon, 

T. 31 N., R. 36 E., Dun Glen 15' quadrangle. 15 coral 

specimens in limestone matrix collected by R.J. Roberts in 

1956 and dated Mississippian by H.M. Duncan in 1957 

(memorandum on shipment MD-51-64)(see Roberts and 

others, 1958, p. 2847).

AREA 7 OSGOOD MOUNTAINS, 

HUMBOLDT COUNTY

12108: Goughs Canyon Formation, limestone bed in 

graywacke and volcanic sequence. East Fork, near intersection with Cherry Creek, west side of Osgood Mountains, 

near Getchell Mine, SW'A sec. 11, T. 38 N., R. 41 E., 

Adam Peak 7.5' quadrangle. 9 coral specimens in limestone 

matrix collected by R.J. Roberts in 1950(?) and dated Mississippi an(?) by H.M Duncan in 1950 (report on shipment 

MD-50-13).

14026: Same unit and area as 12108 but on bank 

north of main stream of Cherry Creek in NW'ANW1 ^ 

sec. 27, T. 38 N., R. 41 E. 27 coral specimens in limestone matrix collected by P.E. Hotz in 1952 and dated 

Mississippian by H.M. Duncan in 1952 and 1953 (reports 

on shipments MD-52-18 and MD-52-23). Brachiopods in 

same collection were dated early Osagean by Mackenzie 

Gordon, Jr., in 1961 (see Hotz and Willden, 1964, p. 26, 

27).

14027: Same unit and area as 12108 but from 

SW'ANW'A sec. 22, T. 38 N., R. 41 E. 2 coral specimens in limestone matrix. Collection data same as 

14026.

14029: Same unit and area as 12108 but from southwest corner SEl /4 SE1 /4 sec. 28, T. 38 N., R. 41 E. 3 coral 

specimens in limestone matrix. Collection data same as 

14026 (see Hotz and Willden, 1964, p. 27).

19807: Same unit and location as 12108. 50 coral 

specimens collected by P.E. Hotz and R.J. Roberts in 1951 

and dated Late Mississippian by H.M. Duncan in 1952 

(report on shipment MD-51-26)(see Hotz and Willden, 

1964, p. 26).

19808: Same unit and area as 14026 but from center 

of SW'A sec. 11. 8 coral specimens in limestone matrix. 

Same collection data as 19807 (see Hotz and Willden, 

1964, p. 26).
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F25

38080: Same unit and area as 12108 but from 

SW1ASW1 /4 sec. 11. One coral specimen in limestone 

matrix collected by L.B. McCollum in 1991 and dated 

Late Mississippian (middle Meramecian) by Sando in 

1991 (letter to McCollum).

38081: Same unit and location as 38080. 1 coral 

specimen in limestone matrix. Same collection data as 

38080.

38082: Same unit and area as 38080 but from 

NW'ASW'A sec. 11. 7 coral specimens in limestone 

matrix. Same collection data as 38080.

38083: Same unit and area as 38080 but from 

NEV4NWV4 sec. 12. One coral specimen in limestone 

matrix. Same collection data as 38080.

38084: Same unit and location as 38083. 200 coral 

specimens in limestone matrix. Same collection data as 

38080.

AREA & MOUNTAIN CITY DISTRICT, 

ELKO COUNTY

15384: Banner Formation. Mountain City, Mountain 

City 15' quadrangle. 9 coral specimens in limestone matrix 

collected by T.B. Nolan in 1932 and dated Late Mississippi^?) by G.H. Girty in 1932 and Permian(?) by H.M. 

Duncan in 1955 (memorandum to Nolan and Ferguson).

16093: Same unit as 15384. Mill Creek, south of 

Mountain City, above Nelson ranch in SE1 ^ sec. 3, T. 45 N., 

R. 53 E., Mountain City 15' quadrangle. 17 coral specimens 

in limestone matrix collected by J.R. Coash in 1955 and 

dated Mississippian(?) by H.M. Duncan in 1958 (letter to 

Coash on shipment O-56-41)

17659: Banner Formation(?). Same area as 16093 

but at coordinates N2,568,100 and £363,800. 8 coral specimens in limestone matrix collected by R.R. Coats in 

1957. No previous dating.

17662: Same unit and area as 16093 but near quarter 

corner sees. 2 and 11, T. 45 N., R. 53 E. 70 coral specimens in limestone matrix collected by R.R. Coats in 1957 

and dated Late Mississippian in 1960 by H.M. Duncan 

(report on shipment MD-57-38). Also dated Late Mississippian (middle and late Meramecian) by Sando (in Little, 

1987, Appendix A, p. 1).

19526: Same unit and area as 16093 but coordinates 

N2,573,700 and £38,300, Owyhee 7.5' quadrangle. 2 coral 

specimens in limestone matrix collected by R.R. Coats in

1959 and dated Late Mississippian by H.M. Duncan in

1960 (report on shipment MD-59-25). Also dated Late 

Mississippian (Meramecian) by Sando (in Little, 1987, 

Appendix A, p. 1)

19527: Same unit and area as 19526 but at station 

138 of Coats (exact location unstated). 13 coral specimens 

in limestone matrix. Same collection data as 19526. Also 

dated Late Mississippian (middle or late Meramecian) by 

Sando (in Little, 1987, Appendix A, p. 1)

19528: Same unit and area as 19526 but 200 ft (62 

m) south of station 138 of Coats. 1 coral specimen in 

limestone matrix. Same collection data as 19526. Also 

dated Late Mississippian (middle or late Meramecian) by 

Sando (in Little, 1987, Appendix A, p. 2).

21588: Same unit and area as 16093 but from 

SWi/4 SEi/4 SWi/4 sec. 8, T. 46 N., R. 55 E., 0.55 mi 

(0.9 km) southeast of Enright Hill on 7300' contour and 

N. 45° W. of "2" in 7250' contour, downslope from 

small hill and trail cutting across south side and 0.05 

mi (0.08 km) below trail. 14 coral specimens in limestone matrix collected by R.R. Coats in 1962 and dated 

Late Mississippian (probably Meramecian) by Sando in 

1971 (report on shipment SW-62-23) and Late Mississippian (middle Meramecian) by Sando (m Little, 1987, 

Appendix A, p. 2).

22813: Same unit and area as 16093 but from north 

slope of Mill Creek opposite and northwest of IdahoNevada mine shaft, 100-150 ft (30-46 m) above valley 

floor in NW»/4NE»/4 sec. 9, T. 45 N., R. 53 E. 50 coral 

specimens in limestone matrix collected by R.R. Coats, 

Mackenzie Gordon, Jr., and Donald Dean in 1964 and 

dated Late Mississippian (probably Meramecian) by H.M. 

Duncan in 1967. Also dated Late Mississippian (middle 

Meramecian) by Sando (m Little, 1987, Appendix A, p. 2).

28314: Same unit and area as 16093 but from sec. 

17, T. 46 N., R. 55 E. 1 coral specimen in limestone matrix 

collected by R.R. Coats in 1981 and dated Late Mississippian (early Meramecian) by Sando in 1982 (report on shipment WMR-82-1). Also dated Late Mississippian (early 

Meramecian) by Sando (m Little, 1987, Appendix A, p. 3).

NOTE

After this report had been submitted for publication, 

M.B. McCollum called to my attention two publications by 

S.A. Shaver (1987, 1991) in which Devonian corals are 

reported from area 4 (North San Antonio Mountains). 

These corals were collected by Shaver from limestone outcrops in sec. 32, T. 6 N., R. 42 E., Nye County, which is 

essentially the same location as USGS localities 26248-PC 

and 26249-PC, from which I identified corals of Late Mississippian (Zone HID) age. The corals were identified as 

probably of middle Early Devonian age by W.A. Oliver, 

Jr. (U.S. Geological Survey, Washington, D.C.), and the 

rocks were assigned to the Nevada Formation by Shaver.

I studied the thin sections of fragmentary solitary and 

colonial(?) corals that formed the basis for Oliver's age 

diagnosis and identified Faberophyllum sp. and undetermined fragments that may belong to Siphonodendron, 

from which I conclude that the beds regarded as Devonian 

are actually of Late Mississippian (Zone IV) age and 

belong to the unnamed carbonate unit of Poole. Hence, 

the limestone sequence in area 4 probably ranges from
F26 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

Zone HID into Zone IV. I discussed this matter with 

Oliver, and he concurs with my revision of his identification and age assignment.

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Tonopah, Lone Mountain, Klondike, and Northern Mud Lake 

quadrangles, Nevada: Nevada Bureau of Mines and Geology 

Bulletin 92,136 p.

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and sections of the Osgood Mountains quadrangle, Humboldt 

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County, Nevada: Nevada Bureau of Mines and Geology Bulletin 99 A, 172 p.

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implications for the Mississippian of North America: International Congress of Carboniferous Stratigraphy and Geology, 

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1984, Stratigraphy and structure of the Schoonover sequence, 

northeastern Nevada Implications for Paleozoic platemargin tectonics: Geological Society of America Bulletin, v. 

95, p. 1063-1076.

Muller, S.W., Ferguson, H.G., and Roberts, R.J., 1951, Geology of 

the Mount Tobin quadrangle, Nevada: U.S. Geological Survey 

Geologic Quadrangle Map GQ-7, scale 1:125,000, with text.

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organic reef complex: Bulletin of Akiyoshi-dai Science 

Museum, no. 5,44 p.

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geology of the Akiyoshi Limestone Group: Bulletin of 

Akiyoshi-dai Museum of Natural History, no. 12, p. 1-32.

Poole, F.G., 1974, Flysch deposits of the Antler foreland basin, 

western United States, in Dickinson, W.R., ed., Tectonics and 

sedimentation: Society of Economic Paleontologists and Mineralogists Special Publication 22, p. 58-82.

Poole, F.G., Baars, D.L., Drewes, Harold, Hayes, P.T., Ketner, 

K.B., McKee, E.D., Teichert, Curt, and Williams, J.S., 1967, 

Devonian of the southwestern United States, in Oswald, D.H., 

ed.. International Symposium on the Devonian System, Calgary, Alberta, September, 1967: Alberta Society of Petroleum 

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Stevens, C.H., and Fritsche, A.E., eds., Paleozoic paleogeography of the western United States, Pacific Coast Paleogeography Symposium 1: Pacific Section, Society of Economic 

Paleontologists and Mineralogists, p. 67-85.

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Stevens, C.H., eds., Paleozoic paleogeography of the western 

United States-II, v. 1: Pacific Section, Society of Economic 

Paleontologists and Mineralogists, Book 67, p. 107-136.
MISSISSIPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F27

Roberts, R.J., 1951, Geology of the Antler Peak quadrangle. 

Nevada: U.S. Geological Survey Geologic Quadrangle Map 

GQ-10, scale 1:62,500, with text.

Roberts, R.J., Hotz, P.E., Gilluly, James, and Ferguson, H.G., 

1958, Paleozoic rocks of north-central Nevada: Bulletin of 

American Association of Petroleum Geologists, v. 42, no. 12, 

p. 2813-2857.

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and adjacent States, in Woodward, Jane, Meissner, F.F., and 

Clayton, J.L., eds., Hydrocarbon source rocks of the Greater 

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corals in the western conterminous United States: Acta Palaeontologia Polonica, v. 25, no. 3-4, p. 619-631.

 1984a, Biostratigraphy, Introduction: Palaeontographica 

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 1984b, Biostratigraphic utility of upper Paleozoic syringoporoid corals, Western Interior region, conterminous USA: 

Palaeontographica Americana, no. 54, p. 453-458.

 1985, Revised Mississippian time scale, Western Interior 

region, conterminous United States: U.S. Geological Survey 

Bulletin 1605-A, p. A15-A26.

 1989, Dynamics of Carboniferous coral distribution, Western Interior, USA: Association of Australasian Palaeontologists Memoir 8, p. 251-265.

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Forschungs-Institut Senckenberg, v. 130, p. 173-187.

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localities in Antler orogen, central Nevada: Rocky Mountain 

Section, Geological Society of America, May 1992, Ogden, 

Utah, Abstracts with Program, p. 60.

Sando, W.J., and Bamber, E.W., 1985, Coral zonation of the Mississippian System in the Western Interior Province of North 

America: U.S. Geological Survey Professional Paper 1334, 

61 p.

Sando, W.J., Bamber, E.W., and Armstrong, A.K., 1975, Endemism and similarity indices Clues to the zoogeography of 

North American Mississippian corals: Geology, v. 3, no. 11, 

p. 661-664.

 1977, The zoogeography of North American Mississippian 

corals, in Second Symposium on Corals and Fossil Coral 

Reefs, Paris, 1975: Bureau de Recherches Geologiques et 

Minieres Memoire 89, p. 175-184.

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volcanism recorded in northern San Antonio Mountains, Nye 

County, Nevada: Geological Society of America Abstracts 

with Program, v. 19, p. 450.

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County, Nevada, in Raines, G.L., and others, eds., Geology and 

ore depositis of the Great Basin: Geological Society of Nevada 

Symposium Proceedings, p. 303-332.

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and structure of northwestern Nevada: Geological Society of 

America Special Paper 72, 53 p.

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C.W., coordinators, Paleotectonic investigations of the Mississippian System in the United States: U.S. Geological Survey 

Professional Paper 1010, pt. 1, p. 273-328.

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Trip 6), in Lintz, Joseph, Jr., ed., Western geological excursions, v. 4: University of Nevada at Reno, Department of Geological Science, p. 66-80.

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1977, Diablo Formation, central and western Nevada 

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Coast Paleogeography Symposium 1: Pacific Section, Society 

of Economic Paleontologists and Mineralogists, p. 301-314.

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Columbus quadrangles, Mineral and Esmeralda Counties, 

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scale 1:24,000.

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auloporidid corals in the Akiyoshi Limestone Group, southwest Japan, in Paleoecological studies of reef-building organisms in the Akiyoshi organic reef complex, I: Bulletin of 

Akiyoshi-dai Museum of Natural History, no. 25, p. 7-25.

 1991, Reef facies and paleoecology of some reefbuilding corals found in the lower part of the Akiyoshi 

Limestone Group (Carboniferous), southwest Japan: International Symposium on Fossil Cnidaria, including Archaeocyatha and Porifera, 6th, Muenster, Germany, September, 

1991, Abstracts, p. 88-89.

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quadrangle, Pershing County, Nevada: U.S. Geological 

Survey Open-File Report 78-407, scale 1:48,000.

Published in the Central Region, Denver, Colorado 

Manuscript approved for publication February 22, 1993 

Cartography by Wayne Hawkins 

Photocomposition by Marie F. Melone 

Edited by Judith Stoeser
F28 EVOLUTION OF SEDIMENTARY BASINS EASTERN GREAT BASIN

APPENDIX FORAMINIFERA AND 

ALGAE

By B.L. Mamet (Universite* de Montreal, Quebec, 

Canada)

CANDELARIA HILLS (AREA 1) 

LOCALITY 25584

Microfacies: Recrystallized crinoid wackestone containing

large sponge megascleres.

Biota:

Earlandia vulgaris (Rauzer and Reitlinger)

Endothyra sp.

Eoendothyranopsis scitula (Toomey)

Eoendothyranopsis of the group scitula (Toomey)

Globoendothyra sp.

Priscella sp.

Tetrataxis sp. 

Age: MFZ 13-14 (late middle to early late Vise"an).

SOUTH SAN ANTONIO MOUNTAINS (AREA 3)

LOCALITY 24944

Microfacies: Crinoidal packstone. 

Biota:

Brunsia sp.

Earlandia sp.

Eoendothyranopsis sp.

Eoendothyranopsis ermakiensis (Lebedeva)

Eotuberitina sp.

Globoendothyra sp.

Mametella sp.

Paracaligelloides sp.

Pseudotaxis sp.

Skippella sp.

Tetrataxis sp. 

Age: MFZ 13-14, most probably 14 (early late Vise"an).

LOCALITY 26252

Microfacies: Very recrystallized crinoidal packstone containing brachiopods and corals. 

Biota:

Earlandia sp.

Endothyra sp.

Endothyranella sp.

Eoendothyranopsis scitula (Toomey)

Mametella sp.

Priscella sp. 

Age: MFZ 13-14 (late middle to early late Vise"an).

LOCALITY 26253

Microfacies: Very recrystallized crinoidal packstone containing corals. 

Biota:

Earlandia sp.

Endothyra sp.

Priscella sp.

Tetrataxis sp. 

Age: Sample too poor for precise zonation.

LOCALITY 26254

Microfacies: Recrystallized, chertified, fuzzy crinoid 

wackestone containing large sponge megascleres. 

Biota:

Earlandia vulgaris (Rauzer and Reitlinger)

Endothyra sp.

Eoendothyranopsis of the group E. ermakiensis 

(Lebedeva)

Globoendothyra of the group G. tomiliensis 

(Lebedeva)

Pseudotaxis sp.

Tetrataxis sp. 

Age: MFZ 13-14 (late middle to early late Vise"an).

LOCALITY 26255

Microfacies: Recrystallized coral-brachiopod-crinoid

packstone.

Biota:

cf. Asphaltinaf sp.

Endothyra sp.

Two-layered Palaeotextulariidae

Tetrataxis angusta Vissarionova

Age: Sample too poor for precise zonation. Two-layered 

Palaeotextulariidae occur for the first time in MFZ 15, but 

they range much higher. The sample is MFZ 15 or 

younger.

LOCALITY 26256

Microfacies: Reworked clasts in crinoid-bryozoan packstone containing brachiopod spines(?). 

Biota:

Endothyra sp.

Globoendothyra sp.

Pseudotaxis sp.

Tetrataxis angusta Vissarionova

Age: Sample is similar to 26255, but it is too poor for 

precise zonation.
MISSISSBPPIAN CORALLIFEROUS CARBONATE SHELVES, CENTRAL NEVADA F29

TOIYABE RANGE (AREA 5)

LOCALITY 25580

Microfacies: Recrystallized fossil packstone or pseudograinstone containing bryozoans and echinoderm fragments. 

Biota:

Earlandia vulgaris (Rauzer and Reitlinger)

Endothyra of the group E. bowtnani Phillips in 

Brown emend. Brady

Eoendothyranopsis scitula (Toomey)

Eoendothyranopsis of the group E. scitula (Toomey)

Globoendothyra sp.

Globoendothyra of the group G. tomiliensis 

(Lebedeva)

Priscella sp.

Pseudoammodiscus sp.

Tetrataxis sp.

Age: MFZ 13-14 (late middle to early late Vise"an). Similar to 25584 and 26252.

LOCALITY 25581

Microfacies: Sandy, crinoidal, recrystallized pseudograinstone containing angular quartz grains, reworked bryozoan 

bioclasts, and reworked algal nodules (some with Girvanella, others with Sphaerocodiutri). Probably a gravityflow deposit. 

Biota (all reworked)

Asphaltina sp.

Latiendothyra sp.

Septabrunsiina sp.

Septaglomospiranella sp.

Solenoporid nodules

Age: This is a mixed assemblage of Devonian(?) to 

Tournaisian age. Sphaerocodium is abundant in the 

Devonian up to the Frasnian but is extremely rare in the 

Carboniferous.

LOCALITY 26251

Microfacies: Crinoid-bryozoan packstone.

Biota

Earlandia vulgaris (Rauzer and Reitlinger) 

Endothyra of the group E. bowtnani Phillips in 

Brown emend. Brady

Eoendothyranopsis sp.

Eoendothyranopsis donica Brazhnikova and

Rostoveeva 

Eoendothyranopsis of the group E. ermakiensis

(Lebedeva) 

Eoendothyranopsis cf. E. robusta (McKay and

Green)

Globoendothyra sp. 

Priscella sp. 

Tetrataxis sp. 

Age: MFZ 15 (middle late Vise"an).

OSGOOD MOUNTAINS (AREA 7) 

LOCALITY 14027

Microfacies: Hematite-stained crinoidal packstone containing fish plates, altered volcanic fragments, and pebbles 

of fuzzy recrystallized crinoidal wackestone containing 

bryozoans and sponge spicules. This could be a gravityflow deposit. 

Biota:

Earlandia vulagaris (Rauzer and Reitlinger)

Endothyra sp.

Eoendothyranopsis sp.

Epistacheoides sp.

Mametella sp.

Tetrataxis sp.

Age: Sample is too poor for precise zonation and is 

extensively reworked. It is at least partly late Meramecian.

GENERAL COMMENT ON THE ECOLOGY

AND BIOGEOGRAPHY OF THE

MICROFOSSILS

The middle to late Meramecian samples (all but 

25581), which contain abundant crinoid and bryozoan 

remains, have a less diversified microfauna and microflora 

than most coeval strata on the Cordilleran platform east of 

the Antler orogen. Although the biota of the Antler samples is typically North American in aspect and contains no 

exotic elements, the Antler biofacies suggests somewhat 

deeper (30-40 m, 100-130 ft) or cooler water than normally indicated by other Western Interior shallow-water 

biofacies.

PLATES 1-4

Contact photographs of the plates in this report are available, at cost,

from U.S. Geological Survey Photographic Library, Federal Center,

Denver, Colorado 80225
PLATE 1

[All figures x4]

Figure 1. Lophophylluml sp. Transverse thin section, USNM 469351, from USGS locality 14206-PC. 

Unnamed carbonate unit, area 7.

2. Ufimia sp. Transverse thin section, USNM 469352, from USGS locality 14026-PC. Unnamed carbonate unit, area 7.

3. Syclmoelasma cf. 5. ulriclianum (Girty). Transverse thin section, USNM 469353, from USGS locality 

25581-PC. Unnamed carbonate unit, area 5.

4. Cyathaxonia sp. Transverse thin section, USNM 469354, from USGS locality 14026-PC. Unnamed

carbonate unit, area 7.

5, 6. Michelinial sp. Transverse and longitudinal thin sections, respectively, USNM 469355, from USGS 

locality 14026-PC. Unnamed carbonate unit, area 7.
U.S. GEOLOGICAL SURVEY BULLETIN 1988-F PLATE 1

REPRESENTATIVE CORALS OF CORAL ZONE HB
PLATE 2

[All figures x2]

Figure 1. Koninckopliylluml sp. Transverse thin section, USNM 469356, from USGS locality 25583-PC. 

Unnamed carbonate unit, area 1.

2. Canadiphyllum sp. Transverse thin section, USNM 469357, from USGS locality 14027-PC. 

Unnamed carbonate unit, area 7.

3. Amplexizaphrentis? sp. (may be young Canadiphyllum). Transverse thin section, USNM 469358, 

from USGS locality 14027-PC. Unnamed carbonate unit, area 7.

4. Ekvasopliyllum sp. Oblique calicular view of etched silicified corallum, USNM 469359, from USGS

locality 26250-PC. Unnamed carbonate unit, area 1. 

5, 6. Siphonodendron aff. S. sinuosutn (Warren). Longitudinal and transverse thin sections, respectively,

USNM 469360, from USGS locality 26253-PC. Unnamed carbonate unit, area 3. 

7, 8. Siphonodendron cf. S. whitneyi of Meek (diphymorph). Longitudinal and transverse thin sections,

respectively, USNM 469361, from USGS locality 26254-PC. Unnamed carbonate unit, area 3.
U.S. GEOLOGICAL SURVEY BULLETIN 1988-F PLATE 2

8

REPRESENTATIVE CORALS OF CORAL ZONE IHD
PLATE 3

[Figures x4 unless otherwise noted]

Figure 1. Stelechophylluml sp. Transverse thin section, USNM 469362, from USGS locality 17662-PC. Banner Formation, area 8.

2, 3. Sciophyllum sp. Longitudinal and transverse thin sections, respectively, x2, USNM 469363, from

USGS locality 25584-PC. Unnamed carbonate unit, area 1.

4. Multithecopora morphogroup A of Sando (1984b). Transverse thin section, USNM 469364, from 

USGS locality 24944-PC. Unnamed carbonate unit, area 3.

5, 6. Pleurosiphonella morphogroup A of Sando (1984b). Transverse and longitudinal thin sections, 

respectively, USNM 469365, from USGS locality 26254-PC. Unnamed carbonate unit, area 3.

7, 8. Syringopora morphogroup G of Sando (1984b). Longitudinal and transverse thin sections, respectively, USNM 469366, from USGS locality 14029-PC. Coughs Canyon Formation, area 7.
U.S. GEOLOGICAL SURVEY BULLETIN 1988-F PLATE 3

REPRESENTATIVE CORALS OF CORAL ZONE EID
PLATE 4

[Figures x2 unless otherwise noted]

Figures 1, 2. Siphonodendron cf. 5. whitneyi of Meek. Longitudinal and transverse thin sections, respectively,

USNM 469367, from USGS locality 26256-PC. Unnamed carbonate unit, area 3. 

3, 4. Faberophyllum sp. Transverse and longitudinal thin sections, respectively, USNM 469368, from

USGS locality 26251-PC. Unnamed carbonate unit, area 5. 

5, 6. Pleurosiphonella morphogroup A of Sando (1984b). Longitudinal and transverse thin sections,

respectively, x4, USNM 469369, from USGS locality 26256-PC. Unnamed carbonate unit,

area 3.
U.S. GEOLOGICAL SURVEY BULLETIN 1988-F PLATE 4

REPRESENTATIVE CORALS OF CORAL ZONE IV

ftU.S. GOVERNMENT PRINTING OFFICE: 1993-774-049/66065

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