Paleoecology of the Eurekaspirifer Pinyonensis Zone, Eureka County, Nevada
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AN ABSTRACT OF THE THESIS OF WALTER WARD NIEBUHR II for the MASTER OF SCIENCE (Name) (Degree) in GEOLOGY presented on September 19, 1973 (Major) (Date) Title: PALEOECOLOGY OF THE EUREKASPIRIFER PINYONENSIS ZONE, EUREKA COUNVI, NEVADA Abstract approved: Redacted for privacy G. Johnson Five measured sections serve as the source of data in studying the community structure and depositional history of the Eurekaspirifer pinyonensis Zone in Eureka County, Nevada, Sections were estab- lished at McColley Canyon in the Sulphur Springs Range, Coal Canyon in the Simpson Park Range, Cooper Peak in the northern Roberts Mountains, and at Lone Mountain in order to collect large paleonto- logical samples keyed to measured sections.The research is essen- tially confined to the Bartine Member of the McColley Canyon Forma- tion.The Bartine is characteristically an argillaceous, slope-forming limestone.Samples were taken from the measured sections wherever significant faunal or lithologic changes were observed. Detailed study of the measured sections allows certain trends within the Bartine to be recognized.Progressively increasing water depth is indicated by the lithologies and faunas in all sections.The Mc Colley Canyon section shows shallowing in the Bartine after initial deepening.The lower Bartine at Coal Canyon is indicative of an environment different from those elsewhere on the shelf.As the trend toward deeper water continued, the Coal Canyon section became increasingly like that of Lone Mountain. A time line has been established through the Bartine on the basis of the last appearance of the coarsely costate Atrypa sp. and the first appearance of Atrypa nevadana.The Atrypa time line demon- strates that the Bartine Member is a transgressive unit, older in the west than in the east.The oldest Bartine is at Coal Canyon.The Bartine Member is believed to intertongue with the Kobeh Member between Coal Canyon and Cooper Peak and between Lone Mountain and McColley Canyon. Communities defined in the Bartine are the Eurekaspirifer pinyonensis Community, the Atrypa nevadana Community and its homolog the Atrypa sp. Community, the G-A-S Community, the Leptocoelia infrequens Community, and the Restricted Leptocoelia infrequens Community, The Eurekaspirifer pinyonensis, A. nevadana, and G-A-S Communities occupy positions on the shelf progressively farther from shore.The Restricted Leptocoelia infrequens and Leptocoelia infrequens Communities are characteristic of special environmental conditions at Coal Canyon,All communities are believed to lie within benthic assemblage 3. Paleoecology of the Eurekaspirifer pinyonensis Zone, Eureka County, Nevada by Walter Ward Niebuhr II A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science June 1974 APPROVED: Redacted for privacy Profet' or of Geology rge of major Redacted for privacy "Cting Chairman of Department of Geology Redacted for privacy Dean of Graduate School Date thesis is presented September 19, 1973 Typed by Mary To Stratton forWalter Ward Niebuhr II ACKNQWLEDGEMENTS I would like to express my gratitude to the faculty and staff of the Department of Geology at Oregon State University, all of whom have assisted in some large or small way in the preparation of this thesis.I would like especially to thank the members of my committee, Drs. J. G. Johnson and A. J. Boucot of the Department of Geologyat Oregon State University, who have exhibited utmost patience in granting my demands on their time and knowledge.R, A. Flory of Oregon State University and Dr. M. A. M_urphy of the University of California at Riverside were of great assistance in the field, and I was grateful to be able to draw on their experience inthe Devonian stratigraphy of Nevada. Finally,I should like to give a special acknowledgement to my wife, Claire, without whose unfailing moral and financial support this project probably never would have been completed. TABLE OF CONTENTS Page INTRODUCTION 1 Purpose and Scope 1 Location and Accessibility 2 Previous Work 2 Geological Setting 4 Methods of Investigation 6 ANALYSIS OF MEASURED SECTIONS 10 Mc Colley Canyon Section 10 Section Description 10 Interpretation of Fauna and Litho logy 38 Lone Mountain Section 46 Section Description 46 Interpretation of Fauna and Litho logy 55 Cooper Peak Section 56 Section Description 56 Interpretation of Fauna and Lithology 71 Coal Canyon Section N-1 7 3 Section Description 73 Interpretation of Fauna and Lithology 98 Coal Canyon Section N-3 100 Section Description 100 Interpretation of Fauna and Lithology 102 SUMMARY 105 Relationships Between Measured Sections 105 Community Distribution Through Time and Space 114 CONCLUSION 120 REFERENCES CITED 123 APPENDICES Appendix A.Faunal Lists and Localities 127 LIST OF FIGURES Figure Page 1 Index map of study area. 2 Atrypa nevadana in],ife position from the Bartine Member, Telegraph Canyon, Sulphur Springs Range, Eureka County, Nevada. 28 3 Relationship between transported tabulate coral colony and disarticulated Atrypa nevadana brachial valve. 29 4 Shell of Eurekaspirifer pinyonensis showing injuries incurred and subse- quently repaired during the animal's lifetime. 32 5 Litho logy at 197 feet on section MCN-1. 34 6 Litho logy at Telegraph Canyon from the same stratigraphic horizon as sample MCN-17b. 36 7 Cooper Peak showing location of section CPN-1. 57 8 Photomicrograph showing graded bedding in sample CPN-13a. 63 9 Photomicrograph of lithology at CPN-12. 68 10 Looking into canyon east of Coal Canyon at sections CCN-1 and CCN-3. 74 11 Illustration of burrows on polished section in sample CCN-119. 89 12 Illustration of microlaminae around trans- ported horn coral on polished section of sample CCN-119. 91 Figure Page 13 Photomicrograph of burrowing bivalve in section CCN-3. 103 14 Diagrammatic cross-section of Bartine Member from Coal Canyon, Simpson Park Range to Mc Colley Canyon, Sulphur Springs Range, Eureka County, Nevada. 113 15 Diagrammatic representation of distribu- tion of brachiopod communities in Upper Eurekaspirifer pinyonensis Zone, Eureka County, Nevada. 118 LIST OF TABLES (Tables are in back pocket) Table Relative abundances of brachiopod species in section MCN-1. 2 Relative abundances of brachiopod species in section LMN-1. 3 Relative abundances of brachiopod species in section CPN -l. 4 Relative abundances of brachiopod species in section CCN-1. 5 Relative abundances of brachiopod species in section CCN-3. PALEOECOLOGY OF THE EUREKASPIRIFER PINYONENSIS ZONE, EUREKA COUNTY, NEVADA INTRODUCTION Purpose and Scope During the Spring of 1972 the writer was engaged in a small- scale research problem involving the Early Devonian brachiopods in the J. G. Johnson collection.Attention was centered around the brachiopods from the Eurekaspirifer pinyonensis Zone of Eureka County, Nevada. Certain patterns of associations between the brachiopod species which intimated at community structures were recognized in the course of this research,The collections were not keyed to measured sec- tions, however, so communities could neither be defined with cer- tainty nor related in time and space.The strata of the Eurekaspirifer pinyonensis Zone were known to be abundantly fossiliferous andthe writer and Dr. Johnson agreed that the fauna of this biostratiographic zone would provide an excellent subject for a Masterof Science thesis in Paleontology.The primary goal of the research was to define brachiopod communities within the zone and to determine their vertical and lateral distribution. A secondary goal was to learn something about the depositional environment and history of the strata containing the Eurekaspirifer pinyonensis fauna. The Eurekaspirifer pinyonensis Zone is containedalmost entirely within the Bartine Member of the Mc Colley Canyon Formation.The problematic overlying Elythyna beds of the Coils Creek Member, once included within the E. pinyonensis Zone, arebeyond the scope of this project. Location and Accessibility The study area is located in north-central Nevadanorth of the town of Eureka in Eureka County. From north to south,measured sections were established at Mc Colley Canyon in the northernSulphur Springs Range, Coal Canyon in the Simpson Park Range, CooperPeak in the northern Roberts Mountains, and at Lone Mountain, asshown on the index map as Figure 1. The general study area is well-served by two-lane pavedroads. All of the section localities are approachable by single-lane dirtroads to within one or two miles.Off-road travel, even with four-wheel drive vehicles, is difficult due to, the rugged, blockyterrain and the high, dense sagebrush. Previous Work The pioneering biostratigraphy in Eureka County wasdone by C. W. Merriam who first defined and established therelative position of the Eurekaspirifer pinyonensis Zone and the Acrospiriferkobehana MILES 0 20 30 encessamel---Issainclaeller 0 20 30 KILOMETERS1 LO0 Elkou It3 4 33 boltRiver Hum Bottle Mountain Deowowe 1 27 v. rt. tu fv/IcColley Canyon 0 ne Cortez 1O P 0 0 iz:r \ .ii Mk ANA Cool Cony° co i 4.411co. a_ 1 ci. Alt Z' 'C' co cc 24 Willow Creek 0 D Birch Creek. A,AlI J.e.°W °Mina -J ct I23W < t r c6 I 0._ cou-1,i 0 Roberts Creek 22 P1 :1,-1 0 -4 0 V ;\ cI , 21 4 47 . 0_ 49 50 1 51 52 53 54 55' 56 57 1 o Lonej--"- Mountain '.42u.., e 'Eureka U EK A i / is 1111 Combs Peak , o 0 Atrypa Peok 18' affill 2 q.)1 ,--- <1,' <1" 17 )1).. i 1 <I z----o 0 Z ..-til I i i-- 16 Ham'ton. t 1 abbit Hill 0_ i5 0 olkes Canyon N Y E Sowlod'Rid9e J, Fig. i INDEX MAP OF STUDY AREA Zone (Merriam, 1940).The E. pinyonensis Zone was later recognized in the Sulphur Springs Range by Carlisle and others (1957), andin the Simpson Park Range by Johnson (1965).Johnson also recognized and named the unique Leptocoelia infrequens Subzone in the SimpsonPark Range (Johnson, 1965). The three-fold lithologic character of the Mc ColleyCanyon Formation was recognized by Gronberg (1967), whodefined and described the Kobeh, Bartine and Coils Creek Membersat Lone Mountain.Murphy and Gronberg (1970) Later recognizedand mapped the Bartine and Kobeh Members in the Roberts Mountainsand Sulphur Springs Range.