U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY THE IBEXIAN SERIES (LOWER ORDOVICIAN), A REPLACEMENT FOR "CANADIAN SERIES" IN NORTH AMERICAN CHRONOSTRATIGRAPHY by Reuben J. Ross Jr. 1 , Lehi F. Hintze2, Raymond L. Ethington3, James F. Miller4, Michael E. Taylor5 , and John E. Repetski6 With a section on ECHINODERM BIOSTRATIGRAPHY by James Sprinkle7 and Thomas E. Guensburg8 Chapter B in PALEOZOIC BIOCHRONOLOGY OF THE GREAT BASIN, WESTERN UNITED STATES Michael E. Taylor5, Editor Open-File Report 93-598 1993 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. A contribution to the Eastern Great Basin Project of the Evolution of Sedimentary Basins Program, Harry E. Cook and Christopher J. Potter, Coordinators. Department of Geology, Colorado School of Mines, Golden Colorado 80401; Department of Geology, Brigham Young University, Provo, Utah 84602-4646; Department of Geological Sciences, University of Missouri, Columbia, Missouri 65211; Department of Geography, Geology and Planning, Southwest Missouri State University, Springfield, Missouri 65904-0089; 5U.S. Geological Survey, Box 25046 MS 919, Denver Federal Center, Colorado 80225-0046; and 6U.S. Geological Survey, National Center 970, Reston, VA 22092. Department of Geological Sciences, University of Texas, Austin 78712, and 8Physical Science Division, Rock Valley College, Rockford, IL 61114. CONTENTS Page Abstract................................................................................................... 8 Introduction .............................................................................................. 8 Ibex!an Series Type Area and Sections ..................................................... 9 Definition of the Ibexian Series ...................................................................... 11 Lithostratigraphy........................................................................................ 17 Notch Peak Formation ......................................................................... 17 Hellnmaria and Red Tops Members................................................. 17 Lava Dam Member ..................................................................... 19 House Limestone................................................................................ 19 Fillmore Formation............................................................................. 19 Basal Ledge-Forming Limestone Member (1)..................................... 19 Slope-Forming Shaly Siltstone Member (2)........................................ 21 Light-Gray Ledge-Forming Member (3) ........................................... 21 Brown Slope and Ledge Member (4)................................................ 21 Calcarenite Member (5)................................................................ 21 Calathiwn Calcisiltite Member (6)................................................... 21 Wah Wah Limestone .......................................................................... 21 Ibexian Biostratigraphy................................................................................ 22 Introductory Statement......................................................................... 22 Pre-Ibexian Faunal Zones ..................................................................... 22 Ibexian Stages and Trilobite Zones.................................................................. 24 Skullrockian Stage (new)...................................................................... 24 Eurekia apopsis Zone.................................................................. 24 Missisquoia Zone ....................................................................... 25 Symphysurina Zone (= Zones A and B, revised) ................................ 25 Bellefontia-Xenostegium Zone (= Zone B, upper part)......................... 26 Paraplethopeltis Zone (= Zone C).................................................. 27 Stairsian Stage (new)........................................................................... 27 Leiostegium-Kainella Zone (= Zone D)............................................ 27 Tesselacauda Zone (= Zone E)...................................................... 28 Rossaspis superciliosa Zone (= Zone F).......................................... 29 Tulean Stage (new)............................................................................. 29 Hintzeia celsaora Zone (= Zone G-l).............................................. 30 Protopliomerella contracta Zone (= Zone G-2).................................. 30 Blackhillsian Stage (new)...................................................................... 31 Trigonocerca typica Zone (= Zone H)............................................. 31 Presbynileus ibexensis Zone (= Zone I)........................................... 32 Pseudocybele nasuta Zone (= Zone J)............................................. 33 Hesperonomiella minor Zone (= "Zone K" of Hintze, 1953)................. 33 Whiterockian Series .................................................................................... 34 Rangerian Stage (new)......................................................................... 34 Paralenorthis-Orthidiella Zone (= Zone L)....................................... 34 Ibexian Conodont Zones............................................................................... 35 Introductory Statement......................................................................... 35 Pre-Ibexian Conodont Zones.................................................................. 36 Cordylodusproavus Zone (= Fauna A, lower part)..................................... 36 Cordylodus intermedius Zone (= Fauna A, upper part) ................................ 36 Cordylodus lindstromi Zone (= Fauna B, lower part)................................... 37 lapetognathus Zone (new) (= Fauna B, middle part) ................................... 37 Cordylodus angulatus Zone (= Fauna B, upper part)................................... 37 Rossodus manitouensis Zone (= Fauna C)................................................ 38 Low Diversity Interval (= Fauna D, lower part)......................................... 38 Macerodus dianae Zone (new) (= Fauna D, middle part).............................. 38 Acodus deltatus/Oneotodus costatus Zone (new) (= Fauna D, upper part)......... 39 Oepikodus communis Zone (= Fauna E, lower part).................................... 39 Reutterodus andinus Zone (new) (= Fauna E, middle part)............................ 40 Whiterockian Conodont Zones ....................................................................... 40 Tripodus laevis Zone (new) (= Fauna E, upper part)................................... 40 Historical Perspective.................................................................................. 41 Background and Appeals for Tradition..................................................... 41 Alternative Viewpoints......................................................................... 41 Geographical Perspective.............................................................................. 42 North America................................................................................... 42 Utah and Southeastern Idaho.......................................................... 42 Canadian Rocky Mountains........................................................... 43 Eastern Canada......................:................................................... 43 Appalachian Province.................................................................. 44 Southern Midcontinental U.S......................................................... 44 Mexico.................................................................................... 45 Outside North America ........................................................................ 45 South America........................................................................... 45 Wales...................................................................................... 45 Tasmania.................................................................................. 46 Australia .................................................................................. 46 Republic of Kazakhstan................................................................ 47 Jilin Province, China................................................................... 47 Cambrian-Ordovician Boundary...................................................................... 48 Summary.................................................................................................. 48 Acknowledgments....................................................................................... 48 Appendixes A-C. Taxonomic Notes................................................................ 50 Appendix A: Trilobita......................................................................... 50 Appendix B: Conodonta ...................................................................... 55 Appendix C: Brachiopoda.................................................................... 61 Appendix D: Echinodermata......................................................................... 61 ECHINODERM BIOSTRATIGRAPHY by James Sprinkle and Thomas E. Guensburg. 61 References Cited ........................................................................................ 64 CAPTIONS Plates Plate I. Observed ranges of trilobites from the Ibexian Series composite stratotype