() . Paleogeo.graphy of the Late Cretaceous of the Western Interior otMfddle North America+­ j?'oal .Blstribution anct,Sedimen~cumulation By Laura N. Robinson Roberts and Mark A. Kirschbaum U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1561 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1995 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director For sale by U.S. Geological Survey, Information Services Box 25286, Federal Center Denver, CO 80225 Any use of trade, product, or finn 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 Roberts, Laura N. Robinson. Paleogeography of the Late Cretaceous of the western interior of middle North America : coal distribution and sediment accumulation I by Laura N. Robinson Roberts and Mark A. Kirschbaum. p. em.- (U.S. Geological Survey professional paper ; 1561) Includes bibliographical references. Supt. of Docs. no.: I 19.16: 1561 1. Paleogeography-Cretaceous. 2. Paleogeography-West (U.S.). 3. Coal­ Geology-West (U.S.). I. Kirschbaum, Mark A. II. Title. III. Series. QE50 1.4.P3R63 1995 553.2'1'0978-dc20 94-39032 CIP CONTENTS Abstract........................................................................................................................... 1" Introduction ................................................................................................................... Western Interior Seaway ... .. ... ... ... .. .. ... .. .. ..... .. .. ... .. .. ..... .. .. ... ..... .. ... ... .. .. l Methods.................................................................................................................. 3 Biostratigraphy....................................................................................................... 3 Basin Summaries.................................................................................................... 5 Isopach Maps.......................................................................................................... 12 Paleogeographic Maps............................................................................................ 12 Acknowledgments .. ......................... ..... ................ .................................. ................ 14 Discussion of Maps . .. ... ... ... .. ... ... .... ... .. .... ... .. ... .. .. ... .. .. ..... .. .. .. ... .. .. ... .. ... .. 15 Cenomanian ...................................................... ~..................................................... 15 Isopach Map . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 15 Paleogeography .. ... ... .. .... .. .. .. ... .. .. ... .. ... .. .. ... ... .. .. ... .. .. ... .... ... .. .. .. 15 Eastern Side of the Seaway .................................................... ................ 19 Western Side of the Seaway................................................................... 21 Turonian.................................................................................................................. 24 Isopach Map . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 24 Paleogeography .. .. .. .. .. ... .. .. .. ... .... .. .. ... ... .. ..... .. ... .. .. ..... .. .. ..... .. .. .. ..... .. 24 Coniacian-Santonian............................................................................................... 25 Isopach Map .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 25 Paleogeography ....... ..................... ......................... ......................................... 27 Campanian I ... ~........................................................................................................ 30 Isopach Map . .. .. .. .. .. .. .. .. .. .. .. .. ... .. .... .. .. ... .. .. .. .. .. .. ... .. .. .. ... .. .. .. ... .. 30 Paleogeography ................... ..................... ......... ................................. ............ 32 Campanian II.......................................................................................................... 33 Isopach Map .. .. .. ... .. .. .. .. .. .. .. .. .. .. .. ... .. ... .. ... .. .. ... .. .. .. .. .. .. ... ... 33 Paleogeography .. .. .. .. .. .. ... .. ... .. ... .. .. .. .. ... .. .. .. .. .. .. ..... ..... .. ... .. .. .. ... 36 Maastrichtian .. .. .. .. ... .. .. .. .. .. .. .. ... .. .. ... .. ... .. .. .. ... .. .. .. ... .. ... .. .. ..... .. ... .. .. 42 Isopach Map . .. .. .. .. .. .. ... .. .. .. ... .. .. .. .. .. ... .. ... .. .. ... .. .. ... .. ... .. 42 Paleogeography . .. ... .. .. .. .. ... .. .. ... .. .. .. .. .. ... .. .. ... .. ... .. .. .. .. ... .. .. ... .. 42 Summary .. :...................................................................................................................... 48 References Cited............................................................................................................. 49 Appendix . .. .. .. .. .. ... .. .. .. ... .. .. ... .. ... .. .. .. .. ... ..... .. ... .. .. .. ... .. ... .. .. ... .. .. 65 III IV CONTENTS PLATE [Plate is in pocket] 1. Biostratigraphic chart for the Late Cretaceous, showing ammonite zonations and other selected biozonations, Western Interior, middle North America. FIGURES 1. Map showing extent of Cretaceous Western Interior seaway and paleolatitudes....................................................... 2 2. Index map of study area.............................................................................................................................................. 4 3. Generalized chronostratigraphic cross section A-A'.................................................................................................. 6 4. Generalized chronostratigraphic cross sections B-B', C-C', and D-D' ..................................................................... 8 5. Index map of basin summary locations . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 13 6. Isopach map of Cenomanian rocks............................................................................................................................. 16 7. Paleogeographic reconstruction map of the Cenomanian . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 17 8. Reference map of Cenomanian paleogeography........................................................................................................ 20 9. Isopach map of Turonian rocks ................................................................................................. _....... .. .. .. .. .. .. 22 10. Paleogeographic reconstruction map of the Turonian ................................................................................................ 23 11. Reference map of Turonian paleogeography.............................................................................................................. 26 12. Isop~ch map of Coniacian-Santonian rocks ............................................................................................................... 28 13. Paleogeographic reconstruction map of the Coniacian-Santonian . .. .. .. .. .. .. .. .. .. .. .. .. 29 14. Reference map of Coniacian-Santonian paleogeography........................................................................................... 31 15. Isopach map of Campanian I rocks............................................................................................................................ 34 16. Paleogeographic reconstruction map of the Campanian I.......................................................................................... 35 17. Reference map of Campanian I paleogeography........................................................................................................ 37 18. Isopach map of Campanian II rocks ...................... :···································································································· 38 19. Paleogeographic reconstruction map of the Campanian 11......................................................................................... 39 20. Reference map of Campanian II paleogeography . ... ........ ... ..... .... ........... ...... .... ................. .... .... .... .... ...... ... .... .... .... .. 41 21. Isopach map of Maastrichtian rocks ........................................................................................................................... 44 22. Paleogeographic reconstruction map of the Maastrichtian......................................................................................... 45 23. Reference map of Maastrichtian paleogeography ...................................................................................................... 47 TABLES 1. References used in figures 3, 4, 8, 11, 14, 17, 20, 23, and on plate 1listed in numerical order................................ 9 2. General location and identification number for basin summaries listed in the appendix........................................... 11 Paleogeography of the Late Cretaceous of the Western Interior of Middle North America-Coal Distribution and Sediment Accumulation By Laura N. Robinson Roberts and Mark A. Kirschbaum ABSTRACT INTRODUCTION A synthesis of Late Cretaceous paleogeography of the This report is a synthesis of the paleogeography and Western Interior, from Mexico to southwestern Canada, sediment accumulation patterns within the Western Interior emphasizes the areal distribution of peat-forming environ­ foreland