Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1997 High-Resolution Facies Analysis of Deltaic Subenvironments of the Pennsylvanian Atoka Formation, Arkansas. Tanwi Gangopadhyay Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Gangopadhyay, Tanwi, "High-Resolution Facies Analysis of Deltaic Subenvironments of the Pennsylvanian Atoka Formation, Arkansas." (1997). LSU Historical Dissertations and Theses. 6462. https://digitalcommons.lsu.edu/gradschool_disstheses/6462 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 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HIGH RESOLUTION FACIES ANALYSIS OF DELTAIC SUBENVIRONMENTS OF THE PENNSYLVANIAN ATOKA FORMATION, ARKANSAS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Geology and Geophysics by Tanwi Gangopadhyay B.Sc., University of Calcutta, 1988 M.Sc., University of Calcutta, 1991 August, 1997 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 9808719 UMI Microform 9808719 Copyright 1997, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. f ACKNOWLEDGMENTS Sincere thanks goes to Dr. Arnold Bouma for the support and guidance he provided as the author’s major advisor. The author appreciates his input during field seasons and suggestions in organizing and documenting the present work. Deep appreciation also goes to Dr. Barun K. Sen Gupta for his guidance on analysis of microfossils, for suggestions in preparing this document, and for serving as the minor advisor to the committee. Dr. James Coleman is especially thanked for his time in accompanying the author to the field and introducing the basics of delta processes. Dr. Harry Roberts deserves special praise for providing information on deltaic geology through his course and on occasions when the author sought specific help. The author owes much thanks to Dr. John Wrenn for serving in the committee and providing laboratory facilities and suggestions for palynological analysis. Dr. Ray Ferrell was very cooperative in providing help and information regarding X-ray and smear slide analysis of clays. Dr. Randall Hall has provided valuable time to serve as the graduate school representative in the committee. Heartfelt gratitude goes to Charlie Stone, from the Arkansas Geological Commission, for introducing the author to the geology of the Arkoma Basin and for his immense help during field seasons. Rick Young, Wanda LeBlanc, and post doctoral fellows Gang Lu and Xiaogang Xie deserve special thanks for their help in the rock preparation, clay analysis, paleomagnetic, and microprobe laboratories, respectively. Martine Hardy, fellow graduate student and friend, is ii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. thanked for her sincere help in palynological analysis. Mary Lee Eggart and Clifford. P. Duplechin were extremely helpful in preparing some figures for this document. The author thanks the Department of Geology and Geophysics, Louisiana State University for supporting her as a teaching assistant for five years. The Arkansas Geological Commission and the Gulf Coast Association of Geological Societies provided funds that helped defray field expenses in 1993 and 1995, respectively. Pamela Bome, Richard Loftin, Thomas Buerkert, Ricky Boehme, Kush Tandon, and David Hinds, her fellow graduate students deserve special thanks for their support and help during trying times. Most importantly, much thanks goes to the author’s husband Debnath, for providing devoted support and motivation. 111 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ACKNOWLEDGMENTS................................................................................................ii LIST OF TABLES.......................................................................................................... vii LIST OF FIGURES________________________________ via ABSTRACT................................................................................................................... xiii CHAPTERS 1 GENERAL GEOLOGY OF THE ARKOMA BASIN AND INTRODUCTION TO THIS DISSERTATION.................................................. 1 1.1 Introduction ..................................................................................................... 1 1.2 Objectives and Approaches .............................................................................2 1.3 Previous Work on Deltas ................................................................................5 1.4 General Geology and Stratigraphy of the Arkoma Basin .............................. 7 2 DEPOSITIONAL FRAMEWORK OF THE PENNSYLVANIAN DELTAIC DEPOSITS IN ARKANSAS..............................................................................16 2.1 Introduction ....................................................................................................16 2.2 Deltaic Model of the Atoka Formation versus Alternative Models ............ 16 2.3 Fluvially-Dominated Deltaic Model for the Atoka Formation ................... 20 2.3.1 Basic morphologic and stratigraphic framework of various types of deltas from modem and ancient examples ......................22 2.3.2 Establishing a Fluvial-Dominated Origin for the Atoka Formation Deltas ............................................................................31 3 DESCRIPTION AND INTERPRETATION OF DELTAIC SUBENVIRONMENTS......................................................................................35 3.1 Introduction ...................................................................................................35 3.2 Methods ........................................................................................................ 35 3.3 Description of Outcrops and Characterization of Deltaic Deposits from Various Subenvironments ............................................................................ 36 3.3.1 Freshour Quarry ............................................................................ 36 3.3.2 Conway Roadcut ........................................................................... 47 3.3.3 Second Morrilton Roadcut (2MOR) ............................................ 54 3.3.4 Third Morrilton Roadcut (3MOR)................................................59 3.3.5 Fourth Morrilton Roadcut ............................................................. 65 3.3.6 Boston Mountain Roadcut ............................................................ 68 3.3.7 Searcy Quarry.................................................................................74 iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 ADDITIONAL APPROACHES IN THE CHARACTERIZATION OF DELTAIC DEPOSITS FROM VARIOUS SUBENVIRONMENTS...............79 4.1 Trace Fossils .................................................................................................79 4.1.1 Introduction ................................................................................... 79 4.1.2 Identification ................................................................................