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And Type the TITLE of YOUR WORK in All Caps THE GEOCHEMICAL AND MINERALOGIC EXPRESSION OF SEQUENCE BOUNDARIES IN MISSISSIPPIAN CARBONATES OF THE APPALACHIAN BASIN, GEORGIA AND TENNESSEE by DANIEL EDWARD BULGER (Under the Direction of PAUL SCHROEDER) ABSTRACT The clay mineral corrensite is a regularly ordered interstratified chlorite-smectite that is the result of low temperature diagenesis of Mg-rich minerals. Chemically, the smectite to chlorite transition through corrensite involves a decrease in alkali and alkaline earth metals with decreasing Si/(Si+Al), increase in Al+3 for Si+4 substituition in tetrahedral sites and variability in Fe/(Fe+Al) of octahedral cations, which appears to be strongly influenced by whole-rock composition. High resolution transmission electron microscopy has revealed two possible mechanisms for the chloritization of smectite. A comparison of two contrasting depositional sequences was conducted to test the potential for corrensite as a proxy for sequence boundary identification in carbonate sequences deposited in arid-semiarid marine environments. X-ray diffraction analysis of clay minerals within the normal marine sequence of the Tuscumbia and Monteagle Formations reveal the presence of corrensite in association with sequence boundaries and late highstand systems tract (HST) deposits. Transgressive systems tract (TST) and early HST deposits representative of normal marine conditions contain smectite, illite and minor kaolinite. In contrast, corrensite dominates the TST and HST of the restricted marine sequence of the Saint Louis Formation. The Reelsville unit exposed at Jellico, Tennessee is a depositionally complex, well- developed unconformity bounded unit. Field and petrographic observations combined with clay mineral, stable oxygen and carbon isotopes and quantitative bulk rock mineral analysis was conducted on single hand samples. Excursion patterns in mean δ13C and δ18O values and dolomite concentration correlate with features indicative of subaerial exposure observed in the field. In addition, high variance in δ13C and δ18O values occurred at these positions with one exception. Six surfaces of subaerial exposure in the Reelsville unit were identified. Petrographic observations of faunal diversity combined with traditional facies and mineral analysis suggest that the Reelsville unit was deposited in an inner ramp setting. Petrographic analysis and field observation identified three parasequences in the Reelsville unit. Diverse faunal elements suggest the base of parasequence occurred under open marine salinity conditions; however, massive dolomitized mudstone at parasequence tops suggests deposition under restricted conditions. The occurrence of corrensite throughout the Reelsville suggests deposition under high salinity conditions. INDEX WORDS: Sequence boundary, Tuscumbia Formation, Monteagle Formation, Reelsville unit, Dolomite, Carbon and oxygen isotopes THE GEOCHEMICAL AND MINERALOGIC EXPRESSION OF SEQUENCE BOUNDARIES IN MISSISSIPPIAN CARBONATES OF THE APPALACHIAN BASIN, GEORGIA AND TENNESSEE by DANIEL EDWARD BULGER BS, Bradley University, 1987 MS, Northeastern Illinois University, Chicago, 2002 A Dissertation Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY ATHENS, GEORGIA 2014 © 2014 DANIEL EDWARD BULGER All Rights Reserved THE GEOCHEMICAL AND MINERALOGIC EXPRESSION OF SEQUENCE BOUNDARIES IN MISSISSIPPIAN CARBONATES OF THE APPALACHIAN BASIN, GEORGIA AND TENNESSEE by DANIEL EDWARD BULGER Major Professor: Paul Schroeder Committee: Steve Holland R. Bruce Railsback Gerald Kuecher Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia May 2014 iv ACKNOWLEDGEMENTS I would like to thank all the people that made this project possible. First, I would like to thank the members of my dissertation committee, Dr. Schroeder, Dr. Holland, Dr. Railsback and Dr. Kuecher for their participation in this study as members of my committee. I am indebted to Dr. Schroeder for serving as my advisor under difficult circumstances. In addition, if it weren’t for Dr. Schroeder’s clay mineralogy class project, I would have never been introduced to the clay mineral corrensite, which is the focus of this dissertation. I would like to thank Dr. Holland for his guidance throughout my graduate studies as well as introducing me to the concepts of sequence stratigraphy, which defines the framework of this study. I thank Dr. Railsback for introducing me to carbonate petrography and geochemistry. The knowledge I gained from his classes has been invaluable. I appreciate Dr. Railsback open door policy and allowing me to randomly show up in his office to talk over topics that clearly took away from his own work. I would like to thank Dr. Kuecher for his knowledge and support over these years, which extends back to my days at Northeastern Illinois University. It was Dr. Kuecher who first kindled my interest in clay minerals. I would like to thank all the organizations that provided student research grants for this project. This list of contributors includes the following: Gulf Coast Association of Geological Societies, Society for Sedimentary Geology, Geological Society of America, Society of Petrophysicists and Well Log Analysts, Clay Mineral Society, GDL Foundation and Miriam Watts-Wheeler Graduate Studies Student Fund. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS........................................................................................................... iv LIST OF TABLES....................................................................................................................... viii LIST OF FIGURES ....................................................................................................................... ix CHAPTER 1 INTRODUCTION.........................................................................................................1 Importance of Study.................................................................................................1 Regional Background and Sequence Stratigraphy...................................................2 Purpose of Study......................................................................................................5 Questions, Hypotheses and Methods.......................................................................6 Dissertation Format................................................................................................10 2 CORRENSITE.............................................................................................................12 Introduction............................................................................................................12 Corrensite Structure ...............................................................................................13 Precursor Minerals to Corrensite ...........................................................................18 Temperature of Formation and Stability................................................................20 Rock Fluid Effects.................................................................................................21 Inorganic Reactive Interactions .............................................................................24 Organic-Inorganic Reactive Interactions...............................................................28 Continuous and Discontinuous Transition.............................................................29 iv Chemical Characterization of the Smectite-Corrensite-Chlorite Transition..........34 HRTEM of the Smectite-Corrensite-Chlorite Transition ......................................44 Conclusions............................................................................................................48 3 SEQUENCE STRATIGRAPHIC DISTRIBUTION OF THE CLAY MINERAL CORRENSITE IN TWO CONTRASTING MISSISSIPPIAN DEPOSITIONAL ENVIRONMENTS......................................................................................................50 Introduction............................................................................................................50 Corrensite as a Geochemical Proxy .......................................................................52 Facies Description..................................................................................................55 Sequence Stratigraphy Key Definitions.................................................................55 Sequence Thickness and Accomodation................................................................64 Geologic Setting of North America during the Mississippian Period ...................64 Regional Stratigraphic Framework........................................................................68 Methods..................................................................................................................73 Results....................................................................................................................74 Disscussion ............................................................................................................82 Corrensite as a Proxy for Sequence Boundary Position ........................................84 Confirmation of Facies Interpretation....................................................................85 Conclusions............................................................................................................85 v 4 GEOCHEMICAL AND MINERALOGIC EXPRESSION OF SUBAERIAL EXPOSURE
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