Lower Carboniferous Bangor Limestone in Alabama: a Multicycle Clear Water Epeiric Sea Sequence
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Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1974 Lower Carboniferous Bangor Limestone in Alabama: a Multicycle Clear Water Epeiric Sea Sequence. Robert Francis Dinnean Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Dinnean, Robert Francis, "Lower Carboniferous Bangor Limestone in Alabama: a Multicycle Clear Water Epeiric Sea Sequence." (1974). LSU Historical Dissertations and Theses. 2720. https://digitalcommons.lsu.edu/gradschool_disstheses/2720 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]. 75- 14,243 DINNEAN, Robert Francis, 1932- LOWER CARBONIFEROUS BANGOR LIMESTONE IN ALABAMA: A MULTICYCLE CLEAR WATER EPEIRIC SEA SEQUENCE. The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1974 Geology Xerox University Microfilmst Ann Arbor, Michigan 48106 LOWER CARBONIFEROUS BANGOR LIMESTONE IN ALABAMA A MULTICYCLE CLEAR-WATER EPEIRIC SEA SEQUENCE 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 by Robert Francis Dinnean B.S., University of Alabama, 1954 M.S., Louisiana State University, 1958 December, 1974 ACKNOWLEDGEMENTS The writer wishes to acknowledge the guidance and support provided by Dr. C. H. Moore, Jr., who served as Comnittee Chairman and supervised manuscript preparation. Acknowledgement is also due Doctors R. E. Ferrell, Jr., D. H. Kupfer, J. P. Morgan, C. 0. Durham, Jr., H. V. Andersen and L. P. Knauth for reviewing the manuscript and making many helpful suggestions. A special expression of gratitude is due my wife, Jo Ann, and my children, Jacquelyn, Timothy, Angela and Todd, for their support and understanding throughout the study. Acknowledgement is also due Texasgulf, Inc., Houston, Texas, for financial support, and R. L. Lyon for encouragement in the latter stages of the study. The author also wishes to thank C. W. Copeland of the Alabama Geological Survey for his assistance in the initial stage of the study. ii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ............................................. li LIST OF T A B L E S ............................................... iv LIST OF F I G U R E S ............................................. v ABSTRACT...................................................... vi INTRODUCTION .................................................. 1 Purpose ............................................. I Location ............................................. 1 Previous Work......................................... 3 Method of Investigation............................... 4 STRATIGRAPHY .................................................. 7 LITHOLOGY .................................................... 11 Pelmicrite Facies................ 12 Oosparite Facies ..................................... 16 Biomicrite Facies..................................... 18 Shale F a c i e s ............................................ 20 BANGOR DEPOSITIONAL ENVIRONMENTS ............................. 38 Carbonate Environmental Criteria ..................... 40 ENVIRONMENTAL SYNTHESIS.......................................... 46 SUMMARY AND CONCLUSIONS.......................................... 56 REFERENCES...................................................... 58 APPENDIX A Field Notes of Measured Sections and Details of Cycle I at Huntsville Section ......... 66 APPENDIX B Bangor Markov A n a l y s i s .............................104 VITA ............................................................112 iii LIST OF TABLES TABLE PAGE 1. Summary of Bangor facies thicknesses .................... 21 2. Thickness of Bangor facies at each measured section . 52 3. Thin-section descriptions - Cycle I at Huntsville .... 76 4. Chi-Square values ........................................ 108 iv LIST OF FIGURES Figure Page 1. Location m a p ............................................ 2 2. Stratigraphic column ................................... 8 3. Stratigraphic cross-section............................. 9 4. Photographs: Pelmicrite facies......................... 22 5. Photographs: Pelmicrite facies......................... 24 6. Photographs: Pelmicrite facies......................... 26 7. Photographs: Pelmicrite facies......................... 28 8. Photographs: Oosparite facies ......................... 31 9. Photographs: Biomicrite facies......................... 34 10. Photographs: Biomicrite facies and storm sequence . 36 11. Bangor Limestone environmental subdivisions............ 39 12. Environmental criteria................................. 41 13. Environments of deposition - Bangor facies ............ 45 14. Cycle I: Huntsville measured section................... 47 15. Order of succession - Bangor lithofacies .............. 50 16. Distribution of Bangor facies........................... 53 17. Diagrammatic Carboniferous paleogeographic map ........ 54 18. Bangor Limestone - Markov matrlciea....................... 105 v ABSTRACT A microfacies study of six outcrops and one core-hole indicates the Bangor consists of 260 to 306 feet of four facies defined herein as the oosparite, the pelmicrite, the shale and the biomicrite facies, in decreasing order of abundance. Environ mental criteria taken from literature were used to determine Bangor environments of deposition. Irwin's (1965) energy zones were used as a framework for classifying environments of deposition. The bio micrite facies was deposited both in the low-energy, marine X-zone and in the low-energy, restricted marine Z-zone. The oosparite facies was deposited in the high-energy, barrier Y-zone, and the pelmicrite facies was deposited in the relatively restricted Z-zone. Zone Z was herein subdivided into the Z-l lagoonal zone, the Z-2 intertidal zone, and the Z-3 supratidal zone. As a result of a lithofacies unit-by-unlt environmental deter mination, six and a half depositional cycles, within the Bangor, were identified at each of the five most complete measured sections. Each cycle consists of a basal transgressive phase and an overlying regressive phase. The marine fluctuations probably resulted from the interplay of varying rates of subsidence and sediment accumulation. Geographical variation in facies, in particular the greater percentage of the oosparite facies in the vicinity of the Nashville Dome and the Sequachie Anticline, indicate bathymetric highs, due to structural growth, existed at those areas during Bangor deposition more often than at intervening areas. vi The Bangor Limestone appears to be a clear-water, epeiric, carbonate sequence in north Alabama. The Bangor is, in part, equivalent to the overlying Pennington terrigenous, marine-sheIf facies, the Park- wood deltaic facies, the Lower Pottsville barrier-beach facies, and the Upper Pottsville deltaic facies as postulated by Ferm and Ehrlich (1967). Terrigenous influx came from the east, south and west. vii INTRODUCTION Purpose Most studies of the Upper Mlsslssipplan Bangor Limestone have been of a stratigraphic nature and phrases such as "coarsely crystalline limestone" or "thln-bedded dolomite" have been used to describe the formation. The Bangor has not been examined using a detailed mlcro- facles analysis similar to that espoused by Carrozi and Textoria (1967). W. E. Smith (1967) recommended the microfacies approach for the study of Mississippian limestones in Alabama, and Emerson (1967) used carbonate thin-sections to study the Chesterian Series in North Alabama. Emerson's study was more stratigraphic in nature, and inferred environments of deposition were stated in general terms. Moore (Professor of Geology, Louisiana State University, personal communication) suggested the Bangor be examined in more detail by using the techniques and the environmental criteria which have been developed from carbonate studies conducted mostly within the last two decades, and to determine the relationship, if any, to the overlying formations in Alabama. With this objective in mind, a bed-by-bed analysis of six relatively complete Bangor outcrops in North Alabama, and one core- hole in Georgia, was initiated. Emphasis was placed on assigning an environmental interpretation to each lithofacies unit in the vertical succession at each outcrop in order to determine both the nature of the Bangor sequence and factors which may have controlled sedimentation. Location Figure 1 shows the generalized outcrop pattern of Mississippian rocks in Alabama and location of the six measured sections and one 1 Cottanooga TENNESSEE ALABAMA CARBONIFEROUS - MISSISSIPPIAN OUTCROP PATTERN INSET SCALE Figure 1. Location map. 3 core-hole used for this study. Upper Mississippian outcrops in north Alabama form part of a discontinuous escarpment peripheral to the southern part of the Nashville Dome: they are part of the Eastern Interior Uplands and Basins physiographic subdivision as defined by Hammond (1963). Mississippian rocks are overlapped unconformably by Upper Cretaceous strata in northwest Alabama. Breached anticlines in northeast Alabama have linear northeast-southwest trends of Upper Mississippian