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Effect of Dissolution of the Florida Carbonate Platform on Isostatic Uplift and Relative Sea-Level Change Michael Alan Willett

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Effect of Dissolution of the Florida Carbonate Platform on Isostatic Uplift and Relative Sea-Level Change Michael Alan Willett Florida State University Libraries Electronic Theses, Treatises and Dissertations The Graduate School 2006 Effect of Dissolution of the Florida Carbonate Platform on Isostatic Uplift and Relative Sea-Level Change Michael Alan Willett Follow this and additional works at the FSU Digital Library. For more information, please contact [email protected] THE FLORIDA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES EFFECT OF DISSOLUTION OF THE FLORIDA CARBONATE PLATFORM ON ISOSTATIC UPLIFT AND RELATIVE SEA-LEVEL CHANGE By MICHAEL ALAN WILLETT A Thesis submitted to the Department of Geological Sciences in partial fulfillment of the requirements for the degree of Master of Science Degree Awarded: Summer Semester, 2006 The members of the Committee approve the Thesis of Michael Alan Willett defended on April 25, 2006. ________________________________ Joseph F. Donoghue Professor Directing Thesis ________________________________ Sergio Fagherazzi Committee Member ________________________________ Jennifer E. Georgen Committee Member ________________________________ Sherwood W. Wise Committee Member Approved: ______________________________________________ A. Leroy Odom, Chair, Department of Geological Sciences The Office of Graduate Studies has verified and approved the above named committee members. ii This thesis is dedicated to my wife, Claire. iii ACKNOWLEDGMENTS The author would like to acknowledge and thank the members of his committee, Joseph Donoghue, Jennifer Georgen, Sherwood W. Wise and Sergio Fagherazzi. He would like to also thank the members of the Florida Geological Survey Springs Team and the members of the Florida Geological Survey Oil and Gas Section. iv TABLE OF CONTENTS List of Tables .................................................................................... vi List of Figures .................................................................................... vii Abstract .......................................................................................... x 1. INTRODUCTION............................................................................... 1 Statement of Problem ................................................................... 1 Classification of Springs................................................................. 6 Karst Processes ............................................................................. 8 Isostatic Rebound .......................................................................... 12 Isostatic Response to Carbonate Removal by Springs ............ 13 Hypotheses Tested ....................................................................... 14 Potential Significance of the Work ................................................. 14 2. STUDY AREA ................................................................................... 15 Introduction .................................................................................... 15 Hydrology ...................................................................................... 20 Sea-level Change and Marine Terraces of Florida......................... 28 Geologic Structure ......................................................................... 32 Previous Work................................................................................ 35 3. METHODS …................................................................................. 43 Springs Data Collection.................................................................. 43 Field Parameters....................................................................... 43 Water Sampling ........................................................................ 44 Discharge Measurements ......................................................... 45 Dissolved CaCO3 ..................................................................... 47 Borehole Data Collection................................................................ 47 Data Reduction and Isostatic Calculations .................................... 50 v 4. RESULTS .................................................................................... 51 Introduction .................................................................................... 51 Thickness of Florida Carbonate Sequence .................................... 51 Depth to Basement Beneath the Carbonate Platform .................... 54 Carbonate Mass Loss Calculations ............................................... 55 Calculation A: Florida Platform Dissolution due to Spring Activity ................................................................... 56 Calculation B: Isostatic Uplift with a Single Density Change through the Carbonate Layer............................... 58 Calculation C: Isostatic Uplift Results with Density Changes for the Upper (a) and Lower (b) Portions of the Carbonate Layer 61 5. DISCUSSION.................................................................................... 64 Calculation A Analysis.................................................................... 64 Calculation B Analysis.................................................................... 64 Calculation C Analysis.................................................................... 66 Suggestions for Future Work.......................................................... 66 6. CONCLUSIONS................................................................................ 68 APPENDIX A. SPRINGS LOCATION AND DATA ................................. 72 APPENDIX B. SPRING ALKALINITY AND DISCHARGE GROUPED BY COUNTY AND ZONE ......................... 88 APPENDIX C. BOREHOLE DATA SHOWING DEPTHS TO TOP OF BASEMENT AND/OR BOTTOM OF LIMESTONE..... 92 REFERENCES .................................................................................... 96 BIOGRAPHICAL SKETCH .................................................................... 103 vi LIST OF TABLES Table 1: Spring classification based on discharge.................................. 7 Table 2: Springs used in this study......................................................... 23 Table 3: Summary data for Florida platform dissolution due to spring activity ................................................................ 59 Table 4: Calculation B - Isostatic uplift results using one density change through the carbonate layer ...................................................... 60 Table 5: Calculation C - Isostatic uplift results using two density changes through the carbonate layer ...................................................... 62 Table 6: Summary results of isostasy calculations ................................ 63 Table 7: Summary results of calculations A-C........................................ 63 vii LIST OF FIGURES Figure 1: Physiographic diagram of the eastern United States ............. 2 Figure 2: The Florida Platform ............................................................... 3 Figure 3: Physiographic regions of Florida ............................................ 4 Figure 4: LandSat GeoCover satellite image map of Florida ................. 9 Figure 5: Young karst landscape ........................................................... 10 Figure 6: Early stage of karst development ........................................... 10 Figure 7: Advanced karst areas ............................................................ 11 Figure 8: Detail of advanced stage of karst formation ........................... 11 Figure 9a: Geologic map of Florida ....................................................... 16 Figure 9b: Geologic map of the state of Florida – geologic units ........... 17 Figure 9c: Geologic map of the state of Florida – cross section A-A’ .... 18 Figure 9d: Geologic map of the state of Florida – cross section B-B’ .... 19 Figure 10: Karst areas related to first magnitude springs ...................... 21 Figure 11: First magnitude springs of Florida ........................................ 22 Figure 12: Map location of sampled springs .......................................... 25 Figure 13a: Location of the known offshore springs of Florida .............. 27 Figure 13b: Known offshore springs in the Florida Big Bend Region .... 28 Figure 14: Physiographic diagram of Florida.......................................... 30 Figure 15: Florida Trail Ridge shoreline ................................................ 31 Figure 16: Florida cross section along the Gulf of Mexico ..................... 32 Figure 17: Structural features that affect the Floridan aquifer ............... 34 viii Figure 18: East-west cross section through the Peninsular arch............ 35 Figure 19: Elevations of shoreline features of Trail Ridge, Penholoway, and Talbot levels (from Opdyke, 1984) ........... 37 Figure 20: Karst areas and major springs of north-central Florida (from Opdyke, 1984)............................................................. 38 Figure 21: Florida county map, with counties grouped by zones ........... 48 Figure 22: General location of boreholes with depths to basement & depth to base of carbonate sequence ............................... 49 Figure 23: Depth to bottom of carbonate sequence (meters)................. 52 Figure 24: East-West cross sections through zones 1-6 ....................... 53 Figure 25: Depth to basement (meters).................................................. 54 Figure 26: Density changes within the carbonate platform..................... 65 ix ABSTRACT Florida is typically considered to be tectonically stable and representative of global eustatic sea level with little evidence for any anomalous
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