The University of Southern Mississippi The Aquila Digital Community Master's Theses Summer 8-2016 Determining the Viability of Recent Storms as Modern Analogues for North-Central Gulf of Mexico Paleotempestology Through Sedimentary Analysis and Storm Surge Reconstruction Joshua Caleb Bregy University of Southern Mississippi Follow this and additional works at: https://aquila.usm.edu/masters_theses Part of the Atmospheric Sciences Commons, Climate Commons, Geology Commons, Geomorphology Commons, Oceanography Commons, Other Earth Sciences Commons, Other Oceanography and Atmospheric Sciences and Meteorology Commons, Sedimentology Commons, and the Stratigraphy Commons Recommended Citation Bregy, Joshua Caleb, "Determining the Viability of Recent Storms as Modern Analogues for North-Central Gulf of Mexico Paleotempestology Through Sedimentary Analysis and Storm Surge Reconstruction" (2016). Master's Theses. 198. https://aquila.usm.edu/masters_theses/198 This Masters Thesis is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Master's Theses by an authorized administrator of The Aquila Digital Community. For more information, please contact [email protected]. DETERMINING THE VIABILITY OF RECENT STORMS AS MODERN ANALOGUES FOR NORTH-CENTRAL GULF OF MEXICO PALEOTEMPESTOLOGY THROUGH SEDIMENTARY ANALYSIS AND STORM SURGE RECONSTRUCTION by Joshua Caleb Bregy A Thesis Submitted to the Graduate School and the Department of Marine Science at The University of Southern Mississippi in Partial Fulfillment of the Requirements for the Degree of Master of Science Approved: ________________________________________________ Dr. Davin J. Wallace, Committee Chair Assistant Professor, Marine Science ________________________________________________ Dr. Vernon L. Asper, Committee Member Professor, Marine Science ________________________________________________ Dr. Grant L. Harley, Committee Member Assistant Professor, Geography and Geology ________________________________________________ Dr. Karen S. Coats Dean of the Graduate School August 2016 COPYRIGHT BY Joshua Caleb Bregy 2016 Published by the Graduate School ABSTRACT DETERMINING THE VIABILITY OF RECENT STORMS AS MODERN ANALOGUES FOR NORTH-CENTRAL GULF OF MEXICO PALEOTEMPESTOLOGY THROUGH SEDIMENTARY ANALYSIS AND STORM SURGE RECONSTRUCTION by Joshua Caleb Bregy August 2016 The northern Gulf of Mexico has been devastated by recent intense storms. Camille (1969) and Katrina (2005) are two notable hurricanes that made landfall in virtually the same location in Mississippi. However, fully understanding the risks and processes associated with hurricane impacts is impeded by a short and fragmented instrumental record. Paleotempestology could potentially use modern analogues from intense storms in this region to extend the hurricane record back to pre-observational time. Existing empirically-based models can back-calculate surge heights over coastal systems as a function of transport distance, particle settling velocity, and gravitational acceleration. We collected cores in a pond (3) and adjacent beach (1) in Hancock County, Mississippi. Loss-on-ignition and grain-size analyses were conducted on cores in the context of a Bayesian statistical age model using 137Cs and 14C dating. Using Camille/Katrina to calibrate the archive, similar coarse-grained deposits were identified, and inverse sediment transport models calculated paleosurge intensities similar in magnitude to Camille over the 2500 year record. However, these are conservative estimates, as the shoreline was further seaward from its modern location approximately ii 700 yr BP. Our multi-millennial annual average landfall probability (0.48%) closely matches previously published studies from the Gulf of Mexico, indicating that intense hurricanes have not varied over these timescales. Over centennial timescales, active intervals occurred between 900 to 600 and 2200 to 1900 yr BP, and quiescence between 1900 to 900 yr BP. Comparison with previously published sites suggests southerly shifts in the Loop Current may be responsible for regional variability. iii ACKNOWLEDGMENTS First, I would like to express my gratitude to my committee chair, Dr. Davin Wallace, and my other committee members, Drs. Vernon Asper and Grant Harley. Their constant guidance and support throughout the duration of both this research and my time at the University of Southern Mississippi have been invaluable resources. They have helped me discovered my niche in the scientific community, and as I take the next step in my career, I am sincerely grateful for the pivotal role my committee has played. Second, I would like to thank the individuals that helped either in the field, the lab, or while writing this manuscript. Dr. Davin Wallace, Justin Blancher, Clayton Dike, and Victoria Young: I appreciate your help with fieldwork, either by actually collecting cores or loaning equipment to me that made fieldwork possible. Valerie Cruz: Thank you for answering my constant questions regarding the instruments in the lab. I also want to thank Kelsey Kuykendall and Dr. Eric Powell for their expertise in bivalve taxonomy, which was useful for a shell valve found in one of my cores. Finally, I want to thank Jesse Chambliss and Kaitlin Doucette for proofreading my manuscript. Finally, I would like to thank the Mississippi Department of Marine Resources for granting me a sampling permit and the National Academy of Sciences for providing funding. iv DEDICATION This thesis is dedicated to my loved ones, friends and family alike, all of whom have been an unwavering source of support and guidance. Without them, I would not be who I am today. v TABLE OF CONTENTS ABSTRACT ........................................................................................................................ ii ACKNOWLEDGMENTS ................................................................................................. iv DEDICATION .................................................................................................................... v LIST OF TABLES ............................................................................................................. ix LIST OF ILLUSTRATIONS .............................................................................................. x LIST OF ABBREVIATIONS ............................................................................................ xi CHAPTER I - INTRODUCTION ...................................................................................... 1 1.1 Background ............................................................................................................... 1 1.1.1 Introduction ........................................................................................................ 1 1.1.2 Storm Sediment Dynamics and Characteristics ................................................. 5 1.1.2.1 Landfalling hurricane processes. ................................................................ 5 1.1.2.2 Transport and sediment characteristics. ...................................................... 8 1.1.2.3 Tempestite formation and preservation. ..................................................... 9 1.1.3 Numerical Models ............................................................................................ 11 1.1.3.1 Inverse modeling. ...................................................................................... 11 1.1.3.2 SLOSH model. .......................................................................................... 14 1.1.4 Study Goals ...................................................................................................... 16 CHAPTER II - METHODOLOGY .................................................................................. 17 2.1 Study Sites .............................................................................................................. 17 vi 2.2 Fieldwork ................................................................................................................ 19 2.3 Sample Analysis...................................................................................................... 20 2.3.1 Loss-on-ignition (LOI)..................................................................................... 20 2.3.2 Percent coarse .................................................................................................. 21 2.3.3 Grain-size Analysis .......................................................................................... 21 2.3.4 Radiometric Dating .......................................................................................... 22 2.3.4.1 Cesium-137 dating. ................................................................................... 22 2.3.4.2 Radiocarbon dating. .................................................................................. 22 2.3.5 Bacon age-depth model.................................................................................... 23 CHAPTER III - RESULTS ............................................................................................... 25 3.1 Core Descriptions.................................................................................................... 25 3.1.1 Silver Slipper West .......................................................................................... 25 3.1.2 Silver Slipper Beach ........................................................................................ 26 3.2 Lithological Analysis .............................................................................................