The Provenance and Geochemical Alteration of Bermudan Eolianites By Jordan Reginald Peter Rouse A thesis submitted to Department of Geological Sciences and Geological Engineering In conformity with the requirements for the Degree of Master of Science Queen’s University Kingston, Ontario, Canada September, 2016 © Jordan Reginald Peter Rouse, 2016 i Abstract Large calcareous eolianites cover the remote island of Bermuda, accounting for more than 90% of the limestone bedrock. This study examines the sedimentology and geochemistry of these eolianites to better understand Pleistocene oceanography and the meteoric alteration of subtropical carbonate sediments. Cluster analyses reveal that the eolian carbonate sediments fall into two natural groups that represent lagoonal and reefal end members of marine sediment production. Coral fragments are uncharacteristically absent, possibly destroyed prior to their incorporation into eolian deposits by endolithic microboring organisms or broken up during transport. Sediment assemblages lead to the following interpretations of the Bermudan offshore environment: (1) the Ledge Flats reef system along the southwestern coast has been active since MIS 11, contributing coralline algal-rich sediment to the northern beaches of Sandy’s Parish and acting as an energy barrier in the south, allowing for low energy sedimentation in the quiet back- reef region; (2) on the northeastern coast, the low energy back-reef region landward of the Ledge Flats has thrived since MIS 11; (3) during MIS 5e, slightly warmer water temperatures led to the hindrance of coralline algal growth along the southern coast and in the North Lagoon. These are the first interpretations of Pleistocene marine assemblages on Bermuda. Meteoric fluids progressively transformed the pristine carbonate sediments into hardened limestones in a predictable solubility-dependent manner. The progressive alteration is coincident with: (1) divergence of δ18O and δ13C values from those similar to unaltered sediment towards those of calcrete, due to interaction with CO2-charged meteoric fluids; (2) depletion of elements with low partitioning coefficients and low meteoric concentrations, such as barium, boron, magnesium, potassium, sodium, strontium, and uranium; (3) enrichment of iron from Terra Rossa-hosted iron oxides; (4) enrichment of aluminum via detrital minerals sourced from protosol horizons; and (5) manganese concentrations that remain uncharacteristically low, owing to the lack of a consistent manganese source. Elemental correlations are useful for characterizing ii meteoric diagenesis, assuming the primary mineralogy is recognized, all components have been fully altered, and inter-particle cements are ubiquitous. iii Statement of Co-Authorship The thesis is my own work, as overseen by my supervisors. Dr. Noel James and Dr. Kurt Kyser who provided academic and editorial support over the course of this project and are co- authors of the thesis. The manuscript is structured as follows: a brief introduction of the natural system that is Bermuda and the focuses of this study (Chapter 1), two individual papers, to be submitted to scientific journals following the submission of this thesis (Chapter 2 & 3), and overall conclusions and implications of this study (Chapter 4). iv Acknowledgements There are a great number of people that made my six years at Queen’s University a truly memorable time in my life. First, I’d like to emphasize that my Mom and Dad, Michele and Jim Rouse, have provided me with endless support, motivation, and encouragement throughout my entire academic career. Without them behind me to catch me when I fell, I would never have gotten this far. Dr. Noel James and Dr. Kurt Kyser have been mentors to me since I was a wide-eyed 2nd year student blindly roaming the hallways of Miller Hall. Through their guidance in and out of the classroom, they opened my eyes to a world of possibilities that I never knew existed. Noel, you were always there with an open door, a friendly smile, and the occasional ginger cookie. I am forever grateful for our discussions about life after Queen’s; you always assured me that I could persevere in whatever I put my mind to and gave me self-confidence when I needed it most. Kurt, you and the QFIR staff took me in at a critical point in my life, giving me invaluable experience in both the lab and the middle of nowhere (Athabasca). You were always there to address my extensive list of questions on geochemistry and correct my questionable grammar and I will always remember our talks in Bermuda. Thank you both for everything, I won’t forget your many lessons as I move onto the next chapter in my life. This project would not have been possible without the financial support of the Ontario Graduate Scholarship (OGS) Program, the Canadian Associates of the Bermudan Institute of Ocean Sciences (CABIOS), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Petrographic Preparation Facility of Acadia University, and Queen’s University. With the help of these sponsors, two fieldwork expeditions became reality. These expeditions were based out of the Bermuda Institute of Ocean Sciences (BIOS), whose helpful and friendly staff arranged my accommodations and made me feel right at home. Many people, including Bill Martindale and Peir Pufahl, offered invaluable academic insights and suggestions while in the field and I thank them for that. v Christabel, Chips, Agatha, Evelyne, April, and Steve, whether it was thesis edits, infinite clay separates, or just another day with a broken silicate line, you and the rest of the QFIR staff were always there with me. Thank you for the years of experience, patience, and friendship. Kent, Alex, Jeryes, Neil, Ryan, Marina, and Justin, thanks for travelling along this path with me and the road that lies ahead. Finally thank you Chris for your quick edits when I was in a pinch. Katie Lafreniere, you’ve been there with me through the best and worst times. You make me a better person every day and I hope you know that none of this would have been possible without you. Also, your endless patience with all of my rock-talk is forever appreciated, but no, it won’t be over any time soon. vi Table of Contents Abstract ........................................................................................................................................ ii Statement of Co-Authorship ................................................................................................ iv Acknowledgements .................................................................................................................. v List of Tables ............................................................................................................................... x List of Figures .............................................................................................................................xi List of Abbreviations ............................................................................................................. xii CHAPTER 1 ................................................................................................................................... 1 Introduction ................................................................................................................................ 1 1.1 The Bermuda Platform ....................................................................................................... 1 1.2 Calcareous Eolianites .......................................................................................................... 1 1.3 Research Objectives ............................................................................................................. 3 CHAPTER 2 ................................................................................................................................... 4 The Provenance and Temporal Trends of Bermudan Eolianite Sediments ......... 4 2.1 Abstract................................................................................................................................. 4 2.2 Introduction .......................................................................................................................... 4 2.3 Setting ................................................................................................................................... 6 Location & Geology ............................................................................................................ 6 The Modern System .......................................................................................................... 13 2.4 Methods............................................................................................................................... 16 2.5 Results ................................................................................................................................. 17 Cluster Analysis ................................................................................................................ 20 vii 2.6 Interpretation ..................................................................................................................... 24 Crustose Coralline Algae .................................................................................................. 24 Homotrema rubrum ........................................................................................................... 25 Halimeda ..........................................................................................................................