A Thesis entitled Origins of Basal Sediment within Kettle Lakes in Southern Michigan and Northern Indiana by Mitchell R. Dziekan Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Geology ________________________________________ Timothy G. Fisher, Ph.D., Committee Chair ________________________________________ James M. Martin-Hayden, Ph.D., Committee Member ________________________________________ Henry M. Loope, Ph.D., Committee Member ________________________________________ B. Brandon Curry, Ph.D., Committee Member ________________________________________ Amanda Bryant-Friedrich, PhD, Dean College of Graduate Studies The University of Toledo October 2017 Copyright 2017, Mitchell Ryan Dziekan This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of Origins of Basal Sediment in Kettle Lakes in Southern Michigan and Northern Indiana by Mitchell R. Dziekan Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Geology The University of Toledo October 2017 Finding datable material to constrain ages of deglaciation is a key challenge faced by many Quaternary geologists. Often kettle lakes contain datable material in the form of wood and other terrestrial macrofossils within their basal sediment. These sediment units are frequently sandy layers interpreted as being deposited during downwasting as ice blocks melt within a growing kettle basin. This melting process takes time, resulting in a lag between deglaciation and the radiocarbon ages obtained from these units. Though extensively used in dating deglacial events associated with the retreat of the Laurentide Ice Sheet, little effort has been made to study this lag time and quantify its duration. This study’s main objective was to characterize the depositional environment of these “basal trash layers” and determine the extent of melt-out time lags in the region previously covered by the Saginaw Lobe of the Laurentide Ice Sheet. Six lakes along the Shipshewana and Sturgis moraines in northern Indiana and southern Michigan were cored and two separate lithofacies were consistently recovered: a lower pebbly sand with variable organic content, and an upper lacustrine mud. The lower pebbly sand does not exhibit the depositional characteristics frequently described for i basal trash layers. Instead, the stratigraphic, geochemical, and physical characteristics of this lower facies suggest deposition by glaciofluvial, fluvial, and/or littoral processes. Radiocarbon and optically stimulated luminescence chronology from these cores largely does not constrain the extent of melt-out time lags within these basins, aside from two lakes, where melt-out time lags of 5 ka and 7 ka are documented based on differences between basal OSL and radiocarbon ages. These OSL ages provided potential minimum ages for the Sturgis and Shipshewana moraines of 20.4 ± 1.4 ka and 23.6 ± 1.1 ka respectively, and may also provide evidence of an earlier retreat of the Saginaw Lobe than previously inferred. Furthermore, basal radiocarbon sampling from these lakes continuously provided ages of ~16.0 cal ka BP. This consistency may mark a regional climate signal, indicative of warming in this region of North America, potentially related to Heinrich Event 1 and the climate conditions of the mystery interval between 17.5─14.9 ka. ii Acknowledgements This work would not have been possible if it were not for the support of a number of individuals along the way. Dr. Timothy Fisher, my primary advisor, was instrumental in helping develop my skills as a writer, a presenter and as a scientist. My committee members Dr. James Martin-Hayden, Dr. Henry Loope, and Dr. B. Brandon Curry all provided me with insight and guidance throughout the research process. Thanks are also extended to Dr. Kenneth Lepper and Dr. Francine McCarthy for their collaboration in this project through OSL dating and pollen analysis, respectively. I thank my fellow students Jonathan Luczak, John Dilworth, Lucas Groat and Amy Towell for their help in the field and in the lab. Roy Schneider and Daniel Brainard at the UTMC for their assistance in CT scanning of sediment cores. Kristina Brady and the rest of the staff at LacCore for the amazing experience in Minneapolis. The USDA lab at UT for their help with CN analysis. Lastly I would also like to thank the multiple land owners who graciously took the time to chat with me and invited me onto their property (in some cases with absolutely no guidance and one herd of very friendly cows). Funding for this research was provided by the USGS Mapping Coalition, the Indiana Geologic Survey, a GSA graduate research grant, the LacCore and Continental Scientific Drilling Coordination Office (CSDCO) Visiting Graduate Student Travel Grant Program, and the University of Toledo’s Department of Environmental Sciences. iii Table of Contents Abstract ................................................................................................................................ i Acknowledgements ............................................................................................................ iii Table of Contents ............................................................................................................... iv List of Tables ................................................................................................................. viii List of Figures .................................................................................................................... ix 1 Introduction ..........................................................................................................1 1.1 Introduction ........................................................................................................1 1.2 The Laurentide Ice Sheet ...................................................................................2 1.3 The Saginaw Lobe .............................................................................................3 1.4 Radiocarbon Dating and the Saginaw Lobe .....................................................10 1.5 Melt-out Time Lags .........................................................................................12 1.6 The Sturgis Moraine ........................................................................................14 1.7 Deposition of Basal Trash Layers ....................................................................15 1.8 Depositional Systems in Post-glacial Landscapes ...........................................18 1.9 Objectives and Hypothesis ...............................................................................20 2 Methodology ........................................................................................................21 2.1 Introduction ......................................................................................................21 2.2 Lake Selection and Coring ...............................................................................22 2.3 X-Ray Computed Tomography........................................................................23 iv 2.4 The Limnological Research Center (LRC), Minneapolis, MN ........................23 2.5 Grain Size Analysis..........................................................................................24 2.6 Loss-on-ignition ...............................................................................................25 2.7 Carbon/Nitrogen Ratios ...................................................................................25 2.8 Radiocarbon Dating .........................................................................................26 2.9 Pollen Analysis ................................................................................................26 2.10 Optically Stimulated Luminescence Dating ..................................................27 3 Results ........................................................................................................29 3.1 Introduction ......................................................................................................29 3.2 Lake Stratigraphy .............................................................................................29 3.2.1 Thompson Lake ................................................................................32 3.2.2 Fish Lake ...........................................................................................36 3.2.3 Bullhead Lake ...................................................................................38 3.2.4 Hunter Lake ......................................................................................41 3.2.5 Stone Lake ........................................................................................41 3.2.6 Meteer Lake ......................................................................................45 3.3 Facies Descriptions ..........................................................................................46 3.4 Chronology ......................................................................................................50 3.4.1 Radiocarbon Dating ..........................................................................50 3.4.2 Optically Stimulated Luminescence Dating .....................................51 3.4.3 Pollen ................................................................................................52