Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2020 A multi-proxy reconstruction of sea ice extent and primary productivity during Marine Isotope Stage 11 in the Bering Sea Natalie Sarah Thompson Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Recommended Citation Thompson, Natalie Sarah, "A multi-proxy reconstruction of sea ice extent and primary productivity during Marine Isotope Stage 11 in the Bering Sea" (2020). Graduate Theses and Dissertations. 18237. https://lib.dr.iastate.edu/etd/18237 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. A multi-proxy reconstruction of sea ice extent and primary productivity during Marine Isotope Stage 11 in the Bering Sea by Natalie Thompson A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Co-Majors: Geology; Environmental Science Program of Study Committee: Beth Caissie, Co-major Professor Alan Wanamaker, Co-major Professor William Gutowski Chris Harding Elizabeth Swanner The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this dissertation. The Graduate College will ensure this dissertation is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2020 Copyright © Natalie Thompson, 2020. All rights reserved. ii DEDICATION For the many teachers in my life. Thank you for guiding me, challenging me, and inspiring me. iii TABLE OF CONTENTS Page LIST OF FIGURES ........................................................................................................................... vii LIST OF TABLES ............................................................................................................................ xvi ACKNOWLEDGMENTS ................................................................................................................ xvii ABSTRACT .................................................................................................................................... xix CHAPTER 1. INTRODUCTION .......................................................................................................... 1 Motivation ................................................................................................................................. 1 The Role of Sea Ice in the Global Climate System ..................................................................... 3 Effects of Arctic Sea Ice Decline ................................................................................................ 4 Dissertation Structure ............................................................................................................... 6 CHAPTER 2. BACKGROUND AND LITERATURE REVIEW ................................................................ 14 Study Area ............................................................................................................................... 14 Physiography and Oceanography of the Bering Sea .......................................................... 14 Sea Ice Variability in the Bering Sea ................................................................................... 16 Primary Productivity in the Bering Sea .............................................................................. 19 Marine Isotope Stage 11 ......................................................................................................... 22 Marine Isotope Stage 11 in the Bering Sea ............................................................................. 25 Summary ................................................................................................................................. 27 References ............................................................................................................................... 28 CHAPTER 3. EVALUATING THE PALEOENVIRONMENTAL SIGNIFICANCE OF SEDIMENT GRAIN SIZE IN BERING SEA SEDIMENTS DURING MIS 11 ............................................................. 42 Abstract ................................................................................................................................... 42 Introduction ............................................................................................................................ 43 Study Area ............................................................................................................................... 45 Location and Oceanographic Setting ................................................................................. 45 Sedimentation in the Bering Sea ........................................................................................ 46 Core Sites ........................................................................................................................... 47 Methods .................................................................................................................................. 48 Geochronology ................................................................................................................... 48 Grain Size Measurements .................................................................................................. 48 Statistical Analyses ............................................................................................................. 49 Smear Slide Analyses ......................................................................................................... 51 Results ..................................................................................................................................... 52 Sediment Composition ....................................................................................................... 52 Grain Size Parameters ........................................................................................................ 53 iv Size Fractions ................................................................................................................ 53 Statistical Measures ...................................................................................................... 56 Discussion ................................................................................................................................ 59 Interpreting Grain Size Parameters .................................................................................... 59 Proxy for Sediment Transport and Deposition .................................................................. 59 Distinguishing Sediment Facies .......................................................................................... 62 Proxy for Ice Rafting ........................................................................................................... 66 Proxy for Paleocurrent Strength ........................................................................................ 70 Proxy for Paleoproductivity ............................................................................................... 72 Summary ................................................................................................................................. 77 References ............................................................................................................................... 78 CHAPTER 4. A MULTI-PROXY RECONSTRUCTION OF CHANGES IN SEA ICE AND PRIMARY PRODUCTIVITY AT IODP SITE U1339 (UMNAK PLATEAU, BERING SEA) DURING MARINE ISOTOPE STAGE 11 ....................................................................................................................... 89 Abstract ................................................................................................................................... 89 Introduction ............................................................................................................................ 90 Background ............................................................................................................................. 91 Marine Isotope Stage 11 .................................................................................................... 91 Study Area .......................................................................................................................... 94 Oceanographic Setting ................................................................................................. 94 Core Site Location ......................................................................................................... 96 Methods .................................................................................................................................. 96 Geochronology ................................................................................................................... 96 Sediment Sampling ............................................................................................................ 98 Grain Size and Sedimentological Analyses ......................................................................... 99 Published