Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Marine Isotope Stage (MIS) 5 on the Umnak Plateau, Bering Sea (IODP Site U1339): diatom taxonomy, grain size and isotopic composition of marine sediments as proxies for primary productivity and sea ice extent Derrick Ray Vaughn Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Geology Commons Recommended Citation Vaughn, Derrick Ray, "Marine Isotope Stage (MIS) 5 on the Umnak Plateau, Bering Sea (IODP Site U1339): diatom taxonomy, grain size and isotopic composition of marine sediments as proxies for primary productivity and sea ice extent" (2015). Graduate Theses and Dissertations. 14705. https://lib.dr.iastate.edu/etd/14705 This Thesis 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]. Marine Isotope Stage (MIS) 5 on the Umnak Plateau, Bering Sea (IODP Site U1339): Diatom taxonomy, grain size and isotopic composition of marine sediments as proxies for primary productivity and sea ice extent by Derrick Ray Vaughn A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Geology Program of Study Committee: Beth E. Caissie, Major Professor Alan D. Wanamaker, Jr. William J. Gutowski, Jr. Iowa State University Ames, Iowa 2015 Copyright © Derrick Ray Vaughn, 2015. All rights reserved. ii TABLE OF CONTENTS Page LIST OF FIGURES ................................................................................................... iv LIST OF TABLES ..................................................................................................... v NOMENCLATURE .................................................................................................. vi ACKNOWLEDGMENTS ......................................................................................... viii ABSTRACT………………………………. .............................................................. ix CHAPTER 1 INTRODUCTION .......................................................................... 1 1.1. Basis for Research......................................................................................... 1 1.2. Productivity, Nitrate Utilization, and Sea Ice Proxies .................................. 2 1.3. Thesis Outline ............................................................................................... 4 CHAPTER 2 LITERATURE REVIEW ............................................................... 6 2.1. The Bering Sea .............................................................................................. 6 2.1.1. Bering Sea Circulation ......................................................................... 7 2.2.2. Atmospheric Patterns in the Bering Sea .............................................. 9 2.2. Sea Ice Formation and Transport .................................................................. 11 2.3. Primary Productivity ..................................................................................... 13 2.3.1. Nitrogen Limitation ............................................................................. 16 2.3.2. Iron Limitation ..................................................................................... 17 2.4.Paleoclimate Proxies ...................................................................................... 18 2.4.1. Nitrogen Isotopes ................................................................................. 18 2.4.2. Carbon Isotopes ................................................................................... 20 2.4.3. Grain Size............................................................................................. 21 2.4.4. Diatom-based Proxies .......................................................................... 23 2.5. Marine Isotope Stage 5 ................................................................................. 24 2.5.1. Marine Isotope Stage 5 in Beringia ..................................................... 25 2.5.2. Marine Isotope Stage 5 in the Bering Sea ............................................ 27 2.6. Application .................................................................................................... 30 CHAPTER 3 MARINE ISOTOPE STAGE (MIS) 5 ON THE UMNAK PLATEAU, BERING SEA (IODP SITE U1339): DIATOMS, GRAIN SIZE AND SEDIMENTARY NITROGEN ISOTOPES AS PROXIES FOR PRIMARY PRODUCTIVITY AND SEA ICE EXTENT ........................................ 32 3.1. Abstract ......................................................................................................... 32 iii 3.2. Introduction ................................................................................................... 33 3.3. Study Area .................................................................................................... 35 3.3.1. Bering Sea ............................................................................................ 35 3.3.2. Umnak Plateau ..................................................................................... 36 3.4. Background ................................................................................................... 36 3.5. Methods......................................................................................................... 38 3.5.1. Sediment Cores .................................................................................... 38 3.5.2. Age Model ........................................................................................... 39 3.5.3. Diatom Analysis................................................................................... 39 3.5.4. Isotopic Analysis .................................................................................. 41 3.5.5. Grain Size Analysis.............................................................................. 42 3.6. Results… ....................................................................................................... 42 3.6.1. Diatom Analysis................................................................................... 42 3.6.2. Geochemical Analysis ......................................................................... 44 3.6.2.1. Nitrogen Isotopes ..................................................................... 44 3.6.2.2. Carbon Isotopes ....................................................................... 45 3.6.2.3. Total Organic Carbon .............................................................. 45 3.6.2.4. C/N Values ............................................................................... 46 3.6.3. Grain Size Analysis.............................................................................. 46 3.7. Discussion ..................................................................................................... 47 3.7.1. MIS 6 and Deglaciation at the Umnak Plateau .................................... 47 3.7.2. MIS 5 at the Umnak Plateau ................................................................ 49 3.7.2.1. MIS 5e and MIS 5d .................................................................. 49 3.7.2.2. MIS 5c and MIS 5b .................................................................. 51 3.7.2.3. MIS 5a ...................................................................................... 53 3.7.3. MIS 4 at the Umnak Plateau ................................................................ 54 3.8. Conclusions and Future Work ...................................................................... 55 APPENDIX A INVESTIGATING VARIATIONS IN DIATOM IDENTIFICATION.................................................................................................... 61 A.1. Abstract ........................................................................................................ 61 A.2. Introduction .................................................................................................. 61 A.3. Methods ........................................................................................................ 62 A.4. Results ......................................................................................................... 63 A.5. Discussion and Summary ............................................................................. 66 APPENDIX B DOES CRUSHING SEDIMENT AFFECT IDENTIFICATION ... 67 B.1. Abstract ........................................................................................................ 67 B.2. Introduction .................................................................................................. 67 B.3. Methods ........................................................................................................ 67 B.4. Results ......................................................................................................... 69 B.5. Discussion and Summary ............................................................................. 75 REFERENCES .......................................................................................................... 76 iv LIST OF FIGURES Page Figure 1 Bering Sea Map.......................................................................................... 31 Figure 2 δ15 N, Chaetoceros RS percentages, Diatom Abundances