Washington University in St. Louis Washington University Open Scholarship All Theses and Dissertations (ETDs) 12-2-2013 Iron Isotope Cosmochemistry Kun Wang Washington University in St. Louis Follow this and additional works at: https://openscholarship.wustl.edu/etd Part of the Earth Sciences Commons Recommended Citation Wang, Kun, "Iron Isotope Cosmochemistry" (2013). All Theses and Dissertations (ETDs). 1189. https://openscholarship.wustl.edu/etd/1189 This Dissertation is brought to you for free and open access by Washington University Open Scholarship. It has been accepted for inclusion in All Theses and Dissertations (ETDs) by an authorized administrator of Washington University Open Scholarship. For more information, please contact [email protected]. WASHINGTON UNIVERSITY IN ST. LOUIS Department of Earth and Planetary Sciences Dissertation Examination Committee: Frédéric Moynier, Chair Thomas J. Bernatowicz Robert E. Criss Bruce Fegley, Jr. Christine Floss Bradley L. Jolliff Iron Isotope Cosmochemistry by Kun Wang A dissertation presented to the Graduate School of Arts and Sciences of Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy December 2013 St. Louis, Missouri Copyright © 2013, Kun Wang All rights reserved. Table of Contents LIST OF FIGURES ....................................................................................................................... vi LIST OF TABLES ......................................................................................................................... ix ACKNOWLEDGEMENTS ............................................................................................................ x ABSTRACT OF THE DISSERTATION ..................................................................................... xii CHAPTER 1 : INTRODUCTION ............................................................................................... 1 1.1. Overview ........................................................................................................................... 2 1.2. Meteorite Classification .................................................................................................... 4 1.3. Nucleosynthesis of Iron Isotopes ...................................................................................... 9 1.4. Iron Isotope Mass-dependent Fractionation .................................................................... 12 1.5. Anion-exchange Chromatographic Separation for Iron .................................................. 18 1.6. MC-ICP-MS Analysis for Iron Isotopes ......................................................................... 24 Copyright and Permissions ....................................................................................................... 28 References ................................................................................................................................. 29 CHAPTER 2 : 58Fe AND 54Cr IN EARLY SOLAR SYSTEM MATERIALS .......................... 33 Abstract ..................................................................................................................................... 34 2.1. Introduction ..................................................................................................................... 35 2.2. Samples and Analytical Procedures ................................................................................ 38 2.2.1. Sample Treatments ................................................................................................... 38 2.2.2. Isotopic Measurements ............................................................................................ 41 2.3. Results ............................................................................................................................. 42 2.4. Discussion ....................................................................................................................... 45 References ................................................................................................................................. 48 CHAPTER 3 : HOMOGENEOUS DISTRIBUTION OF FE ISOTOPES IN THE EARLY SOLAR NEBULA ........................................................................................................................ 51 Abstract ..................................................................................................................................... 52 3.1. Introduction ..................................................................................................................... 53 3.2. Methods ........................................................................................................................... 56 ii 3.2.1. Sample Descriptions ................................................................................................ 56 3.2.2. Sample Preparation and Chemical Purification of Fe .............................................. 57 3.2.3. Fe Isotope Analyses ................................................................................................. 58 3.3. Results ............................................................................................................................. 61 3.4. Discussion ....................................................................................................................... 66 3.4.1. Fe Isotopic Homogeneity of the Early Solar Nebula ............................................... 66 3.4.2. Fe Isotope Fractionation between Chondritic Components ..................................... 67 3.5. Conclusions ..................................................................................................................... 74 References ................................................................................................................................. 75 CHAPTER 4 : THE FE ISOTOPE COMPOSITION OF ENSTATITE METEORITES: IMPLICATIONS FOR THEIR ORIGIN AND THE METAL/SULFIDE FE ISOTOPIC FRACTIONATION FACTOR ..................................................................................................... 80 Abstract ..................................................................................................................................... 81 4.1. Introduction ..................................................................................................................... 83 4.2. Samples and Method ....................................................................................................... 86 4.2.1. Sample Description .................................................................................................. 86 4.2.2. Analytical Methods .................................................................................................. 86 4.3. Results ............................................................................................................................. 88 4.3.1. Iron Isotope Compositions of the Whole-rock Meteorites ...................................... 88 4.3.2. Iron Isotope Compositions of the Separated Mineral Phases .................................. 91 4.4. Discussion ....................................................................................................................... 98 4.4.1. The Homogeneous Iron Isotope Composition of Enstatite Chondrites ................... 98 4.4.2. Implications on Bulk Earth Fe Isotope Composition ............................................. 101 4.4.3. Iron Isotope Fractionation in EL6 Chondrites ....................................................... 107 4.4.4. Iron Isotope Fractionation in Enstatite Chondrite Impact Melts ........................... 111 4.4.5. Iron Isotope Fractionation in Aubrites ................................................................... 112 4.4.6. Iron Isotope Fractionation between Metal and Sulfide in Enstatite Meteorites ..... 115 4.5. Conclusions ................................................................................................................... 119 References ............................................................................................................................... 121 CHAPTER 5 : FE ISOTOPE FRACTIONATION IN PLANETARY CRUSTS .................... 129 iii Abstract ................................................................................................................................... 130 5.1. Introduction ................................................................................................................... 131 5.2. Samples and Method ..................................................................................................... 134 5.2.1. Sample Descriptions .............................................................................................. 134 5.2.2. Analytical Methods ................................................................................................ 136 5.3. Results ........................................................................................................................... 146 5.3.1. Earth and Moon ...................................................................................................... 146 5.3.2. Martian meteorites ................................................................................................. 147 5.3.3. HED Meteorites ..................................................................................................... 147 5.3.4. Angrites .................................................................................................................