UNIVERSITY OF CALIFORNIA Los Angeles Carbon in the Deep Earth: A Mineral Physics Perspective A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Geochemistry by Sarah Eileen Maloney Palaich 2016 © Copyright by Sarah Eileen Maloney Palaich 2016 ABSTRACT OF THE DISSERTATION Carbon in the Deep Earth: A Mineral Phyiscs Perspective by Sarah Eileen Maloney Palaich Doctor of Philosophy in Geochemistry University of California, Los Angeles, 2016 Professor Abby Kavner, Co-Chair Professor Craig E. Manning, Co-Chair Carbon is an essential component to life on Earth, and plays a role in the carbon cycle at the surface of the Earth. Beyond these surface interactions lies the deep carbon cycle. This cycle controls the flux of carbon subducting into the earth and provides clues as a possible carbon reservoir in the deep earth. The studies included in this dissertation examine various forms of carbonate under high pressure, high temperature conditions found in the deep earth. Carbon is subducted as carbonate in calcite, aragonite and dolomite, as elemental carbon or as CO2. To achieve these the high pressures experienced by subducting material, diamond anvil cells are ii used to expose milligrams of material to extremem conditions. The experiments detailed here were conducted using a wide range of diamond anvil cell techniques and the data was collected at numerous synchrotron and neutron diffraction facilities across the globe including the Advanced Light Source, Lawrence Berekely National Laboratory, the Spallation Neutron Source, Oak Ridge National Laboratory and the European Synchrotron Radiation Facility, Grenoble France. These experiments are the result of fruitful collaborations that brought scientist from around the globe together to study the thermoelastic properties of carbonate and CO2. I found important thermoelastic properties for the following minerals: hanksite, tychite, kutnohorite, aragonite and carbon dioxide. Each study yields isothermal bulk modulus data and the studies on aragonite and carbon dioxide also yield thermal expansion data. The equation of state, phase stability and thermoelastic data derived from these experiments will inform models of planetary interiors while giving insight into the evolution of carbon at the high pressures and temperatures of the Earth’s interior. iii The dissertation of Sarah Eileen Maloney Palaich is approved. Edwin Arthur Schauble Mark S. Goorsky Craig E. Manning, Committee Co-Chair Abby Kavner, Committee Co-Chair University of California, Los Angeles 2016 iv DEDICATION To my husband and often co-author Rob Heffern, my dear friends Barbara and Gunther Liebhart, my scientific inspirations Anjali and Stephen Arnold and my ever supportive parents, Greta Maloney and Bob Palaich. v TABLE OF CONTENTS Chapter 1: Introduction 1 1.1 Carbon in the earth and planets ............................................................................................... 2 1.2 Deep Carbon ........................................................................................................................... 3 1.3 Overview of the dissertation ................................................................................................... 5 1.3.1 Changing coordination of carbon at depth ...................................................................... 5 1.3.2 CO2, carbon coordination and phase stability ................................................................. 6 1.3.3 Carbonate and CO2 experiment summaries ..................................................................... 6 1.4 References ............................................................................................................................... 8 Chapter 2: Spectroscopic and X-ray diffraction study of hanksite and tychite at high pressure, and a model for the compressibility of sulfate minerals 10 2.1 Introduction ........................................................................................................................... 11 2.2 Experiment setup ................................................................................................................... 12 2.3 Results and Discussion .......................................................................................................... 15 2.3.1 Raman Spectroscopy ..................................................................................................... 15 2.3.2 X-Ray diffraction .......................................................................................................... 16 2.3.3 Effects of non-hydrostaticity ......................................................................................... 17 2.3.4 Sulfate systematics ........................................................................................................ 18 2.4 Summary ............................................................................................................................... 20 2.6 Tables .................................................................................................................................... 21 2.7 Figures ................................................................................................................................... 29 2.8 References ............................................................................................................................. 40 Chapter 3: High-pressure compressibility and phase stability of Mn-dolomite (kutnohorite) 44 3.1 Introduction ........................................................................................................................... 45 3.2 Experimental Methods .......................................................................................................... 45 3.3 Results and Discussion .......................................................................................................... 47 3.4 Implications for dolomite structures ..................................................................................... 50 3.5 Summary ............................................................................................................................... 50 3.6 Tables .................................................................................................................................... 52 3.7 Figures ................................................................................................................................... 53 3.8 References ............................................................................................................................. 57 Chapter 4: High-Pressure Compressibility and Thermal Expansion of Aragonite 59 4.1 Introduction ........................................................................................................................... 60 4.2 Experimental Methods .......................................................................................................... 62 4.3 Results ................................................................................................................................... 63 4.3.1 Phase stability and lattice compressibility ..................................................................... 63 4.3.2 Axial ratios and polyhedral evoltion ............................................................................. 65 4.3.3 Atomic evolution and polyhedral distortion .................................................................. 68 vi 4.3.4 Thermal expansion ........................................................................................................ 70 4.4 Implications ........................................................................................................................... 71 4.5 Summary ............................................................................................................................... 73 4.6 Tables .................................................................................................................................... 74 4.7 Figures ................................................................................................................................... 76 4.8 References ............................................................................................................................. 86 Chapter 5: Structure, stability, and thermoelastic properties of CO2-IV 89 5.1 Introduction ........................................................................................................................... 90 5.2 Experimental Methods .......................................................................................................... 91 5.3 Results and Discussion .......................................................................................................... 95 5.3.1 Phase stability ................................................................................................................ 95 5.3.2 Compression and bulk modulus .................................................................................... 96 5.3.3 High temperature data ................................................................................................... 99 5.4 Implications ......................................................................................................................... 100 5.5 Summary ............................................................................................................................. 102 5.6 Tables .................................................................................................................................