UNIVERSITY OF CALIFORNIA SANTA CRUZ Understanding Stability and Cycling of Volatiles in the Mantle with High Pressure Experiments A dissertation submitted in partial satisfaction of the requirements for the degree DOCTOR OF PHILOSOPHY in EARTH SCIENCES by Cara Elizabeth Vennari June 2019 The Dissertation of Cara Elizabeth Vennari is approved: ___________________________________ Professor Quentin Williams, Chair ___________________________________ Professor Elise Knittle ___________________________________ Christine Beavers, Ph.D. ___________________________________ Quentin Williams Acting Vice Provost and Dean of Graduate Studies i ii Table of Contents Chapter 1: The Ammonium Ion in a Silicate under Compression: Infrared Spectroscopy and Powder X-ray diffraction of NH4AlSi3O8—Buddingtonite to 30 GPa .......................................................................................................................... 1 1.1 Abstract ....................................................................................................................... 1 1.2 Introduction ................................................................................................................ 2 1.3 Experimental Methods ............................................................................................. 5 1.4 Results .......................................................................................................................... 8 1.4.1 Powder diffraction ....................................................................................... 8 1.4.2 Infrared Spectroscopy: Aluminosilicate framework .................................. 14 1.4.3 Ammonium Vibrations .............................................................................. 19 1.4.4 Ammonium tetrahedral force constants ..................................................... 25 1.5 Implications .............................................................................................................. 28 1.6 Acknowledgements .................................................................................................. 30 Chapter 2: High-Pressure/Temperature Behavior of the Alkali/Calcium Carbonate Shortite (Na2Ca2(CO3)3): Implications for Carbon Sequestration in Earth’s Transition Zone ........................................................................................... 31 2.1 Abstract ..................................................................................................................... 31 2.2 Introduction .............................................................................................................. 32 2.3 Materials and Methods .......................................................................................... 35 iii 2.3.1 Raman Experiments ................................................................................... 35 2.3.2 X-Ray Diffraction ...................................................................................... 36 2.4 Results and Discussion ........................................................................................... 38 2.4.1 Room Pressure Single Crystal Refinement ................................................ 38 2.4.2 Equation of State ........................................................................................ 39 2.4.3 High Pressure Structural Changes ............................................................. 41 2.4.4 Shortite-II Structure ................................................................................... 44 2.4.5 Shortite: Raman Results ............................................................................. 47 2.4.6 Shortite: Room-Temperature, High-Pressure Raman ................................ 49 2.4.7 Nature and causes of the 300 K phase transitions(s) in shortite ................ 56 2.4.8 Nyerereite: Raman Spectra ........................................................................ 59 2.4.9 A high pressure/high temperature phase in shortite above 12 GPa ........... 61 2.5 Conclusions ............................................................................................................... 68 2.6 Acknowledgments, Samples, and Data ............................................................... 70 2.7 Supporting Information ......................................................................................... 71 2.7.1 Supporting Text: Refinement of shortite-II ............................................... 71 2.7.1 Supporting Figures and tables .................................................................... 72 Chapter 3: A Novel Carbon Bonding Environment in Deep Mantle High- Pressure Dolomite ..................................................................................................... 80 3.1 Abstract ..................................................................................................................... 80 3.2 Introduction .............................................................................................................. 80 iv 3.3 Experimental Methods ........................................................................................... 82 3.4 Results and Discussion ........................................................................................... 84 3.4.1 Dolomite-III: Lattice modes at high pressure ............................................ 85 3.4.2 Dolomite-III: Carbonate modes at high pressure ....................................... 86 3.5 3+1 Coordination of the carbonate ion ............................................................... 88 3.6 Implications .............................................................................................................. 91 3.8 Supplemental Information .................................................................................... 93 3.8.1 Discussion: dolomite-I and -II: .................................................................. 93 3.8.2 Discussion: a new low frequency mode and the dolomite to dolomite-II transition ............................................................................................................. 94 3.8.3 Dolomite-III further discussion: ................................................................ 95 3.8.4 Tables and Figures ..................................................................................... 95 Chapter 4: High Pressure Raman and Nd 3+ Luminescence Spectroscopy of Bastnäsite-(REE)CO 3F ........................................................................................... 101 4.1 Abstract ................................................................................................................... 101 4.2 Introduction ............................................................................................................ 102 4.3 Experimental Methods ......................................................................................... 104 4.4 Results ...................................................................................................................... 106 4.5 High Pressure Raman Results and Discussion ............................................... 110 4.5.1 Bastnäsite-I: Raman spectroscopy under pressure ................................... 110 v 4.5.2 Bastnäsite-II: Raman spectroscopy under pressure ................................. 113 4.5.3 Bastnäsite-III: Raman spectroscopy under pressure ................................ 116 4.6 High Pressure Nd 3+ Luminescence Results and Discussion ......................... 118 4 4 4.6.1 F3/2 I9/2 luminescence under pressure ................................................. 120 4 4 4.6.2 F3/2 I11/2 luminescence under pressure ................................................ 122 4 2 4 4.6.3 F5/2 + H9/2 I9/2 luminescence under pressure ....................................... 125 4.6.4 R1-R2 separation ..................................................................................... 127 4.6.5 Separation of energy levels with pressure ............................................... 129 4.6.6 Anomalous pressure shifts in Nd 3+ luminescence ................................... 131 4.7 Implications ............................................................................................................ 132 4.8 Acknowledgments ................................................................................................. 133 4.9 Supplementary Information ............................................................................... 134 Chapter 5. Slip Systems and Strength of Natural Pyrope Garnet ((Mg,Fe) 3Al 2(SiO 4)3) at High Pressures ................................................................ 139 5.1 Introduction ............................................................................................................ 139 5.2 Methodology ........................................................................................................... 142 5.3 Background ............................................................................................................. 143 5.4 Results ...................................................................................................................... 144 5.4.1 Differential Stress and Elasticity ............................................................. 144 5.4.2 Texture and Plasticity .............................................................................. 147 vi 5.4.3 Active slip systems .................................................................................. 148 5.5 Seismic signature