UCLA

The deep Earth volatile cycle has far-reaching impacts on the atmosphere, climate, hydrologic cycle, and biosphere of our planet. Volatile species in minerals are exchanged between Earth’s surface and interior. Earth’s interior contains the largest reservoir of volatiles on the planet. However, our understanding of this reservoir is limited. The deep Earth cannot be directly sampled, so we rely on models and laboratory experiments to simulate analogous conditions. Prior experiments have determined equations of state and the phase stabilities of many abundant mineral species at deep Earth conditions, however less work has been done on volatile-bearing minerals. Determining the behavior of volatile-bearing minerals using high pressure and temperature experiments can resolve which mineral phases store volatiles in the deep Earth. These experiments give additional insight into chemical processes in the deep Earth, and will help to shed light on the formation and chemical evolution of our planet. In this dissertation, I use Raman and infrared spectroscopy to investigate the high-pressure behavior of the lead sulfate, anglesite (PbSO4), in the diamond anvil cell. This work gives insights into the behavior of sulfates, commonly subducted sulfur-bearing minerals, at mantle pressures. I produce the first high-pressure infrared spectroscopy measurements on anglesite, extend the pressure range studied with Raman spectroscopy, and discover a previously unknown phase transition. I make measurements of the bulk modulus and its pressure derivative for anglesite using X-ray diffraction and the Birch-Murnaghan equation of state. This study confirms previous observations of a phase transition in anglesite and produces a thorough X-ray diffraction dataset to 50 GPa. Using X-ray diffraction and Raman spectroscopy, I measure the bulk modulus and Gr�neisen parameters of the nickel carbonate, gasp�ite (NiCO3). These experiments produce the first high-pressure Raman measurements on gasp�ite and greatly extend the pressure range studied with X-ray diffraction. This work reveals systematic trends among the transition metal carbonates: gasp�ite, having the smallest cation radius, is the most stable at high pressures. To aid our understanding of the relative phase stability of mantle minerals, I perform a pioneering set of experiments to determine the reaction products of CO2 and manganese metal. The results of these experiments inform us of the relative stabilities between carbonates and oxides and give insights into minerals that could store carbon in the deep Earth.