Earth and Planetary Sciences ETDs

Publication Date

Fall 11-16-2022

Abstract

Wadsleyite and ringwoodite are major minerals in the Earth’s Mantle Transition Zone. Global and local seismic studies have detected strong lateral variations in seismic velocity and anisotropy in the Mantle Transition Zone, reflecting temperature and possible composition variations. Interpretation of these seismic observations requires knowledge of thermoelastic properties of wadsleyite and ringwoodite with different compositions (water and Fe contents) under high pressure-temperature conditions. In this dissertation, we have measured single-crystal elastic properties of wadsleyite and ringwoodite under high pressure-temperature conditions by Brillouin spectroscopy. Based on our measurements and previous experimental results, we further model the effects of water and Fe on elasticity of wadsleyite and ringwoodite, respectively. Finally, we combine experiments-obtained mineral physics elasticity data with global and local seismic observations to understand temperature and composition variations in the Mantle Transition Zone,

We have also conducted phase equilibrium experiments on 3 different Martian basalts (Yamato 980459, GUSEV basalt (Humphrey), NWA 8159) along a typical Martian areotherm to understand their composition and density changes as functions of depth. We then compare their densities with those of the ambient Martian mantle to understand the likelihood of Earth-like plate tectonics in Martian history.

Degree Name

Earth and Planetary Sciences

Level of Degree

Doctoral

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Brandon Schmandt

Second Committee Member

Jin Zhang

Third Committee Member

Charles Shearer

Fourth Committee Member

Carl Agee

Fifth Committee Member

Bin Chen

Language

English

Keywords

Earth, Mantle Transition Zone, Elasticity, Mars, Plate tectonics

Document Type

Dissertation

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