Phase Relations and Equations of State of the Earth's Lower Mantle

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9903014DuffyInterpretation of recent seismic observations for the Earth's lower mantle is dependent upon a detailed understanding of the physical and chemical properties of materials under these extreme conditions. Understanding the Earth's lower mantle is also crucial to answering fundamental questions about the Earth's origin, evolution, and structure. This work will examine crystal structures, phase relations, and equations of state of lower mantle minerals and mineral assemblages through experimental measurements conducted directly under the pressure (25-135 GPa) and temperature (1000-4000 K) conditions that exist within the deep Earth. The experimental technique will combine in situ synchrotron x-ray diffraction with double-sided laser heating in the diamond anvil cell. The experimental program will include study of single phases relevant to the lower mantle, as well as complex mineral assemblages. For the latter, new techniques using area detectors will be developed. The results of these studies will be used to address fundamental questions regarding the nature of the lower mantle. Specifically, the mineralogy and bulk composition of the lower mantle will be explored through combination of experimental results with seismic data.