Thermal Equations of State of Mantle and Core Materials

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Seismic waves generated by any substantial earthquake travel through the Earth?s inside, providing information on material properties of the Earth?s interior. In order to understand the seismic observations, we perform laboratory experiments to obtain physical properties of earth materials under high pressure (P) and temperature (T) conditions equivalent to the Earth?s interior. The experimental data are then used to directly compare with the observations and build models of the Earth?s interior. In this proposal, we will measure densities of silicate perovskite and ferropericlase (two dominant phases of the Earth?s lower mantle) and iron-nickel alloy (the main constituent of the Earth?s inner core) at high pressure and temperature, using synchrotron X-ray diffraction techniques. We will use newly developed laser heating and combination of external resistance and laser heating techniques in the diamond anvil cell to simulate conditions of the Earth?s interior. The emphasis of the proposed research is to obtain high-quality data while expanding the experimental P-T range. Using the new data, we can directly evaluate if a peridotitic mantle model is consistent with the observed mantle density profile and constrain the amount of light elements in the inner core. The results will have important implications for mantle convection, core dynamics, and composition models of the Earth?s interior. The project will develop high-pressure techniques that will be available for researchers in broad scientific communities and provide opportunity for young researchers at all levels to gain research experience in high-pressure research. Knowledge obtained from the proposed study will improve our general understanding of the planet Earth, especially, its interior.