9526763 Hemley The goal of this project is to study the fundamental chemical properties of minerals at pressures and temperatures of the Earth's deep interior in order to obtain direct experimental constraints on the chemical composition, formation, and evolution of the mantle and core. Deep mantle phases will be examined under high pressure and temperature conditions using a variety of new x-ray diffraction and spectroscopic techniques. In particular, high-pressure transitions in SiO2, AlO3, (Mg, Fe)SiO3 perovskite, the unusual high-pressure behavior of Fe-bearing oxides, and the stability of garnet in the lower mantle will be examined. High pressure and temperature experiments on whole rock samples of appropriate mantle chemistries (e.g., peridotite, chondrite, basalt) will be performed at deep earth conditions and synchrotron x-ray diffraction, Raman spectroscopy, and infrared spectroscopy will be used for phase identification. Also, deep mantle mineral inclusions in diamond will be examined with the new micro-analytical techniques. phase relations of iron and iron alloys at core conditions will be performed using new in situ high pressure and temperature x-ray diffraction techniques. Core-mantle boundary reactions will be explored both in situ and in quenched samples.
