This proposal is focused on the study the elastic properties of two unquenchable mantle phases, high pressure phase of clinoenstatite, and calcium silicate perovskite. This project will utilize the DIA-type cubic anvil high pressure apparatus (SAM85) installed at beamline X17B1 of the NSLS at Brookhaven National Laboratory (BNL) using synchrotron X-ray radiography and X-ray diffraction techniques in conjunction with high pressure ultrasonic interferometry. The investigators will use an X-ray radiography technique to record the sample image at the same time as the travel time through the sample is measured, providing the length of the sample needed for the calculation of velocity. When the formation of the unquenchable phase is confirmed by X-ray diffraction, simultaneous measurement of pressure, temperature, volume, Vp, Vs, and the length of the sample (P-V-T-Vp-Vs-L) at subsequent P-T conditions will provide data for both equation of state analysis and the determination of the pressure and temperature derivatives of the elastic bulk and shear moduli. Such data for clinopyroxene and calcium silicate perovskite phases are crucial for interpreting seismic observations to determine the composition and the mineralogy of the mantle.
