Compressibility and Structure of Silicate Melts at High Pressure

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Manghnani EAR-0074285 The elastic properties of silicate melt and its structure provides insight into not only magmatic processes in the Earth but also into the possible origin of the planet's primordial stratification. This project will study the elastic and structural properties of simple (binary) alkali silicate and germanate melts under in-situ high pressure and temperature conditions in the externally heated diamond-anvil cell. The elastic properties will be investigated by Brillouin spectroscopy (light-scattering technique); a newly developed "modified" platelet scattering geometry will be employed. In conjunction with the Brillouin measurements, Raman studies will be conducted to correlate the measured elastic properties with the structure of the melt. The Brillouin and Raman studies will be conducted on alkali silicates and germinates with a range of cation sizes and different degrees of melt polymerization. As such, the investigators anticipate that their data will constrain the structural systematics of the melt elasticity and pressure, and this will in turn provide insight into the role of pressure-induced changes in melt structure in altering melt compressibility at depth in the Earth's interior.