In Situ Characterization of Hydrous Silicate Melts

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9973050StixrudeThe proposed research addresses fundamental petrological questions regarding the interaction of magmas and aqueous fluids within the solid earth. The objectives are to characterize the solubility of water in silicate melts at pressures throughout the magma genetic regime and the speciation mechanisms as a function of pressure and temperature. These data are expected to place important new constraints on the interaction of silicate melts and aqueous fluids at magma genetic conditions and on those igneous processes that are affected by volatile solubility. Our approach consists of in situ visual observation and Raman spectroscopy of melt-fluid systems in the hydrothermal diamond anvil cell. Experiments will be performed in a new laboratory facility built by the P. I. With funds from the University of Michigan. Visual observation of saturated melts in the diamond cell including measurement of the geometries of coexisting phases will be investigated as a method for quantifying phase equilibria in situ. Investigation of the Raman spectrum of the liquid state will include careful and extensive comparison with suites of quenched glasses of known water content. Pilot theoretical calculations of the Raman and IR spectra of model glass structures based on density functional theory will further assist in the assignment of Raman bands and will help reveal the connection between vibrational spectra and structure and bonding.