Presidential Young Investigator Award: Ionic Transport in Molten and Glassy Silicates

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This grant initiates funding for the principal investigator's Presidential Young Investigator award. To date, the PI has received a Petroleum Research Fund Award of $18,000 that qualifies for NSF matching funds (American Chemical Society, Petroleum Research Fund, Grant 1987). Accordingly, $43,000 in funds are provided in this action ($25,000 for the base award plus $18,000 in matching funds). The PI`s work involves studies of ionic and transport properties of materials of geological and geophysical interest. Several avenues of investigation are being pursued. Direct determination of the frequency-dependent AC impedance of two-phase systems (crystal-melt systems) at high temperatures and pressures will lead to models incorporating both textural parameters and frequency into the theoretical formulations of bulk impedance of multiphase systems. Geophysically, these results will be significant in terms of characterization of shallow geothermal anomalies and in terms of interpretation of upper mantle electrical conductivity anomalies and the thermal and physical state of the upper mantle. Additional experiments are being developed to determine electrical conductivities of volatile-bearing melts at elevated P and T. Determination of the effects of volatiles, especially H.2O and CO.2, on ionic transport is of significance not only in the geological problems of magma formation, ascent, and eruption, but also in materials science and ceramic engineering in terms of corrosion and weathering resistance. A novel type of experiment combines tracer diffusion studies with electrochemically-induced migration studies of volatiles in melts. These studies will enable determination of the complete array of ionic transport, chemical equilibrium, and isotopic exchange parameters in melt-volatile systems.