Structure and Solubility of H2O and Silicate in Silicate Melts and Aqueous Fluids in the Earth's Deep Crust and Upper Mantle

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Energy and mass transfer processes in the Earth and terrestrial planets involve melting, crystallization, hydration, and dehydration at high temperature and pressure. These processes control materials recycling near convergent plate boundaries, govern lithosphere destruction and creation, often are responsible for volcanic and seismic hazards, and impact on distribution and availability of economic and energy resources in the Earth. Water-rich magmatic liquids (silicate melts) and silicate-rich aqueous fluids play central roles in these processes. In order to characterize these processes, experimental data will be obtained of silicate and H2O solubility in aqueous fluids and silicate melts, determination of their structure (in-situ while at high pressure and temperature), and modeling of solubility behavior in and physicochemical properties of silicate-rich aqueous fluids and hydrous silicate melts for compositions, temperatures, and pressures corresponding the Earth's deep crust and upper mantle. The solubility and structure data will be acquired as a function of (i) alkali metal/Si and alkaline earth/Si in simple metal oxide-silica-H2O systems, (ii) Al/(Al+Si) of aluminosilicate melts, and (iii) and the type and proportion of metal cations (K, Na, Ca, Fe, and Mg) in binary metal oxide silicate, and ternary and quaternary metal oxide aluminosilicate systems in the pressure and temperature regime of the deep crust and the upper mantle of the Earth. The proposed research program is an integral part of a broader research effort that is focused on the influence of H2O on rock-forming processes in the Earth and terrestrial planets. In addition to the application of the research to mass and energy transfer processes in the Earth and terrestrial planets, the projected experimental information also has application to the glass, ceramics, and solid and nuclear waste industry because H2O dissolved in silicate melt and glass govern properties such as durability, density, crystallization behavior, expansivity and compressibility, element diffusion, and related transport properties. Interaction between aqueous fluids and waste-containing glass depends on the same melt and glass properties.