This experimental program will determine the viscosities and densities of anhydrous and hydrous naturally-occurring and simple analog silicate melts at high pressures. The study will use proven methods of high-pressure research that utilize the multianvil device and real-time radiography by synchrotron radiation to monitor motion of marker spheres in the experimental sample chambers and determine the rates of oxygen self-diffusion. Falling sphere experiments are carried out using a variety of pure metal and composite marker spheres that differ in size and density in order to extract simultaneous measurements of melt viscosity and density from solutions to Stokes' equation.
The data acquired for a broad range of silicate melt compositions will be used to extend parameterizations of melt viscosity and density up to 12 GPa with direct applications to modeling convection and crystal-liquid segregation during solidification of the early Earth magma ocean, melt migration and two-phase flow in partially molten mantle source regions beneath modern spreading ridges, arcs and intraplate volcanoes, and the fate of volatile-rich melts in the deep mantle. Insights gained from the proposed experimental program will contribute to our scientific and technological understanding of industrial fabrication of fiber optic cable, reinforcing structural composites, woven-fiber insulation, among other products where pressure and melt rheology are the key variables during glass fiber extrusion and injection molding processes. The experimental results from this study will be shared with the community and the resulting models widely distributed. This project will train graduate and undergraduate students in research methods of experimental petrology utilizing synchrotron radiation and will foster closer ties with researchers at the national laboratories.
