Generation and movement of silicate liquids (magmas) represent the most efficient means of heat and mass transport in Earth's mantle. Presently magmatic processes concentrate within 200 km of the surface, but liquids at high pressure played an important role in the dynamical and geochemical processes that took place in Earath's early evolution. It is key to establish the maximum depths from which silicate liquids may buoyantly rise to the surface. Because silicate liquids are highly compressible, their properties change rapidly with increasing pressure. There is good evidence that the density of liquids exceeds that of coexisting solids at modest pressures, the nature of the solid-liquid density crossover depending critically on composition. The evidence that exists shows substantial pressure-induced modification including changes in the coordination state of Al, Si, and other cations. A goal of this research is to investigate structural, thermal, and conductive properties of silicate melts of natural composition. (Spera, Siepmann, Saad, and Baroni).

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