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).