The PIs propose to conduct a range of high-pressure experimental studies designed to constrain the bonding, structures, elasticity and chemical compositions of a suite of materials relevant to both the Earth's volatile budget and subduction processes. Specifically, they plan to focus on three distinct, but complementary topics: 1) the manner in which water is retained at high pressures in hydrous phases likely to predominate within subduction zones within the Earth's upper mantle; 2) continue studies of the densities of anhydrous high pressure phases of oceanic crust with a goal toward understanding how the density differences which drive the subduction process have evolved since the Archean, and 3) measure the equations of state of a range of iron alloys at high pressure (and following heating), with the primary focus being to constrain the pressure derivatives of their bulk modulus, a parameter which the PIs have shown to be virtually the only discriminant which provides a geophysical constraint on core chemistry.
