Laboratory data on melting, crystallization, and mass transport of magma and aqueous fluids in the Earth's crust and upper mantle will be employed to characterize materials recycling in the Earth. The project integrates acquisition of solubility data and solubility behavior of H2O in magmatic liquids and of silicate in aqueous solutions in the pressure and temperature range of the Earth's crust and upper mantle. Solubility data and structural information will be obtained primarily in peralkaline aluminosilicate systems with a range of compositions so as to be able to model magmatic liquids including basalt, andesite, and rhyolite compositions. To this end, we will examine the effect of melt polymerization, the influence of Al2O3, and relative effects of metal cations (alkalis and alkaline earths) on both on the H2O solubility behavior in hydrous melts and the silicate solubility in aqueous solutions. Solubility measurements will be carried out by combinations of instrumental techniques on quenched materials as well as phase equilibrium measurements when the melts and fluids to not quench to a homogeneous phase. Structural information on both melts and fluids will be obtained by using confocal microRaman spectroscopy in conjunction with the externally heated diamond anvil cell. Nuclear magnetic resonance will be employed when needed to assign Raman bands and to calibrate Raman band intensities to obtain quantitative information on the abundance of structural units in hydrous melt and silicate-rich fluids. The results will be used to establish the links between melt and fluid structure on the one hand and properties such as composition-activity relations among structural units in melts and fluids, liquidus phase relations, density and viscosity of hydrous magmatic liquids and silicate-saturated aqueous solutions.
