Phase relations of phase A, clinohumtie, and chondrodite in the system MgO-SiO2-H2O

Abstract

An internally-consistent thermodynamic data set for phase A, clinohumite, and chondrodite has been derived by mathematical programming analysis of phase equilibrium and thermophysical data. The derived thermodynamic data are in excellent agreement with measured volumes and most experimental phase equilibrium data. Calculated phase diagram suggests that, at pressures higher than ca. 8 GPa, clinohumite and/or chondrodite are stable in the average mantle composition. This suggests that, at the conditions, these phases may play an important role for hydration of mantle wedge peridotite.