Fusion of pyrope at high pressures and rapid crystal growth from the pyrope melt

Abstract

Pyrope Mg₃Al₂Si₃O₁₂ is the magnesium end member of the pyralspite garnet series, which is an important constituent of the upper mantle. Melting experiments at high pressure are necessary to clarify the chemical heterogeneity in the deep mantle and the origin of various magmas. Some authors have suggested the possibility of the pressure-induced structural change of silicate melts and discussed its importance on the magma generation and the differentiation in the mantle^1,2. We report here melting experiments on pyrope at pressures up to 10 GPa as a first stage in extending the pressure range of model systems for the upper mantle and examining the possibility of the pressure-induced structural change of the melt at high pressure. The correlation between the melting curve and the change of the quenched phases from the melt is the first evidence of a structural change of the pyrope melt at high pressure.