Experimental determination of phase relations in the system KMASH at pressures between 8 and 11 GPa for a better understanding of deeply subducted or delaminated crustal rocks

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Synthesis experiments should serve for the determination of phase relations in the chemical system K2O-MgO-Al2O3-SiO2-H2O, the simple system describing pelitic or acidic rocks, at pressures between 8 and 11 GPa and temperatures ranging from 800° up to 1250°C using a walker-type multi-anvil press. The experiments would be conducted in the presence of a small amount of water. Especially in this PT-region previous thermochemical calculations suggest severe changes in the phase relations leading to strong changes in the density of those rocks. Thus, crustal rocks are expected to reach depths of 300 km or more. All experiments may serve also for a recalculation of a thermodynamic data base including phases present at these conditions, which will allow a better prediction of the phase relations, the changes in rocks-density and dehydration behavior of crustal rocks at these ultra-high-pressure conditions.