Liquid segregation parameters from amphibolite dehydration melting experiments

We have experimentally obtained some of the parameters necessary for understanding the segregation of silicate liquid from amphibolite undergoing dehydration melting at 1 GPa and 750–1000°C. The solidus for this calcic amphibolite (68% Mg-Hb, 32% Pl (An_(90))) is <750°C. Amphibolites begin to melt at relatively high temperatures in the garnet-absent field, but the solidus appears to backbend at ∼1 GPa, coincident with the garnet-in boundary. Hornblende breakdown due to garnet formation releases H_2O and causes melting. Thus, in the garnet-present field (≥1 GPa), the amphibolite dehydration melting solidus may be coincident with the H_2O-saturated solidus. Liquid interconnectivity may be achieved at <900°C and