Melting of a dry peridotite at high pressures and basalt magma genesis

The solidus comprises three curves, corresponding to subsolidus mineral assemblages with cusps at about 11 and 26 kbar. A thin layer of basalt was sandwiched between compressed blocks of powdered peridotite minerals and then was equilibrated with its host at melting temperatures. The basalt melt, was completely homogenized with the partial melt in the peridotite matrix within 24 hours. The role of K 2 O in the melting was investigated. Hypothesis of shallow-depth origin for MORBS is supported.--Modified journal abstract.