The Effect of Redox Conditions on Melting Temperature of Mantle Rocks: Implications for Formation of Early Earth Magma Ocean

Abstract

Extensive melting of early Earth’s mantle is considered to occur due to accretionary impacts, resulting in a deep magma ocean. Oxygen fugacity of the mantle is thought to have increased over accretion and core formation. However, the effect of oxygen fugacity on the solidus of mantle materials has not been constrained. Here we discuss the effect of oxygen fugacity based on results on the solidus temperature of mantle pyrolite at a high oxygen fugacity. We find that the solidus of pyrolite under oxidizing conditions is significantly lower than those under more reducing conditions. The strong influence requires reassessment of models of early Earth thermal evolution and core formation.