Underplating of oceanic lithosphere in the Archean: a possible mechanism for the formation of Archean komatiites

Abstract The thermal evolution of a subducting Archean oceanic lithosphere suggests that amphibole and phlogopite can transport water to depths of about 100 km. Water released from the oceanic crust hydrates the overlying depleted peridotitic lithosphere, lowering its melting temperature and causing a high degree of partial melting. Temperatures at the top of the Archean asthenosphere only about 150°C higher than the present value are sufficient to produce over 50% melting in the bottom of the overlying lithosphere under wet conditions, and generate peridotitic komatiites.