Thermal history of the Moon: Implications for an early core dynamo and post-accertional magmatism

Abstract

Thermal evolution models for the Moon starting from a hot and differentiated initial state are presented. The main effect of the cooling is the growth of the thermal lithosphere to a thickness of about 700 km while the lower mantle and core cool relatively little. The heat flow from the core decreases substantially during the first bilion years to a value at which the core cools conductively. This allows a core dynamo to operate during the time before roughly 3 Ga b.p. as is suggested by paleomagnetic data. The dynamo is then shut off. During the first 2 billion years hot upwelling plumes from the lower mantle cause pressure release partial melting in the mid to upper mantle. This is in accord with evidence for post-accretional magmatism.