[P-PS06] Lunar Science and Exploration

[PPS06-11] The thermal history of the Moon: implications for its early evolution

★Invited Papers

*Masaki Ogawa¹ (1.Division of General Systems Studies, Graduate School of Arts and Sciences, University of Tokyo)

Keywords:Moon, mantle convection, magmatism, early evolution

The radial expansion of the Moon that occurred for the first several hundred million years of its history is probably a consequence of partial melting of the mantle caused by internal heating and mantle convection, as suggested from our numerical models. The calculated history of mantle melting is, indeed, consistent with the observed history of mare volcanism that became more active with time as the planet expanded and peaked at around 4-3.5 Gyr ago. The expansion, therefore, suggests that the lunar mantle was not so extensively molten at the beginning of its history. It is not clear if this inference is consistent with current understanding of the earliest history of the Moon dominated by a giant impact, solidification of the magma ocean, and subsequent mantle overturn. In my presentation, I first review our numerical models of the lunar thermal history where the mantle evolves owing to heat and mass transport by mantle convection and magma-migration and then discuss what observational and theoretical constraints are currently imposed on the era of the magma ocean and the subsequent mantle overturn.