Viscous relaxation of the Moho under large lunar basins

Viscously relaxed topography on the Moon is evidence of a period in lunar history of higher internal temperatures and greater surface activity. Previous work has demonstrated the viscous relaxation of the Tranquilitatis basin surface. Profiles of the lunar Moho under nine basins were constructed from an inversion of lunar gravity data. These profiles show a pattern of increasingly subdued relief with age, for which two explanations have been proposed. First, ancient basins may have initially had extreme Moho relief like that of younger basins like Orientale, but, due to higher internal temperatures in early lunar history, this relief viscously relaxed to that observed today. Second, ductile flow in the crust immediately after basin formation resulted in an initially shallow basin and subdued mantle uplift. The intent is to test the first hypothesis.