Thrust Faults Bound an Elevated Mantle Plug Beneath Several Lunar Basins

Abstract

AbstractThe lunar maria are large expanses of basalt that infill antecedent impact basins and show evidence for postemplacement deformation. Landforms within many of these basins suggest a period of compressive tectonics, although their formation mechanism has yet to be established. Previous work for Mare Crisium demonstrated that basin‐circumferential wrinkle ridges, which typically demarcate the inner edge of an annulus of elevated terrain, are the result of deep‐seated thrust faults that preferentially form along the boundary of an elevated superisostatic portion of mantle and a thick, subisostatic collar of crustal material. Here, we show that a similar fault architecture exists for several other mascon‐bearing basins, including Maria Serenitatis, Nectaris, Moscoviense, and, to a lesser degree, Humorum and Imbrium. These deeply penetrating basin‐circumferential thrust faults, as for Mare Crisium, form a (partial) outward‐dipping ring‐fault system that bounds the elevated mantle plug beneath each basin as a geometric consequence of mascon evolution. If this geometric arrangement is unique to the Moon, then some characteristic(s) of lunar mascon evolution enables the formation of such mascon‐bounding faults. Despite the ubiquitous nature of mascon‐bound thrust ring faults at several lunar basins, whether such structures exist at mascon basins on other terrestrial worlds remains an open question.