Searching for deep-seated thrust faults on the moon

The lunar maria are large expanses of basalt that infill antecedent impact basins and show evidence for post-emplacement deformation. Landforms within many of these basins suggest a period of compressive tectonics, although the mechanism for their formation remains an open question. 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 Serenititis, 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, the prevalence of such structures at mascon basins on other terrestrial worlds remains an open question.