Fig. 3: Compositional evidence for excavation of the late-stage lunar magma ocean.
From: Southward impact excavated magma ocean at the lunar South Pole–Aitken basin
a, Model of the pre-SPA basin crustal thickness distribution (global map, centred on the far side). b, Schematic of the distribution of the magma ocean trapped beneath areas of thinner crust during progressive crystallization through a transect along the dashed line in a. c–f, Models of the thickness of the residual magma ocean (c–e) at two stages of crystallization representing 96.5 PCS (c), 98.8 PCS (d), at which point the SPA basin-forming impact is proposed to have occurred, and 99.9 PCS (e), matching the final distribution of KREEP-rich material (f). The locations of the SPA basin and Imbrium are labelled in c–f. g,h, Remnant magma ocean thickness at the SPA basin at the proposed time of impact at 98.8 PCS, for which the residual magma ocean is present only beneath the southwestern half of the basin (g), matching the distribution of Th-rich material in the ejecta blanket (h) (outer outlined zone; inner ellipse based on the rim fitting; projection as in Fig. 1a). The location of the south pole and nearby Artemis landing sites is labeled in g (asterisk).
