Geologic structure generated by large-impact basin formation observed at the South Pole-Aitken basin on the Moon

The South Pole-Aitken (SPA) basin is the largest clearly recognized basin on the lunar surface. Determining the composition and structure of the SPA basin interior provides critical constraints on the deep crustal and/or mantle composition of the Moon and improves our understanding of large-basin-forming impact processes. Here we present a new mineralogical map of the SPA basin interior, based on high-spatial-resolution reflectance spectra using the SELENE (Kaguya) multiband imager, which is combined with topographic data in order to interpret the geologic context. The derived mineralogical map suggests extensive distribution of ejected low-Ca pyroxene-dominant mantle material with the presence of purest anorthosite crustal materials surrounding a possible melt pool of 0.26 to 0.33 of the basin diameter near the basin center, which is significantly smaller than that suggested by the crater-scaling law. The absence of clear evidence of lower crustal material is consistent with recent impact simulation results. Key Points <list list-type="bulleted" id="grl51622-list-0001"> <list-item id="grl51622-li-0001">Stratigraphy of the lunar mantle was revealed within the Moon's largest basin <list-item id="grl51622-li-0002">A smaller melt pool was suggested than that derived by the crater-scaling law <list-item id="grl51622-li-0003">Absence of clear evidence of lower crustal material is suggested by mineralogy