KREEP-like lithologies in the South Pole–Aitken basin reworked by the Apollo basin impact at 4.16 Ga

Abstract

The early impact flux recorded by the Moon, especially the first billion years during the basin-forming epoch, is pivotal to understanding the evolution of inner Solar System bodies. However, our current understanding of this critical epoch is impeded by the lack of samples that have a clear provenance from specific ancient impact basins. Here we examine three impact-melt clasts in the Chang’e-6 lunar regolith collected from the Apollo basin within the gigantic South Pole–Aitken basin. We found that the impact-melt rocks, which have KREEP-like compositional signatures, probably originated from the differentiates of a South Pole–Aitken basin impact-melt sheet or pool, which were later reworked by the Apollo basin-forming event at ~4.16 Ga. This study suggests that the basin-forming epoch did not occur within the narrow timespan of ~3.8–4.0 Ga proposed for a cataclysmic late heavy bombardment.