Possible Non-Mare Lithologies in the Regolith at the Chang’E-5 Landing Site: Evidence From Remote Sensing Data

The Chang’E-5 (CE-5) mission returned a total of 1,731 g of lunar regolith from the northern Oceanus Procellarum (NOP). Despite that the CE-5 landing site is covered by Eratosthenian-aged mare basalts, non-mare lithologies might also have been collected owing to the lateral mixing introduced by nearby craters. Here we employed FeO and thorium abundance data obtained by the Lunar Prospector Gamma Ray Spectrometer to investigate the chemical composition of the NOP region. Four major compositional groups (feldspathic highland materials, Imbrium basin ejecta, Aristarchus ejecta, and mare basalts) and several subgroups have been identified. Their corresponding geographical locations were constrained using an interactive scatter-plot tool in ENVI® software. We also determined the first-order mixing trends occurring within the NOP region as well as the CE-5 landing site. Aristarchus crater may have contributed highly evolved materials to the CE-5 site. Rock fragments derived from Aristarchus ejecta are important for the interpretation of magmatic differentiation and non-mare volcanism on the Moon. We proposed that thorium enrichments of CE-5 landing site are due to the geochemical nature of local mare basalts rather than impact mixing. Highland ejecta, along with mare basalts, would expand Apollo and Luna sample collection diversity.