Crust–mantle architecture of the Moon’s South Pole–Aitken basin from Chang’e-6 samples

Chang’e-6 mission retrieved the first samples from the lunar farside South Pole–Aitken (SPA) basin. As the Moon’s largest and deepest impact basin, the SPA basin provides a unique window into the lunar interior, particularly its mantle. While spectral data indicate exposed deep-seated materials in this basin, their mantle origin remains contentious, and the basin’s deep structure is still poorly constrained. Here we combine Chang’e-6 impact-melt norites with thermodynamic modelling to reconstruct SPA impact melting and melt sheet differentiation. Our results reveal that the crystallization sequence observed in Chang’e-6 norites for the SPA melt sheet is most consistent with an orthopyroxene-dominated mantle source with 20–30% highland crustal contribution. We find that the massive SPA impact triggered lunar crust–mantle reorganization, forming a three-layer differentiated basin composed of 51% dunite, 5% orthopyroxenite, and 44% norite from the base upwards. The lower dunite and orthopyroxenite layers collectively constitute a nascent mantle superimposed on the primordial magma ocean mantle. Based on our findings and spectral data, we suggest that both mantle materials have been exposed across the SPA basin. Impact-melt norites collected by Chang’e-6 have an orthopyroxene-dominated mantle source and a 20-30% contribution of lunar highland crust, according to petrologic analyses and thermodynamic modelling which suggests a three-layer differentiated South-Pole Aitken basin