Complex basalt evolution in the Chang'e-6 landing area

Abstract

China's Chang'e-6 (CE6) sample return mission targeted the southern part of the Apollo basin inside the South Pole-Aitken (SPA) basin on the lunar farside. The spectrally peculiar mare basalts in the CE6 landing area had undergone complex evolution: (1) At least three mare floodings with low- to intermediate-titanium (Ti) contents and a total volume of > 798 km³ occurred during the Imbrian and Eratosthenian periods; (2) The scales of basalt eruption decreased with time, and nine wrinkle ridges (WRs) formed during different stages of floodings; (3) Exotic non-mare materials at the CE6 sampling site might be chiefly from noritic Chaffee S crater (∼16.6 cm-thick) and anorthositic Vavilov crater (∼1.7 cm-thick). (4) Impact gardening would mix local low/intermediate-Ti basalts and exotic non-mare materials. After analyzing the local basalt-dominant samples collected by the CE6 probe with sophisticated instruments in the terrestrial laboratories, a series of lunar scientific problems would be addressed definitely, for example, the ages and compositions of the mare basalts, the evolution of the low- and intermediate-Ti basalts, and the effects of solar wind on the lunar regolith. In addition, if the returned samples contain exotic impact melts and ejecta of both the Apollo and SPA basins, analyses on these non-mare materials would help to constrain the timing of the Apollo and SPA impact events, the extent and composition of the proposed (differentiated) SPA melt pool, and even the compositions of the lunar lower crust/upper mantle. Addressing these fundamental problems would be a significant contribution to the lunar science community.