Chronology, Local Stratigraphy, and Foreign Ejecta Materials at the Chang'e-6 Landing Site: Constraints on the Provenance of Samples Returned From the Moon's Farside

Abstract

China's Chang'e-6 (CE-6) mission has returned the first-ever lunar farside samples from a mare plain on the southern Apollo basin floor. The crater statistics of the CE-6 mare unit and the provenance of the samples are crucial in interpreting the CE-6 sample analysis results and re-calibrating the crater chronology function. Here, we conduct a thorough survey of the formation sequence and main source craters of ejecta materials at the sampling area. Our results show that the sampling mare unit has a model age of ∼2.8 Ga and the CE-6 scooped and drilled samples mainly come from the proximal ejecta of nearby small craters and the local regolith. The total abundance of foreign (non-mare) materials, primarily from Chaffee S and Vavilov craters, is ∼9.3%. The Chaffee S ejecta may contain lunar upper mantle materials previously excavated by the South Pole-Aitken impact, which will shed light on the materials of the Moon's interior.