Unusual corona texture around olivine in Chang’e-5 regolith formed by impact process on the Moon

Abstract Impact-cratering is a ubiquitous geologic process on the Moon. The impact-induced mineralogical micro-structures in lunar sample can provide information about their formation conditions on the Moon. However, the interpretation of these micro-structures remains challenging due to the complex and variable nature of impact processes. In this study, a piece of impact ejecta was recognized in Chang’e-5 regolith and characterized using petrographic and geochemical techniques. Using the mineralogical texture (i.e., corona texture around olivine) in such impact ejecta, the formation conditions were constrained to T > 1300 °C, stress-free, and a cooling rate 12 °C/min. These conditions are different from those previously reported for impact-induced rocks on the Moon, which are typically buried under impact melt sheets and ejecta blankets. These results indicate that lunar impact ejecta exposed at the surface record high-temperature, rapid quenching conditions distinct from buried impact rocks. Graphical Abstract