Impact-induced fayalite glass from Chang'e-5 regolith revealed by electron pair distribution function and ReaxFF molecular dynamics

Impacts play a vital role in lunar formation and evolution. The mineral phase transformations induced by impacts are crucial for understanding the impact processes, such as the amorphization of olivine. In this study, we investigated the formation mechanism of fayalite glass in Chang'e-5 breccia using the electron pair distribution function and molecular dynamics simulations. The results show that fayalite glass formed during pressure release, with temperatures ranging from 3200 to 3400 K before fayalite melt quenching and a residual pressure of around 1 GPa. By integrating micro-regional analyses, the results suggest that impact-induced particle fragmentation creates shear surfaces, where particle friction generates enough heat to cause local melting of fayalite, followed by rapid quenching to produce the glass. This study provides a microscopic perspective on the formation mechanism of impact glass, enhancing our understanding of the impact processes in the solar system.