Lunar impact history recorded by melt beads from Apollo 17 regolith 76501

Abstract Rapidly quenched particles of melt formed as ejecta from meteoritic impacts are ubiquitous in the lunar regolith. Isotopic and geochemical data for impact‐produced glassy particles from Apollo 17 regolith sample 76501 document their major and trace element compositions and U–Pb chronologies. Their U–Pb isotopic compositions are consistent with ages ranging from a few million years to about 3.7 billion years, while their chemical compositions can be explained by the local targets represented in the rock and regolith collection delivered by the Apollo 17 mission and rock fragments present in Apollo 17 core samples. The age frequency distribution pattern obtained for 76501 impact beads defines broad peaks at about 3.6–3.7 Ga, between about 400 and 1000 Ma, and in the last 150 Ma. These broad peaks are similar to those shown by impact bead populations from Apollo 14 soil 14163 and the Chang'e 5 sample and include beads of both mare and highlands compositions from all landing sites. In combination, these similarities support the idea that they reflect global impact rates or a cluster of events. Although the number of beads in any single sample of lunar regolith likely represents a combination of temporal changes in impact rates, destruction, burial and resurfacing during regolith evolution, the similarity of age patterns between landing sites and across different compositions suggests a global‐scale record of impacts rather than site‐specific controls.