Geospatial analysis of lunar impacts craters: a meta-analysis of impact glasses from all Apollo and Chang'e 5 missions

High-speed impacts are the most fundamental of the currently known geological process in the Solar System. Luna preserves a comprehensive record of impacts since its formation 4.53 billion years age (Ga). Particles of silicate glass formed by impact melting may have recorded the timing of the impact event and reflected the composition of crustal target materials. Previous studies have used ³⁹Ar-⁴⁰Ar and U-Pb chronometric systems to date lunar impact glasses, while their source characteristics were assessed using major and trace element data. The return of the Chang'e 5 sample provides an opportunity for a more comprehensive analysis of lunar impact history by comparing the ages of impact glasses from different locations.

 

In this study, we collected approximately 800 sets of isotopic age data and corresponding major and trace element data for impact glasses, primarily from samples returned from the Apollo series of missions and the recent Chang’e 5 mission. Impact glasses for which no age data could be obtained were removed. Impact flux curves were generated by normalizing the estimated age data. Sampling points on the lunar nearside show three distinct curve patterns. The impact flux curves of Chang'e 5 and Apollo 12 exhibit a common, prominent impact interval during the lunar Copernicus Period. The impact flux curves based on the Apollo 17 samples show only one prominent impact interval, namely the Late Heavy Bombardment (LHB) Event period (3.8-4.1 Ga). The intermediate region samples (Apollo 14, 15,16) exhibit both of these common, prominent impact intervals. These three impact flux curve patterns may be related to the geographic distribution of the sampling sites. To validate this potential relationship, we utilized a global catalog of lunar impact craters containing over 1.3 million craters to analyze the distribution of craters of similar diameter in contemporary regions. Preliminary results indicate that there are differences in the distribution of impact craters across different regions within the same geological period. These differences may be related to the Moon's rotation and orbital characteristics.