Submicron-scale craters on Chang’e-5 lunar soils: records of complex space weathering processes

作者：Lixin Gu, Yangting Lin, Yongjin Chen, Yuchen Xu, Xu Tang, Jinhua Li · 发表于：Geochimica et Cosmochimica Acta · 年份：2025 · DOI：10.1016/j.gca.2025.04.004 · 被引用次数：12 · 研究领域：Planetary Science and Exploration、Astro and Planetary Science、Space Science and Extraterrestrial Life

Hyper-velocity impacts are dominant agents in the physical and chemical alteration of lunar surface materials. Natural small-scale craters on lunar soils provide an opportunity to understand the impact process and specific space weathering effects on minerals, however, they have not been systematically studied. Here, we report the morphology and microstructure of submicron-scale craters on Chang’e-5 lunar soils. Craters are found only on a few soil grains. Most identified craters exhibit large diameter-to-depth (D/d) ratios (>3) or are spatially clustered, indicating that they are formed by secondary ejecta rather than primary micrometeoroid impacts. Advanced electron microscopy investigations revealed that the microstructures of these craters are complex. Craters on the surfaces of two pyroxenes and one olivine have continuous nanophase iron (npFe 0 )-bearing rims that extend over the crater and beyond over the crystal substrate, even when covered by an impact-produced redeposition layer. These features provide reliable evidence of solar wind exposure prior to the impact events that formed the craters. The possibility cannot be ruled out that the npFe 0 particles present in these craters were previously produced by solar wind irradiation and not by impact. However, no clear signs are observed to establish the chronological order of formation of npFe 0 particles in other craters studied. Furthermore, a crater on ilmenite has a minimum D/d value of 2.6, suggesting that this cr...