- 1State Key Laboratory of Lithospheric and Environmental Coevolution, University of Science and Technology of China; Hefei, 230026, China
- 2Deep Space Exploration Laboratory; Hefei, 230026, China
All the lunar landings and photographic investigations show that several meter-thick regolith layers cover the lunar’s surface. The regolith layer records its space weathering and meteorite bombardment history, and understanding its formation and evolution is of great importance to lunar exploration. The Chang’E-6 (CE6) mission landed at the south of the Apollo crater inside the South Pole-Aitken (SPA) basin at the lunar’s far side. The CE6 regolith thus provides a rare opportunity to compare with near-side regolith returned from the Apollo, Luna, and Chang’E-5 (CE5) missions. Here, we conducted analyses on the chemical and Fe isotope compositions on two portions of bulk regolith and nine tiny clasts separated from the scooped CE6 regolith (CE6C0400YJFM004).
Elemental analyses show that the bulk regolith has slightly higher MgO (7.84 and 8.26 wt.%), and much higher FeO (21.01 and 19.08 wt.%) and Al2O3 (17.2 and 18.5 wt.%) than the previously reported values in Li et al. (2024), indicating the chemical heterogeneity in scooped CE6 regolith. EPMA analyses on agglutinate clasts show glasses with three kinds of compositions: (1) similar to pristine local basalt; (2) similar to Mg-suite rocks; (3) intermediate between local basalt and Mg-suite rocks. Based on mass-balance calculations, it indicates that the CE6 regolith contains 20-50% exotic ejecta with compositions similar to norite. These exotic materials should originate from the Chaffee S crater, which is situated approximately 100 km from the CE6 landing site.
The clasts in CE6 regolith show overall heavy Fe isotope compositions with δ57Fe from 0.263 to 1.411‰. No correlations exist between δ57Fe and MgO or FeO, ruling out the effect of magmatic differentiation. Instead, the δ57Fe variation should be caused by evaporation during impact. The clasts, which have the smallest grain size, show the heaviest Fe isotope composition (1.411‰) and indicate a high energy impact. This clast may have formed through recondensation from the vapor generated by the intense impact associated with the formation of the Apollo crater.
Reference:
Li, C. et al. Nature of the lunar farside samples returned by the Chang'E-6 mission. National Science Review (2024). https://doi.org:10.1093/nsr/nwae328
How to cite: Huang, F., Kang, J., Yu, H., and Qin, L.: Impact-controlling Chang'E-6 regolith formation on the Moon’s far-side, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9610, https://doi.org/10.5194/egusphere-egu25-9610, 2025.
