Heterogeneous Weathering Process of Lunar Regolith Revealed by Polarimetric Attributes Analysis of Chang'E-4 Lunar Penetrating Radar Data Acquired During the Yutu-2 Turnings

This paper provides analyses to quantify the maturity of regolith within 24 m depth using a novel polarimetric attributes analysis of lunar penetrating radar (LPR) data. The results demonstrate that LPR signals were mainly from subsurface rock fragments of different sizes and were rarely from strata interfaces. The averages and ranges of maturities for the near-surface (0-2 m), the fine-grained regolith (2-12 m), and the coarse-grained ejecta (12-24 m) are 68.98% (0%-99.82%), 82.61% (41.52%-96.56%), and 72.33% (5.91%-96.66%), respectively. Local regions with anomalously low maturities on the lunar surface may be due to the dense materials formed by local impacts or the rock fragments from distal impacts; a newly discovered sandwich structure with low maturity at a depth between 12 and 18 m is formed by the heterogeneous weathering in a paleo-crater. Based on these new insights, we infer a heterogeneous weathering process of the regolith.

Automated summary

This paper provides analyses on the maturity of lunar regolith at different depths and identifies the factors contributing to the variations in maturity levels. The results reveal that the near-surface regolith has a higher maturity compared to deeper layers, with localized regions exhibiting anomalously low maturity. Additionally, a newly discovered sandwich structure with low maturity between 12 and 18 m depth is attributed to heterogeneous weathering in a paleo-crater.