Work

Widespread ilmenite contributions to the surface water cycle in lunar Procellarum KREEP Terrane

Year: 2025

Type: article

Abstract: The role of widespread ilmenite in lunar mare regions in the abundance and diurnal variations of surficial OH/H2O remains controversial. Here, we report the water content and hydrogen isotopes in the rims of lunar ilmenites from Chang’e-5 soil samples using an ion microprobe. Ilmenite rims exhibit higher water contents (~730 − 3,700 ppm) and lower δD values (−884 to −482‰) than that of the lunar mantle, indicating a predominantly endogenic origin from solar-wind (SW) implantation. Our data further reveal that although ilmenite and silicate minerals overlap in the δD vs. H2O diagram, almost all ilmenites fall above those of silicates with SW-like δD values. This signature is consistent with the drastic difference in vesicle abundance between ilmenite and silicate minerals. Thus, the lower water content in ilmenite rims most likely reflects a faster dynamic equilibrium between SW-hydrogen implantation and outgassing than in other silicates. These findings suggest that ilmenite may play a critical role in the surface water cycle of lunar maria within the Procellarum KREEP Terrane. This is also crucial for assessing the in-situ resource utilization potential of the region, highlighting the need to reevaluate ilmenite as a viable resource for future lunar exploration. The study shows that lunar ilmenite preserves less solar wind-generated water than silicate minerals, likely due to faster water escape. This finding suggests that ilmenite may critically influence surface water variations within the lunar Procellarum KREEP Terrane.

Source: Nature Communications

DOI: 10.1038/s41467-025-62914-4