^1,2Tian Zhang, ^1,2,3Hong Tang, ^1,2,3Xiongyao Li, ^1,3Bing Mo, ¹Yuanyun Wen, ⁴Sheng Zhang, ^1,3Wen Yu, ^1,2Chuanjiao Zhou, ^1,2Haiyan Long, ^1,2,3Jianzhong Liu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.11.047]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
²College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
³CAS Center for Excellence in Comparative Planetology, Hefei 230026, China
⁴College of Resources and Environment Engineering, Guizhou University, Guiyang 550025, China
Copyright Elsevier

The degassing of solar wind-related volatiles is thought to contribute to volatile cycling on the Moon. However, it remains uncertain which lunar minerals preferentially release them. Here, we report an unusual foamy texture found only on the surface of ilmenite crystals within a Chang’e-6 (CE-6) basalt clast. The distribution and chemical composition of this texture indicates that it results from in-situ melting of the ilmenite surface rather than from an impact-induced splash melt. Considering the evidence—including the long exposure time, presence of deep-seated planar defects, open vesicles, large spherical np-Fe⁰ particles, and a rutile-like mineral—the foamy texture is interpreted to result from the intense release of abundant solar wind-related volatiles (e.g., H/H2, He, and OH/H2O) by an impact-induced conductive heating event. Restriction of the foamy texture to the surface of ilmenite within the CE-6 basalt clast indicates that solar wind composition, especially for H-related volatiles, are released more intensely from ilmenite than from silicate minerals such as pyroxene and plagioclase. Our findings suggest that solar wind-related volatiles released from high-Ti mature regolith likely made a greater contribution to the lunar exosphere and the lunar surface volatiles, including polar deposits, relative to those from low-Ti immature regions. This has important implications for understanding volatile cycles and future in-situ resource utilization on the Moon.