¹Kanako Yoshihara,²Akira Yoshiasa,³Huimin Shao,⁴Makoto Tokuda,⁵Ginga Kitahara,²Hiroshi Isobe
Meteoritics & Planetary Science (in Press) Open Access Link To Article [https://doi.org/10.1111/maps.70180]
¹Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan
²Department of Earth and Environmental Sciences, Faculty of Advanced Science and Technology, Kumamoto University,Kumamoto, Japan
³Chinese National Space Science Center, Beijing, China
⁴Institute of Industrial Nanomaterials, Kumamoto University, Kumamoto, Japan
⁵Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tokai, Ibaraki, Japan
Published by arrangement with John Wiley & Sons

Ni, Co, and Fe K-edge X-ray absorption fine structure (XAFS) measurements were performed, revealing an unexpected local structure around Co in well-known iron and stony-iron meteorites. Cobalt is enriched in kamacite but remains in taenite at concentrations of at least 0.3 atom%. The Co K-edge X-ray absorption near-edge structure (XANES) spectra of taenite with a face-centered cubic (FCC) structure in all examined iron meteorites exhibited an unexpected body-centered cubic (BCC)-type local coordination, with Co showing a coordination number of 8 + 6. The local FCC and BCC structures can be clearly distinguished based on their XANES patterns. In taenite, up to 20% of the local structure is inferred to be BCC in regions where three-dimensional periodicity is maintained. Moreover, local BCC structures are likely to predominate in subregions that do not contribute to three-dimensional periodicity. Co transforms into a locally ordered BCC structure within the high-temperature parent FCC phase of iron meteorites. In this phase, Co appears to have a stronger affinity for Fe than for Ni, leading to the formation of Co-Fe clusters with a regular BCC arrangement.

^1,2,3,5Hongmei Yang, ^1,2,3Xiaoju Lin, ^1,2,3Xiao Wu, ^1,2,3,4Haiyang Xian, ^1,2,3,4Jianxi Zhu, ^1,2,3,4Shan Li, ^1,2,3Jiaxin Xi, ^1,2,3Yiping Yang, ^1,2,3,4Hongping He
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2026.117209]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²Center for Advanced Planetary Science, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
³Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
⁴University of Chinese Academy of Sciences, Beijing 100049, China
⁵Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
Copyright Elsevier

Impact is one of the most crucial geological processes on the lunar surface. As the main mafic mineral in lunar mare basalts, pyroxene can be transformed into an amorphous phase under the high-temperature and high-pressure conditions triggered by impact events. However, the formation mechanism of impact-induced pyroxene glass and its implications for the impact history of the lunar surface have yet to be elicited. In this study, we investigated the formation mechanism of augite glass from a Chang’e-5 breccia using the electron pair distribution function and molecular dynamics simulations. The results show that the augite transformed into dense melt under the high-temperature and high-pressure conditions induced by impact, with subsequent quenching leading to glass formation. Atomic structural analysis indicates that the augite dense melt solidified at a temperature of approximately 4100 K and a residual pressure of about 10 GPa. The mosaicization of this augite glass in the breccia clasts indicates that it had experienced a later impact event with a shock intensity of M-S2 after its formation. By establishing the link between the atomic structure of augite glass and its formation pressure-temperature conditions, this study provides a robust method for inverting impact parameters from natural lunar glass samples. It also offers a new perspective for deciphering the multi-stage impact history of the lunar surface and the evolutionary processes of lunar regolith, and holds universal reference value for studies of impact processes on the Moon and other terrestrial planets.