^1,2,3Xuhang Zhang et al. (>10)
Earth and Planetary Science Letters 671, 119666 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119666]
¹Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
²Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
³Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
Copyright Elsevier

Understanding the elemental and isotopic composition of the Sun is key to reconstructing planetary formation, atmospheric evolution and solar activity over time. Noble gases from solar wind implanted into lunar regolith provide a unique archive of solar history, but their interpretation is complicated by implantation uncertainties and secondary processes (e.g., diffusion, regolith gardening, solar and galactic cosmic ray exposure). Here we report the isotopic composition of the noble gases (helium, neon, and argon) in thirty six high-purity plagioclase grains from Chang’e-5 lunar soil to assess the preservation of implanted solar wind in lunar materials. Compared with plagioclase from several Apollo sites, the grains retain a more pristine solar wind record, revealing a dynamic equilibrium between solar wind and cosmic ray irradiation and intense diffusive loss driven by localized heating likely due to micro-impacts or temperature gradients at the lunar surface. These coupled mechanisms explain the observed inter-grain He/Ne/Ar variations. Our data further indicate that kinetic diffusion during solar wind implantation, rather than post-implantation alteration, is the primarily driver of elemental fractionation relative to original solar wind values in plagioclase. Collectively, these findings reveal pathways of solar wind-driven noble gas retention and loss in lunar materials and further accounts for the presence of solar wind-derived He and Ne in the lunar exosphere. They also underscore the need to correct for process-related modifications when reconstructing past solar wind compositions, thereby enabling improved inference of solar evolution, planetary volatiles origins, and the initial solar nebula composition.

¹M. Yesiltas,¹T. D. Glotch
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70067]
¹Department of Geosciences, Stony Brook University, Stony Brook, New York, USA
Published by arrangemetn with John Wiley & Sons

CM chondrites have undergone varying degrees of aqueous alteration and thermal metamorphism on their parent bodies. Consequently, the petrologic grade of CM chondrites spans the entire type 2 scale (e.g., types 2.0–2.9). A 12236 is a very primitive petrologic type 2.9 carbonaceous chondrite that offers a unique window into the complex formation and evolution histories of CM chondrites. Based on its chemical composition, it is one of the least altered CM chondrites identified to date and one of the most primitive meteorites. Here, we present a comprehensive characterization of the organic and inorganic constituents of A 12236, determined through electron microscopy, micro-Raman, and s-SNOM nano-FT-IR spectroscopy. We identified FeNiS phases, including pentlandite, pyrrhotite, and troilite, within a fine-grained matrix composed predominantly of crystalline and amorphous silicates, including phyllosilicates. Raman spectroscopic results suggest that A 12236 experienced less thermal metamorphism than type 3 carbonaceous chondrites and contains polyaromatic organic matter with slightly differing structural order. Nano-FT-IR spectroscopy revealed chemically distinct aliphatic and aromatic organic phases, with observed compositional heterogeneity indicating variations in organic precursors and accreted materials. Correlation analysis highlights the complex associations between organic matter and phyllosilicates, along with evidence of differing aromatic compositions within the matrix. The varying abundances of nanoscale organics in different areas of A 12236 suggest that the organic matter is highly heterogeneously distributed within the matrix. Our findings demonstrate the effectiveness of nano-FT-IR spectroscopy for high-resolution, nondestructive analysis of extraterrestrial samples.