^1,2Julia Neukampf, ²Yves Marrocchi, ²Johan Villeneuve, ³Mathieu Roskosz
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2026.01.041]
¹The University of Manchester, Oxford Road, M13 9PL Manchester, UK
²Université de Lorraine, CNRS, CRPG F-54000 Nancy, France
³Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Muséum national d’Histoire naturelle, Sorbonne Université, CNRS, F- 75005 Paris, France
Copyright Elsevier

We report high-precision lithium (Li) abundances and isotopic compositions of olivine crystals from type I chondrules in carbonaceous chondrites (Murchison, NWA 852, Renazzo) and type II chondrules in ordinary chondrites (NWA 11752, NWA 12462, NWA 12581, NWA 13501). Olivine crystals in type I chondrules exhibit large Li isotopic fractionations both within and between grains, with δ⁷Li values ranging from −46.6‰ to + 9.9‰ and Li concentrations of 3.8–9.0 ppm. Olivine grains in type II chondrules, including Mg-rich relict cores, show δ⁷Li values from −38.0‰ to + 8.4‰ (Li = 0.6–5.6 ppm), while their Fe-rich overgrowths exhibit lower variability, with δ⁷Li values between −30.6‰ and + 4.7‰ (Li = 0.6–11.9 ppm). Our data indicate that the observed variations are not attributable to low-temperature aqueous alteration or dry thermal metamorphism, fractional crystallisation, or simple degassing of the chondrule melt. Instead, the Li isotopic signatures are best explained by kinetic fractionation during open-system gas–melt exchange with a volatile-rich vapour, enriching the chondrule melts in Li. Such open-system processes produced larger isotopic fractionations than expected during closed-system crystallisation. These findings suggest that some type II chondrules may have originated from type I chondrules through reprocessing in an open-system environment, providing new insights into the complex physicochemical evolution of early solar system solids.

¹Ryan S. Jakubek, ²Marc D. Fries, ³Francis M. McCubbin, ³Devin L. Schrader, ⁴Andrew Steele, ²Jemma Davidson
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2026.01.036]
¹Amentum, NASA Johnson Space Center, Houston, TX, USA
²Astromaterials Acquisition and Curation Office (XI2), Astromaterials Research and Exploration Division, NASA Johnson Space Center, Houston, TX 77058, USA
³Astromaterials Research and Exploration Science (ARES) Division, XI3 Research Office, NASA Johnson Space Center, Houston, TX 77058, USA
⁴Carnegie Institute of Washington, Washington, DC, USA
Copyright Elsevier

We collected Raman images of 78 chondrules and their surrounding matrix from 12 Antarctic meteorite thin sections. We identified three spatially zoned, distinct structural populations of insoluble organic matter (IOM). A majority of IOM is spatially associated with the matrix and is consistent with Raman analysis of matrix and bulk demineralized IOM reported in the literature. We observe an IOM population within most chondrules that is more thermally altered compared to the chondrule’s surrounding matrix. The chondrule IOM population is observed in all chondrite types examined in this work: OC, CO, CV, CM, and CR, and shows a structural dependence on petrologic type, similar to that reported for matrix/bulk IOM, indicating that the chondrule IOM population was present during parent body thermal metamorphism. The structural differences between the chondrule and matrix IOM populations decrease with increasing petrologic type as thermal alteration homogenizes the IOM. Petrologic type 1–2 chondrites show the largest chondrule-matrix IOM structural differences, indicating significant differences between these populations at the time of parent body accretion. These results suggest that IOM material in matrix and chondrule precursors experienced different alteration histories prior to parent body accretion. The chondrule IOM Raman spectra contain features consistent with alteration by flash heating–cooling, possibly implicating the chondrule formation event(s) as an alteration pathway that differentiates it from matrix IOM. We also observe a disordered IOM population referred to as broad IOM. The broad IOM is observed across matrix, chondrules, and clasts, indicating its formation after parent body accretion. In several Raman images of low petrologic type CO meteorites, broad IOM is found co-located with magnetite though the current dataset is not sufficient to prove a statistical correlation. We hypothesize that broad IOM is an aqueous alteration product and propose a few possible formation pathways including oxidation of iron carbide and/or precipitation from a C-O–H bearing fluid.