¹Yingnan Zhang, ¹Mi Zhou, ¹Liping Qin, ¹Bing Yang, ¹Haolan Tang, ²Thomas Smith, ²Huaiyu He
Earth and Planetary Science Letters 674, 119738 Link to Article [https://doi.org/10.1016/j.epsl.2025.119738]
¹National Key Laboratory of Deep Space Exploration/State Key Laboratory of Lithospheric and Environmental Coevolution, University of Science and Technology of China, Hefei 230026, China
²State Key Laboratory of Lithospheric and Environmental Coevolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, 19 Beitucheng Western Road, Box 9825, Beijing 100029, China
Copyright Elsevier

The fingerprints of ancient stars are preserved in the isotopic anomalies of meteorites, revealing how the Solar System’s building blocks formed and evolved. Potassium, a moderately volatile element, exhibits isotopic anomalies that can serve as tracers of volatile inventories in meteorites and terrestrial planets. We measured the K isotopic compositions in a range of meteorites. After correcting for cosmic-ray effects, all meteorites show ε40K values that are the same as or slightly higher than Earth’s. The lack of correlation with other neutron-rich isotopes, but a clear link to 30Si and 43Ca, points to stellar burning as the main source of 40K. Large 40K enrichments in CI chondrites and Tagish Lake indicate the addition of 40K-rich material, while other subgroups of carbonaceous chondrites show evidence of various degrees of mixing with this component. These patterns suggest inward migration of CI-like volatile-rich carriers in the protoplanetary disk. The uniform enrichment in meteorites implies that Earth’s slightly lower ε40K required a missing, 40K-depleted building block, likely from early-formed planetesimals that had avoided this late addition of CI-like material.