^1,2C. Deligny,¹M. J. Whitehouse,³R. E. Merle,¹H. Jeon,^4,5A. A. Nemchin,⁶B. L. Jolliff
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70204]
¹Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden
²School of Physical Sciences, The Open University, Milton Keynes, UK
³Department of Earth Sciences, Uppsala University, Uppsala, Sweden
⁴School of Earth and Planetary Sciences, Curtin University, Perth, Australia
⁵School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
⁶Department of Earth, Environmental, and Planetary Sciences and the McDonnell Center for the Space Sciences, WashingtonUniversity in St. Louis, St. Louis, Missouri, USA
Published by arrangement with John Wiley & Sons

Basaltic sample 12032,366-18 from the Apollo 12 landing site is distinct among basalts collected at this site, other Apollo landing sites, and lunar meteorites in terms of its age, bulk rock composition, and isotopic composition. We present new Pb isotopic data obtained by in situ Secondary Ion Mass Spectrometry on multiple mineral phases in 12032,366–18. These data yield a crystallization age of 3400 ± 16 Ma, older than other Apollo 12 basalts, which crystallized between ~3.1 and 3.3 Ga. The initial Pb isotopic composition plots slightly below the mixing line between KREEP (an incompatible-element-rich lunar reservoir enriched in K, rare Earth elements, and P) and a depleted lunar mantle reservoir with low-μ (μ = ²³⁸U/²⁰⁴Pb) value. The bulk composition is characterized by elevated incompatible trace element abundances, including high thorium (~7 ppm), relatively high FeO, and intermediate Ti contents, distinguishing it from other Apollo 12 and lunar basalts. Although it shares some affinities with Apollo KREEP basalts, its higher bulk rock Al₂O₃ content and the presence of olivine are more consistent with high-Al basalts. Together, 12032,366–18 is not indigenous to the Apollo 12 landing site but instead represents material transported from a distant source region, most plausibly within western Oceanus Procellarum, potentially linked to the Kepler impact crater region.