^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.

^1,2Jennika Greer,³Alexander M. Kling,^4,5,6Luke Daly,^7,8Dieter Isheim,^7,8David N. Seidman,³Michelle S. Thompson,^2,9Philipp R. Heck
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70196]
¹Division of Microstructure Physics, Chalmers University of Technology, Göteborg, Sweden
²Robert A. Pritzker Center for Meteoritics and Polar Studies, Negaunee Integrative Research Center, Field Museum of NaturalHistory, Chicago, Illinois, USA
³Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA
⁴School of Geographical & Earth Sciences, University of Glasgow, Glasgow, UK
⁵Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, Australia
⁶Department of Materials, University of Oxford, Oxford, UK
⁷Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, USA
⁸Northwestern University Center for Atom Probe Tomography, Northwestern University, Evanston, Illinois, USA
⁹Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
Published by arrangement with John Wile & Sons

Space weathering significantly alters the optical, chemical, and structural properties of lunar regolith at micro- and nanoscales; yet detailed nanoscale variability within individual soils remains underexplored. Here we apply transmission electron microscopy (TEM) and atom probe tomography to four mineral grains (olivine, ilmenite, and two agglutinitic grains) from mature Apollo 17 soil 79221, characterizing solar wind-induced damage, vesiculation, nanophase Fe formation, and volatile retention with nanometer resolution. Our analyses reveal pronounced heterogeneity in vesicle morphology, nanophase Fe abundance, and volatile content that varies with mineralogy and exposure history. Oxygen depletion near grain surfaces indicates sputtering effects. Beyond confirming nanoscale heterogeneity, our coordinated analyses resolve, by APT, the Fe-depleted halos around npFe0 in mature ilmenite that we previously documented with the same technique in submature Apollo 17 ilmenite. We identify impact-melt quench textures that contribute non-weathering npFe0 to agglutinitic grains, and find a thick damage rim with few npFe0 in Mg-rich olivine accumulates. TEM observations of elongated, linear vesicles aligned parallel to ilmenite blade margins within a bladed agglutinitic grain further suggest crystallographic rather than directional control of vesicles in ilmenite inclusions. We also establish that vesicles distort APT reconstructions and degas during field evaporation, complicating quantitative inventories of npFe0 and volatiles in space-weathered grains.