^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.