¹D. S. Burnett et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14313]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Published by arrangement with John Wiley & Sons

Solar wind Fe and Mg fluences (atoms/cm2) were measured from Genesis collectors. Fe and Mg have similar first ionization potentials and solar wind Fe/Mg should equal the solar ratio. Solar wind Fe/Mg is a more valid measure of solar composition than CI chondrites and can be measured more accurately than spectroscopic photospheric abundances. Mg and Fe fluences analyzed in four laboratories give satisfactory agreement. Si and diamond-like carbon collector fluences agree for both elements. The Mg and Fe fluences are 1.731 ± 0.073 × 1012 and 1.366 ± 0.058 × 1012 atoms/cm2. All plausible sources of errors down to the 1% level are documented. Our value for the solar system Fe/Mg, 0.789 ± 0.048 agrees within 1 sigma errors with CI chondrites, spectroscopic photospheric abundances, and with the solar wind data from the ACE spacecraft. CI samples from asteroid Ryugu give Fe/Mg in agreement with Genesis and meteoritic CI samples despite very small sample sizes. The higher accuracy of the Genesis solar Fe/Mg permits a comparison with chondritic Fe/Mg at the 10% level. Intermeteorite Fe/Mg averages differ among the main C chondrite groups but are within, or very close to, the ±1 sigma Genesis solar Fe/Mg.

¹B. H. Oliveira,¹J. F. Snape,¹R. Tartèse,¹J. F. Pernet-Fisher,²D. van Acken,³M. J. Whitehouse,¹K. H. Joy
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14305]
¹Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK
²UCD School of Earth Sciences, University College Dublin, Dublin, Ireland
³Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden
Published by arrangement with John Wiley & Sons

The Calcalong Creek lunar meteorite is a regolith breccia with a lithologically diverse array of clasts set in a glassy, highly vesicular matrix. Here, we present a comprehensive new analysis of the meteorite. Comparisons to remote sensing data, lunar sample lithologies, and lunar sample ages indicate that it was likely sourced from regolith surrounding the Moon’s nearside Procellarum KREEP Terrane, as opposed to the farside South Pole-Aitken basin as has been previously suggested. Partial and complete reset dates of ~3.9 Ga suggest a disturbance at this time, which aligns with that of the Imbrium basin-forming event, and to a lesser degree we see evidence of a ~4.2 Ga impact, which may be related to the formation of the Serenitatis basin. Analysis of Calcalong Creek clasts, thus, provide insights not only on the timing of major impact basin formation but also on the volcanic history of the Moon. The meteorite also samples some ancient ~4.3 Ga evolved magmatism, manifested in the presence of granophyre clasts, which may have originated from a high-μ, KREEP-like source, as well as younger, ~3.7 Ga low-Ti basaltic magmatism.