^1,2Yogita Kadlag,²Jason Hirtz,¹Harry Becker,²Ingo Leya,³Klaus Mezger
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13756]
¹Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100, Berlin, 12249 Germany
²Physikalisches Institut, Universität Bern, Sidlerstrasse 5, Bern, 3012 Switzerland
³Institut für Geologie, Universität Bern, Baltzerstrasse 1+3, Bern, 3012 Switzerland
Published by arrangement with John Wiley & Sons

Different solar system objects display variable abundances of neutron-rich isotopes such as 54Cr, 50Ti, and 48Ca, which are commonly attributed to a heterogeneous distribution of presolar grains in different domains of the solar system. Here, we show that the heterogeneity of 54Cr/52Cr and the correlation of 54Cr/52Cr with Fe/Cr in metal fractions of EH3 chondrites and in inner solar system bodies can be attributed to variable irradiation of dust grains by solar energetic particles and variable mixing of irradiated material in the different domains of the inner solar nebula. The isotope variations in inner solar system objects can be generated by ∼300 y long local irradiation of mm- to cm-sized solids with average solar energetic particle fluxes of ∼105 times the modern value. The relative homogeneity of 53Cr/52Cr in inner solar system objects can be a consequence of the production of 53Mn by the early irradiation of dust, evaporation, and nebula-wide homogenization of Mn due to high temperatures, followed by Mn/Cr fractionation within the first few million years of the solar system. The 54Cr/52Cr of the Earth can be produced by irradiated pebbles and <15 wt% of CI chondrite like material. Alternatively, Earth may contain only a few % of CI chondrite like material but then must have an Fe/Cr ratio 10–15% higher than CI chondrites.

¹Åke V. Rosén,^1,2Beda A. Hofmann,³Frank Preusser,⁴Edwin Gnos,¹Urs Eggenberger,⁵Marc Schumann,⁶Sönke Szidat
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13758]
¹Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, Bern, 3012 Switzerland
²Natural History Museum Bern, Bernastrasse 15, Bern, 3005 Switzerland
³Institute of Earth and Environmental Sciences, University of Freiburg, Alberstrasse 23b, Freiburg, 79104 Germany
⁴Natural History Museum of Geneva, 1, Route de Malagnou, Geneva, 1208 Switzerland
⁵Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, Freiburg, 79104 Germany
⁶Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012 Switzerland
Published by arrangement with John Wiley & Sons

We combine the search for young meteorites in the Omani-Swiss collection (˜1140 fall events collected 2001–2018) using 22Na and 44Ti with luminescence and 14C sediment ages from the Ramlat Fasad (RaF) dense collection area (DCA) of Oman to obtain combined terrestrial ages and maximum accumulation times, and test whether the proportion of young meteorites is consistent with the models of meteorite flux and weathering. Gamma-ray spectrometry data for 22Na show that two (0.17%) of the meteorites in the collection fell during the 20 yr preceding this study, consistent with the rates of meteorite accumulation. In the RaF DCA, meteorites are found on Quaternary to Neogene sediments, providing constraints for their maximum terrestrial ages. 44Ti activities of the RaF 032 L6 strewn field found on deflated parts of active dunes indicate an age of 0.2–0.3 ka while dune sand optically stimulated luminescence ages constrain an upper age of 1.6 ka. Extensive sediment dating using luminescence methods in the RaF DCA area showed that all other meteorite finds were made on significantly older sediments (>10 ka). Dense accumulations of meteorites in RaF are found on blowouts of the Pliocene Marsawdad formation. Our combined results show that the proportion of meteorites with low terrestrial ages is low compared to other find areas, consistent with the previously determined high average terrestrial age Oman meteorites and significantly older than suggested by models of exponential decay. Oman meteorites may commonly have been buried within dunes and soils over extended periods, acting as a temporary protection against erosion.