¹Mohammad Tauseef,¹Ingo Leya,²Jérôme Gattacceca,³Sönke Szidat,²Régis Braucher,⁴Pascal M. Kruttasch,⁴Anna Zappatini,²ASTER Team
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14355]
¹Physics Institute, Space Research and Planetology, University of Bern, Bern, Switzerland
²CNRS, Aix Marseille Université, IRD, INRAE, CEREGE, Aix-en-Provence, France
³Department of Chemistry, Biochemistry and Pharmaceutical Sciences & Oeschger Center for Climate Change
Research, University of Bern, Bern, Switzerland
⁴Institute of Geological Sciences, University of Bern, Bern, Switzerland
Published by arrangment with John Wiley & Sons

This study presents a refined approach to determine 14C saturation activities and 14C/10Be saturation activity ratios in chondritic meteorites with the goal to improve terrestrial age dating. By combining new model calculations for 10Be, 14C, and cosmogenic (22Ne/21Ne)cos, along with experimental data from 17 freshly fallen chondrites, we established reliable correlations for 14C production rates and 14C/10Be production rate ratios as a function of (22Ne/21Ne)cos. The experimental data agree with the model calculations, and they fully confirm that 14C production rates and 14C/10Be production rate ratios depend on shielding. Constrained correlations describe the experimental data for all shielding conditions and all ordinary chondrites mostly within the uncertainties given by the model. The new correlations therefore provide a significant improvement compared to the earlier approaches, in which average meteorite-type-dependent 14C production rates and average 14C/10Be production rate ratios were assumed. Ignoring the shielding dependence introduces a size-dependent bias into the terrestrial age database. This study enables the determination of shielding-corrected 14C saturation activities and 14C/10Be production rate ratios to calculate shielding-corrected terrestrial ages for meteorites reducing or eliminating a size bias in the database. In addition, this novel approach enables to give reliable uncertainty estimates of within 15% for the 14C and 14C-10Be terrestrial ages.