Evaluating 14C and 14C/10Be terrestrial age dating systems for meteorites using experimental data and model calculations

This study presents a refined approach to determine 14C saturation activities and C-14/Be-10 saturation activity ratios in chondritic meteorites with the goal to improve terrestrial age dating. By combining new model calculations for 10Be, C-14, and cosmogenic (Ne-22/Ne-21)cos, along with experimental data from 17 freshly fallen chondrites, we established reliable correlations for C-14 production rates and C-14/Be-10 production rate ratios as a function of (Ne-22/Ne-21)cos. The experimental data agree with the model calculations, and they fully confirm that C-14 production rates and C-14/Be-10 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 C-14 production rates and average C-14/Be-10 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 C-14 saturation activities and C-14/Be-10 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 C-14 and C-14-10Be terrestrial ages.