Tauseef, Mohammad (2025). 14C and 14C–10Be Terrestrial Age Dating System for Stony Meteorites. (Thesis). Universität Bern, Bern
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Abstract
This project aims to improve the accuracy of meteorite terrestrial age dating by refining the 14C and 14C-10Be dating system. By studying how 14C production rates and 14C/10Be ratios vary with shielding depth, this research project establishes a more reliable method for determining terrestrial ages of meteorites. Physical model calculations indicate that neither the 14C production rates nor the 14C/10Be production rate ratios are constant enough to be reasonably approximated by average values. The experimental data, from 21 freshly fallen chondrites, agree with the model calculations, and they fully confirm that 14C production rates and 14C/10Be production rate ratios depend on shielding. We established reliable correlations for 14C production rates and 14C/10Be production rate ratios as a function of (22Ne/21Ne)cos. 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. Additionally, 21Necos concentration is used to estimate the cosmic ray exposure age of meteorites to evaluate 10Be saturation equilibrium, which help constrain the 14C/10Be dating system. The results of the improved 14C and 14C/10Be dating systems are then applied to re-calculate terrestrial age of strewnfield meteorites from Oman and refining terrestrial age of meteorites from other hot and cold deserts, such as meteorites from Saharan Desert, Australia, and Antarctica. Ultimately, this research will contribute to a better understanding of cosmogenic (14C and 10Be) nuclide production in meteorite in space, and improve the methods used for dating meteorites that have fallen to Earth, which in turn helps in other scientific topics such as the meteorite flux estimates and its life on Earth.
| Item Type: | Thesis |
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| Dissertation Type: | Cumulative |
| Date of Defense: | 31 March 2025 |
| Subjects: | 500 Science > 520 Astronomy |
| Institute / Center: | 08 Faculty of Science > Physics Institute |
| Depositing User: | Hammer Igor |
| Date Deposited: | 19 Sep 2025 09:11 |
| Last Modified: | 19 Sep 2025 09:12 |
| URI: | https://boristheses.unibe.ch/id/eprint/6716 |
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