Assessing kinetic fractionation in brachiopod calcite usingclumped isotopes.

Bajnai, D., Fiebig, J., Tomasovych, A., Milner Garcia, S., Rollion-Bard, C., Raddatz, J., Löffler, N., Promo-Ramos, C., Angiolini, L., Henkel, Daniela and Brand, U. (2018) Assessing kinetic fractionation in brachiopod calcite usingclumped isotopes. Open Access [Talk] In: 8. International Brachiopod Congress 2018. , 11.-14.09.2018, Milano, Italy .

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Brachiopod shells are the most widely used geological archive for the reconstruction of the temperature and the oxygen isotope composition of Phanerozoic seawater. However, it is not conclusive whether brachiopods precipitate their shells in thermodynamic equilibrium. In this study, we investigated the potential impact of kinetic controls on the isotope composition of modern brachiopods by measuring the oxygen and clumped isotope compositions of their shells. Our results show that clumped and oxygen isotope compositions depart from thermodynamic equilibrium due to growth rate-induced kinetic effects. These departures are in line with incomplete hydration and hydroxylation of dissolved CO2. These findings imply that the determination of taxon-specific growth rates alongside clumped and bulk oxygen isotope analyses is essential to ensure accurate estimates of past ocean temperatures and seawater oxygen isotope compositions from brachiopods.

Document Type: Conference or Workshop Item (Talk)
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Projects: BASE-LiNE Earth
Date Deposited: 05 Mar 2019 15:05
Last Modified: 05 Mar 2019 15:05

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