Assessing kinetic fractionation in brachiopod calcite using clumped isotopes

作者：Bajnai David^*; Fiebig Jens; Tomasovych Adam; Garcia Sara Milner; Rollion Bard Claire; Raddatz Jacek; Loeffler Niklas; Primo Ramos Cristina; Brand Uwe

来源：Scientific Reports, 2018, 8(1): 533.

DOI：10.1038/s41598-017-17353-7

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.

• 出版日期2018-1-11
• 单位国家气候中心