期刊
NATURE COMMUNICATIONS
卷 10, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/s41467-019-08336-5
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资金
- Region Ile-de-France
- Direction des Sciences de la Matiere du Commissariat a l'Energie Atomique
- Institut National des Sciences de l'Univers, Centre National de la Recherche Scientifique
- Universtite de Versailles/Saint-Quentin-en-Yvelines
- Australian Research Council [DP110102185, DP160102969]
- Universite Paris-Saclay
- LSCE
- Commissariat a l'Energie Atomique
- Agence Nationale de la Recherche project AMOR
- MACARBI project (IUEM)
Oxygen-isotope thermometry played a critical role in the rise of modern geochemistry and remains extensively used in (bio-)geoscience. Its theoretical foundations rest on the assumption that O-18/O-16 partitioning among water and carbonate minerals primarily reflects thermodynamic equilibrium. However, after decades of research, there is no consensus on the true equilibrium O-18/O-16 fractionation between calcite and water ((18)alpha(cc/w)). Here, we constrain the equilibrium relations linking temperature, (18)acc/w, and clumped isotopes (Delta(47)) based on the composition of extremely slow-growing calcites from Devils Hole and Laghetto Basso (Corchia Cave). Equilibrium (18)alpha(cc/w) values are systematically similar to 1.5% greater than those in biogenic and synthetic calcite traditionally considered to approach oxygen-isotope equilibrium. We further demonstrate that subtle disequilibria also affect Delta 47 in biogenic calcite. These observations provide evidence that most Earth-surface calcites fail to achieve isotopic equilibrium, highlighting the need to improve our quantitative understanding of non-equilibrium isotope fractionation effects instead of relying on phenomenological calibrations.
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