Most Earth-surface calcites precipitate out of isotopic equilibrium.

ABSTRACT: 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 ¹⁸O/¹⁶O partitioning among water and carbonate minerals primarily reflects thermodynamic equilibrium. However, after decades of research, there is no consensus on the true equilibrium ¹⁸O/¹⁶O fractionation between calcite and water (¹⁸α_cc/w). Here, we constrain the equilibrium relations linking temperature, ¹⁸α_cc/w, and clumped isotopes (Δ₄₇) based on the composition of extremely slow-growing calcites from Devils Hole and Laghetto Basso (Corchia Cave). Equilibrium ¹⁸α_cc/w values are

SUBMITTER: Daeron M 

PROVIDER: S-EPMC6347637 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature