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A generalizable box model for kinetic clumped isotope effects in the CaCO3 -DIC-H2O system
  • James Watkins,
  • Laurent Devriendt
James Watkins
University of Oregon

Corresponding Author:[email protected]

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Laurent Devriendt
University of Oregon
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Abstract

Most Earth surface carbonates precipitate out of isotopic equilibrium with their host solution, complicating the use of stable isotopes in paleoenvironment reconstructions. Disequilibrium can arise from exchange reactions in the DIC-H2O system as well as during crystal growth reactions in the DIC-CaCO3 system. Existing models account for kinetic isotope effects in these systems separately but the models have yet to be combined in a general framework. Here, a box model is developed for describing disequilibrium carbon, oxygen, and clumped isotope effects in the CaCO3-DIC-H2O system. The model is applied to inorganic calcite precipitation experiments where there is a known CO2 influx and CaCO3 outflux. The example provided can be adapted to other situations involving CO2 absorption (e.g., corals, foraminifera, high-pH travertines) or degassing (e.g., speleothems, low-pH travertines, cryogenic carbonates) and/or mixing with other DIC sources.