Equilibrated Gas and Carbonate Standard-Derived Dual (Δ47 and Δ48) Clumped Isotope Values.

Carbonate clumped isotope geochemistry has primarily focused on mass spectrometric determination of 47 CO for geothermometry, but theoretical calculations and recent experiments indicate paired analysis of the 47 (COO) and 48 (COO) isotopologues (referred to as and ) can be used to study non-equilibrium isotope fractionations and refine temperature estimates. We utilize 5,448 and 3,400 replicate measurements of carbonate samples and standards, and 183 and 195 replicate measurements of gas standards from 2015 to 2021 from a multi-year and multi-instrument data set to constrain and values for 27 samples and standards, including Devils Hole cave calcite, and study equilibrium -, -temperature, and -temperature relationships. We compare results to previously published findings and calculate equilibrium regressions based on data from multiple laboratories.

Carbonate clumped isotope analysis (Δ ) of 21 carbonate standards determined via gas-source isotope-ratio mass spectrometry on four instrumental configurations using carbonate-based standardization and multiyear data sets.

Rationale: Clumped isotope geochemistry examines the pairing or clumping of heavy isotopes in molecules and provides information about the thermodynamic and kinetic controls on their formation. The first clumped isotope measurements of carbonate minerals were first published 15 years ago, and since then, interlaboratory offsets have been observed, and laboratory and community practices for measurement, data analysis, and instrumentation have evolved. Here we briefly review historical and recent developments for measurements, share Tripati Lab practices for four different instrument configurations, test a recently published proposal for carbonate-based standardization on multiple instruments using multi-year data sets, and report values for 21 different carbonate standards that allow for recalculations of previously published data sets.