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 m/z 47 CO(2) for geothermometry, but theoretical calculations and recent experiments indicate paired analysis of the m/z 47 ((13)C(18)O(16)O) and m/z 48 ((12)C(18)O(18)O) isotopologues (referred to as [Formula: see text] and [Formula: see text]) can be used to study non-equilibrium isotope fractionations and refine temperature estimates. We utilize 5,448 [Formula: see text] and 3,400 [Formula: see text] replicate measurements of carbonate samples and standards, and 183 [Formula: see text] and 195 [Formula: see text] replicate measurements of gas standards from 2015 to 2021 from a multi-year and multi-instrument data set to constrain [Formula: see text] and [Formula: see text] values for 27 samples and standards, including Devils Hole cave calcite, and study equilibrium [Formula: see text] – [Formula: see text] , [Formula: see text]-temperature, and [Formula: see text]-temperature relationships. We compare results to previously published findings and calculate equilibrium regressions based on data from multiple laboratories. We report acid digestion fractionation factors, [Formula: see text] and [Formula: see text] , and account for their dependence on the initial clumped isotope values of the mineral.