A Unified Clumped Isotope Thermometer Calibration (0.5-1,100°C) Using Carbonate-Based Standardization

The potential for carbonate clumped isotope thermometry to independently constrain both the formation temperature of carbonate minerals and fluid oxygen isotope composition allows insight into long-standing questions in the Earth sciences, but remaining discrepancies between calibration schemes hamper interpretation of temperature measurements. To address discrepancies between calibrations, we designed and analyzed a sample suite (41 total samples) with broad applicability across the geosciences, with an exceptionally wide range of formation temperatures, precipitation methods, and mineralogies. We see no statistically significant offset between sample types, although the comparison of calcite and dolomite remains inconclusive. When data are reduced identically, the regression defined by this study is nearly identical to that defined by four previous calibration studies that used carbonate-based standardization; we combine these data to present a composite carbonate-standardized regression equation. Agreement across a wide range of temperature and sample types demonstrates a unified, broadly applicable clumped isotope thermometer calibration.

Automated summary

The study analyzed a diverse sample suite in order to address discrepancies between calibration schemes for carbonate clumped isotope thermometry. The results showed no statistically significant offset between sample types, leading to the proposal of a composite carbonate-standardized regression equation. The agreement across a wide range of temperatures and sample types demonstrates a unified and broadly applicable clumped isotope thermometer calibration.