Analytical effects on clumped isotope thermometry: Comparison of a common sample set analyzed using multiple instruments, types of standards, and standardization windows.

Rationale: Carbonate clumped isotope geothermometry is being increasingly used in multiple disciplines in the geosciences. However, potential interlaboratory issues are arising from different standardization procedures that may contribute to the multiple Δ -temperature calibrations reported in the literature. We investigate this issue by comparing a common temperature calibration sample set across three different mass spectrometers, using multiple standardization methods.

Methods: The same temperature calibration sample set was analyzed on three different mass spectrometers. Several standardization methods were utilized, including the use of carbonate versus gas standards, and different types of background correction were applied to the raw data.

Results: All standardization types applied resulted in statistically indistinguishable Δ -temperature slopes, with the exception of standardization calculations that did not correct for background effects. Some instruments and standardizations showed different intercepts relative to each other. The use of carbonate standards improved comparability between different instruments relative to gas standards.

Conclusions: Our results show that background effects are the largest factor potentially affecting Δ results, and there may be an improvement in interlaboratory precision using carbonate standards. Critically, all techniques used for standardizing Δ results converge on a common slope as long as background effects are properly corrected. The use of carbonate standards is recommended as a component of standardization procedures.