InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards

Abstract

The exclusive use of carbonate reference materials is a robust method for the standardization of clumped isotope measurements • Measurements using different acid temperatures, designs of preparation lines, and mass spectrometers are statistically indistinguishable • We propose new consensus values for a set of 7 carbonate reference materials and updated guidelines to report clumped isotope measurements

Full Propagation of Analytical Uncertainties in Δ47 Measurements

“…agated Δ 47 errors may also be treated as Gaussian for all practical purposes. What is more, as reported by Bernasconi, Daëron et al (2021), using this framework yields a very reasonable (p = 0.19) prediction for the distribution of inter-laboratory scatter in Δ 47 values within the InterCarb data set.…”

“…Because the relative contributions of the autogenic and allogenic error components defined above (Equations 11-13) are sensitive to the distribution of analyses among anchor and unknown samples and on the isotopic composition of unknowns relative to the anchor polygon, they are expected to vary greatly between laboratories and/or sessions. The InterCarb data set, comprising over five thousand analyses from 22 different laboratories (Bernasconi, Daëron, et al, 2021), offers an excellent opportunity to quantify these two components in a wide range of realistic settings. which plots within the anchor polygon defined in (δ 47 , Δ 47 ) space by ETH-1/2/3, are generally slightly smaller than autogenic errors, resulting in a modest increase of the total Δ 47 error (σ 47 ) relative to the autogenic error.…”

“…Petersen et al (2019) tested the first two of these hypotheses and found that using unified methods for 17 O correction and subsequent data processing reduced inter-laboratory discrepancies without eliminating them. Testing the third hypothesis is one of the goals of the recently completed inter-laboratory comparison exercise "In-terCarb", whose results are reported in a companion study (Bernasconi, Daëron, et al, 2021).…”

Coupled Mg/Ca and Clumped Isotope Measurements Indicate Lack of Substantial Mixed Layer Cooling in the Western Pacific Warm Pool During the Last ∼5 Million Years

“…Δ 47 values for both the calibration and our samples were originally derived using values for ETH1-3 as published by Bernasconi et al (2018). However, thanks to a community-wide effort to improve inter-laboratory comparison, the accepted values for these standards have recently been updated (I-CDES scale; Bernasconi et al, 2021). Although measured prior to this recent advance, our Δ 47 data were fully recalculated using the updated standard values and reported on the I-CDES scale.…”

“…This recalculated version of the calibration by Meinicke et al (2020) should be used instead of the original version (Meinicke et al, 2020, Equation 2) for future studies that are based on the I-CDES scale proposed by Bernasconi et al (2021).…”