InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards
Stefano M. Bernasconi, Mathieu Daëron, Kristin Bergmann, Magali Bonifacie, Anna Nele Meckler, Hagit P. Affek, Noah Anderson, David Bajnai, Eugeni Barkan, Emily J. Beverly, Dominique Blamart, Landon Burgener, Damien Calmels, Carine Chaduteau, Matthieu Clog, Brett Davidheiser‐Kroll, Amelia Davies, Florian Dux, John M. Eiler, Ben Elliott, Anne C. Fetrow, Jens Fiebig, Samuel L. Goldberg, Michaël Hermoso, Katharine W. Huntington, Ethan G. Hyland, Miquela Ingalls, Madalina Jaggi, Cédric M. John, A. B. Jost, Sarah A. Katz, Julia R. Kelson, Tobias Kluge, Ilja Kocken, Amzad H. Laskar, Thomas Jan Leutert, Mao‐Chang Liang, Jamie Lucarelli, Tyler Mackey, Xavier Mangenot, Niklas Meinicke, Sevasti Modestou, Inigo A. Müller, Sean T. Murray, Ashling Neary, N. R. Packard, B. H. Passey, E.M. Pelletier, Sierra Petersen, Alison Piasecki, Andrew J. Schauer, Kathryn E. Snell, Peter K. Swart, Aradhna Tripati, Deepshikha Upadhyay, Torsten Vennemann, Ian Z. Winkelstern, Drake Yarian, Naohiro Yoshida, Naizhong Zhang, Martin Ziegler
Abstract
Abstract Increased use and improved methodology of carbonate clumped isotope thermometry has greatly enhanced our ability to interrogate a suite of Earth‐system processes. However, interlaboratory discrepancies in quantifying carbonate clumped isotope (Δ 47 ) measurements persist, and their specific sources remain unclear. To address interlaboratory differences, we first provide consensus values from the clumped isotope community for four carbonate standards relative to heated and equilibrated gases with 1,819 individual analyses from 10 laboratories. Then we analyzed the four carbonate standards along with three additional standards, spanning a broad range of δ 47 and Δ 47 values, for a total of 5,329 analyses on 25 individual mass spectrometers from 22 different laboratories. Treating three of the materials as known standards and the other four as unknowns, we find that the use of carbonate reference materials is a robust method for standardization that yields interlaboratory discrepancies entirely consistent with intralaboratory analytical uncertainties. Carbonate reference materials, along with measurement and data processing practices described herein, provide the carbonate clumped isotope community with a robust approach to achieve interlaboratory agreement as we continue to use and improve this powerful geochemical tool. We propose that carbonate clumped isotope data normalized to the carbonate reference materials described in this publication should be reported as Δ 47 (I‐CDES) values for Intercarb‐Carbon Dioxide Equilibrium Scale.