S. V. Petersen, University of Michigan
W. F. Defliese, Texas A&M University
C. Saenger, University of Washington
M. Daëron, Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France
K. W. Huntington, University of Washington
C. M. John, Department of Earth Science and Engineering, Imperial College London, London, UK
J. R. Kelson, University of Washington
S. M. Bernasconi, Department of Earth Sciences, ETH-Zurich, Zurich, Switzerland
A. S. Colman, University of Chicago
T. Kluge, Institute of Environmental Physics and Heidelberg Graduate School of Fundamental Physics
G. A. Olack, University of Chicago
A. J. Schauer, University of Washington
D. Bajnai, Institute of Geosciences
M. Bonifacie, Institut de Physique du Globe de Paris, Paris, France
S. F. Breitenbach, Institute for Geology
J. Fiebig, Institute of Geosciences
A. B. Fernandez, Department of Earth Sciences, ETH-Zurich, Zurich, Switzerland
G. A. Henkes, Stony Brook University
D. Hodell, Cambridge University
A. Katz, Institut de Physique du Globe de Paris, Paris, France
S. Kele, Institute for Geological and Geochemical Research
K. C. Lohmann, University of Michigan
B. H. Passey, University of Michigan
M. Y. Peral, Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France
D. A. Petrizzo, Jet Propulsion Laboratory, Pasadena, CA, USA
B. E. Rosenheim, University of South FloridaFollow
A. Tripati, University of California
R. Venturelli, University of South Florida
E. D. Young, University of California
I. Z. Winkelstern, Grand Valley State University

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clumped isotopes, stable isotopes, calibration, standardization

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The clumped isotopic composition of carbonate-derived CO2 (denoted Δ47) is a function of carbonate formation temperature and in natural samples can act as a recorder of paleoclimate, burial, or diagenetic conditions. The absolute abundance of heavy isotopes in the universal standards VPDB and VSMOW (defined by four parameters: R13VPDB, R17VSMOW, R18VSMOW, and λ) impact calculated Δ47 values. Here, we investigate whether use of updated and more accurate values for these parameters can remove observed interlaboratory differences in the measured T-Δ47 relationship. Using the updated parameters, we reprocess 14 published calibration data sets measured in 11 different laboratories, representing many mineralogies, bulk compositions, sample types, reaction temperatures, and sample preparation and analysis methods. Exploiting this large composite data set (n = 1,253 sample replicates), we investigate the possibility for a “universal” clumped isotope calibration. We find that applying updated parameters improves the T-Δ47 relationship (reduces residuals) within most labs and improves overall agreement but does not eliminate all interlaboratory differences. We reaffirm earlier findings that different mineralogies do not require different calibration equations and that cleaning procedures, method of pressure baseline correction, and mass spectrometer type do not affect interlaboratory agreement. We also present new estimates of the temperature dependence of the acid digestion fractionation for Δ47 (Δ*25-X), based on combining reprocessed data from four studies, and new theoretical equilibrium values to be used in calculation of the empirical transfer function. Overall, we have ruled out a number of possible causes of interlaboratory disagreement in the T-Δ47 relationship, but many more remain to be investigated.

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Citation / Publisher Attribution

Geochemistry, Geophysics, Geosystems, v. 20, issue 7, p. 3495-3519

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