InterCarb: A community effort to improve inter-laboratory
standardization of the carbonate clumped isotope thermometer using
carbonate standards
Magali Bonifacie
Université de Paris, Institut de Physique du Globe de Paris, Université de Paris, Institut de Physique du Globe de Paris, Université de Paris, Institut de Physique du Globe de Paris, Université de Paris, Institut de Physique du Globe de Paris
Author ProfileAbstract
Increased adoption and improved methodology in carbonate clumped isotope
thermometry has greatly enhanced our ability to interrogate a suite of
Earth-system processes. However, interlaboratory discrepancies in
quantifying Increased use and improved methodology of carbonate clumped
isotope thermometry has greatly enhanced our ability to interrogate a
suite of Earth-system processes. However, inter-laboratory discrepancies
in quantifying carbonate clumped isotope (Δ47) measurements persist, and
their specific sources remain unclear. To address inter-laboratory
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 δ47 and Δ47
compositions, 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 inter-laboratory discrepancies entirely
consistent with in-laboratory 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 inter-laboratory 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
Δ47 (I-CDES) for Intercarb-Carbon Dioxide Equilibrium Scale.