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Carbon and Oxygen Isotopic Normalization Tool for Carbonates

What is the "Carbon and Oxygen Isotopic Normalization Tool for Carbonates" ?

To enable researchers worldwide to publish the same δ18O value (within experimental uncertainty) for the same carbonate sample, the reported acid fractionation factors for calcite at 25, 50, and 75 °C have been re-evaluated by

Kim, S.-T., Coplen, T. B., and Horita, J., 2015, Normalization of Stable Isotope Data for Carbonate Minerals: Implementation of IUPAC Guidelines: Geochimica et Cosmochimica Acta, in press.

A revised relation has been proposed for the temperature dependence of oxygen isotopic acid fractionation factor, αCO2(ACID)-calcite, of

1000lnαCO2(ACID)-calcite = 3.48(103 / T ) – 1.47

where T is temperature in kelvin. At 25 °C, αCO2(ACID)-calcite = 1.01025, the most commonly accepted value for this quantity. In this article, the authors propose a normalization protocol in which (1) the internationally distributed carbonate isotopic reference materials NBS 18 and NBS 19 are interspersed among carbonate samples analyzed by treatment with phosphoric acid, (2) the δ18O values of the calcite reference materials and the carbonate samples are calculated, respectively, by using the αCO2(ACID)-calcite relation above and oxygen-isotope acid fractionation factors appropriate for the sample mineralogy and reaction temperature, (3) the δ18O values of solid carbonate samples are determined on the VPDB scale (δ18OVPDB) with IUPAC-recommended scale expansion, such that the δ18O of SLAP reference water is –55.5 ‰ relative to VSMOW reference water by normalizing δ18O values of carbonate samples with 2014-IUPAC-recommended δ18O values of NBS 18 and NBS 19, and (4) δ18O values on the VPDB scale are converted to δ18O values on the VSMOW-SLAP scale by using IUPAC recommendations.

To facilitate implementation of the unified normalization protocol, a computer application, "Carbon and Oxygen Isotopic Normalization Tool for Carbonates", has been developed for computers running the Windows® operating system. The program requires either Access 2007 (or later) or the free Access Runtime that enables users who do not have Access to run this Access software application.

Obtaining the Carbon and Oxygen Isotopic Normalization Tool for Carbonates