USGS

U.S. Geological Survey Open-File Report 01-257

By Kinga M. Revesz, Jurate M. Landwehr, and Jerry Keybl


SUMMARY

Calcium carbonate or calcite (CaCO3) can be analyzed for the stable isotopes of carbon and oxygen. A new method was developed to analyze small samples (approximately 400 µg of calcium carbonate). The new method streamlines the classical H3PO4 - CaCO3 reaction method by making use of a Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. The method was tested by analyzing calcite from Devils Hole, Nevada core DH-11.

Results using the new GasBench II were comparable to the results obtained when the classical method was used. The advantages of the new method are that it requires less sample materials, making finer sampling resolution possible as well as automating several processes resulting in considerable time saving. These advantages make the GasBench II method a viable alternative to the classical method.


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