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On August 24, 1976 the IUGS Subcommission on Geochronology4 met in Sydney, Australia, during the 25th International Geological Congress. They unanimously agreed to recommend the adoption of a standard set of decay constants and isotopic abundances in isotope geology. Values have been selected, based on current information and usage, to provide for uniform international use in published communications. The Subcommission urges that all isotopic data be reported using the recommended values (see appendix).

The recommendation represents a convention for the sole purpose of achieving inter laboratory standardization. The Subcommission does not intend to endorse specific methods of investigation or to specifically select the works of individual authors, institutions, or publications. All selected values are open to and should be the subjects of continuing critical scrutinizing and laboratory investigation. Recommendations will be reviewed by the Subcommission from time to time to bring the adopted conventional values in line with significant new research data.

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