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OF ISOTOPIC AGES FOR BRITISH COLUMBIA : BCAGE 2003

Isotopic age determinations form a critical part of the geoscientific knowledge base for British Columbia. Isotopic ages were first reported for rock units in British Columbia in 1960, with the advent of the potassium-argon (K-Ar) method of dating. Subsequent decades witnessed the widespread application of additional dating methods, such as the Rb-Sr method in the mid-1970’s, the U-Pb and fission-track methods in the mid-1980’s, and the Ar/Ar and Nd-Sm methods in the late 1990’s. More recently, age determinations utilizing the Lu-Hf, Re-Os or (U-Th)-He systems are increasingly being reported as these dating methods are refined. Isotopic dating has been widely used in British Columbia for more than four decades, and the number of isotopic ages which have been generated from rock units within British Columbia is very large. However, because all of the data was never collated into a single database, accessing and utilizing these age determinations for geologic study has been difficult. Firstly, while it is generally known that some older age determinations are not reliable due to either revision to applicable decay constants, outdated systematics and/or analytical techniques, most users do not have the technical background required to evaluate the reliability of a reported age. Secondly, not all reported dates are properly indexed or keyworded such that they can be found by an indexing engine such as GeoRef. Finally, a great many isotopic ages are reported in “grey literature” such as unpublished theses, which are difficult and in some cases expensive to obtain, and are commonly only available in a cumbersome format such as microfiche. Theses are also usually not consistently indexed on any search engine, and contained age data must be laboriously extracted by searching each university’s individual library catalogue.