Precise cross-calibration of 40Ar/39Ar, Rb-Sr and U-Pb chronometers: towards an integrated geochronology toolbox

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Application of the 40Ar/39Ar isotopic geochronometer to dating rocks, minerals, fossils and meteorites is limited by insufficient precision and consistency in existing determinations of the half-life of its parent isotope 40K. This project proposes novel methods for determination of the half-life and branching ratio of 40K, by age comparison against well calibrated 87Rb-87Sr and 40K-40Ca geochronometers. The ages with all isotopic systems will be determined in the same minerals, thus eliminating the main source of uncertainty in the previous studies. Independently The project will measure the 40K decay rate by decay counting of highly enriched 40K salt and expects a five-fold improvement in precision and accuracy of known 40K decay rate.