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

40 Ar/39 Ar同位素地质年代计在岩石、矿物、化石和陨石定年方面的应用受到限制，因为现有的40 K同位素半衰期测定方法精度和一致性不足。本项目提出了新的方法来确定半衰期和分支比的40 K，年龄比较良好的校准87 Rb-87 Sr和40 K-40 Ca地质年代计。所有同位素系统的年龄将在相同的矿物中确定，从而消除了以前研究中不确定性的主要来源。该项目将通过对高浓缩40 K盐的衰变计数来测量40 K衰变率，并预计已知40 K衰变率的精度和准确度将提高五倍。

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.