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

40Ar/39Ar同位素地质年代仪在岩石、矿物、化石和陨石测年中的应用受到现有母体同位素40K半衰期测定精度和一致性不足的限制。这个项目提出了一种新的方法来确定40K的半衰期和分支率，方法是通过与刻度良好的87Rb-87Sr和40K-40Ca地质计时器进行年龄比较来确定。所有同位素体系的年龄将在相同的矿物中确定，从而消除了以前研究中的主要不确定性来源。该项目将独立地通过对高度浓缩的40K盐进行衰变计数来测量40K衰减率，并预计已知的40K衰减率的精密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.