Lu-hf total-rock isochron for the eucrite meteorites

Abstract

The isotope 176Lu (2.6% of natural lutetium) decays by β- to 176Hf, with a long half life. We present here the first Lu-Hf isochron. The eucrite meteorites, a suite of planetary igneous rocks of known age, 4,550 Myr, define a 10-point total-rock isochron with a slope of 0.0934 ± 40, leading to a value of 3.53 ± 0.14 ×1010yr for the β--decay half life of 176Lu. The isochron intercept of 0.27973 ± 12 gives the initial 176Hf/177Hf for the inner Solar System at the time of accretion. © 1980 Nature Publishing Group.