ABSTRACT

Analyses of noble gases released by stepwise heating of Josephinite reveal two radiogenic components, radiogenic ¹²⁹Xe≈ 1 × 10^-12ccSTP/g and radiogenic ⁴⁰Ar≈1×10^-6ccSTP/g, and the following components of trapped noble gases: He with ³He/⁴He≈4×10^-5, Ne with ²⁰Ne/²²Ne = 10.5, Ar with ⁴⁰Ar/³⁶Ar = 3×10², and Kr and Xe with isotopic compositions similar to those observed in iron meteorites. The excess of ⁴⁰Ar and literature values of K in bulk Josephinite yield an apparent K-Ar age of ≈4.6×10⁹ years.