Measurements of Ir concentration in geological standard samples using neutron activation analysis with multiple gamma-ray coincidence method

In this study, the Ir concentrations in some standard rock samples were determined by using the multiple γ-ray detection method. The use of the multiple γ-ray detection method, which was developed for nuclide quantification, yielded better resolution and sensitivity than the ordinary singles γ-ray detection method. Iridium is one of the least abundant elements in Earth’s crust, with an average mass fraction of 0.001 ppm in a crust rock. However, iridium is relatively more abundant (concentration: 0.5 ppm or more) in undifferentiated meteorites. Therefore iridium abundance anomalies in geological samples provide important information about meteorite impact. The standard rock samples used in this study were SARM-76, FC-1 and FC-2. The SARM-76 was prepared from a platinum ore, and issued by the south African bureau of standards. FC-1 and FC-2 were obtained from fish clay sediment samples from Stevens Klint, Denmark.