CHAI, CF (reprint author), ACAD SINICA,INST HIGH ENERGY PHYS,POB 2732,BEIJING 100080,PEOPLES R CHINA.
Article; Proceedings Paper
Molecular activation analysis (MAA) of iridium in geological samples, based on a combination of a newly-developed chemical sequential dissolution method and radiochemical and instrumental NAA, was described to study the distribution pattern and chemical species of iridium in various fractions ( soluble carbonate, metal, sulfide, oxide, silicate and acid-insoluble residue) of geological boundary samples, meteorites, ultrabasic rock and volcanic lava. The correlations of Ir with Au, Os, siderophile, chalcophile and lithophile elements were discussed. In addition, the role of kerogen and noble-nugget in the Ir enrichment was scrutinized. The MAA results of Ir favors a mixed effect of asteroid impact, volcanic eruption and post-depositional redistribution to interpret the extant Ir anomaly at Cretaceous-Tertiary boundary layer.