Typical features of platinum group minerals (PGMs) and the results of 190Pt-4He dating of the Fe-Pt solid solutions are presented for complex gold-platinum-diamond placers with unidentified sources of the Anabar River basin. For the first time, the 190Pt-4He isotopic system is used for determination of the possible age of the primary source of a PGM placer from the example of ferroan platinum with a disordered structure along with isoferro- platinum. The PGMs of these placers mostly include ferroan platinum and isoferroplatinum and rare Ru-Ir-Os alloys. The calculated bulk composition of the silicate inclusion of Ir platinum corresponds to the rocks of the ijolite-melteigite series. The 190Pt-4He age of the Fe-Pt solid solution grains is 261 ± 13 Ma. Thus, our data indicate the relation between placer PGMs of the Anabar River basin and Permian-Triassic complexes of alkaline-ultramafic rocks.
