关键词: 铂族元素, 地球化学行为, 铂族金属矿床类型, Urals杂岩体

Abstract:

Platinum group elements (PGE) deposits in the world can be divided into six types：(1)those associated with mafic-ultramafic layered intrusions；(2)those hosted in Cu-Ni sulfide deposits；(3)those associated with Urals complexes；(4)those associated with ophiolites；(5)those related to hydrothermal activity and (6)Placer PGE deposits. Except for the fourth type, all other types are economic. The genesis of PGE deposits are chiefly related to the nature of mantle-derived magmas and the processes of magmatic evolution. Large scale activities of mantle-derived magma and sulfursaturation in the magmatic evolution processes provide favour conditions for the generation of PGE deposits. The magmatism-related hydrothermal fluid can cause PGE transport and deposit under some special environments, thus sometimes it is good for the formation of PGE deposits. The good conditions for PGE concentrations are that the magmas are well differentiated, and that there is a condition for a high R factor in the mafic-ultramafic layered intrusions. The crystal differentiation of sulfide melt provides a good condition for the formation of PGE deposits for Cu-Ni sulfide deposits. For the PGE deposits associated Urals complexes, the platinum group metals (PGM) of Pt-Fe and Pt-Ir alloys formed because of sulfur-undersaturation in the early stage of magmatism, and they are mainly associated with chromitites. In contrast, Pd-rich PGM formed in the later stage of magmatism, and they are associated with Cu-Fe-V-Ti-P metals. In the ophiolite complexes, the major PGMs are Ir-, Os-, Pt alloys, and minor sulfides, and most of them are hosted in chromitites.

Key words: platinum group elements, geochemistry behavior, types of PGE deposits, Urals complex