Platinoid deposits of the North-Asian craton and its framing: Metallogeny and geodynamics

Regularities in occurrence and formation of leading commercial and potentia lly commercial platinoid deposits in the North-Asian craton and its framing are tentatively defined. These deposits are associated with taphrogenic st ructures of the Aldan-Severnaya-Zemlya, Far-East, Arctic, Amur-Altai, and C entral-Asia-Chinese Pt-bearing belts. Globally, these structures are relate d to deep-seated faults and demonstrate anomalies in the Earth's crust and multistage character of geodynamic cycles, tectonomagmatic and minerogenic processes complicated or transformed by taphrogenesis, separation, and subd uction. As a result, ore-forming systems became polygenetic and polychronou s, and not only the belts themselves but also their separate constituents ( Pt-bearing provinces) consist of many formations. Circum-cratonic zoning marked by Riphean, Paleozoic, and Mesozoic black-sha le complexes has been recognized in distribution of Pt-bearing structure-fo rmational complexes. This zoning reflects the geochemical evolution of the Earth's crust and mantle. The objects which are the most promising for plat inum metals are localized by higher-rank taphrogenic zones, and the platino id ore genesis is related to subduction and fluid-thermal phenomena. The relationship between geodynamic processes and Pt-ore-forming systems, a s it is described in this paper, reflects, as a rule, general regularities in the metallogeny and geodynamics of the region.