EXPERIMENTAL MODELING OF ZONING IN COPPER-NICKEL SULFIDE ORES

Abstract

The formation of copper–nickel sulfide deposits of the Norilsk and Sudbury types is related to the ore-bearing layered mafic–ultramafic intrusions that are confined to local platform depressions. The initial stages of the deposit formation include the separation of mafic magma into immiscible silicate and sulfide melts, the secondary layering of the sulfide liquid into the fractions enriched in Ni and Cu, and their subsequent gravitational differentiation. The solidification of the Fe–Ni sulfide melt produces pyrrhotite–pentlandite mineralization, while the progressive crystallization of the second fraction leads to the formation of pyrrhotite–pentlandite–chalcopyrite and other ores, including the mineral assemblages with chalcopyrite, bornite, and other minerals. These processes provide the zonal arrangement of ores of different types at the deposits with spatial differentiation of mineral assemblages accompanied by regular variations in contents of both major and trace elements (including PGE) throughout orebodies.