Cu-Ni-PGE mineralization in the Morrison deposit, Sudbury

Abstract

Ore in Morrison deposit (Sudbury) is rich in copper, nickel, platinum, palladium and gold. Chalcopyrite dominates mineral assemblage, while the main Ni-bearing phases are pentlandite and millerite. Cubanite, pyrrhotite, mackinawite, magnetite, sphalerite and galena are accessory minerals. Platinum occurs as discrete minerals: moncheite ($PtTe_{2}$) grains with hessite ($Ag_{2}Te$), maslovite (PtBiTe) and sperrylite ($PtAs_{2}$). Palladium might occur as a substitution in pentlandite and as a discrete PGM phases: michenerite (PdBiTe) and paolovite ($Pd_{2}Sn$). Observed zonation in the deposit can be explained by fractional crystallization of magmatic sulfides. There is a possibility of partial remobilization of precious metals (especially gold) by later hydrothermal and/or metamorphic processes which are represented by authigenic quartz, silicates (epidote, amphiboles) and secondary magnetite containing sulphide inclusions.