The Role of Sulphurization in the Genesis of Iron-Nickel Sulphide Deposits of the Porcupine District, Ontario

CIM Bulletin, 1966

A. J. Naldrett Department of Geology, Queen's University, Kingston, Ontorio.

Sulphurization of peridotite, that is 'to say reaction between sulphur from an external source and iron and nickel in the silicate minerals of the peridotite or in partially consolidated magma, is believed to be the mechanism by which the small ironnickel sulphide deposits associated with the ultrabasic rocks of the Porcupine district have formed. The pyrrhotite-pentlandite ore at the Alexo mine, Dundonald township, is localized by a shear that closely follows the lower contact of a peridotite lens. In the past, to account for this orebody, the magmatic segregation hypothesis has been advanced on the basis of textural evidence and the presence of the sulphides at the base of the lens. The nickel sulphide deposits of the Porcupine, however, are not characteristically found along the basal contacts of bodies of peridotite. Furthermore, this study has shown that textures formerly thought indicative of magmatic segregation have been formed in certain deposits by the selective replacement of silicates by sulphides.
Keywords: Deposits, Meteoritic Sulphur, pentlandite, peridotite, pyrrhotite, Thompson-Moak Lake Nickel Belt, nickel, Ore, Ores, sulphide, Sulphides, sulphur