Evolution of sulfide liquid at Kingashsky ultramafic massif formation (north-west of Eastern Sayan)

Abstract

The study subject of the paper is the sulphide mineralization of rocks of the Kingashsky dunite-wehrlite-picritic massif, which is the standard of an object of ultramafic complex in the Kan block (north-western part of the Eastern Sayan) with the same name and which includes eponymous large Cu-Ni deposit with PGE. Despite the increased interest of many researchers to the massif, a number of issues on its petrological nature and mechanisms of formation and localization of Pt-Cu-Ni ores in it are still controversial. The paper attempts to trace the evolution of the material composition of sulfide melt at formation of the massif rocks and their subsequent metamorphic changes. The paper introduces typomorphism, mineral and chemical composition of sulfide minerals. The carried out studies show that sulphide mineralization is spatially associated with all breeds of Kingashsky array, but the ore industrial amounts are mainly found out in dunites. The features of sulfide association indicate high iron index in Kingashskaya ore-magmatic system as a whole and brings it closer to the copper-nickel deposits of the Early Proterozoic. The genetic feature of sulfide mineralization of the Kingashsky massif is relatively rapid temperature decrease of sulfide melt without its significant fractionation at high rate of magma transportation from the magmatic chamber into the upper floors of the lithosphere. Typomorphic characteristics and chemical composition of sulfide minerals, their relationship and paragenesis allowed supposing two stages in formation of the noted mineralization (magmatic and low temperature epimagmatic) as well as reconstructing the evolution of sulfide melt when crystallizing massif rocks.

Keywords

• Kingashsky massif
• ultramafites
• sulfide mineralization
• chemistry
• evolution of liquid