Petrology of the Mount General'skaya layered intrusion, Kola Peninsula

The Early Proterozoic (similar to 2.5 Ga) platinum-bearing layered intrusion of Mount General'skaya (Luostari) is situated in the northeastern contact zone of the Pechenga segment of the large rift structure Pasvik-Pechenga-Imandra-Varzuga. On the basis of a detailed study of cores from several deep holes and considerable analytical data, a scheme of stratification is proposed for the massif. Its cumulus and intercumulus parageneses, phase and cryptic layering, and ore associations are characterized in detail. Petrologic and geochemical factors of the localization of PGE-Cu-Ni mineralization are discussed. It is suggested that the formation of PGE-Cu-Ni mineralization in the massif was caused by a number of interrelated processes of matter differentiation in magma chambers resulting in the accumulation of residual fluid-saturated intercumulus melt enriched in volatile and incompatible components in the central part of the massive.