Petrochemical Composition of Magnesian Traps as a Criterion in Forecasting Deposits of Sulfide Ores on the Siberian Platform

This paper deals with the previously published petrochemical composition of a large range of intrusive magnesian traps as a criterion for predicting the occurrence of sulfide Cu-Ni mineralization. Comparing sample intrusives with the composition of the reference ore-bearing intrusives that contain industrial mineralization (Norilsk I, Verkhne-Talnakh), assessment can be made from the diagrams relating MgO with rock-forming oxides and with a series of petrochemical parameters suggested by A. M. Vilenskii. It was shown that the commercial ore-bearing traps can be distinguished from all other magnesian traps by the following parameters: silica content, Al.–Ac. (minimum values), fractionation coefficient, differentiation degree, basicity, heating loss, and Fe2O3 (maximum). Less suitable are concentrations of FeO, alkalies, Al2O3, TiO2, P2O5, and some others yielding intermediate values. The above features can be used both directly and for sorting objects by logical-mathematical analysis.