Petrophysical grouping of schist rocks of the Nerkayu complex (the Nether-Polar Urals)

The article presents results of petrophysical grouping of schist rocks of the Nerkay complex using petrophysical, petrographic and mineralogical data. Among crystalline schists, four petrogroups differing by material composition, physical parameters and genesis are identified for the first time. Two petrogroups are distinguished by density. The first petrogroup with low densities is represented by highly foliated garnet-bearing and garnet quartz-clinozoisite-amphibole-chlorite-muscovite-albite schists formed over clayey rocks. The second petrogroup of rocks with increased densities consists of gneissose rocks, the protolith of which was sandstones, as well as apobasaltic predominantly amphibole schists. According to their magnetic properties, four petromagnetic groups are distinguished: two non-magnetic, depending on the rock-forming minerals, and two magnetic, determined by the amount of magnetite formed during secondary (superimposed) processes.