Metasedimentary rocks from the Bol’shoi Cheremshan Group in the East European Platform basement: Initial mineral composition and petrogeochemical properties

The initial normative mineral composition of some metasedimentary rocks (high-alumina crystalline schists, aluminous gneisses, and eulysites) from the Archean Bol’shoi Cheremshan Group is considered. Based on some data (distribution of data points available for these rocks in diagnostic diagrams, values of several indicator ratios, and initial rock composition), it is assumed that examined rocks were partly formed after highly mature sediments (high-alumina crystalline schists and gneisses), while biotite-garnet-andesine gneisses represent products of graywacke sediments. Elevated concentrations of some indicator elements (Fe, Cr, Ni, V, Zn, Pb, and others) imply that material in the sedimentation paleobasin was likely derived from provenances composed of variable lithologies (ultramafic, mafic, intermediate, and acid rocks). It seems that conditions in this paleobasin were favorable for the development of organic life. It is shown that correlation between some elements (Ti, V vs. Al; Ba, Pb vs. K; Sr vs. Ca; La vs. Na; and others) typical of Phanerozoic sedimentary rocks is also observed in the rocks. The possible contents of organic matter (Corg) and U in primary sediments of metasedimentary rocks of the Bol’shoi Cheremshan Group in the East European Platform basement are reconstructed.