THE DISTINCTIVE FEATURES OF MINERAL COMPOSITION OF THE CARBONACEOUS SHALE IN THE RYLSKAYA STRUCTURE (VORONEZH CRYSTALLINE MASSIF) AS AN INDICATOR OF ROCK GENESIS

The subject of research in this study is the carbonaceous shale exposed by the drill-holes within the Rylskaya rift structure of the Kursk block of the Voronezh crystalline massif. The analysis of the examined rock revealed a complex of rock-forming and accessory minerals, i.e. apatite, pyrite, pyrrhotite, sphalerite, chalcopyrite, magnetite, rutile, garnets, zircon, staurolite, olivine, barite, moissanite, synchisite, bastnesite, which was for the first time described using the modern research methods. Therewith, moissanite, synchisite, and bastnesite were discovered in the shale of the Rylskaya structure for the first time. Several varieties of rutile, garnets, staurolites and zircons were for the first time identified by their physical characteristics and chemical composition. Fine-grained phlogopite and terrigenous K-feldspar were found in the main shale tissue. The discovered features of the shale’s mineral composition allow to define some of the aspects of the protolith nature and the sedimentation conditions of the studied rock. The wide range of accessory minerals, especially allogenic, that are characteristic of rocks of both acidic and basic-ultrabasic composition, as well as the presence of potassium feldspars in the rock tissue alongside with quartz, indicate the presence of rocks of various petrographic compositions with a low degree of weathering in the erosion areas.

carbonaceous shales, Kursk unit, mineralogy, Precambrian