Home – Home – Jornals – Russian Geology and Geophysics 2023 number 7

The leading role of lithostratigraphic, structural/tectonic, magmatic, metamorphic, and fluid geologic factors in the formation of a graphite deposit is substantiated. We present the petrographic and chemical compositions of rocks and minerals of igneous rocks, the δ¹³С values of graphites and calcitites, the δ¹⁸O values of carbonates, the δ³⁴S values of sulfides, and the ⁸⁷Sr/⁸⁶Sr and ⁸⁷Rb/⁸⁶Sr ratios in calcitites and microdolerite injections. The thermal effect of magmatic melt on coal led to its degassing and graphitization. The steaming of microdolerite injections with hydrocarbon fluids was probably accompanied by the removal of iron from them and the crystallization of low-Fe clinopyroxene, and the interaction of fluids with basaltic melt in the upper endocontact zone of the intrusion led to the segregation of the melt and the formation of a globular structure of rocks. The presence of a calcite lens and a sulfide vein between the roof of the intrusion and the graphite bed is due to the earlier intrusion of sulfate salt melt and its subsequent interaction with hydrocarbon fluids, which resulted in sulfate reduction and the formation of calcites. The sulfate reduction terminated with iron sulfurization in the basaltic melt and the formation of a sulfide vein. Sulfate salt melt was a source of heavy sulfur isotope (δ³⁴S = 14.9-17.5‰) for sulfides and of calcium for calcites. The similar isotope compositions of calcites (δ¹³С_PDB = -22.5 to -23.5‰), coals (-22.6 to -25.5‰, n = 25), and graphites (-23.5 to -25.0) suggest that coal is a source of carbon for calcitites. In the isotopic compositions of strontium (⁸⁷Sr/⁸⁶Sr ≈ 0.70834-0.70885) and oxygen δ¹⁸O ≈ 15‰) the calcites are similar to the Devonian evaporites of the Siberian Platform. The isotope data (δ³⁴S, δ¹⁸O, δ¹³С, and ⁸⁷Rb/⁸⁶Sr) point to the participation of the coal seam and anhydrite as sources of substance in the formation of calcitite and sulfide mineralization.