No 6 (2025)

The gold-bearing zone of the Yagodnoye ore occurrence was studied to determine the nature of metasomatic alterations in the host rocks, the chemical composition of chlorite, and the conditions of its formation. Metasomatites exhibit mineralogical and textural-structural characteristics typical of propylites from the epidote-chlorite subfacies. Petrographic analysis was conducted by Nikon Eclipse LV 100 ND optical microscope, while chlorite composition was determined via Tescan Vega 3 LMH scanning electron microscope equipped with an Oxford Instruments X-Max energy-dispersive spectrometer. The chemical composition of the studied chlorite corresponds to clinochlore. The temperature of mineral formation was estimated by a chlorite geothermometer. Clinochlore (pycnochlorite), associated with gold-bearing pyrite metacrystals, formed at 306–235 °C. Clinochlore (pennine) is found only in the form of single inclusions in pyrite, is significantly enriched in Si, and its formation temperature is 185–157 °C. The paragenetic association of chlorite with gold-bearing pyrite metacrysts suggests that both minerals were co-precipitated simultaneously during a single metasomatic process at 306–157 °C with a peak temperature of 306–235 °C.

For the first time, based on geological, paleoglaciological and paleogeomorphological factors of glaciolithogenesis and their influence on the formation of the composition of moraines, the lithological and paleogeographic zoning of the European North-East of Russia was carried out. 32 littoral regions were identified, which were elementary units of zoning, within which the lithological correlation of moraines was carried out without hindrance in any direction. The map of littoral regions was compiled taking into account the results of a comprehensive lithological study of moraines. The structural (granulometric) characteristics of the Pechora (Dnieper) and Vychegda (Moscow) moraines of the Middle Neopleistocene were obtained, the mineral composition of the fine-sand fraction and the petrography of the coarse-grained material from the moraine horizons were studied. Mineralogical and petrographic features, orientation of detrital material, index rocks in moraines, as well as potassium-argon dating of boulders of crystalline rocks allowed reliable identification of locations of feeding glacial provinces. The compiled map is proposed to be used as a basis for regional and interregional lithological comparisons of moraines.

On June 23–25, 2025, the All-Russian Lithological Conference with International Participation «Geology of Reefs — 2025» was held at the Institute of Geology FRC Komi SC UB RAS under the auspices of the Ministry of Science and Higher Education of the Russian Federation and the Scientific Council on Lithology and Sedimentary Minerals of the Earth Sciences Department RAS. The program enlightened the study of reefogenic deposits in three areas: lithology and geochemistry of carbonate platforms and organogenic buildups, bacterial lithogenesis, and oil and gas potential of carbonate deposits. The conference also focused on the isotopic and geochemical characteristics of reef rocks, the modern formation of marine carbonates and organogenic buildups, and the role of gas fluids in the formation of bottom-level carbonates. The meeting was attended by representatives of more than forty scientific and industrial organizations and universities from Russia, Thailand and Kazakhstan. During practical classes of the youth school, young researchers studied samples and thin sections from the Upper Carboniferous and Lower Permian skeletal hills of the Northern and Subpolar Urals, and the structure of microbialites in the Lower Carboniferous deposits (Unya River, Northern Urals). The speakers noted the richness of the program and a high quality of the reports.