pdf № 336, December

DOI: 10.19110/geov.2022.12.1

A lithological description of natural outcrops of Upper Silurian rocks in the section of the Sizimcelebeyshor creek of the Chernov uplift has been presented. Based on the results of the studies, the sedimentation gap at the end of Gerd'yu superhorizon is characterized. We consider breccias and interlayers of red-green plastic eluvial clays associated with the unconformity as occurrences of the Silurian paleocarst. This factor should be taken into account in the local forecast of zones with improved reservoir properties for carbonate rocks. The conducted studies allow significantly replenishing the sedimentological and chronostratigraphic characteristics of this area of work, which in the future can contribute to solving problems of regional correlation, paleofacial reconstructions and optimization of geological exploration.

Keywords: Upper Silurian, Gerd'yu and Greben' superhorizons, lithology description, regional unconformity, brachiopods, conodonts, Chernov Uplift.

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DOI: 10.19110/geov.2022.12.2

The Chernyshev Swell is one of the poorly studied and promising areas for the hydrocarbon (HC) exploration in the north of the Timan-Pechora Petroleum Province. Lower Devonian carbonate deposits as part of the Middle Ordovician-Lower Devonian petroleum complex are considered as a priority object for the HC exploration. The study of the Lower Devonian deposits in well core and outcrop showed that the reservoirs were represented mainly by fractured-cavern-pore and cavern-fractured dolomites. The porosity of the rocks reaches 9.3 % with a predominance values in the range of 0.5–1.5%. The permeability values up to 1.0×10^–15 m² are predominant, less often in the range of 1–10×10^–15 m². Such filtration and capacitive properties characterize them as low-capacity and low-permeable reservoirs. The best properties of reservoirs are associated with facies of carbonate shallows, small biostomes and biogerms. The petroleum source rocks are contained in the clay-carbonate unit of the Ovinparma Formation. The OM richest rocks (C_org — 1.08–1.88%) are characterized by the values of (S₁+S₂) generation potential — 2.18–8.65 mg HC/g rock and hydrogen index HI — 153–432 mg HC/g C_org, which classifies them as medium petroleum source rocks. Thus, the presence of reservoirs, petroleum source rocks and overlapping by the Upper Devonian regional seal is a favorable condition for the formation of HC deposits in the Lower Devonian.

Keywords: Chernyshev Swell, Lower Devonian, reservoirs, porosity, permeability, hydrocarbons.

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DOI: 10.19110/geov.2022.12.3

The results of the study of textural and structural features of acidic volcanites of the extrusive-subvolcanic body of the Lyadgey Complex (lV₂ld) between the Pravy Izyavozh and the Levy Izyavozh creeks of the southern part of the Enganepe Ridge are reported. We found that the extrusive-subvolcanic formation had an inhomogeneous structure due to the zonal arrangement of rock varieties: massive, fluid and spheruloid rhyolites, clusters of rhyolite and dacite composition. Prominence in relief, signs of extrusion of viscous lava, flow textures, successive change from west to east of fluid varieties by massive and then spheroid, the presence of clastolaves of rhyolite and dacitic compositions allow classifying the studied object as an extrusive genetic type.

Keywords: extrusive-subvolcanic body, rhyolite, clastolava, Enganepe Ridge.

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DOI: 10.19110/geov.2022.12.4

We refined the age of carbonate and clastic volcanomictic rocks of the Toupugol'egart Formation (D_1–2tg) of the Voikar Belt of the Polar Urals, which formed at the final stage of the Polar Ural Island arc development. The analysis of the stratigraphic distribution of fossils of the Toupugol'egart Formation was based on a revision of previously published data and new collections of the authors (algae, tabulatomorphic corals). The stratigraphic range of the Toupugol'egart Formation was extended up to the Karpinsky-Langur regional stages of the Emsian‑Eifelian of the Devonian. The similarities of the structure, lithological composition and paleontological associations of carbonate sequences of the Toupugol'egart Formation and the upper part of the Malyj Ural Formation (Voikar Belt of the Polar Urals), as well as the Terrigenous-Volcanogenic Formation (eastern slope of the Middle Urals) were noted. The accumulation of these deposits took place in the Late Emsian‑Early Eifelian, probably during joint sedimentary-volcanogenic cycle within a single extended island-arc system. We assumed a similar evolution of the Polar Ural and Tagil island arcs at the final stage of their formation.

Keywords: tabulatomorphic corals, calcareous algae, biostratigraphy, island arc, Toupugol'egart Formation, Emsian, Eifelian, Devonian, Polar Urals.

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DOI: 10.19110/geov.2022.12.5

The relevance of the material presented in this article is related to the identification of the dependence of the anomalous heat flux magnitude on the angle and velocity of lithospheric subduction, and assuming the constancy of the effective viscosity of the upper mantle material and the conductive mechanism of dissipative heat transfer. We analytically solved the equation of dissipative heat transport in a mantle wedge over a flatly subducting lithospheric plate on the basis of the method estimating the anomalous heat flux carried to the day surface from the mantle wedge in the rear of subduction zones. As a result, exemplified by Amur and Adriatic plates, for which the velocity of subduction is determined by modern geodetic methods (approximately 10 mm per year) and the angle of subduction — from seismological data (25–30 degrees), the obtained dependence of the anomalous heat flux on the angle and velocity of lithospheric subduction is proved valid. The previously unmeasured velocity of the Black Sea microplate subduction under the Crimea was estimated of 3 mm per year. With the obtained velocity of matter in the mantle wedge at the roof of the mantle, the upward conductive flow can provide the observed removal of heat and hydrocarbons from the mantle to the day surface and the formation of hydrocarbon deposits.  

Keywords: angle, velocity of subduction, heat flux anomalies, dissipative heating.

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DOI: 10.19110/geov.2022.12.6

A preliminary assessment by the optical-mineralogical analysis can often be sufficient to solve production tasks, to study the raw composition, and to choose a processing method at the initial stages of technological researches. Such an assessment will also help to determine the vector of further studies. The material for the primary mineralogical assessment was a waste sample from the Kuznetskaya Central Processing Plant. We used the method of optical-mineralogical analysis during the mineralogical study. Factory wastes are related to the technogenic mineral raw of the first group. We have shown that it is necessary to involve coal mining wastes in the comprehensive recycling with the obligatory mineralogical and technological assessment to determine methods of preparing raw for processing and technology of its enrichment. Our conclusion is that gravity processing methods can be used for the primary concentration of coal from tailings.

Keywords: mineralogy of coal deposits, optical-mineralogical analysis, technogenic mineral wastes, coal mining wastes, comprehensive processing of mineral raw materials.

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DOI: 10.19110/geov.2022.12.7

The article presents novel information about tourmaline inclusions in pyrite from Riphean terrigenous deposits of the Middle Timan. The inclusions are predominantly small (up to 100 µm), belong to the alkaline group and the hydroxy-subgroup of the tourmaline supergroup. In chemical composition and Raman spectra they correspond to schorl, dravite; uvite and feruvite are less common. The nature of the relationship between tourmaline and pyrite, perfect short and long prismatic shape of the crystals, and the low degree of roundness suggest that they were formed at the time of pyrite crystallization.

Keywords: pyrite, tourmaline, Middle Timan.

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