pdf № 334, October

DOI: 10.19110/geov.2022.10.1

Detailed geological and geophysical studies discovered intensive local gravimetric anomalies (Frolovskaya, Chetdinskaya, Lokchimskaya, Kynmemtila and others) in the south of the Komi Republic, which were promising for the discovery of bodies of the basic (ultrabasic ?) composition in the production of geological and geophysical works [8, 9].

Within them, a database of XYZ (recorded and extrapolated) in arbitrary units of the gravity field and their rectangular coordinates was created in the Microsoft EXCEL program, with more than 1600 values, and formed grid files, based on them, formed the basis for calculations in the Golden Software SURFER program for constructing models of the deep structure. As a result of the interpretation of the gravity field, geological and geophysical models of the deep structure of the Frolovskaya, Chetdinskaya and Lokchimskaya local gravity anomalies of increased intensity of different signs were built.

Keywords: anomalous gravity field, deep structure, orthogonal fault zones.

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DOI: 10.19110/geov.2022.10.2

The peat from the Cherny Yar section at the Vychegda river was studied by a complex of palynological and geochemical methods. We determined that among the aliphatic hydrocarbons of bitumen, the maximum concentrations were characteristic for odd n-alkanes with a predominance of C₂₇-C₃₁ homologues, as well as 18-norabietane. Aromatic hydrocarbons are mainly represented by structures formed during the fossilization of diterpenoids and triterpenoids of higher vegetation. Among the aromatic diterpenoids, there are 18-norabieta-8,11,13-triene, 18-norsimonellite and retene, which are markers of conifers, as well as 18-norabietane of the aliphatic fraction. Among the aromatic triterpenoids, numerous transformation products of compounds with the carbon skeleton of lupan, oleanan, and ursane, characteristic of angiosperms, have been identified. For example, dinorolean(ursa)-1,3,5(10),13(18)-tetraene, dinorolean(ursa)-1,3,5(10)-triene, pentanoroleana-1,3,5(10), 6,8,11,13,17(18)-octaene and others. The data on the composition of hydrocarbons confirm the palynological data about the presence of coniferous and hardwood pollen in the composition of peat. The change in the composition of hydrocarbons along the section confirms the change in the species composition of vegetation in the study area, diagnosed by microfossils. The comparison of the composition of peat biomarker hydrocarbons with palynological data revealed their consistency with each other and possibility of conjugated use of these methods in paleogeographic reconstructions.

Keywords: biomarker-hydrocarbons, peat, Middle Vychegda, n-alkanes in peat, aromatic terpenoids, palynology, paleogeographic reconstructions.

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DOI: 10.19110/geov.2022.10.3

In contrast to the established ideas about the relationship of gold mineralization with any specific source, a model is proposed for the evolution of different sources during the formation of geological structures in the eastern framing of the Siberian Platform. The model is based on the calculation of regional clarkes of sedimentary, igneous rocks and minerals with the allocation of stratigraphic levels of primary gold enrichment in sedimentary rocks. The poly-stage and multi-stage nature of the evolution of sources is established through the redistribution of gold in the composition of sedimentary rocks and minerals under the influence of various endogenous heat and mass transfer agents, in particular, under the influence of carbonatites. The main condition for the localization of gold mineralization in the region is the presence of levels of primary supraclarke gold concentrations in turbidites R₃, C₃—P₁, T₃ of the deltaic facies of submarine slopes. The main gold concentrators in sediments are marcasite and pyrite. Under the influence of various heat and mass transfer agents, gold is redistributed along the heat flow front, forming zones of dispersed mineralization with its high contents in pyrite and arsenopyrite. Then, under the conditions of late superimposed hydrothermal-metasomatic processes, gold-bearing pyrites and arsenopyrites are released from most of the gold, which appears in the composition of ores of the late stage of ore formation in the form of visible gold particles.

Keywords: Eastern Yakutia, evolution of gold sources, regional clarkes of rocks and gold-concentrating minerals.

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DOI: 10.19110/geov.2022.10.4

We present results of study of Middle Pleistocene intermorainic deposits by palynological and diatom methods. Intermorainic deposits are assigned to the Rodionov interglacial period. Two climatic optima have been identified: pollen Pinus sylvestris dominates in the lower optimum, and pollen Picea sp., Pinus sylvestris dominates in the upper one. The deposits were generally formed in a shallow freshwater reservoir.

Keywords: interglacial period, palynology, diatom analysis, paleogeographic settings.

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DOI: 10.19110/geov.2022.10.5

The problem of asbestos geoecology remains relevant. Asbestos is considered potentially dangerous, because when asbestos-containing materials are destroyed, thin elongated fibers are released and damage organs and tissues of mammals and humans. On the other hand, unique fire-resistant thermal properties of asbestos support using it in a wide range of products.

Mineralogical study of asbestos ore from the Kiembayevsky deposit, depositing media (dust) and production products used in shipbuilding was carried out by optical microscopy and X-ray analysis.

We determined that the methods of optical microscopy and X-ray analysis, and, if necessary, their integration, allowed obtaining reliable information about the presence of chrysotile asbestos and its content in various objects, which was necessary for solving problems not only in the geological industry, but also in other areas of the national economy. A quantitative assessment of the content of chrysotile-asbestos, amphibole-asbestos and asbestos-like respirable fibers (natural and artificial) in rocks, technogenic formations (mainly deposit media), and anthropogenic production products is presented.

Keywords: geoecology, mineralogical features, quantitative assessment of asbestos, amphibole-asbestos, chrysotile-asbestos, asbestos-containing materials.

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DOI: 10.19110/geov.2022.10.6

The layered distribution of the isotopic composition (d¹⁸О) in the snow mass under conditions of different dust pollution of the near-surface atmosphere was studied on the territory of two scientific test sites of the IAO SB RAS: the Fonovaya observatory and the suburban BEK test site (Tomsk). Interlayer differences in isotopic characteristics and the activity of snow chemical reactions were evaluated in conjunction with the analysis of the dispersed composition of the precipitated aerosol substance, the radiation transparency of snow in the UV range, and taking into account reverse trajectories of air mass transfer. Interlayer fluctuations in d¹⁸О values were established, the variability of which increased in layers confined to the thermal diffusion geochemical barrier. We suggested that due to the geochemical activity of snow and its ultraviolet transparency, as well as the presence of iron-containing dust-aerosol particles in the snow mass, conditions arose that initiated photoactivated snow-chemical reactions. Their occurrence may be accompanied by free radical oxidation of the precipitated aerosol matter and the formation of stable photoreaction products, which may be evidenced by the established post-sedimentary interlayer differences in the isotope stratification of the snow mass.

Keywords: iron aquacomplexes, aerosols, dynamic light scattering, oxygen isotopes, crystalline hydrates, ultraviolet transparency of snow, snow cover, snow chemical reactions, trajectory analysis.

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