pdf № 315, March

DOI: 10.19110/geov.2021.3.1

The paper summarizes results of work on the geochronological confirmation of the age of metamorphic structures occurring at the base of the Precambrian of the north of the Urals and the age of overlying Upper Precambrian basal sediments. It is shown that the occurrences of early stages of metamorphism of rocks of metamorphic (polymetamorphic) complexes date back to about 2.1 Ga. Their substrate is unambiguously related to the Lower Precambrian. We determined that Mesoproterozoic strata are absent Upper Precambrian sections of the north of the Urals, in contrast to more southern regions of the Urals. The basal strata in the Lyapin and Kharbey-Marunkeu anticlinoria, according to the data obtained, are dated to the Middle Neoproterozoic (cryogenian). The established fact of the absence of deposits of a huge age interval (Mesoproterozoic — at least 600 Ma) in the north of the Urals can be explained by a high standing of the territory of the northeast (in modern coordinates) of the Baltic craton, a fragment of which at that time was the Timan-Northern Ural lithospheric segment, and the location in the interiors of the Columbia (Nuna) supercontinent.

Keywords: North of the Urals, Lower and Upper Precambrian, basal deposits, geochronology.

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DOI: 10.19110/geov.2021.3.2

Ultramafic rocks of the Enganepe Uplift are transformed into serpentinites, magnesite-dolomite-talc and quartz-magnesite-dolomite metasomatites belonging to the beresite-listvenite formation. All apoultramafic rocks contain high chromium and nickel inherent in protolith. Chrome-spinel of the magmatic stage is represented by alumochromite, which, in the process of metamorphic and metasomatic transformation of rocks, has been replaced by secondary chrome-spinel (subferrialumochromite, ferrichromite) and chromium-bearing magnetite. The main nickel minerals are millerite and gersdorffite. In quartz-magnesite-dolomite rocks, nickel is party contained in Ni-Cr-chlorite.

Keywords: serpentinites, magnesite-dolomite-talc metasomatites, quartz-magnesite-dolomite metasomatites, beresite-listvenite formation.

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DOI: 10.19110/geov.2021.3.3

We present results of geological-mineralogical-geochemical studies of the Tebinbulak scandium-containing titanium-magnetite deposit in Western Uzbekistan. The levels of scandium content in ores and rocks of the pyroxene-hornblende massif have been analyzed. The potential for the associated extraction of scandium from ores, which can significantly increase the profitability of the industrial development of the deposit, is discussed.

Keywords: Uzbekistan, Tebinbulak deposit, titanomagnetite ores, associated extraction of scandium, profitability of industrial development.

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DOI: 10.19110/geov.2021.3.4

When crystal faces grow unequally, the crystal symmetry distorts and generally decreases. According to the Curie dissymmetry principle this distrortion can provide useful information about the conditions of crystal formation. The estimation of the distorted symmetry is a separate problem, and the accuracy of its solution affects the correct conclusions. One of the methods to evaluate distorted symmetry was proposed by I. I. Shafranovsky half century ago. It consists in comparing the areas of the crystal faces that transform into each other during symmetric transformations. Unfortunately, this method, maybe for its methodological complexity, did not receive due attention then. Modern computer capacities allow us to reanimate it. In this paper the first results on the modernization of I. I. Shafranovsky’s method are presented.

Keywords: symmetry, crystal, Curie dissymmetry principle, I. I. Shafranovsky.

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DOI: 10.19110/geov.2021.3.5

The ecogeochemistry is the application of geochemical features to study animal ecology. This approach is promising for using in reconstructions of ancient pelagic ecosystems. Among other Paleozoic fossils of pelagic animals, remains of conodonts are the most suitable for ecogeochemical investigations. The article reviews ecogeochemical applications of Middle to Late Paleozoic conodont elements. The following features are considered as the most informative: calcium isotopic composition and element ratios (e.g. Sr/Ca) of conodont apatite, and isotopic composition of carbon of conodont elements. These parameters allow us supposing ecological specialization of conodont species, and temporal and spatial dynamics of the ecogeochemistry of conodonts can be used to reconstruct transformations of ancient pelagic ecosystems.

Keywords: conodonts, pelagic ecosystems, ecogeochemistry, Paleozoic.

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DOI: 10.19110/geov.2021.3.6

At the current stage, museum collections on natural history play an important role in the fundamental and applied research activity and are an essential part of popularizing Earth sciences. This article focuses on natural-scientific collections of the Institute of Coal (which is a structural unit of the Federal Research Center for Coal and Petrochemistry of the Siberian Branch of the Russian Academy of Sciences), documenting interdisciplinary scientific knowledge about coal. Through methods of petrochemical, petrographic and geological research, as well as museological approach systematizing natural samples, the systematic, thematic and educational collections have been formed. They include coals of the Kuzbass and other coal basins, rock formations and paleonthological objects. Being a specific form of preservation of certain natural history processes of regional and global significance, a systematized collection is a tangible and informational resource of scientific explorations. Realization of its scientific-informational potential promotes popularization of the scientific knowledge and search for answers to solve environmental problems.

Keywords: coal in collections, natural scientific collections of the Institute of Coal of the Federal Research Center for Coal and Petrochemistry of the Siberian Branch of the Russian Academy of Sciences (FRC CCP SB RAS), systematizing coal, distribution of scientific knowledge, museification of knowledge about coal.

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