pdf № 335, November

DOI: 10.19110/geov.2022.11.1

The article describes a new species of ostracods of the genus Leperditia from the Upper Silurian deposits of the western slope of the Subpolar Urals (Shchugor River basin). Leperditia unituber Saldin sp. nov. differs from all other species of Leperditia by the presence of a tubercle near the ventral margin of the right valve, a stable diagnostic character.

The shell is truncated-oval, elongated, widening towards the posterior end. The ventral margin is gently and asymmetrically arched. Longitudinal axis at a slight angle to the length. A narrow marginal border is observed along the ends of the shell. The posterior dorsal swelling on the left valve is pronounced. On the right valve near the ventral part, where the greatest height of the shell is observed, there is a tubercle or spiny outgrowth.

Keywords: ostracodes, Leperditia, Silurian, Subpolar Urals.

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DOI: 10.19110/geov.2022.11.2

Novo-Uchaly essentially zinc (C_Zn>>C_Cu) VMS deposit is one of the largest in the Urals. Currently, it is under additional exploration by fans of underground drilling wells and mine workings. The paper describes a novel geochemical zonation of the sulphide deposit (the example of Cu, Zn, Au and In), discusses conditions of formation and factors that caused its complication. We carried geostatistical calculations in addition to the analysis of the zonation of the deposit. The ore deposit is represented by a large subvertical ribbon of a whimsical structure, inclined southward, which is confined to the wing of an inverted large anticlinal fold, cut by mafic dikes and characterized by a complex, combined geochemical zonality. The distribution of Cu and Zn is generally asymmetric. Сopper-rich ores tend to the northern wedge of the deposit, and to the south, along its declination, the concentration of Zn increases, while Cu decreases, and the middle part of the deposit is represented by zinc-rich ores. In the section, copper maxima are more often noted in the footwall side of the deposit, and zinc — in the hanging side. The intrusion of a thick gabbro-diorite dyke and subsequent dynamometamorphism, including hydrothermal solutions, caused the redeposition of more mobile Cu in the near-contact zones of the dyke and areas of swell of the ore body thickness. Within the swell of the thickness of the deposit, in the hinge of the fold of the 2nd order, rich copper-zinc ores occur, which are enriched by Zn, Pb, Au, Ag, In, Ba and some other rare elements. The similarity of their behavior in ores is confirmed by their high positive pair correlation. In the ore body, the distribution patterns of gold and indium are rather symmetrical. High concentrations of gold and indium are confined to a sharp bend in the ore body, and small indium maxima occur in the footwall of the ore lode. As a result of dynamometamorphism, the deposit acquired a whimsical structure with the formation of thick swells; ores were significantly recrystallized, and locally enriched by non-ferrous and precious metals.

Keywords: Novo-Uchaly VMS deposit, geochemical zonality, contact metamorphism, copper, zinc, gold, indium, dynamometamorphism.

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DOI: 10.19110/geov.2022.11.3

On the basis of the analysis of dramatical history of development of the concepts of building units in crystal growth we discuss the genesis of non-classical concepts of crystal growth. We show that in the 21^st century the competent advantage in the theory of crystal growth transits to notions about building units larger than individual atoms and molecules. New experimental data, testifying to a stable life of prenuclear clusters-quatarons or other organized groups of atoms in crystal-forming environments and their participation in crystal growth and also already formed crystalline particles, allow not only solving the old “Kossel vs. Balarev” problem, but also proving non-classical mechanisms of crystal growth.

Keywords: non-classical mechanisms of crystal growth, nucleation and growth of crystals, growing units, prenuclear clusters, quatarons.

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DOI: 10.19110/geov.2022.11.4

The paper considers the problem of instability of tetraethoxysilane hydrolysis in an ethanol medium in the presence of ammonia as a catalyst to obtain monodisperse spherical silica particles of a given size. This problem is associated with the presence of various impurities affecting rate of particle formation and, as a consequence, their size, monodispersity and shape. To solve this problem, we present novel studies of possible application of ultrafiltration for hydrolysis of initial tetraethoxysilane and ethanol through hydrophobic filters with a pore size of 50 nm. In both cases, we noted a decreasing intensity of light scattering after filtration. The elemental analysis of filtered impurities showed a significant content of SiO₂ solid phases in tetraethoxysilane, and a number of impurities in ethanol. The experiments on the synthesis of silica particles from pre-filtered components showed that the resulting silica particles had a greater degree of monodispersity, and their sizes were much more reproducible, regardless of the used tetraethoxysilane. Thus, according to the obtained data, ultrafiltration is one of the effective ways to solve the problem of instability in the synthesis of monodisperse spherical silica particles.

Keywords: monodisperse spherical silica particles, supramolecular structures, ultrafiltration.

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DOI: 10.19110/geov.2022.11.5

The dating of young peatlands with ²¹⁰Pb method is a difficult task. Standard ²¹⁰Pb dating models require an exponential decrease in activity down the peat profile. In Arctic peatlands, we note a significant migratory capacity of lead, therefore, for accurate dating of peat, it is necessary to improve the existing dating models to eliminate the effect of migration and their verification using independent isotope chronometers, for example, ¹³⁷Cs. We applied several models CA, CFCS, PF, CF together with the Monte Carlo method for peat core samples taken within the European Subarctic of Russia (Arkhangelsk region). Comparison with the specific activities of ¹³⁷Cs, determined at a depth of 19—21 cm, associated with the global fallout in 1963, showed that the closest age to the specified reference point is given by the CFCS and CF models (1965 and 1962, respectively). Among these two options, CF using the Monte Carlo method turned out to be preferable, since it provided, taking into account the error, a slightly better agreement with the specific activities of ¹³⁷Cs in the reference horizon. Despite the difficulties associated with the complex distribution of ²¹⁰Pb over the peat section due to migration, the dating methods used were successful and, in the future, can be applied to dating other peat deposits.

Keywords: peat core, dating, ²¹⁰Pb, ¹³⁷Cs, Arkhangelsk region, Russia.

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DOI: 10.19110/geov.2022.11.6

Today the introduction of «smart» automated systems is the basis in system engineering and operations management in various industries, but not yet widespread in the field of mineral processing.

The object of the study is the process of interphase changes of kaolinite (Vezhayu-Vorykvinsky deposit, Knyazhpogost district, Komi Republic) during thermal treatment at a temperature range of 25—1200 °C. XRD examinations (Rietveld method and Profex programs) were carried out for quantitative estimation of the phase transformations. XRD patterns were processed by algorithms for determining the positions and heights of peaks implemented in the Python programming language.

We obtained a novel simplified mathematical model of kaolinite phase transformations during mullite synthesis based on XRD. The main parameters, influencing the kinetics of mullite synthesis process, have been specified.

Keywords: kaolinite, mullite, mineral phases, solid-phase synthesis, structural transformations, mathematical model, composite.

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