pdf № 294, June

DOI: 10.19110/2221-1381-2019-6-3-11

The article presents results of the first U-Pb-dating of detrital zircons from sandstones in the aleurolite-sandstone strata at the base of the Uralides section at the Manitanyrd Ridge. It was established that main sources of terrigenous material for sandstones were Early Vendian to Early Ordovician complexes at various stages of Protouralides-Timanides formation. We made conclusion that the aleurolite-sandstone strata belong to the upper member of the Manitanyrd Group — Middle Ordovician Malopaypudynskaya Formation — a stratigraphic analog of the Saledskaya Formation at the Subpolar Urals. Based on a comparison of the ages of detrital zircons from various Lower Paleozoic sections of the Subpolar and Polar Urals, we assume that this area had the same geological history in the Late Riphean — Early Paleozoic.

Keywords: detrital zircons, sandstone, clastic material, U-Pb-age.

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DOI: 10.19110/2221-1381-2019-6-12-19

The object of the study is the ultramafites of the Agardag chromite-bearing massif, which is part of the South Tuva ophiolite belt. The work presents a petrographic characteristic of rocks and ores, and features of the mineralogical composition of ultramafites. Harzburgites with the subordinate role of dunites, and their serpentinized varieties, are widely developed in the massif. Among dunites and, more rarely, harzburgites, small bodies of chromitites with various types of structures were found: interspersed, densely interspersed and drain. Chrome spinelides in harzburgites and dunites have a homogeneous chemical composition and are represented by chromites and rarely subferrichromites. Analysis of variations in the composition of chrome spinelides in chromitites allows us to distinguish two trends in their evolution. The first trend reflects the deep mantle conditions of intense depletion of the substance of the upper mantle in the process of intense plastic deformations. The second trend in the evolution of chrome spinelides in chromitites is conditioned by the metamorphogenic transformations of chromitites, which took place in the process of moving ultramafites to the upper parts of the earth's crust.

Keywords: ultramafites, chromitites, chrome spinelids.

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DOI: 10.19110/2221-1381-2019-6-20-27

The Chudnoe gold deposit, located at the Subpolar Urals, is unique. Gold is generally concentrated in fuchsite veins in rhyolites, where associated with palladium and rare earth minerals in the absence of sulphides. Impurities of silver, copper and palladium are characteristic of native gold in fuchsite veins; heterogeneous structure is often noted. In deep horizons the authors established Pd-Au-sulphide mineralization confined to andesites and enclosed by rhyolites. Native gold and palladium arsenoantimonides in andesites most often form inclusions in pyrite, less often in allanite; accompanying minerals: cobaltine (including Pd-containing), galena, sphalerite, chalcopyrite, magnetite. Gold is homogeneous and contains only silver as an impurity, its rate is within 756–875 ‰. The mineral associations of gold in andesites differ sharply from the main mineralization in rhyolites, but with common gold-palladium nature of mineralization, which suggests its formation during a single process, in which the presence or absence of sulfides in host rocks was important. The presence of palladium in the ores and mineralized zones, as well as chromium in the composition of fuchsite, indicates an important role of deep sources of matter.

Keywords: Chudnoe deposit, native gold, stibiopalladinite, isomertieite.

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DOI: 10.19110/2221-1381-2019-6-28-33

The data obtained on the Earth’s hot heterogeneous accretion and fractionation of a global magma ocean can well explain specific isotope ages and Sr isotope ratios of igneous rocs. The oldest ages of the onset of formation of acid igneous rocks are due to generation of large volumes of acid residual melts upon low–pressure fractionation of the near-bottom parts of an early magma ocean. These parts crystallized under effect of the growing load of the upper parts formed during accretion. The long-term crystallization and fractionation of the deep layers of the magma ocean are responsible for the younging of ages of the onset of formation of various magmas in ancient platforms in the following sequence: acid — alkaline intermediate and basic — alkaline ultrabasic and carbonatitic — kimberlitic. The growing impact heat release in the process of accretion provided the existence of reverse geothermal gradient in the mantle and to the absence of present-day geodynamic setting in the Early Precambrian. They appeared in the Late Proterozoic following the mantle heating by the core. This is the reason for relatively young ages of oceans, oceanic basites and subduction-related igneous rocks.

Keywords: hot accretion, magma ocean, isotope age, igneous rocks.

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DOI: 10.19110/2221-1381-2019-6-34-38

The paper deals with intergrowth boundaries of mineral grains in igneous rock in terms of their geometry, crystallography and energy accumulated in the course of ontogenesis of individuals and their aggregations. So, all the geometric features of the boundaries, such as the area, length, angular relationships, can be obtained in flat cross-sections of mineral aggregates or in petrographic thin sections, which are used to diagnose rock-forming and accessory minerals as well as rocks. Crystallographic identification of the boundaries of mineral individuals can also be measured and calculated for most of the boundaries in thin sections; sometimes the characteristic of flat cross-sections of mineral grains can be used according to the degree of cross-section contours’ approximation to idiomorphic or xenomorphic forms. The energy characteristic of the mineral aggregate internal boundaries can be estimated indirectly as a result of calculating the projection of a unit cell of the mineral grain’s crystal lattice on the plane of the individual's boundary. Each of these methods of consideration and characteristics of individual’s boundaries and intergrowth’s boundaries in the aggregate is a source of information for the restoration of comparative conditions for the mineral aggregate formation, ontogenesis.

Keywords: mineral aggregate, mineral individuals, mineral grains, boundaries, geometric, crystallographic and energy characteristics of the boundaries.

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DOI: 10.19110/2221-1381-2019-6-39-45

The article considers the data on the microhardness of mineralized tissues of conodonts, represented by organo-mineral composites based on collagen and fluorohydroxyapatite. Information on the mechanical properties of tissues is important for biomechanical interpretations, and also provides an opportunity to evaluate the functional significance of tissue differentiation of conodont elements. The conodont elements of good preservation from the Upper Devonian — Carboniferous of the East European Platform, the east of the Pechora Plate, and the southern Cis-Timans were used for the study. The peculiarities of the composition and structure of the main tissues were studied and their Vickers’ microhardness was measured. According to the results of microprobe analysis, the average composition of the mineral component of various tissues differs slightly. At the same time, the tissues vary significantly in the content of the protein component and the structural and textural characteristics. Microhardness measurements showed differences between tissues and the presence of variations within a single tissue type. Paralamellar tissue has the highest average microhardness (3.1 GPa), this value is somewhat lower in albid tissue (2.9 GPa), and even lower in lamellar and interlamellar tissues (2.6 GPa and 2.1 GPa, respectively). Microhardness demonstrates the absence of a significant dependence on variations in the chemical composition of the mineral component (content of F, Sr, and Na), but it strongly depends on the content of organic matter and tissue porosity. In general, the differentiation of tissues by microhardness is due to textural and structural differences and variations in the content of the organic component.

Keywords: conodonts, mineralized tissues, microhardness.

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DOI: 10.19110/2221-1381-2019-6-46-52

The aggravation of the ecological and economic situation in the areas of mining and processing of ferrous and non-ferrous metals in the South Urals requires the development of new approaches to recycling and prospects for the future processing of mining waste. We discussed criteria that determined the type of technogenic massif formed — syngenetic or epigenetic on the basis of complete information about the processes of mineral formation, material composition and morphostructural features of the mineral phases that formed the technical stone. The subject of the study was the sample of stowage with the age of hardening of 180 days, the components of the filling mixture — granulated blast furnace slag of PJSC MMK, the tailings of the enrichment of copper-plated ores of the Gaisk concentrator. Using a complex of mineral-analytical methods — optical microscopy (optical-petrographic and minerographic), x-ray and thermal methods — allowed the authors to assess the morphological features of the constituent components of the stowage, the chemical composition, the newly formed mineral phases and characterize the technogenic massif formed from the stowage as epigenetic.

Кeywords: enrichment tails, blast furnace slag, technical stone, stowage, complex of mineral-analytical methods, mineral phases, neoplasms, syngenetic, epigenetic.

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DOI: 10.19110/2221-1381-2019-6-53-57

Based on the theory of random processes, we created a statistical model describing the work of a research team. The model is based on the employee's working time on a research project. The scientific significance of the research work is reflected in the status of the publication of a peer reviewers. Therefore, the calculation of the effectiveness of a researcher can be performed according to arbitrary rules, adopted in this team, for all its publications within a specified billing period. In compliance with a number of statistical requirements according to the limit transition theorem, the distribution of the performance indicator of the research team of the Institute should be subject to the exponential law. At the same time, the method of assessing the results of scientific work — articles, monographs, patents and others accepted in the scientific team — does not matter. Thus, the indicator of the effectiveness of a scientific organization is not sensitive to the peculiarities of the branch of science, which is analogous to the temperature for the equilibrium thermodynamic system. The algorithm of calculation of this scientometric indicator is developed.

Keywords: statistics, random processes, probability, scientometry, efficiency indicator.

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