pdf № 275, July

DOI: 10.19110/2221-1381-2019-7-3-7

The carbon isotope composition of different in polarity fractions and individual n‑alkanes of Lower Paleozoic oils in the northern part of the Timan-Pechora basin, showing geochemical signs of an organic matter of Ordovician age, formed by the remains of the problematic Gloeocapsomorpha prisca (G. prisca) alga, was studied. It is shown that the carbon of all fractions of the studied oils has a relatively light isotopic composition of about –31.5  d¹³C on average, which is significantly lower than the carbon of previously studied Upper Devonian oils genetically related to Domanik deposits. The carbon isotope profiles of the n‑alkanes of the studied oils do not have pronounced anomalies, only for the C₁₇ hydrocarbon, a slightly depleted in heavy carbon isotope is observed, n‑C₁₉ is not distinguished by carbon isotopic composition from the neighboring even homologues. The data obtained are compared with previously published data for oil of the basins of Illinois (USA) and Canning (Australia) similar in Ordovician G. prisca origin. It is shown that the isotope profiles of n‑alkanes of the Ordovician oils of these two basins differ in contrast, and the data on the Timan-Pechora basin oils are closer to those of Australia than the United States ones.

Keywords: G. prisca oil, carbon isotopy of n‑alkanes, Timan-Pechora basin.

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DOI: 10.19110/2221-1381-2019-7-8-14

According to geological and geophysical data, two systems of faults are distinguished at the territory of European North of Russia – submeridional-sublatitudinal (N – S, W – E) and diagonal (NW – SE, NE – SW). On the northeastern of the Russian Plate, the Zimneberezhno-Krasnovishersky linear fault zone is most pronounced in geophysical fields, within which we were able to identify the intersection points of orthogonal deep faults: Zimnebrezhny, Vashkinsky and Zimstansky, which obviously have similar mineragenic specificity. At the territory of Timan-Pechora province, the Izhma-Pechora and Korotaikhinsky intersecting orthogonal faults are less clearly identified, which we named after their structural-tectonic affiliation. Reconnaissance geological and geophysical surveys were carried out within the newly allocated Zimstansky intersection site of orthogonal faults.

Based on the interpretation of magnetic and gravimetric fields maps, cosmogeological maps and maps of fault tectonics, as well as the results of studies on the features of the deep structure of the consolidated crust of the Timan-Northern Urals region and adjacent territories of the Russian and West-Siberian plates in the volume of granite-gneiss and granulite of the metabasic structural-material complexes using geophysical data, we were able to identify the Zimnebrezhny, Vashkinsky and Zimstan junction points of orthogonal depths faults on the north-eastern of Russian plate, and within the Timan-Pechora – Izhma-Pechora and Korotaihinskoy.

As a result of the detailed work carried out on the north-eastern outskirts of the Russian Plate (south of the Komi Republic), the location of the Zimstansky junction of deep orthogonal faults is localized and intense local gravimetric anomalies (Frolovskaya, Chetdinskaya and others) that are promising for the detection of the main bodies (alkaline - ultra basic (?)) composition in the production of detailed geological and geophysical works.

Keywords: deep structure, tectonics, fault zones, anomalous of magnetic and gravitational fields, metalgenius.

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DOI: 10.19110/2221-1381-2019-7-15-24

The results of study of sulfide assemblages in altered gabbro Malyutka massif of South Urals Khudolaz differentiated complex were presented in this paper. This massif is a small olivine-hornblende gabbro stock containing Cu-Ni ores located in the footwall.

The platinum group minerals (PGM) — michnerite and sperrylite — were found in the pyrrhotite, chalcopyrite, and pentlandite for the first time. We determined a significant influence of hydrothermal alteration on the ore occurrence. The ore forming process was subdivided into three types of the stages or assemblages: 1) magmatic type (pyrrhotite ± pyrite–chalcopyrite–pentlandite ± violarite + magnetite assemblage containing Rh-sperrylite and Pt-michnerite); 2) early hydrothermal type (pyrite ± pyrrhotite–chalcopyrite–violarite ± pentlandite + magnetite assemblage containing high Sb-michnerite); 3) late hydrothermal type (pyrite–chalcopyrite assemblage, PGE-mineralization not determined). Hydrothermal fluids were responsible for a small Fe and Cu loss from sulfides and further redeposition of these elements. Nickel and Co contents were increased in newly formed minerals such as pyrite and violarite. The first two types of assemblages were characterize of different michnerite composition: magmatic michnerite contained Pt (up to 3.2 %) and no Sb, whereas early hydrothermal michnerite displayed extremely high-Sb contents (up to 9.7 %) and a lack of Pt.

Keywords: Khudolaz complex, Malyutka massif, hydrothermal processes, sulfide-platinum metal assemblages, michnerite.

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DOI: 10.19110/2221-1381-2019-7-25-32

The article presents new data on the mineral vavřínite (found in 2011) in copper-nickel ores of the Pay-Khoy gabbro-dolerite complex located in the far north-east of the European part of Russia, between the Barents and Kara seas, which is currently the third confirmed place of discovery in the world. The mineral is found in within Perviy ore occurrence, which is an intrusive body of a complex type, represented by gabbros and gabbro-dolerites of Late Devonian age. Three types of ore mineralization are distinguished: 1)schlieren-imbedded pentlandite, chalcopyrite, pyrrhotite (includes vavřínite) in marginal parts; 2) vein (injection)-imbedded chalcopyrite, pyrrhotite in leucocratic quartz dolerites; 3) metasomatic substantially disseminated and pyrrhotite in contact-modified rocks. Vavřínite is associated with cobaltine as well as with pyrrhotite, chalcopyrite, pentlandite, nickeline, and non-metalloferrous minerals. Vavřínite is creamy white color, highly anisotropic, and has a Vickers microhardness (VHN_10,20) of 111.6—146.5 kg/mm². The Raman spectra for Pay-Khoy vavřínite was obtained for the first time, with the main bands at 110, 192, and 218 cm^-1.

Keywords: vavřínite, Pervyi ore occurrence, copper-nickel ores, Pay-Khoy Ridge, Ugra Peninsula.

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DOI: 10.19110/2221-1381-2019-7-33-42

The results of model experiments on the extraction of chemical elements from multicomponent solutions by microscopic fungi biomass are presented in the article. The data obtained indicate that the chemical elements sorption affinity to the fungal biomass as a sorbent accords with following series: Bi ≈ Sn ≈ Pb ≈ Fe ≈ Hg ≈ (Sb) ≈ Cr> Cd ≈ Zn ≈ Cu ≈ V ≈ Se> Co ≈ Mn ≈ (Sb) ≈ As ≈ Ni ≈ Sr, which reflects the complex nature of the elements interaction and interinfluence in the multicomponent system. Polymetal neoplasms of complex composition, represented by thin xenomorphic particles (phases, grains), as well as well-faceted crystals, their intergrowths and twin son fungal biomass, were discovered by the method of analytical scanning electron microscopy, which proves the potentiality of extensive metal-bearing biomineralization in organogenic sedimentolites. The extraction complex mechanism of chemical elements from multicomponent solutions is implemented in stages: initial physicochemical sorption (due to electrostatic and Van der Waals interactions), further ion exchange or complexation, followed by some sorbed metal ions recovery.

Keywords: elements, multicomponent solutions, extraction, biosorption, microscopic fungi, biogenic mineral formation, coals.

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DOI: 10.19110/2221-1381-2019-7-43-48

An important feature of the Devonian sediments in the Timan Ridge is that they contain basaltic volcanic rocks. The paper provides results of study of tuff-rich interlayers in the Valsovskaya and Ust’chirkinskaya Formations located in the Pizhma River (Middle Timan) from which zircons were extracted. U-Pb dating of zircons yielded the ages of 376.8 ± 6.7 Ma and 372.4 ± 8.3 Ma respectively. These ages correspond to Late Frasnian and Early Famennian and contradict the biostratigraphic data according to which the age of the rocks is Late Givetian and Early Frasnian. Rejuvenation of the zircon ages is supposed to be related to the time-extended crystallization of zircon crystals.

Keywords: Middle Timan, Devonian, basalt, tuff, sandstone, zircon, age of sediments.

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