The object of research. At the top of the Upper Riphean-Vendian sedimentary sequence of the Bashkirian meganticlinorium (western and central parts of the named structure, corresponding to the stratotypical locality of Riphean) there is a series of fairly well-established hiatuses – the pre-Uk and pre-Bakeevo. One can also assume the existence of the pre-Uruk and pre-Basa hiatuses. During each of them, the thin-grained aluminosiliciclastic’s distribution systems could be subjected to one or another transformations. However, whether this is actually the case is still not entirely clear. To solve this problem, the lithogeochemical features of clayey rocks of the Inzer, Minyar, Uk, Bakeevo and Basa formations are analyzed. If we assume that the hiatuses are accompanied by restructuring of the provenances, then this can/should lead to the appearance of more fresh, previously not subject to weathering, rock complexes at the paleo-watersheds. This circumstance should cause a change in the lithochemical characteristics of the thin-grained aluminosiliciclastics entering to the sedimentation area.
Methods. The analysis of the lithogeochemical features of clayey rocks is based on data on the content of the main rock-forming oxides (about 40 analyzes) and rare and trace elements (total of 70 analyzes). These data make it impossible to investigate the change in different lithogeochemical parameters of clayey rocks (for example, CIA, GM, K₂O/Al₂O₃, or others) from the bottom upwards through the section of each of the formations listed above, therefore we operate with the averages for the formation values of such parameters taking into account the values their standard deviations.
Results and conclusions. On the majority of the discriminant diagrams used by us, the figurative data points of the Basa Fm. mudstones occupy a position that to some extent differs from the position of the clayey rocks of other formations. The only lithostratigraphic subdivision in the part of the Upper Precambrian sedimentary sequence of the Bashkirian meganticlinorium under consideration, whose clayey rocks demonstrate a chemically noticeably less mature, compared to the underlying formations, is the Uk Fm. It may be thought that this is the result of the appearance of more fresh (less transformed by weathering) rock complexes at the provenances. The scales of the pre-Bakeevo and pre-Basa breaks, if they existed, were, most likely, noticeably less significant.

Subject of study. The features of the evolutionary changing of Gzhelian-Asselian conodonts are examined.
Materials. The data on Ural and North American conodonts are used.
Results. The cyclic type of change of the Pa-element morphology in the process of the evolutionary development of the representatives of the genus Streptognathodus is established. Morphological evolutionary trends of gradual development alternate with the periods of the rapid appearance of a group of the forms of original constitution. The species of this group are characterized by wide distribution and short lifetime. Such species are used as the markers of the boundaries of stratigraphic subdivisions. Lower boundary of Gzhelian is determined by the appearance of species of the group simulator; the species of group isolatus mark lower boundary of Asselian. Model of the ensemble evolution of the related species is used for explaining the directed change in the morphology of conodonts. The saltational appearance of the determined indication is explained by the phenomenon of evolutionary oscillations.
Conclusion. We can make conclusion about the sexual multiplication of this group of the organisms according the established alternation of the periods of the slow and rapid morphological evolution of conodonts.

Research subject. In this research, we carried out Sm-Nd- и Rb-Sr-dating of pyrochlore carbonatite from the Vishnevogorsky niobium deposit, Ilmeno-Vishnevogorsky Alkaline Complex, Southern Urals. IVC is located in the Ural fold region and is a carbonatite complex of the linear type. Rare metal (Nb-Zr-TR) deposits and occurrences are related to IVC. The age and the duration of IVC deposits formation remains a matter of debate. To determine the age of IVC carbonatites and related niobium ore, we measured Sm-Nd and Rb-Sr isotopic compositions and concentrations of the elements in the minerals (pyrochlore, calcite, apatite, biotite) and bulk sample of pyrochlore carbonatite.
Materials and methods. The Sm and Nd isotopic compositions and concentrations were determined on a Finnigan MAT-262L (RPQ) seven-collector mass spectrometer in the static regime at the Geological Institute of the Kola Scientific Center, Apatity, Russia. The Sr and Rb isotopic compositions and concentrations were determined on thermos-ionization mass spectrometer Triton Plus (“Geoanalitik”, IGG UD RAN, Ekaterinburg, Russia).
Results. Age of pyrochlore carbonatites from ore zone 140 (Vishnevogorsky deposit, IVC) defined by Sm-Nd and Rb-Sr isotopic methods. Mineral Sm-Nd-isochron (5 points) indicated age 229 ± 16 Ma, mineral Rb-Sr-isochron (5 points) showed similar age 250.5 ± 1.2 Ma.
Conclusions. Results Sm-Nd и Rb-Sr dating indicate that the pyrochlore сarbonatites of ore zone 140 crystallized ≈ 250 Ma ago, at the stage of the postcollisional extension, possibly, in connection with exhumation complex, which was accompanied by decompression, partial melting of rocks, involving fluids, dissolution and precipitation of Ordovician-Silurian alkaline-carbonatitе complex. Thus, the formation of the IVC carbonatites and related Nb-ore, which began in Silurian (S), continued in Permian (P) and Triassic (T1-2) and was associated with the post-collision stage of tectonic activity in the Ural Fold Belt.

Subject of study. The article presents the results of study of trace elements (TEs) in sulfides of the main ore body (borehole 1T) and the northwestern ore body (borehole 200) of the Dergamysh cobalt-bearing massive sulfide deposit hosted in serpentinites (South Urals).
Materials and methods. The chalcopyrite-pyrite-marcasite sandstones of the main ore body and pyrite-chalcopyrite-pyrrhotite “gravelites” of its northwestern satellite were studied with laser ablation with inductively coupled plasma.
Results. The TE contents, distribution and mode of occurrence differ in sulfides of the main ore body and its northwestern satellite. In ores of the main ore body, most TEs (Ag, Sn, Mn, As, Co, Ni, Te, Pb, Au) accumulate in pyrite-1, pyrite-marcasite aggregates concentrate Tl and Bi, marcasite is a host to Mo and Sb, and chalcopyrite contains Zn, Se and Cd. Pyrite-2 is depleted in TEs relative to other sulfides. In sulfides of the northwestern satellite, most TEs are related to chalcopyrite (Bi, Te, Zn, Cd, Se, Pb, Au, Tl, Ni, Co). Tin accumulates in cubanite, As and Ni are hosted in pyrite-4, Ag, Mn and Mo are concentrated in pyrrhotite, Sb is typical of pyrite-3, and Co accumulates in pyrite-2.
Conclusions. Based on the correlation analysis, it is shown that sulfides of the main ore body and its northwestern satellite are characterized by different mode of TE occurrences. The differences are explained by two main reasons: 1) “mafic” and “ultramafic” metal sources for sulfides of the main ore body and its northwestern satellite, respectively, and 2) different degree of diagenetic alteration of sulfides.

Object of study. The article was devoted to investigation of the depth structure of the Earth’s crust and upper mantle along the Mezen–Timan–Pechora seismic profile (MEZTIMPECH), crossing the southern parts of the Mezen syneclise, the Timan ridge and the Pechora syneclise. Total profile length was 525 km.
Materials and methods. In the course of writing the article, the data obtained by performing seismic surveys using the earthquake exchange wave method were used. The processing involved seismic data using the methods of deep seismic sounding, reflected waves, a common depth point, a correlated method of refracted waves, and materials from well geophysical surveys. In interpreting the research results, generalizing models of the deep structure of the territory were employed.
Research results. As a result of the interpretation of the records of the method of exchange waves of earthquakes and the subsequent mathematical modeling, a geological and geophysical section was constructed to a depth of about 100 km and a number of seismic boundaries were identified. The pivotal boundaries of the exchange were: Ф₀ – the surface of the Riphean folded basement, Ф – the surface of the pre-Riphean crystalline basement, M – the surface of Mohorovich, identified with the roof of the upper mantle. Additionally, horizons K₁–K₄ – in the crust of the Earth, M₁, M₂ – in the upper mantle were traced. Four regional geoblocks were distinguished in the seismic section, differing in depth of the basement surface, the Moho sectionand the underlying structural features of the consolidated crust: the Kirov-Kazhim aulacogen, the Vychegda depression, the Timan ridge and the Pre-Ural downfold.
Conclusions. The results of deep seismic studies reflected regional features of the structure of the Earth’s crust and were the basis for the construction of tectonic models of large geological objects.

Study object. The role of strike-slip fault tectogenesis in magmatism of the large (North Eastern Primorye) fragment of the Eastern Sikhote-Alin volcano-plutonic belt (ESAVPB) is studied.
Materials and methods. The materials of geological mapping and field geostructural thematic-line research are used. Study methods are based on the concept of the geostructural patterns being formed by lateral, namely, strike-slip movements of crustal blocks.
Results. There is recognized the system of the NE-trending sinistral faults, whose activation taken place during two stages. The pre-Late-Cretaceous fold-and-strike-slip-fault (orogenic) stage is characterized by the widely developed fold system within the stratified formations covering active strike-slip faults of the pre-Mesozoic consolidated basement. By the Late Cretaceous, the strike-slip faults cut the fold system into narrow blocks, creating the preconditions for the strike-slip faults’ activation during the next destructionand-strike-slip-fault (riftogenic) stage (Late Cretaceous – Cenozoic). During the latter, the strike-slip faults were activated under transtension (strike slip with extension) with formation of volcano-tectonic extension structures (VTES) nearcrosswise the strike-slip faults. The VTES played, on the one hand, the role of magma-feeding channels. On the other hand, the extension caused preconditions for formation of the depression subsidences that accumulated large volumes of the volcanics covering and «crosslinking» the VTES, resulting in wide development of volcanic covers within the ESAVPB.
Conclusion. The VTES’ opening is thereby the effect of lateral (strike-slip) displacements of continental geoblocks that is not consistent with a priori ideas of the development of the East Sikhote-Alin volcano-plutonic belt under the oceanic plates’ subduction. The resulting materials complement the formulations according to which the East Asian volcanic belt formed under the structural-and-dynamic conditions being caused by the evolution of the East Asian global strike-slip fault zone resulting from displacement of the Asian continent to the south-west under the Earth’s rotational geodynamics.

Research objects. Paleozoic (Ordovician–Middle Devonian) volcanic-sedimentary complexes of the contiguous Sakmara and Mugodzharskaya structural zones of the Southern Urals, which have a paleo-oceanic and island-arc nature.
Мaterials and methods.The work was carried out on the basis of many years of personal research of the author with the involvement of literature data on other folded zones of the Southern Urals.
Main results. In the early Devonian, the first intense clustering of different facies complexes of rocks took place, which determined the tectonic face of the modern western part of the fold belt. The uniformity and set of Paleozoic formations in all structures of the Urals are maintained along its entire strike and are not repeated in neighboring zones.The drilling data showed the primary character of bedding of the rocks of the Upper Devonian Zilair Formation on the dislocated volcanogenic-sedimentary deposits of the Lower-Middle Paleozoic. Thrust contacts are observed only in the marginal parts of the zone. The almost textbook views on the cover bedding of the Kraka and Kempirsai hyperbasite massifs are in contradiction with the data on the presence of “roots” up to 4–8 km deep in them. By the beginning of the Devonian, the Kempirsai massif was located within the Sakmara zone and was “cross-linked” with the surrounding effusive rocks of the Middle Ordovician by gabbro-diabase dykes. According to the results of seismometric studies, features of similarity of the deep structure of the base of the Sakmara zone with the structure of the Magnitogorsk-Mugodzharskaya zone, which also revealed a melanocratic basement, have been established.
Conclusions. The formed structural zones of the Southern Urals are distinguished by a set of rocks of the same age, their stratigraphic range, and the autonomy of feeding areas. These differences have survived to this day. All subsequent tectonic episodes, including the sharpening epochs, only complicated the appearance and structure of the Southern Urals, without changing the relative position of structures that arose in the Early Devonian. There was no transfer, swarming of rocks from one zone through another in any of the subsequent stages of compression. The Early Devonian stage was the first, but at the same time the most intense, which determined the tectonic face of the modern western part of the Urals.

Subject. The Upper Ordovician reef Bol’shaya Kos’yu, located on the western slope of the Northern Urals in the basin of the Ilych River is a unique object among coeval reefs due to the weak dolomitization of rocks and the ability to trace the phases of its development.
Materials and methods. The article presents the results of paleontological, paleoecological and microfacial analyses of reef limestones selected by the author from 12 natural outcrops with a total capacity of about 150 m located along both banks of the Bol’shaya Kos’yu River.
Results. The structure of the reef, morphology and taxonomic composition of the frame-forming biota were established, and the important role of sphinctozoal sponges was first identified. Among the reef limestones in the main genetic characteristics that reflect specific depositional environments, was identified three types of microfacies. Type 1 – reef microfacies – framestones and buflestones. Type 2 – microfacies of interbiohermic space and inter-carcass cavities exposed to wave and tidal action – bioclastic and peloid pakstones, biolithoclastic grainstones and lithoclastic rudstones. Type 3 – microfacies of the hidden microcosmic cavities, protected from the active wave impact – wackstone.
Сonclusion. The composition of the microfacies and frame-forming biota characterize difficult differentiated, both on a section, and structure the reef, which was formed in the conditions of the carbonate platform-shelf margin with active hydrodynamics. Its growth occurred during transgression, which ended by the end of the middle katian a major regression that stopped its development. The revealed paleontological, paleoecological and microfacial data indicate that starting from the middle katian the first identified sphinctozoal sponges could settle in sublittoral environments with active hydrodynamics at depths up to 20 m.

Research subject. The object of the study is the Ulyuk-Bar gold deposit ore-bearing rocks, located in the Bashkir meganticlinorium (the Southern Urals).
Methods. The article presents the first data on the distribution of rare earth elements (REE), platinum group elements (PGE) and Au, obtained by inductively coupled plasma mass spectrometry (ICP-MS) on “ELAN- 6100 DRC” and “Agilent 7700” with the use of the computer data processing program “TOTALQUANT”, which includes automatic accounting of isotopic and molecular overlays on the mass spectral analytical lines of the determined elements. The chemical composition of ore minerals (native gold, pyrite, pyrrhotite, gersdorfite, chalcopyrite, arsenopyrite, and galena) was determined using an REMMA-202M scanning electron microscope with an LZ-5 X-ray energy-dispersive spectrometer and detectors for secondary and reflected electrons.
Results. As a result of the studies, the enrichment of heavy lanthanides from ore-bearing rocks of the Ulyuk-Bar deposit in comparison with the sandstones and shales of the Bolshoi Inzer Formation outside of the ore field was established. It is shown that the noble-metal geochemical specialization of ore-bearing sediments of the Bolshoi Inzer Formation of the Ulyuk-Bar deposit is similar in a number of parameters to rocks of the Mashak Formation of the Shatak complex, formed under the influence of Middle Riphean magmatism on sedimentary rocks of the upper layers of the earth’s crust. Based on the calculation of the age of the minerals thorium and uranium, according to the isotopic studies of Rb-Sr (996 ± 26 Ma) and K-Ar (676–706 Ma) methods and galena by the Pb-Pb method (950 Ma), it was established that mineralization was formed in two stages. The first of which is associated with tectono-thermal activation at the border of the Middle and Late Riphean, and the second was realized about 600 Ma ago.
Conclusions. It is concluded that the REE-EPG-Au taxonomy of ore-bearing deposits of the Ulyuk-Bar deposit is due to the polychrony and polygenicity of ore formation processes associated with the Middle Riphean plume magmatism, manifested over a vast territory, and the Late Vendian dynamothermal collisional metamorphism.

Subject. This paper presents the results of studies of the mechanism of primary oil migration in the boundary sediments of the late Jurassic (Bazhenov formation)–early Cretaceous (Achimov pack) on the example of the well 431Р of the Imilor field.
Materias and methods. Based on the working hypothesis of fluid fracturing as the main mechanism of primary oil migration, using optical-petrographic analysis, supplemented by geochemical research methods, systems of interconnected microcracks in the Tithonian-lower Berriasian and early Valanginian deposits were studied.
Results. It is established that the investigated cracks occurred in three stages: 1) formation of primary sedimentary-lithogenetic fissures as a result of dehydration of clays in the stage of diagenesis and hydraulic fractures in the implementation of the Achimov of terrigenous rocks; 2) partial healing of cracks with secondary minerals in the catagenesis; 3) restoration of patency of the cracks in
the generation of large amounts of free hydrocarbons of protopetroleum. It is shown that the migration of hydrocarbons generated by the formation occurred both within the Bazhenov formation itself and through a system of interconnected cracks in the contact zone of the Bazhenov formation with the Achimov formation.
Conclusion. A detailed study of the mechanism of oil migration allows us to expand our understanding of the reservoir properties of the oil column, which in the future will allow us to forecast the reservoir properties of the Bazhenov formation including in the zones of anomalous sections (for example, in the Kogalym region).