Research subject. The article discusses a number of geochemical features (distribution of lanthanides and Th, values of (La/Yb)N and Eu/Eu*) of fine-grained clastic/clay rocks of various Vendian regional stages of the western slope of the Middle Urals. The results were interpreted in the context of data on the composition of the catchment areas of a number of modern rivers and information on the distribution of the same characteristics in suspended matter and modern bottom sediments of the “downstream North Dvina River–White Sea”.

Methods and materials. The content of La, Sm, Eu, Gd, Yb, and Th in as many as 200 samples of shales and mudstones of the Serebryanka and Sylvitsa groups served as a research material. The research method was an analysis of the localization of individual and average data points of clayey rocks of the Laplandian, Redkinian, Belomorian and Kotlinian regional stages on paired diagrams (La/Yb)N–Eu/Eu* and (La/Yb)N–Th developed on the basis of analytical data on the composition of bottom sediments of estuarine parts of different categories/classes of modern rivers.

Results. It was shown that the sedimentary sequences of the western slope of the Middle Urals are mainly composed of fine-grained clastic material belonging to categories 1 (sediments of world major rivers) and 2 (sediments of rivers draining sedimentary/mixed sedimentary formations). This material is likely to have entered the sedimentation area from the east, from the growing Kadomian Varanger-Kanin-Timan folded-thrust belt/Timan orogen, or/and from the west (Riphean sedimentary sequences of Kama-Belsk aulacogen). In addition, the igneous and metamorphic rocks of the East European Platform basement composing the structures, which could be classified as “igneous/metamorphic terranes” under modern classification, were likely to have made a certain contribution.

Conclusions. The obtained results agree well with the conclusions obtained earlier as a result of mineralogical and petrographic studies of the conglomerates and sandstones of the Serebryanka and Sylvitsa groups, as well as with the data from a previous geochemical analysis of clay rocks.

Research subject. A series of research studies was conducted in the Alai Range area, at the junction of the folded Tien Shan and Pamir provinces with the purpose of investigating the morphological structure of alpine deformations in the Paleozoic basement and Mesozoic–Cenozoic sediment cover.

Materials and Methods. Structural and geological observations were carried out in the Alai and Kichi-Karakol inter-mountain depressions and their mountainous surroundings. These investigations included an analysis of the morphology and orientation of the deformation structures of the sedimentary cover and structural inconsistencies based on detailed geological mapping; measurements of the orientations of tectonic slickenlines and slickensides in the zones of active faults; processing the entire complex of data in terms of kinematic strain indicators using proven methods and calculation programs in order to determine the main parameters of the stress-strain state of the upper crustal rock complexes.

Results. The age intervals and kinematic conditions of the main phases of structural transformation of the Southern Tien Shan at the Alpine stage of tectogenesis were determined based new structural and geological data, as well as materials published in previous works. It was demonstrated that, in the territory of Alai, the most significant deformations and activation of the Paleozoic basement faults occurred at the Neogene-Quarter boundary.

Conclusions. At the present stage, the area under study constitutes a relatively stable block, which does not experience significant deformations associated with the encroachment of the upper crustal rock complexes of the Northern Pamir from the south.

Research subject. The article discusses the results of a new detailed study of a reference section of the Upper Silurian in the Subpolar Urals. This study was undertaken to clarify the existing contradictions concerning the age of the Ludlow-Pridoli boundary deposits and the definition of the Ludlow-Pridoli boundary, which is based on the study of different fauna groups.

Materials and methods. The newly collected collections contained more than 100 samples of sedimentary rocks with fossil macro fauna, 22 tests on microfauna, 198 tests on chemical analysis for determining the content of Ba, Sr and δ13C and δ18O isotopes in carbonates. The results of experiments were confirmed by the authors’ bio-sedimentological, paleo-ecological and chemostratigraphic data.

Results. The conducted research confirmed the existence of a gap in sedimentation at the end of Ludlow; clarified the thickness of the Sizim stage in the reference section; elucidated its sedimentological and chemostratigraphic characteristics; allowed changes in biodiversity due to a change in the sedimentation regime, paleoecological impact on biota in the late Ludlow and restoration of biota in the early Pridoli to be traced. The study also demonstrated that the time boundaries of the transgressive and regressive stages in the development of the Northern Ural sea basin and the event-stratigraphic boundary of the Ludlow-Pridoli were directly related to the main global events in the Late Silurian (Lau Event, Lower Pridolian Event), the traces of which are preserved in the studied section.

Conclusions. The intensification of regressive tendencies across the largest part of the Northern Ural paleobasin in the Late Ludlow, widespread development of microbial biota, cessation of the Silurian reef formation, as well as the extinction of Pentamerida brachiopods – exclusively, indicate a significant ecosystematic restructuring in the late Ludlow. It can be assumed that the absence of a significant positive deviation of the δ13C global Lau Event in this section is associated with the identified gap, the amplitude of which correlates with the Ozarkodina snajdri and Ozarkodina crispa zones located above the Polygnathoides siluricus zone in the conodont sequence of the Upper Ludlow.

Research subject. This paper investigates Maastrichtian (Upper Cretaceous) foraminifera complexes present in various parts of the Western Siberia.

Materials and methods. The materials of parametric drilling performed in the last century were reviewed in the context of new data. The characteristics of the main ecological microfauna groups in the Gan’kino horizon (Maastrichtian) were clarified by analysing their taxonomic composition, structure and diversity.

Results. It was shown that, in the typical Yamal-Tyumen district, the Gan’kino horizon consists of three zones: Spiroplectammina variabilis, Gaudryina rugosa (with subzones Bolivina decurrens, Bolivinoides senonicus and Stensioeina caucasica transuralica), Spiroplectammina kasanzevi, Bulimina rosenkrantzi (with subzones Bolivina plaita, Bulimina rosenkrantzi and Heterostomella foveolata) and Brotzenella praeacuta. Here, the horizon volume is limited to the Maastrichtian stages. The Stensioeina caucasica transuralica and Brotzenella praeacuta zones were found to belong to the Upper Maastrichtian.

Conclusions. It was established that, the Early and early Late Maastrichtian was characterized by a gradual increase in the diversity of foraminifera complexes due to immigrants from the Boreal-Atlantic realm. The widespread distribution of foraminifera complexes from the Northern district across the Western Siberia during the Spiroplectammina kasanzevi and Bulimina rosenkrantzi period was associated with the transgression of Arctic waters. The appearance of the foraminifera associations with Heterostomella foveolata reflects a wide levelling of the foraminifera composition throughout the Western Siberia. At the beginning of the Brotzenella praeacuta time, Boreal-Atlantic taxa were widely dispersed across the Western Siberian basin.

Research subject. Changes in the trophic structure of shallow-water pelagic ecosystems at the Devonian/Carboniferous border were investigated by studying the carbon isotope composition of conodont organic matter.

Materials and methods. Two Devonian-Carboniferous shallow-water clayey-carbonate sections located in the southern part of the Pechora-Kozhva Uplift (Pechora Plate) were analysed. The Devonian-Carboniferous boundary was detected by the first occurrences of Siphonodella sulcata, S. semichatovae and Patrognathus crassus, as well as by the last occurrence of Pseudopolygnathus graulichi. The carbon isotope composition was investigated both in whole-rock carbonate samples and the conodont organic matter of two dominant species (Polygnathus parapetus and P. communis communis).

Results. The distribution of stable carbon isotopes in the organic matter of conodont elements accompanied by the data on carbonate isotope composition allowed us to suggest changes in the food composition of the dominant taxa during the Late Famennian-Early Tournaisian transition. It was assumed that the latest Famennian representatives of Polygnathus parapetus and P. communis communis consumed largely phyto- and zooplankton, which is characterized by a light isotopic composition of organic carbon. The nutrition based on phyto- and zooplankton with a heavier isotopic composition of organic carbon was suggested for the early Tournaisian representatives of these species.

Conclusions. The discovered variations in the carbon isotope composition of conodont organic matter in shallow-water facies may correspond to the change from the eutrophic pelagic ecosystem to the oligotrophic ecosystem, and/or global perturbation of the carbon cycle due to climatic changes. Since the available data is limited to two geological sections, it is impossible to unambiguously interpret the scale (local, regional, global) of these variations and their correlation potential.

Research subject. Rocks of the Paleozoic Eastern Ural microcontinent and Magnitogorsk island arc occupy a significant part of the Southern Urals and some part of the Middle Urals. The Western Urals are composed of rocks of the ancient Baltic continent and overthrust oceanic rocks. In the Eastern Urals and Trans-Urals rocks of the accretion complexes, oceanic crust, island arcs, the Eastern Ural microcontinent and the Kazakhstan Paleozoic continent are widespread. Rocks are exposed in the Denisov tectonic zone. The Magnitogorsk simatic Island Arc originated in the Ural Ocean, near the Baltic continent, in the early Devonian, developing from the Emsian to the Famennian. A collision between the Magnitogorsk arc and the Baltic continent occurred in the Famennian century. In the pre-Carboniferous age, the Eastern Ural microcontinent was located in the Ural Ocean. In the Tournaisian period, the Eastern Ural microcontinent accreted with the Baltic continent. The Kazakhstan continental massif was located on the other side of the Ural Ocean. The volcanic belt above the subduction zone was active on the edge of the Kazakhstan continent in the Early–Middle Devonian and in the Early Carboniferous. A subduction under the Baltic and Kazakhstan continents consumed most of the crust of the Ural Ocean by the middle of the Bashkir century. As a result, the Baltic continent (together with the Eastern Ural microcontinent) came into contact with the Kazakhstan continent. The formation of folded orogen began in the Moscow century following the collision of sialic terrains.

Materials and methods. The research was based on the relevant data obtained by several researchers in 2000–2018 on rock paleomagnetism.

Results. The paleolatitudinal positions of the Eastern Ural microcontinent were determined, comprising 5.3 ± 7.4°) in the Middle Ordovician and 8.2 ± 7.2° in the Early–Middle Silurian. The respective paleolatitudinal positions for the Early–Middle Devonian comprised: the Ural margin of the Baltic paleocontinent (7.7 ± 3.7°), the Magnitogorsk island arc (3.2 ± 3.1°) and the Ural margin of the Kazakhstan paleocontinent (20.6 ± 3.8°).

Conclusion. According to the analysed paleomagnetic data, in the Early–Middle Devonian, the distance between the latitudes of the margins of the Baltic and Kazakhstan continents was not less than 600 km provided they were in the same hemisphere, and more than 2,300 km provided they were in different hemispheres. The convergence of the terrains was associated with the subduction of the Ural Ocean crust before its closure, which occurred in the Tournaisian century.

Research subject. The Yamal Peninsula is of interest due to the fact that the concentration of hydrocarbon deposits per unit area is more than 100 times higher than the “world average”, which is confirmed by the reserves of the largest oil and gas fields already discovered. At the same time, the knowledge of the deep horizons of the earth’s crust and mantle within the Yamal and adjacent areas is clearly insufficient in comparison with more southern regions.

Methods. In this work, the method of seismic tomography was used, which makes it possible to identify anomalies in the velocities of seismic waves directly related to the heat flow density and geodynamic activity of the subsurface.

Conclusons. Apparently, the Western Yamal positive thermal anomaly indicates a region of a high geodynamic activity permeable for deep fluid-gas streams. The location of Yamal on a slightly raised shoulder of this anomalous region has determined the high oil and gas potential of this peninsula. Other regions situated in the vicinity of the discovered thermal anomaly may present significant research interest.

Research subject. This paper investigates rock deformations and stress states in mineral excavation sites.

Materials and research methods. On the basis of a 20-year geodeformational monitoring of natural stresses and deformations in the rock mass at mining sites in the Urals, carried out by the Laboratory of Geodynamics and Rock Pressure at the Institute of Geology and Geology of the Ural Branch of the Russian Academy of Sciences, we propose a novel structure of natural stress fields with reference to their change over time. Measuring instruments should be calibrated using standards of length and weight, including surveying tape measures, tapes, wires of various chemical composition, light and radio-range finders.

Results. For the mining sites under study, the parameters of the variable component of stress fields with a chronological reference were determined, along with a forecast of loads both during preparatory and mining stages up to 2022. The experiments showed that, along with lithostatic (gravitational) and tectonic stresses, it is necessary to distinguish variable “astrophysical” rock stresses due to the cyclic expansion and contraction of the Earth.

Conclusions. Using available measurements obtained during the most recent 11-year nanocycle of solar activity, regularities in the formation of rock deformations and stresses were revealed. A forecast of natural stresses with an increase in variable “astrophysical” stresses in the upcoming solar activity cycle was made. Measurements of rock deformations are currently performed using methods based on various physical principles. The results obtained thus far are relative, not permitting to judge about absolute values. The numerical values of dozens of fundamental physical constants are also variable. The international community of scientists should develop a mechanism to track changes in their magnitude over time.

Research subject and methods. The paper presents a review of available information on the atmosphere of Titan and its surface, necessary for the development of concepts of hydrocarbon formation, including the natural hydrocarbon synthesis, formation of prebiogenic states and origin of life. The presence of vast reserves of abiogenic hydrocarbons on Titan is extremely important for the theory of hydrocarbon genesis on the Earth, since any concept of naphthogenesis claiming to be a consistent explanation of the entire set of available facts must take into account the possibility of abiogenic formation of large accumulations of hydrocarbons.

Results. It was shown that the hydrocarbon diversity of the atmosphere and surface of Titan is provided by the inflow of endogenous methane. Degassing processes on Titan are characterized by specific forms due to their flow through a liquid medium: 1) “gas-lifting degassing” forming numerous small depressions with increased fluid levels and, possibly, being the cause of “magic islands” in the sea of Ligeia; 2) limnological emissions of gaseous methane, followed by intensive cloud formation, the development of methane storms and large amounts of precipitation.

Conclusions. It is concluded that the presence of active degassing processes on Titan in combination with the emerging models of its internal structure contribute to clarifying the previously proposed scheme of primary natural hydrocarbon synthesis in the depths of Titan.