Research subject. The structure of the pre-Paleozoic deposits and different-age Precambrian basement of the East European platform based on geological and geophysical data. Aim. To trace the evolution of the area under study and to study the geodynamics of processes in order to reconstruct the paleostructure of the Baltica continent. Materials and methods. The current state of the consolidated crust was studied using a geological interpretation of seismic profiling data (transects: “EB-1”, “Tatseys”, “Magnit”) and materials of gravity and geomagnetic surveys. The material composition of the basement rock complexes was studied based on drilling data. Results. The Baltica continent forms the basement of the modern East European Platform. After the Sveconorwegian folding about 1000 Ma, Baltica had become part of the Rodinia supercontinent and merged with the North American platform. A passive continental margin with the Riphean-Vendian sedimentary cover was formed on the eastern Baltica edge. The Petrozavodsk-Khopersky orogen, which arose in the place of the Karelian (Early Proterozoic) Petrozavodsk-Khopersky paleoocean, was reconstructed. The submeridional suture was a result of this paleoocean closure. The orogen structure, as well as that of the paleocontinent Baltica, was disturbed and partially destroyed by subsequent tectonic processes, which continue at the present time with modern rifting. Conclusions. The closure of the Petrozavodsko-Khopersky paleoocean led to the formation of the Baltica continent, which included three microcontinents – Sarmatia, Fennoscandia and Volga- Uralia. Baltica became part of the Rodinia supercontinent during the Sveconorwegian orogeny. Volga-Uralia was located on the border with the PaleoPacific and had a Late Riphean sedimentary cover of the Rodinia supercontinent. This margin underwent destruction during a collision with the Timanides. The scale and extent of the reconstructed Petrozavodsk-Khopersky orogen is comparable to Paleozoic orogenic belts, such as Cadomides, Caledonides, Variscides, or Timanides.

The ca 2.0 Ga Volgo-Don fold-and-thrust belt, about 500 km in width and at least 600 km in length, covering an area of about 300000 square kilometers intervenes between the Archean Sarmatian and Volgo-Uralian proto-cratonic blocks of the East European Craton, both of which are coupled with 200–300 km thick sub-continental lithospheric mantle keels. The focus of this paper is the elucidation of its nature in order to answer the basic question how this and other thrust-and-fold belts could be formed in the Paleoproterozoic, and whether they are the same as or different from modern collision orogens. The active Himalayan-Tibet orogen is commonly thought of as the most extensively studied large, bi-verging fold-and thrust belt continental collision zone which may provide insight into key tectonic mechanisms for an understanding of orogenic processes in the Earth’s geological past. Precambrian orogens are tentatively perceived yet as something that was distinct from recent orogenic styles and was due to the initial elevated geotherm and higher radio-genic heat production in the early Earth. In this paper we report for the first time the revealation of the large, slightly eroded divergent Paleoproterozoic Volgo-Don orogen which is mostly composed of juvenile metasediments and comprises well-preserved patterns of the crustal orogenic architecture which are characteristic of the archetypal Himalayan-Tibet collisional orogen rather than of hot/ultra-hot Precambrian orogens based on numerical modeling.

Despite the long history of geological exploration and scientific research in the Caspian region many issues of its oil and gas geological zoning remain controversial, including justification the boundaries of oil and gas provinces at the ancient and young platforms: Pre-Caspian, Ciscaucasia-Mangyshlak and North-Ustyurt. This paper discusses problems of the ancient and young platforms sedimentary cover’s oil and gas zoning using the example of Pre-Caspian region. It is proposed to carry out oil and gas geological zoning of these regions with taking into account the types of the Earth’s crust sections and sedimentary cover’s hydrocarbon systems types, as well as the types of the main oil and gas complexes’ structures. The type of the Earth’s crust section is crucial upon identification oil and gas provinces boundaries; the type of hydrocarbon systems is in the foreground when identifying sub provinces; and the boundaries of oil and gas regions are determined by the main types of oil and gas complexes’ sections and structures. In the Pre-Caspian province three sub-provinces are identified and their oil and gas potential is characterized. The proposed boundaries of the province closely coincide with the distribution contours of the Kungur saliferous strata with considerable thickness (hundreds of meters). Due to the lack of a clear structural boundary between the Paleozoic hydrocarbon systems the Pre-Caspian and Volga-Ural oil and gas provinces are proposed to be considered as a single marginal-continental oil and gas mega-province. The obtained materials and conclusions can serve as a basis for basin modeling and hydrocarbon resources forecast’s refinement.

Research subject. A meridional Tastau rift structure located in the Famenian sub-latitude rift system of Central Kazakhstan was investigated, including the specific features of its constituent sediments and volcanism, as well as the stages of its development.Materials and methods. The study was based on data collected during a long period of fieldwork, including a detailed study of the sequence of sedimentation processes, large-scale geocarting, sampling for various types of precision analyses.Results. The typomorphic features of the main rock types were determined. It was shown that basaltoid rocks occurred in the form of pillow structures with a hyaloclastite matrix between the pillows. Siliceous shales are saturated with thin ash silicic acid material. A geological scheme of the Tastau structure and its specific features was presented in a series of cross-sections. The developmental stages of this structure were established. The structure was referred to the rift type.Conclusion. The material and structural features of the investigated Tastau section are shown to be typical of the entire rift system of Central Kazakhstan. The pre-rift (Frasnian) stage is characterized by continental volcanism in the form of highpotassium and ultra-potassium rhyolite ignimbrites composing an encialic island-arc structure. These volcanites belong to the shoshonite and high-potassium lime-alkaline petrochemical series. The rift stage itself began in the Early Famenian age with the formation of a system of narrow deep troughs, into which the sea from the neighbouring Zhongaro-Balkhash sea region started to ingress. The conglomerates are characterized by thin flattened isometric pebbles, whose well-polished surface is similar to that of pebbles in modern sea beaches. The sandstones exhibit a high level of lamination and are characterized by poorly pelletized clastic material. The clastic material is represented by the underlying Frasnian rhyolitic ignimbrites carried in from the sides of the trough. The mature rift stage is characterized by the accumulation (under marine conditions) of pillow basalts and hyaloclastites and thin-layered silicite-clay-carbonate shales with abundant ash. The postrift stage is responsible for the formation of layered limestones of the Lower Tournaisian, developed also widely beyond the specified rift trough.

— The geological and sedimentological interpretation of several time and deep seismic profiles within junction zone of the Volga‒Ural area of the East European Platform, Pre-Caspian Depression, Ural Foredeep, Bashkir Anticlinorium, and northern margin of the Scythian Platform allowed us to identify a number of previously unknown structural features of Later Precambrian and Early Paleozoic formation. On this basis, structural-facies maps were compiled for the Riphean and Vendian stages of development. It was shown that as a result of the collision of the southeastern passive margin of the continent Baltica with Scythia in the Early Vendian and with the Timanides of the Urals in the Later Vendian, a complex tectonic structure of the Orenburg tectonic node was formed, which forms the foundation of the Caspian oil and gas province. The results obtained substantially clarify the structure of the sedimentary cover of the East European Platform and the Pre-Caspian Basin, the stages of the formation and evolution of their structure, and the degree of influence on the sedimentation of structural changes in the adjacent territories of the folded Urals and the Scythian Platform.

Research subject. In this paper, we set out to investigate main paleostructures in Kazakhstan. In particular, we attempt to clarify or revise their existing geodynamic structures and to show key stages in their development on the basis of new data on the age of some stratigraphic units and rocks of the ophiolitic association.Materials and methods. The work was based on the materials of long-standing geological research performed by the authors, including government-funded geomapping, tectonic zoning and paleoreconstruction, as well as the revision of literature data.Results. It is shown that the main sedimentary, volcanogenic, volcanogenic-sedimentary and intrusive complexes were originated in the western part of the Central Asian fold belt (Paleozoic Kazakhstan) in place of various structures differing in their geodynamic environment and tectonic history throughout the Proterozoic and entire Paleozoic periods. The Epigrenville microcontinent disintegrated into individual massifs has been described, along with rift depressions, basins with oceanic crust, island arcs and island arc systems, the Epicaledonian continent, continental depressions, regional volcano-plutonic belts and marginal basins. The tectonic zonality of Kazakhstan has been presented in the form of diagrams. The mapping of the Precambrian Ulutau massif has been conducted. The distribution of the Devonian complexes and the Late Paleozoic complexes of Kazakhstan is schematically represented.Conclusions. We have refined and partially revised the existing concepts and tectonic consecution on the territory of Kazakhstan. On the basis of paleoreconstructions, key stages in the development of main paleostructures have been established; features of the geological evolution of Kazakhstan paleozoids and their relationship with tectonic processes in the Central Asian fold belt have been determined. It is shown that the modern structure of Kazakhstan paleozoids was evolving over a long period and in many stages for almost 900 million years.

The data on the known and assumed subsalt oil and gas prospective structures (traps) of the Pre-Caspian depression are analyzed taking into account the new investigations.Among the major traps are dominated by carbonate (buildups) and terrigenous (fan deep sea deposits) types.A new type of erosion-lithological traps formed during sea level falls was revealed.Large undiscovered traps are located mainly at depths of 6-8 km.The present forecasted resources of hydrocarbons are significantly higher than have been explored ones.

A structural-facies map of the Bashkir stage of the Caspian basin, the southeastern part of the East European platform and the Turan plate is compiled on the basis of drilling data generalization. The sequence of tectonic events and sedimentation processes in the early‒ late Bashkir century of the middle Carboniferous was reconstructed. It is shown that cessation of reef formation, appearance of erosion surfaces and partial destruction of the side ledges of Caspian depression occurred under the influence of Varis orogenesis and the global fall of the World Ocean level due to the glaciation of the Paleogondvana at the turn of early‒middle Carboniferous. It is assumed that oil and gas reservoirs in the rocks of Vise‒Bashkir age are confined to large bodies of carbonate-clastic rocks with clinoform structure that arose on the slopes of the depression due to destruction of its side ledges.

Составлена структурно-фациальная карта башкирского яруса Прикаспийской впадины, юго-восточной части Восточно-Европейской платформы и Туранской плиты на основе обобщения данных бурения. Реконструктуирована последовательность тектонических событий и седиментационных процессов в ранний– поздний башкирский век среднего карбона. Показано, что прекращение рифообразования, возникновение поверхностей размыва и частичное разрушение бортовых уступов Прикаспийской впадины произошло под влиянием варисского орогенеза и глобального падения уровня мирового океана из-за оледенения Палеогондваны на рубеже раннего и среднего карбона. Предполагается, что разервуары нефти и газа в породах визе-башкирского возраста приурочены к крупным телам карбонатно-обломочных пород клиноформного строения, возникших на склонах впадины за счет разрушения ее бортовых уступов.

In this paper we consider the results of geological interpretation of 3DV (Tommot–Skovorodino segment) and Tynda–Amurzet geophysical transects crosscutting the Aldan Shield and the Stanovoi Granite–Greenstone Domain of the Siberian Platform; the Selengino–Stanovoi, Mongolia–Okhotsk, and Gobi–Hinggang foldbelts; and the Argun and Mamyn microcontinents with a total extent of sections of about 1000 km and depth of about 40 km. The data of previous studies and follow-up electric conductivity information have been used. The data of geological mapping, subject studies, and insights into the deep-seated structure of the considered territory obtained with a complex of geophysical methods are discussed. It is shown that Mesozoic strike-slip and thrust faults play the leading role in the present-day structure of the territory and in control rifting and mantle diapirism. It is suggested that Californian-type metamorphic nuclei, which are of structure-forming significance for adjacent territories in the west, have also developed in the studied region.

Рассмотрены и обобщены геологические материалы, полученные к настоящему времени по территории Казахстана и Тянь-Шаня. На этой основе показаны главные особенности строения выделяемых там разнотипных и разновозрастных палеоструктур – континентальных массивов, бассейнов с океанической корой, островных дуг, краевых вулкано-плутонических поясов, а также зон трансформных разломов. Выяснены характер и возможные причины их эволюции и преобразований, отразившихся на формировании и развитии мозаичного структурного ансамбля на окраине существовавшего с неопротерозоя Палеоазиатского океана. Выделены и проанализированы основные этапы геодинамических изменений в истории палеозоид Казахстана и Тянь-Шаня и предложена модель вероятного хода тектонических событий в регионе. Модель проиллюстрирована с использованием опубликованных палеомагнитных данных, серией палеотектонических реконструкций, построенных для интервалов времени 950–900, 850–800, 750–700, 650–630, 570–550, 530–515, 500–470, 460–440 и 390–380 млн лет.

The correlation of geological events and structure-forming processes occurring contemporaneously in the inner parts of cratons and the adjacent paleooceanic basins is discussed in order to understand the effects of these processes on sedimentation and structural rearrangements. For this purpose, a series of paleodynamic reconstructions of the Riphean, Vendian, and Paleozoic epicontinental basins of the East European Platform and zones of their transition to marginal basins of the same age once situated in the Ural, Timan, Caucasus, Scandinavian fold regions and in the Scythian-Turan Plate have been performed on the basis of the available original and published data combined with interpretation of seismic profiles. As a result, a set of structural-facies maps of this territory have been compiled for several time intervals from the Late Riphean to Early Permian.

Статья посвящена корреляции геологических событий и структурообразующих процессов, происходящих одновременно во внутренних частях кратонов и смежных палеоокеанических бассейнах, оценке влияния этих процессов на осадконакопление и структурные преобразования. Для решения этой проблемы на основе обобщения имеющихся оригинальных и опубликованных данных и материалов сейсмопрофилирования выполнена серия палеогеодинамических реконструкций рифейских, вендских и палеозойских эпиконтинентальных бассейнов Восточно-Европейской платформы и зоны их перехода к окраинным бассейнам соответствующего возраста, некогда располагавшихся на месте Уральской, Тиманской, Кавказской и Скандинавской складчатых областей и Скифско-Туранской плиты. В результате составлена серия структурно-фациальных карт этой территории, охватывающих период времени с позднего рифея до ранней перми.

Geological information on Kazakhstan and the Tien Shan obtained up to the present time has been considered and integrated in order to demonstrate the main features of continental massifs, basins with oceanic crust, island arcs, marginal volcanic-plutonic belts, and transform fault zones differing in type and age. We ascertained the character and probable causes of their evolution and transformations resulting in the origination and development of mosaic structural assembly at margin of the Paleoasian ocean that existed from Neoproterozoic. The main stages of the geodynamic history of Paleozoides in Kazakhstan and Tien Shan are characterized, and a model of the probable course of regional tectonic events has been proposed. This model is illustrated by published paleomagnetic data and a series of paleotectonic reconstructions for time intervals 950–900, 850–800, 750–700, 650–630, 570–550, 530–515, 500–470, 460–440, and 390–380 Ma.

The paper considers the morphology, deep structure, and geodynamic features of the Ural–Herirud postorogenic strike-slip fault (UH fault), along which the Moho (the “M”) shifts along the entire axial zone of the Ural Orogen, then further to the south across the Scythian–Turan Plate to the Herirud sublatitudinal fault in Afghanistan. The postcollisional character of dextral displacements along the Ural–Herirud fault and its Triassic–Jurassic age are proven. We have estimated the scale of displacements and made an attempt to make a paleoreconstruction, illustrating the relationship between the Variscides of the Urals and the Tien Shan before tectonic displacements. The analysis of new data includes the latest generation of 1: 200000 geological maps and the regional seismic profiling data obtained in the most elevated part of the Urals (from the seismic profile of the Middle Urals in the north to the Uralseis seismic profile in the south), as well as within the sedimentary cover of the Turan Plate, from Mugodzhary to the southern boundaries of the former water area of the Aral Sea. General typomorphic signs of transcontinental strike-slip fault systems are considered and the structural model of the Ural–Herirud postcollisional strike-slip fault is presented.