Our study was focused on the active tectonics of the southern slope of the Greater Caucasus within Azerbaijan. The study area is the zone of under-thrusting (pseudosubduction) interaction between Southern and Northern Caucasus continental microplates, which caused the tectonic stratification of the Alpine formations into various allochthonous and parauthochthonous thrust slices of southern vergency between the Middle Bajocian and Quaternary periods. These slices are grouped into the nappe complexes that form the modern structure of the trough in the study area. The large linearly stretched tectonic units (megazones) correspond to the axis of the Alpine marginal sea basin, the consolidated crust of which is subjected to destruction and thinning. The trough’s Alpine cover was compressed in the underthrust zone and pushed southwards. As a result, an accretionary prism formed allochthonously overlapping the northern side of the Southern Caucasus microplate by the system of gently dipping overthrusts. During the continental stage of Alpine tectogenesis (starting from the end of Miocene), intensive lateral compression process was caused by intrusion of the frontal wedge of the Arabian indenter into the buffer structures of the southern frame of Eurasia. This is evidenced by the GPS monitoring data on modern geodynamic activity, which demonstrates the Southern Caucasus block’s intensive (up to 29 mm/year) intrusion in the northern rhumbs as compared to the relative stability of the Northern Caucasus microplate (0–6 mm/year). This, in turn, is a reflection of the ongoing pseudosubduction regime (continental subduction or S-subduction) at the band of collision junction of these microplates. It is suggested that this process caused historically observed seismic activity in the study area, wherein the earthquakes occurred mainly in the southern slope’s accretionary prism area and the adjacent strip of the Southern Caucasus microplate. In this article, we analyze and correlate the whole range of seismic events that occurred in the study area until 2017 and the focal mechanisms of the recently recorded earthquakes (2012–2016). It is established that earthquake foci are confined either to the intersection nodes of variously trending ruptures with the faults of different directions or to the planes of deep tectonic ruptures and lateral displacements along the unstable contacts between the material complexes with different competence. The focal mechanisms of seismic events reveal various, mostly near-vertical, planes of normal and strike-slip faults. However, the earthquake foci are generally confined to the intersection nodes between the Caucasus and anti-Caucasus-striking rupture dislocations. The results of our studies are interesting in terms of their real-time application for drawing a regional summary of causes for both geodynamic and seismic activity of the Greater Caucasus system and the adjacent areas of Alpine-Himalayan fold belt.

The Alpine-Himalayan orogenic belt is characterized by longitudinal zoning and transverse segmentation. Using the 3D seismic tomography model, we compiled the sections showing the deviations of seismic P-wave velocities from the average values in the mantle, and analyzed the sections in comparison with the data on the crustal inhomogeneities expressed in geological structures. The sections go across of the central part of the belt from Adriatic to Western Tien Shan, Pamirs, Western Himalayas, and the adjacent territories of the East African rift system, the Arabian, Turanian and Scythian plates, and the East European platform. Our model based on the seismic tomography data is mainly targeted at studying the inhomogeneities in the upper mantle, considering the fact that the resolution of mantle differentiation in terms of P-waves is higher in the upper mantle than in the lower one. Based on the analysis of the sections, we determine the directions of seismically low-velocity upper-mantle flows spreading from the Ethiopian-Afar super-plume, which differ in intensity. The relationships are revealed between these flows and the high-velocity bodies that are subsided into the mantle due to subduction and collision of the plates. The deep-seated features that give evidence of transverse segmentation of the belt are detected.

Differences have been discovered in the deep structures of North and South Kamchatka, which raises a question about a boundary between these regions. This problem has been studied on the basis of the seismologic, inverse seismic tomographic (P-waves) and geoelectrical data obtained in recent years, as well as the information on magnetometry, gravimetry, tectonics and magmatism of the study area. Comprehensive analysis of the geological and geophysical data shows differences in the structure of the crust and upper mantle in North and South Kamchatka and common features of the deep structures of South Kamchatka and the Kuril Islands. A presumed boundary between North and South Kamchatka is related to the zone of transverse deep faults crossing the peninsula. It is evidenced by P-wave velocity anomalies at different levels of the lithosphere. This fault zone is associated with a change in the geometry and strike of the high-velocity focal layer, and reflected in the modern tectonic plan as the Petropavlovsk-Malkinsky zone of transverse dislocations. In this zone, the Avacha-Koryak group of modern volcanoes is also NW-oriented. We propose a geoelectric model showing the depths along the profile constructed across the zone. In its deep part, the model includes sub-vertical anomalies of increased electrical conductivity. The anomalies are related to deep faults. Increased electrical conductivity may be due to the presence of magmatic melts feeding volcanoes. The results obtained in our study give evidence of the common features of the deep structures of South Kamchatka and the Kuril island arc and demonstrate the differences between the deep structures of North and South Kamchatka, being separated by the zone of faults, which may penetrate into the upper mantle. It is suggested that the identified features in the South Kamchatka structure are due to deep processes taking place not only at the side of the Pacific Ocean, but also at the southern margins of the Sea of Okhotsk. These findings are of interest for geodynamics, volcanology, tectonics and other Earth sciences.

The studies of the deep structure and tectonics of the Arctic are important for solving the fundamental problems of modern geodynamics and developing its natural resources. This region is also of interest from the geopolitical point of view, in particular, considering the boundaries of the marginal seas. Our study aims to investigate the lithospheric (anomalous) geomagnetic field in the Norwegian-Greenland region of the Arctic and to correlate the identified anomalies with tectonic structures located in the region under study. The database includes the CHAMP satellite measurements of the modulus of the total geomagnetic field vector (the satellite operated at the altitude of ~280 km). This article describes the satellite data processing method applied to distinguish between the lithospheric part and other components of the geomagnetic field. Map showing the total vector modulus of the lithospheric field has been constructed for the studied area. The article discusses the possible nature of the lithospheric magnetic anomalies and their relation to the processes that occur under the territory of Greenland. According to our interpretation of the maps, the geomagnetic field anomalies are related to the modern large-scale geological and tectonic structures located in the studied area. The obtained results can facilitate further comprehensive geological and geophysical studies and contribute to modeling of the evolution of the lithosphere.

In the territory of Uzbekistan, seismic activity is high, and ensuring seismic safety of the population is among the most important problems for the country. Our study was focused on discovering relationships between the attenuation of the ground oscillation rates, their spectral amplitudes and the distances to the epicentres of the earthquakes of different energy levels, which took place in the region under study. An objective was to quantitatively assess the seismic hazard of the study area. We analyzed the velocity graphs of M 3.8–6.2 earthquakes that occurred in Uzbekistan and the neighbouring territories, and the recorded earthquake spectrum data. For the region under study, it is established that the attenuation of the ground oscillation rates and their spectral amplitudes depend on the distances. Taking into account the sizes of crustal earthquake foci, the spectra of ground oscillation rates were calculated for the near zone. Based on the established regional dependencies, the maximum ground oscillation rates and spectral velocity amplitudes were estimated, and seismic hazard probability for the territory of Uzbekistan was assessed. For several towns and cities of Uzbekistan, the highest predictable spectral amplitudes were determined, which, under given probability P, will not be exceeded within the coming 50 years. The quantitative characteristics of seismic hazard can be converted to the indicators of seismic activity impacts, as required for calculating the seismic loads in earthquake-resistant engineering and construction projects.

The article describes the experience of using the GPR method to study the bottom sediments of Lake Upoloksha located in the Kola Peninsula, Russia. Such sediments are viewed as good archives of various Holocene geodynamic processes, including tectonic and paleoseismic events. This small lake is located in the zone of the active NW-striking lineament, which length is more than 20 km. A series of åsars (eskers) stretches along the lineament. In the previous studies, the bottom sediments of the lake were investigated by geological methods, including core sampling, lithological and micro-palaeontological analysis of sediments. The studies have revealed a horizon which features are indicative of catastrophic changes in the sedimentation conditions due to a single impact. Our study aimed at evaluating the level of informativeness of the GPR method for detecting disturbances in the bottom sediments and new paleoseismic dislocations. The study referred to the hypothesis of the distribution of seismic foci in the Kola Peninsula in the Holocene. A ground-penetrating radar OKO-2 and an antenna unit (150 MHz) were used to survey of Lake Upoloksha in detail. The positions of the main stratigraphic horizons of the bottom sediments were clarified, and their thicknesses were measured more precisely. The GPR measurement error in comparison to the drilling data did not exceed ±0.2 m, which corresponds to the resolution of the antenna used in the survey. The GPR data confirmed the existence of seismic dislocations identified by the geological methods and discovered new zones of displacement and deformation in the organogenic and mineral bottom sediments. The survey detected vertical displacements, which amplitudes vary from 1.3 to 1.7 m, and landslides caused by seismogravitational rock collapse. Based on the GPR data, a bathymetric map was constructed. It shows the positions of the two basins of Lake Upoloksha. The survey provided the basis for a model showing the isosurface of the top of the mineragenous sequence. In the central part of the mineral-base model, there is a series of individual stepwise blocks of the sublatitudinal strike, which result from seismic movements. The GPR survey of Lake Upoloksha demonstrates that the GPR method can be successfully applied to estimate the mineral and organogenic parts of the bottom sediments, study their lithostratigraphic features, and detect changes in the structure of the bottom sediments. Based on the GPR data, it becomes possible to map even the small-scale disturbances.

The article describes the possibility of using the passive satellite measurements of the atmosphere to investigate the vertical patterns of pressure, temperature and relative humidity and simulate the altitude dependence of the refractive index of air. The seasonal parameters were determined for the exponential model showing the tropospheric refraction over observation points IRKM (Irkutsk), ULAZ (Ulan-Ude) and BADG (Badary). Post-processing of the input GPS data was conducted to ensure the highest positioning accuracy. In addition to high-precision geodesy, the global positioning method was used for determining the total tropospheric zenith delays (ZTD), which values are used to solve the problems of radio physics and meteorology. The angles of refraction and the true distances were estimated and compared in different seasons of the year. This study shows that the angles of refraction at the observation points located in the Baikal zone do not differ significantly in order of magnitude from the values estimated for other climatic zones.

High ²³⁴U/²³⁸U activity ratio (AR4/8), identified in groundwater from the Elovka-Kultuk and Nilovka-Mondy inversion sections of the Tunka Valley, coincide with areas of earthquake concentrations. In order to substantiate an approach to earthquake prediction, spatial variations of this parameter were determined in natural water at the western termination of the valley and its temporal variations were monitored in water from the Mon-D well in the Mondy basin in 2013–2017. A recorded gradual decrease of AR4/8 values in water of this well, coeval with preparation and implementation of an earthquake with the energy class K=13.9 in the north of lake Khövsgöl, reflected crack closure that prevented deep water penetration in the Tumelik-Mondy aseismic zone. At the eastern termination of the valley, near the Kultuk village, decreasing AR4/8 values in groundwater were followed with their sharp increasing and transition to low-amplitude variations. Accordingly, crack closing was followed with their opening that facilitated the circulation of deep water and provided seismic events. Leveling of the Mondy anomaly in the Tumelik-Mondy aseismic zone, accompanied by a continuous activity of the Turan and Nilovka anomalies within the Nilovka-Mondy section, emphasized a specific role of the latter as an intermediate chain between the Khövsgöl segment of radial rifts, originated in front of the Hangay orogen, and the largest central basin of the Tunka Valley. The Kultuk, Zaktuy, and North-Tory AR4/8 and earthquake anomalies denoted boundaries of the Elovka-Kultuk section in the Khamardaban lithospheric block flattened at the edge of the Siberian platform basement.

The study was focused on groundwaters sampled from boreholes drilled to deep horizons of the Udachnaya kimberlite pipe and the host sedimentary strata. Brines in the rocks significantly complicate underground mining. Analysis of the hydrogeological setting is required to ensure safety during mining to the design levels. The features of chemical composition and the geochemical evolution of brines in the crust can be clarified in a more detail on the basis of new reliable data on strong chloride saline solutions that formed in complex geological and tectonic conditions. Kimberlite and water samples were taken from the ore bodies and host sedimentary strata at the depth of 680–980 m. Conventional methods of quantitative and instrumental analysis were applied to study the chemical composition of brines. Mineral composition of kimberlite was determined by powder diffractography and X-ray fluorescence methods. Geological, structural and tectonophysical methods were used to reveal and describe the tectonic structure of the kimberlite pipe area. Groundwaters with salinity of 280–406 g/L are strong and very strong calcium chloride brines. The chlorine-bromine ratio has a small range of 48–57; the sodium-chlorine ratio varies from 0.11 to 0.18. According to their geochemical features, the studied groundwaters are metamorphosed brines that have analogues across the Siberian platform. Physical and chemical processes were simulated to investigate the degrees of saturation of strong brines relative to the minerals of water-bearing rocks. The simulation results show that the brines in the Western ore body of the Udachnaya pipe are strongly undersaturated in the deep horizons in comparison to carbonate, sulfate and chloride minerals. This suggests possible dilution of brines during their geochemical evolution. A detailed study of the tectonic structure identified structural elements that control the distribution and migration of groundwaters in the rocks. In the mining sites, brines occur mainly in the fault zones, fault junctions and intersections with the contacts of kimberlite bodies. Integration of hydrogeological and geostructural data can provide a basis for prediction and assessment of the sites with increased water inflow in the deep horizons involved in mining.

The study aims at solving the fundamental and applied problems of hydrogeology and hydrogeochemistry of the Zaeltsovsko-Mochishchensky zone of radon waters in the northwestern district of the city of Novosibirsk. Novosibirsk is one of the few Russian cities built on granites that emit radon (²²²Rn). In geological terms, the study area is confined to the NW near-contact zone of the large Novosibirsk granitoid massif. The available data on radon in this area has not been scientifically consolidated yet. We used the methods of S.L. Shvartsev, N.M. Kruglikov, V.V. Nelyubin, O.N. Yakovlev, and V.M. Matusevich and software packages Visual Minteq, PhreeqC, WATEQ4f and HG-32 and obtained physical and chemical calculations for the forms of migration of trace elements in radon waters and estimated the degrees of radon water saturation with rock-forming minerals. The data from hydrogeological profiles and hydrogeochemical sampling (118 samples from 57 water wells and sources) were analyzed. Radon waters are fissure-type, cold (6–10 °С) and occur at a depth of 50–200 m. By their chemical composition (according to the classification proposed by S.А. Shchukarev), the waters are mainly hydro-carbonate calcium and hydro-carbonate calcium-sodium; the total mineralization amounts to 322–895 mg/dm³. All the water wells drilled in granites and near-contact hornfels were tested for radon. It is revealed that the ²²²Rn concentration in water varies widely, from 11 to 801 Bq/dm³. Therefore, such waters are classified as low-radon and moderate-radon mineral waters (according to the classification proposed by N.I. Tolstikhin). In the wells drilled in hornfels, the ²²²Rn concentration in water is 37–241 Bq/dm³. The concentrations of ²³⁸U and ²²⁶Ra do not exceed 0.098 and 1.9∙10^–9 mg/dm³, respectively. Physicochemical simulation shows that Ag⁺, Ba²⁺, Zn²⁺, Ni²⁺, Mn²⁺, Sr²⁺, Fe²⁺ migrate mainly as free ions, while Be²⁺, Fe³⁺, Zr⁴⁺, Ti⁴⁺ migrate as hydroxide complexes. Uranium is mainly present in uranyl-carbonate complexes of calcium: Ca₂UO₂(CO₃)₃(aq) (61–75 %) and CaUO₂(CO₃)₃^2– (25–36 %). Calculations show abundant saturation of the waters with calcite, dolomite, ferrihydrite, greenalite, hausmannite, manganite, quartz, rutile, siderite, lepidocrocite, goethite, and pyrolusite. The mineral phases, such as aragonite, barite, chalcedony, cristobalite, vaterite, and amorphous silicon dioxide are in equilibrium. Several samples show saturation of the waters with relatively rare phosphorus-containing minerals: hydroxyapatite, manganese hydrogen phosphate, cerargyrite, and lead molybdate. The radon waters are not saturated with monohydrocalcite, calcium molybdate, celestite, chrysotile, copper hydroxide, copper molybdate, epsomite, huntite, amorphous and crystalline iron hydroxide (II), gypsum, iron molybdate (II), magnesite, lansfordite, Na-jarosite, nesquehonite, powellite, strontianite, tenorite, witherite, and zirconium dioxide.

The article is focused on the evolution mechanism of the ‘inert’ and living world around us, which is determined by the creative function of water. Water and igneous rocks of basic and ultrabasic compositions create an abiogenic dissipative system that never reaches an equilibrium and therefore is capable of maintaining its continuous, strictly directed, geologically long-term development and the formation of numerous new minerals that are paragenetically associated with specific geochemical types of water. This system is equilibrium-nonequilibrium. It develops in a thermodynamic area, far from an equilibrium. It is non-linear, irreversible, and internally contradictory. In this system, water has the creative function: the hydrolysis mechanism continuously dissolves some minerals, with which the system is not in equilibrium, and, at the same time, creates others minerals, with which there is an equilibrium, including the mineral that have been absent on our planet. After the occurrence of photosynthesis, the system was supplemented with organic compounds and developed into the ‘water-rock-gas-organic matter’ system. The mechanisms of this system were generally described by V.I. Vernadsky, and we suggest to name this system after him. The Vernadsky system had not only repeatedly became more and more complicated, but acquired the capability of creating more complex organic compounds from simple carbohydrates, such as proteins, lipids, more complex carbohydrates, hemoglobin etc. With time, these components developed into living organisms. Regardless of the repeated complication of the system, the basic mechanisms of its evolution remain essentially the same, and water has preserved and enhanced its creative function through dissolving simple compounds and creating more complex ones. An important factor in the continuous complication of the system is the natural water cycle.

Geological and geophysical studies recently conducted in the White Sea and the adjacent territory have provided new data on the deep structure of this region. Our study aims to conduct complex analysis of the anomalous magnetic field and the geological and geophysical data on the Onega-Kandalaksha paleorift located in the White Sea basin and the adjacent southeastern land area, and to develop a model showing its deep structure. The basis for analysing the magnetic field is the anomalous magnetic field (AMF) map constructed by the authors using the magnetic survey data consolidated by the Marine Arctic Geological Expedition (MAGE) in 2003–2008 and supplemented by the survey data of the Institute of Oceanology RAS in 2001–2004. The parameters of the magnetically active layer are estimated by the independent complementary methods of quantitative interpretation developed by the Laboratory of Geophysical Fields, P.P. Shirshov Institute of Oceanology RAS. This article describes a model showing the structure and formation of the magnetically active layer of the White Sea paleorift. Our study shows that the magnetically active layer of the paleorift system has a complex structure reflecting all the main stages in the evolution of tectonic activity in the White Sea region, from the Middle and Late Riphean to the last glaciation of the Quaternary period. The model includes three structural layers, each corresponding to a certain stage. The bottom structural layer is the base of the magnetically active layer, which reflects the continental rifting stage in the evolution of the White Sea mobile belt in the Middle and Late Riphean. The middle structural layer reflects the Middle Paleozoic (Late Devonian) stage of rifting reactivation, which is characterized by alkaline-ultrabasic magmatism and represented by swarms of alkaline dykes and diatremes, including kimberlite pipes. The top structural layer reflecting a high-frequency component of the AMF is related to the highly magnetic sources of anomalies located in the upper part of this structural layer. The characteristics of the top structural layer suggest that it formed in the Late Pleistocene – Holocene and developed during the final stage the tectonic activation of this region. The deep crustal structure of the White Sea basin is specified in our model showing the magnetically active layer for the low-frequency component of the AMF. In the southeastern part of the basin, magmatism products of the basic (Riphean – Vendian) and alkaline-ultrabasic (Middle Paleozoic) composition are abundant in the crust and provide for a strong magnetic source of anomalies, the lower edges of which are traced at the depths to 30 km. This probably reflects the most active plume-lithospheric interaction. Wedging and uplifting of the magnetically active layer northwestward along the Onega-Kandalaksha rift is related to the White Sea (Belomorsky) deep fault. This fault is a long-lived conduit that channels magma from the central portion of the plume, as evidenced by the igneous bodies of the basic composition in the basement and central parts of the sedimentary wedge in the Kandalaksha graben. The complex analysis of the AMF in the White Sea region suggests the presence of morphologically different igneous bodies in the upper crust in the study region.

The petrographic, lithogeochemical and U-Pb (LA-ICP-MS) geochronological studies were carried out to investigate the terrigenous rocks sampled from the lower part of the Ipsit suite of the Karagass series (Sayan segment of the Sayan-Baikal-Patom belt). These rocks include sandstones, aleurite sandstones and aleurolites, and their mineral compositions are close to that of arkose. Most of the studied rock samples show petrographic features typical of the epigenetic changes at the stage of catagenesis: regeneration of quartz clastic grains, pelitization of potassium-feldspar clastic grains, occurrence of clay-hydromica aggregate, sericitization of plagioclase, chloritization of biotite, and silicification of dolomite pieces, and occurrence of authigenous tourmaline. The above was confirmed by the analysis of the concentrations of petrogenic elements in the studied rocks from the lower part of the Ipsit suite. The analysis results show that the concentrations of K₂O are elevated, while the concentrations of Na₂O are relatively very low, which may be due to the redistribution of these elements during epigenetic transformations. According to the classification by genetic types on the basis of the system of petrochemical modules, the rocks of the lower part of the Ipsa suite are of the petrogenic nature. The acidic igneous rocks are dominant in the source area, as evidenced by the presence of granitoid and quartzite fragments in the clastogenic component, as well as the set of accessory minerals typical of the igneous rocks of the acidic composition, and the distribution pattern of rare and trace elements. According to the U-Pb (LA-ICP-MS) dating of detrital zircons from the aleurite sandstone sampled from the lower part of the Ipsit suite, the zircons are exclusively of the Archean-Early Proterozoic ages. Such ages correlate with the age of the granitoids of the Sayan complex and the felsic volcanites from the Maltsev layer of the Elash series (Biryusa block). Furthermore, the detrital-zircon age spectra of the aleurite sandstone of the lower part of the Ipsit suite are identical to the detrital-zircon age spectra of the terrigenous rocks from the underlying strata of the Shangulezh and Tagul suites of the Karagass series. This study suggests that sedimentation of the Ipsit suite of the Karagass series took place due to the influx of detrital material from the southern part of the Siberian craton into the sedimentation basin, and the acidic igneous rocks of the Biryusa block were one of the main sources of detrital material.

The article presents the results of Sm-Nd isotope geochemical studies of the Upper Paleozoic metasedimentary rocks of the Dzheskogon, Nektera and Bochagor suites of the Dzhagda terrane. These rocks are characterized by slightly varying values of the Nd model age t_Nd(DM)=1.5–1.0 Gyr, which gives evidence that the main sources of protoliths were the rocks of the Mesoproterozoic Nd model age (in average). This Nd model age is similar to the ages of the metaterrigenous rocks of the Teply Klyuch, Garmakan and Alga suites of the Tukuringra terrane of the Mongol-Okhotsk Belt. The results obtained in our studies suggest that the sedimentary rocks of the Dzhagda and Tukuringra terranes developed from the material that was mainly sourced from the Amur superterrane (from the south in modern coordinates). A supply of the material from the southern margin of the North Asian craton (from the north in modern coordinates) was either absent or minimal.

In the study of normal fault zones located in the central Baikal rift, a new approach was applied to process and interpret the shallow-depth electrical resistivity tomography data. This approach is based on the concepts of tectonophysics and considers three-stage formation of a fault and the corresponding three degrees of rock material disturbance, which are regularly detected in the rock mass. The degrees are established by statistical analysis of specific electrical resistance (SER) measured from the electrical resistivity tomography profile across the faults under study. Based on a geoelectrical profile, it is possible to identify the sites wherein the disturbed rocks show the indicators of the early, late and final stages of faulting. The profile provides the basis for specifying the boundaries of the fault zone and the main features of its internal structure. The tectonophysical approach was applied to study a series of normal fault zones varying in ranks. The zones are located on the sides of the Buguldeika-Chernorud graben located near the Olkhon Island in the Western Baikal region. By comparing the geoelectrical profiles constructed under the same methodology, it was established that the near-fault anomalies of electrical resistance are qualitatively similar. Their structure is defined by the general mechanism of normal faulting in the upper crust during sliding along a curved (listric) fault plane. The research results are consolidated in an idealized geoelectrical model: a 2D profile showing a low-resistance anomaly that corresponds to a normal fault zone. This anomaly is asymmetrical and mushroom-shaped, and its internal structure is heterogeneous. In the lying wing of the fault, the anomaly reflects the fan-shaped set of secondary faults caused by the subvertical movements in the normal fault zone, which surface is steeply inclined to the horizon. In the hanging wing, the structure of the anomaly reflects a system of lens-like grabens that form above the surface of the main fault plane that becomes less inclined with depth. The structure of the geoelectrical model proposed for the Olkhon region follows the general regularities controlling formation of listric-shaped normal fault zones. This model can be widely used for diagnostics of tectonic settings and crustal extension structures in other regions.

Modern computational technologies make it possible to simulate practically any concept developed by geologists to investigate the processes of formation of the structures under study, including diametrically opposed ones. Today’s trend is to create complex ‘realistic’ models. Such models are based on a large number of parameters with properly set values and simulate the settings that can be viewed similar to the real situations. However, the adequacy of both the models themselves and the concepts used as the basis for simulation remains the issue of debate. Apparently, it is required to specify a general approach to theoretical constructions in geodynamics, which should ensure that the scope of applicability of the models can be correctly evaluated. Such an approach can be implemented by successive approximations based on the fundamental results of the theory of simple liquids with damping memory, the most general description of irreversible deformation of materials under non-isotropic stress. It is critical to correctly formulate a model in the first approximation. It should be fairly simple and based on reliably established experimental facts, give adequate and clearly interpretable non-trivial results and allow further logical refinement of the details, i.e. the next approximations. This article presents an attempt to strictly follow the requirements and consistently construct a model that can show the occurrence of large epicontinental sedimentary basins, the origin of which has been in the focus of geological studies for many years. Our model is based on the following reliably established facts: (1) at the surface of the planet, in continental areas there is an approximately 300-km-thick thermal boundary layer (TBL), wherein the temperature drop amounts to ~1300–1500 °C; (2) the material of the lithosphere, including the crust, is irreversibly deformed during slow geological processes; (3) the continental crust is the thick layer that is less dense than the material of the mantle. The numerical experiments demonstrate free convection in the upper mantle, which induces countercurrents in the light crust and leads to the occurrence of sedimentary basins above the ascending flows and uplifts above the descending flows, which form platform shields during the transition to the quasi-stationary mode. The parameters of the typical structures formed in the lithosphere and the crust and the sedimentary basins proper are estimated. Revealed are the stages of their evolution, which correlate with the available geological and geophysical data, except for the effects caused, in our opinion, by the higher temperature of the mantle and the dynamics of the resultant melt. (Our next publications will describe modeling with account of decompression melting of the mantle material and separation, migration and freezing of the resultant melt.) The proposed first-approximation model can be used to describe a wide variety of geodynamic processes of similar scales.