Features of the Tien Shan newest orogen morphostructure

Research subject. The concept of morphostructure implies the presence of a relationship between the relief forms of segments of the Earth’s crust and their structural and material content. This article describes the geological ensembles of the Tien Shan orogen, the tectonic structure and modern relief of which differ in their parameters from the general morphostructural plan and which, therefore, belong to the category of morphostructural anomalies. Materials and methods. The data presented in the article were obtained in the course of field structural-geological and morphostructural study of key segments of the Tien Shan orogen, as well as an analysis of materials from previous research, including the results of geophysical sounding of the Earth’s crust and geodesical monitoring of relative modern movements of reference points on the surface.Results. The article demonstrates that, against the background of the general linear-wave morphostructure of the Tien Shan orogen, there are areas whose relief and tectonic structure do not agree with the general tectonic plan of the mountain. Wi thin the considered region, different types of morphostructural anomalies are identified and described, reflecting the speci fics of the evolution and geotectonic position of individual volumes of upper-crust rock complexes: zones of concentrated deformation and tectonic joining; centrally symmetric structures formed on the site of paleoatolls; neotectonic protrusions of the granite basement; trans-regional zone of the Talaso-Ferghana Fault and other structures. Conclusion. The formation of morphostructural anomalies is associated with the presence of non-trivial geodynamic environments operating against the background of the tectonic regime common to the Tien Shan. The modern morphostructure of the Tien Shan is the result of interference between various geodynamic regimes and settings: a regime common to the entire territory of the orogen and particular regimes that manifest themselves sporadically and are reflected in the modern relief.

Study of the tectonic structure and modern geodynamics of the nickel-copper-sulfide Kun-Manyo deposit at the stage of its field the development

Currently, the Kun-Manyo nickel-copper-sulfide deposit in the north of the Khabarovsk Krai is being prepared for development, with part of the reserves expected to be mined by underground mining. To justify the rational order of opening and excavation of sub-ore reserves it is necessary to have objective information on rock mass condition, which can be received as a result of complex geodynamic and geomechanical investigations. The established geodynamic position of the deposit, determined by its location at the junction of actively interacting large tectonic elements of the Euro-Asian tectonic plate – the tectonic stress of the North Asian craton and the Amur plate, as well as within the modern Olekmo-Stanovo seismic zone, has allowed the massif of the field area to be classified as tectonically stressed. An analysis of the data of the GPS-observation points on the territory of the Russian part of the Amur tectonic plate, the results of calculations of the vector field of velocities of modern movements of points, made within the framework of the ITRF – 2000 coordinate system, as well as the results of in-situ geomechanical studies of rock massifs of the Amur Plate’s rock-bump hazardous deposits, have made it possible to establish the current tectonic regime of the deposit area – a region of intense modern compression with a predicted intensity of more than 50 MPa. By methods of morphometric analysis and remote sensing, it has been found that the relative relief excesses were significant (700–1000 m), which may lead to an uncompensated horizontal component of geostatic stress. The most extended lineaments of the relief have predominantly southeasterly extension. The identified features of the tectonic structure and regional neotectonics have made it possible to determine the most probable direction and magnitude of the current main horizontal compression, which could be further used in solving various geomechanical problems in the exploitation of the field.

Geochemical Characteristics of Hydrothermal Volatiles From Southeast China and Their Implications on the Tectonic Structure Controlling Heat Convection

Hot springs and igneous rocks are present widely in southeast China, influenced by the subduction of the Western Pacific and Philippine Sea Plates. This study reports on new data of chemical compositions and He–Ne–C isotopes for gas samples from representative hot springs and wells in the Guangdong and Fujian provinces to identify the origin of hydrothermal volatiles and provide insight into geothermal tectonic affinities. The primary hydrothermal volatile component from southeast China is atmospheric N2, with a volumetric percentage of 82.19%–98.29%. It indicates medium-low temperature geothermal systems where geothermal fluids suffered a shallow circulation in closed fracture systems. Low CO2 and CH4 contents and their depleted δ13C values confirmed the small number of deep-derived components in the study area. However, spatially discernible geochemical characteristics imply enhanced hydrothermal fluid convection in the adjacent area of the two provinces, including the Fengshun, Zhangzhou, Longyan, and Sanming geothermal fields. Specifically, the He–Ne isotopes from this area exhibit mantle He contribution of more than 10% and mantle heat flow accounts for more than half of the total heat flow. Moreover, according to the thermal background calculations, the highest heat flow value of 77.7 mW/m2 is indicated for the Zhangzhou geothermal area and the lowest value of 54.7 mW/m2 is indicated for the Maoming geothermal area. Given the epicenter distributions and the corresponding earthquake magnitudes, the NE-trending faults are heat-control tectonic structures and their intersections with the NW-trending faults provided expedite channels for geothermal fluids rising to the surface. Therefore, the preferred development potential of geothermal resources can be expected in the adjacent area of the two provinces where two sets of active faults crossed. This study provides critical information on understanding the geothermal distribution controlled by the tectonic structure in southeast China.

The Spatio-temporal Analysis of b-value in the Banda Arc, Indonesia

Banda arc is a complex tectonic structure manifests by high seismicity due to the collision of a continent and an intra-oceanic island arc. Using the relocated earthquakes data from ISC-EHB and BMKG catalogues from the time period of 1960 to 2018, we have conducted a spatial and temporal variation of b-value using the Guttenberg-Richter formula in the area. Our results show that the spatial distribution of low b-values located in the south of Ambon Island and southeast of Buru Island. On the other hand, the temporal variation of b-value shows a decrease in the northern part of the Banda sea probably high potential to produce large earthquakes in the future. Therefore, further mitigation is needed to minimize the impact of earthquakes in the area.

STRUCTURAL FEATURES OF THE SOUTH-WESTERN EDGE OF THE EAST- EUROPEAN PLATFORM IN THE CONTEXT OF INTERWAR RESEARCH (1918-1939)

During the Polish occupation between the First and Second World Wars, scientific and exploration work in Western Ukraine was carried out by Polish, Ukrainian, Czech and Hungarian researchers. The Carpathian folded region, the Precarpathian boundary deflection, the Transcarpathian inner deflection and the Volyn-Podillia outskirts of the East European platform were studied. The main areas of research were the Carpathians and Precarpathians in connection with the discovery and development of deposits of liquid and gaseous hydrocarbons discovered here, which attracted the attention of researchers for obvious reasons. The main research conducted during this period was organized by the Geological Institute (Warsaw) and the Carpathian Geological Institute (Boryslav). No special studies have been conducted to study the structure of the Volyn-Podillia part of the East European platform at that time. After thorough work of Laskarev V.D. in 1904-1914, works which dealt mainly with local issues of tectonics appeared. This, however, significantly supplemented the existing ideas about the structural features of the region. A brief overview of studies of the structural features of the East European platform southwestern margin allows us to state the following. The most significant achievements in studying the structure of the described region were noted by such researchers as W. Teisseyre, V. Zykh, G. Teisseyre, Z. Pazdro, S. Nazarevych and others. Thus, as early as 1922 famous Polish tectonist Wawrzyniec Teisseyre proposed to consider the Holohory-Kremenets anticlinal and the Holohory flexure as independent units. They are associated with the migration of the geosynclinal axis of the Carpathians, ie with the division of the Carpathian chain into three rings (meso-, eo- and neo-Carpathians). By studying the tectonics of the foothills, he also singled out the chronological phases of migration. Comparative studies have revealed cycles of development of Precarpathian dislocations in the foothills. The initial stage of flexure development is a flat roof-like elevation preserved on the Podillia plate, with the Holohory-Kremenets anticlinal on the edge. The processes of change and disintegration of such anticlinales cause the formation of later Holohory flexures and extensive deflections. Developing his views on the decisive role of the foundation in the structure of mountain ranges and the important role of tectonic dislocations (flexures, discharges) in the nature of platform tectonics, he emphasized that transverse dislocations are the manifestation of displacements in the deep base. Russian tectonist M. Tetyaev suggested that the structure of the Transcarpathian territory is determined primarily by the folded zone of hercinide, which limits it from the west. According to him, the East European platform near the Carpathians is broken by discharges and partially hidden under the structures of the alpine fold. Ye. Oppokov, who studied the geological structure of the Devonian Podillia (Polissia) shaft, comes to the conclusion about its tectonic nature (anticlinal fold). A. Zirgoffer had a different opinion. According to the study of the relief, he believed that the Podillia shaft is a kind of barrier between the Volyn Plain and the Podillia Upland and was formed due to erosion processes. In 1928, S. Nazarevych suggested the influence of folding on the occurrence of rupture in Transnistria. According to the author the folding of gypsum, fracture of rocks of different ages (from Silurian to Neogene inclusive), the direction of the Dniester, coinciding with the main cracks, the shape of cracks may be the evidence of vigorous movements of the earth's crust, which may be the result of those mountain-building processes, which reached the maximum stress in the third age and formed Carpathians in the West. W.Teisseyre considers the fundamental issues of epeirotectonics. Based on the study of extensive Polish and foreign literature, he concludes that the network of epeirogenic lines does not correspond to the arcs of mountain ranges, and vice versa - the arcs enter at the intersection of different ages. The author opposes the understanding of epeirogenesis in the form of giant sea waves. W.Teisseyre believed that Podillia is one of the main nodes of the mountain movements of Eastern Europe. Within the Precarpathians, deep ridges and depressions are considered, established mainly according to geophysical data (Bibrka - Mykolayiv, Rozdil - Demnia, Kavske - Opary, Stara Sil - Zhuravno, etc.). From the point of view of oil and gas exploration, preference is given to the Precarpathian part of the Holohory-Kremenets-Boryslav line, then to the Dniester-Stryi basin and to the more ancient epeiroanticlinal line Smykivtsi-Kovalivka-Hrabivka-Maidan (“Stanislaviv Horst”). The importance of Transcarpathian anticlines in the search for oil and gas fields is emphasized. It is noted, in particular, that the uplift of Boryslav and Maidan - the main productive areas of the Carpathian oil and gas zone - coincides with the axes of the Podillia-Transcarpathian anticlines Holohory - Kremenets and Smykivtsi - Kovalivka. Some conclusions and generalizations were made by researchers in the interwar period (on the decisive role of the crystalline basement in the structure of mountain ranges, on the inheritance of ancient forms of the foundation surface and the chalk surface with modern relief, identified anticline uplifts in Paleozoic sediments and their oil and gas potential, on the coincidence of the axes of the Transcarpathian anticline uplifts and the main productive areas of the Carpathian oil and gas zone, etc.) have not lost their scientific value in our time and are confirmed by modern research. Studies in the 1920s and 1930s of the tectonic structure of the southwestern outskirts of the ancient East- European platform contributed to the formation of a reliable basis for the establishment and conduction of extensive exploration (oil and gas, coal, sulfur, salts, phosphorites, building materials, etc.) and systematic research in the postwar years. Key words: East European platform, tectonic structure, anticlinal uplifts, crystalline basement.

TECTONIC STRUCTURE OF KERCH-TAMAN FOLD ZONE OF AZOV-KUBAN TROUGH

The nrotectonic structure of the Kerch-Taman folded zone, the southern deformed part of the Azov-Kuban piedmont trough, has a number of structural features and a history of deformation development. The authors divide the zone into five transverse segments, differing in the age of the main phase of folding. In the central Taman segment, folding is still going on, while in the framing segments, the main phases of folding took place in the Pliocene. In the peripheral segments, the main phase of folding is older - Early-Middle Miocene. The boundaries of the Kerch-Taman zone, as well as its youngest, the Taman segment, coincide with the transverse fault (fault-flexure) zones. It is shown that the southern frame of the Kerch-Taman folded zone is the continuation of the structures of the Crimean Mountains and the Northwestern Caucasus. The correlation of mud volcanism manifestations with tectonic elements of the Taman segment is noted to be ambiguous.

GEODYNAMICS

Purpose. The aim of the research presented in this article is to analyze the features of the reflection of the damage to the territory of the Transcarpathian region by landslide processes based on the anomalies in the magnetic and gravitational fields, taking into account tectonic zoning. The study is an important stage in predicting the landslide processes and it is aimed at reducing their negative effects on the environment. The relevance of the research is due to the growing intensification of landslides in the Carpathian region of Ukraine. Methodology. The development of landslides in each structural-tectonic zone is associated with its tectonic structure, and therefore these processes can have different intensity, dynamics, tendencies for further development and distribution area. Lithological-facies composition and bedding conditions of rocks form the physical and mechanical properties of rocks, determining the rate and mechanism of the development of landslides. The spatial confinedness of landslide processes in the fault zones is reflected in the gravitational and magnetic fields. Results. With the help of GIS MapInfo tools, a number of landslides in each tectonic zone, anomalies in the gravitational and magnetic fields, areas affected by landslides, the distance to the fault zones were calculated. The important result of the research is to prove a direct correlation between the spatial distribution of landslides and fault zones, tectonic structure, the lithological composition of rocks, which are reflected in gravimagnetic anomalies. Scientific novelty. The peculiarities of the reflection of the tectonic structure, zones of decompression, fragmentation of rocks and lithological composition in gravimagnetic fields on a regional scale are examined, and their association with landslide processes is evaluated for the first time. Practical significance. The theoretical substantiation of the peculiarities of the behaviour of gravimagnetic fields in the zones of distribution of landslide processes makes it possible to assess the natural conditions for the formation and development of landslides in a given region. The connection between the impact of the fault zones on landslide processes by their reflection in gravimagnetic fields is established, which can be used in the future for spatial forecasting of the development of landslides in territories with related structural-tectonic conditions.

NEW DATA ON THE AGE AND MATERIAL COMPOSITION OF THE ROCKS OF THE PRE-JURASSIC BASE OF THE TAISKO-BARABINSK FACIES REGION BASED IN THE UVATSKY DISTRICT OF THE SOUTH OF THE TYUMEN REGION

In the West Siberia the structural-facies zoning of pre-Jurassic rocks is based on 2 factors: structural and tectonic structure and formation composition of rocks. The central areas of the Uvat district are located within the boundaries of the Tuisko-Barabinskiy facies region, where there are two main points of view on the age of the formations underlying sedimentary cover. Some experts believe that these are rocks of Lower-Middle Paleozoic formations (Caledonides), others believe that these are rocks of Upper Paleozoic-Lower Mesozoic formations (Hercynides). The data obtained from the results of drilling over the past 15 years on the territory of Uvat district on the material composition and the age of pre-Jurassic rocks made it possible to clarify the typical section of these sediments in the Tuisko-Barabinskiy region of facies.

TECTONIC STRUCTURE OF THE RIVER BASIN AK-BURA

В ходе исследований еще раз была подтверждена прямая связь рельефа и неотектоники, которая выражается в том, что в общем случае неотектоническими синклиналям соответствуют понижения рельефа, неотектоническим антиклиналям-возвышенности. In the course of the research, the direct connection between the relief and neotectonics was once again confirmed, which is expressed in the fact that, in the general case, neotectonic synclines correspond to relief depressions and neotectonic anticlines-hills.