TECTONICS AND GRAVITY FIELD STRUCTURE OF CENTRAL KAZAKHSTAN A. E Abetov, A. N Uzbekov Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, 2023 Purpose. Identification of the nature of the manifestation of tectonic elements of different ages in Central Kazakhstan in gravitational fields based on the results of the calculation of regional, intra-crustal and local transformants. Methodology. Synthesis and analysis of the data on integrated interpretation and modeling of gravitational, geomagnetic, geothermal fields, the latest movements of the Earth’s crust and parameters of the seismic regime, tectonics and stratigraphy of rocks. Findings. Regional, intra-crustal and local heterogeneities in the lithosphere manifest themselves differently in blocks of Precambrian rocks, Early and Late Caledonides, Early and Late Hercynides. They may be associated with the processes of Paleozoic intracontinental rifting, with the rise of mantle matter and its emplacement into the Earth’s crust, followed by the manifestation of Late Paleozoic orogenesis, doubling of the thickness of the Earth’s crust, outpourings of magmatic formations. Originality. It is established that large gravitational minima are distinguished in areas with Hercynian folding, characterized by abnormally high amplitudes in the movement of the Earth’s crust. In the regions of the Caledonian folding, the values of gravity field anomalies of intermediate intensity and increased amplitudes of the latest movements of the Earth’s crust are manifested. Areas with Pre-Paleozoic folding have relative maxima of gravitational anomalies and minimum values of the latest movements of the Earth’s crust. Earthquake sources are concentrated in the consolidated crust at the junction of areas with different ages of basement consolidation, in gradient zones of geothermal, geomagnetic and gravitational anomalies. According to the variations of the intra-crustal transformant, it was found that a wide range of changes in the values of the gravitational field corresponds to areas with minimal temperature values, whereas in areas with increased temperature values, the range of changes in the values of gravity anomalies is reduced. The distribution of the local transformant of the gravitational field indicates the existence of highly variable anomalies, which reflects the high-frequency gravitational effect of near-surface objects of the Earth’s crust. Practical value. The distribution of inhomogeneities in the lithosphere with various density, geomagnetic and geothermal anomalies of geophysical fields, the nature of the seismic regime and the latest movements of the Earth’s crust predetermined the formation of geostructures with different types of mineralization, each of which is recommended to be searched and explored by a specific rational set of geophysical methods.
STRUCTURE AND INTERPRETATION OF THE ANOMALOUS GEOMAGNETIC FIELD OF CENTRAL KAZAKHSTAN News of the National Academy of Sciences of the Republic of Kazakhstan Series of Geology and Technical Sciences, 2023 Бас редактор ЖҰРЫНОВ Мұрат Жұрынұлы, химия ғылымдарының докторы, профессор, ҚР ҰҒА академигі, Қазақстан Республикасы Ұлттық Ғылым академиясының президенті, АҚ «Д
STRESS AND STRAIN STATE OF THE KAZAKH SHIELD FROM THE EARTHQUAKE FOCAL MECHANISMS DATA A. N. Uzbekov, N. N. Poleshko Geodynamics and Tectonophysics, 2022 The paper presents the results obtained during the study of seismicity of the Kazakh shield based on the data from seismic stations of the Institute of Geophysical Researches of Kazakhstan which are a part of the international monitoring systems. Emphasis has been placed on seismic activation in 2016–2018 in the middle part of the Central Kazakhstan arch, previously considered aseismic. The earthquake focal mechanisms determined for 40 seismic events recorded in the investigated area are based on the displacement directions of the first arriving P waves.On the basis of the analysis of the earthquake focal mechanism data set, an assessment has been made of the present-day stress-strain state of the Earth’s crust of the low-seismicity Kazakh shield. It is shown that a system of stresses in the investigated area is characterized by conditions for near-horizontal compression whose direction is consistent with the direction of movement of the Alpine geomorphostructures. It has been found that the earthquake sources in the investigated area are dominated by reverse faults and reverse-slip faults which correspond structurally to the northeast-striking and submeridional tectonic faults, thus testifying to present-day seismic activation of the northeastern thrusts.This study allowed for concluding that the seismic events considered are human-induced, i.e. technogenic-tectonic, earthquakes. A long-term technogenic impact reducing the strength of rocks in fault zones can be a cause of critical stress drop in earthquake sources located in the Kazakh shield. The data on the character of motions and stresses in the earthquake sources influencing on shaking intensity will be used in combination with other methods for the assessment of natural and technogenic hazards related to geodynamic processes.
Newest Tectonics and Modern Geodynamics of Mining Industrial Areas of Central Kazakhstan A E Abetov, A N Uzbekov, N N Grib, V I Imaev Iop Conference Series Earth and Environmental Science, 2020 The rapidly developing mining industry in the territory of Central Kazakhstan leads to emergence of near the areas of active mining of tangible earthquakes of technogenic genesis, which creates difficulties in their operation. Displays of irreversible changes in the state of rock mass with the development of new structures, active faults. The features of the formation of potentially dangerous areas of the occurrence of seismicity. We have considered one of the major factors the features of modern tectonics and modern geodynamics of ore-industrial facilities in Central Kazakhstan. The shield of the young platform is a wide area protrusion of the basement of the epigercina platform, adjoining mountain-building area in the southeast, and in all other directions sinking under Mesozoic-Cenozoic deposits. Geomorphologically it is a vault, complicated by increases of a higher order with contrastingly expressed tectonic layers. The seismic events were concentrated on the boundaries of the active of passive blocks of the earth’s crust of Neogene-Quaternary tectonic activity of the Kazakh shield. The active impact on the geological environment of industrial explosions will change the geodynamical activity and as consequence occurring technogenic earthquakes in the fields of central Kazakhstan.
Spatial variability of physical and mechanical properties of rock mass in Central Kazakhstan Periodico Tche Quimica, 2020
Variations in the Geoelectric Properties of the Rock Masses as a Result of the Seismic Effects of Industrial Explosions Nicolay N. Grib, A.N. Uzbekov, V.S. Imaev, G.V. Grib, A.E. Abetov Iop Conference Series Earth and Environmental Science, 2019 In order to obtain some clarity in the matter of assessing the seismic effects from industrial explosions of the state rock massif. Variations of the electrical properties of rock mass before and after explosions were studied by electro tomography. The monitoring studies on the experimental profile selected across the strike one of the regional faults that cut across the career field of the Neryungri was conducted. Observations were made before the explosion, immediately after the explosion, and subsequent observations at intervals of one hour. The electrical resistance increases in the rock mass of tectonic disturbance on the geological structure, which located on the side of the explosion. The electrical resistance decreases in the fault zone, some changes in the electrical resistance of the hanging geological structure. It has been found that the spatial orientation of the fracturing of the rock mass affects the pattern of change in the geoelectric properties of the rock mass. The electrical properties changes in the rock mass from the location of the explosion block in concern to the direction of fracture of the rock mass. In the case when the front of the blast wave propagates along the strike of fractures, the fractures open and the intensity of moisture migration increases significantly, which involve a significant decrease in electrical resistance not only in the zone of tectonic disturbance but also in the underlying geological structure. When the wave front propagates perpendicularly to the stretch of rock mass fractures, cracks also close and moisture migration along the cracks caused by changes in the stress-strain state of the rock mass, is not significant, which is reflected in a slight change in the geoelectric properties of the rock mass in the section of the profile under study.
Tectonic and technogenic earthquakes in central Kazakhstan News of the National Academy of Sciences of the Republic of Kazakhstan Series of Geology and Technical Sciences, 2018
