Tectonics and gravity field structure of Central Kazakhstan

Abstract

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.