Geoelectrical inhomogeneities of the lithosphere of the Pripyat-Dnieper-Donetsk basin along the GEORIFT 2013 profile

Abstract

For the first time, for the Pripyat-Dnipro-Donetsk basin, a geological-geoelectrical interpretation of the synthetic model of the distribution of electrical resistivity in the lithosphere along the GEORIFT 2013 profile was carried out on the territory of Ukraine. Geoelectric heterogeneities of the Earth's crust and upper mantle have been revealed based on the generalization of interpretive parameters of various degrees from one-dimensional inversion to two- and three-dimensional models, which are based on experimental observations of the natural low-frequency electromagnetic field of the Earth. The connection of electrical conductivity anomalies with structural features, which were revealed according to the data of the DSS along the profile, was established. The nature of anomalous electrical conductivity is considered on the basis of a complex analysis of geological and geophysical data, and geoelectrical criteria for the selection of promising areas of hydrocarbon deposits are formulated. The unique distribution of resistivity by depth corresponds to the subvertical contact zone of longitudinal wave velocities, which manifested itself in the interruption of the tracing of the boundaries interpreted according to refracted and/or reflected P-waves. This zone corresponds to a complex knot of tectonic structures: the Kherson-Smolensk transregional tectonic seam, deep Kirovohradsk and Pereyasliv-Khmelnytskyi-Pryluksky fault zones. The coincidence of the depth of the anomalous distribution of electrical conductivity with the zones of low velocities spatially corresponds to tectonic disturbances, such as (from west to east): the Western Kryvorizko-Kremenchutsky thrust, the Kryvorizko-Krupetsky and Kryvorizko-Kremenchutsky deep fault zones. In the joint interpretation of seismic and electromagnetic sounding data, the structural approach is more often used, which increases the informativeness of depth research. It is shown that the zones of high electrical conductivity, which coincide with the zones of low velocities, are caused by the presence of fissures and the saturation of rocks with deep fluids, which must be considered as ways of their migration to the upper horizons of the earth's crust, where they become an important source for all subsequent processes of the formation of oil and gas deposits.