Geophysical Journal | 2016 volume 38 3

The results of electromagnetic studies of the Bragin-Loev ledge and the Chernihiv block of the DDD

© A.N. Kushnir, T.R. Burakhovich, 2016

The distribution of geomagnetic variations and the electric field on the Earth's surface was obtained as a result of the modern experimental observations conducted in 2013 (10 points) in the northwestern part of the Dnieper-Donets depression (DDD) by the methods of magnetotelluric sounding (MTS) and magnetovariation profiling (MVP). It is possible to estimate the value of the electric conductivity and vertical and horizontal geoelectric structure. The processing of these data is done using the modern software system PRC_MTMV that provides the common noise- protected evaluation of the impedance, tipper, horizontal magnetovariation response according to the synchronous MT/MV records.
  The distribution of MVP induction parameters in a wide range of periods, their orientation on the sides of the DDD and the minimum values at the center of the depression, as well as the value of the maximum amplitudes of the horizontal magnetic response suggest the pronounced three-dimensionality of the subsurface, despite the obvious two-dimensional structure of the DDD and deep horizons. According to the qualitative interpretation of the MTS curves, several anomalies of the electrical conductivity are allocated. They correspond to the deep objects, for example, the eastern side of the Pripyat conductivity anomaly, and not deep: in the upper part of the basement (3-5 km), along the axis of the elongated Chernihiv block, and about 8 km on its southern side. The results of the interpretation should be used to construct the model of the resistivity distribution within the three-dimensional environment.
  The conductivity anomalies of the Bragin-Loev ledge and the Chernihiv block of the DDD may indicate the high permeability and the deep hydrocarbon fluid entering.

Key words: experimental electromagnetic studies, conductivity anomalies, the Bragin-Love ledge, the Chernihiv block of the Dnieper-Donets depression.

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