This article is devoted to describing the theory, technique, and first experimental results of a control source electromagnetic (CSEM) study of the Earth’s crust and ionosphere with the use of two...

This paper addresses the Kovdor-2015 Experiment involving frequency electromagnetic soundings of the Archaean basement of the Earth’s crust in the southwestern part of the Kola Peninsula. Eleven soundings were carried out using two transmitting arrangements, 85 km apart. Each arrangement consisted of two mutually orthogonal grounded electric dipoles of 1.5 km long. The distances between the source and the receiver were 25 and 50 km. Interpretation of the results took into account the influence of displacement currents and static distortions. It is found that there is an intermediate conductive layer of the dilatancy–diffusion nature (DD layer) with a longitudinal conductivity of about one siemens at depths ranging from 1.5–2 to 5–7 km. The results are interpreted in the terms of geodynamics.

This paper describes the Murman-2018 experiment on remote electromagnetic sounding in combination with frequency and audio magnetotelluric soundings. The experimental results made it possible...

On the basis of the summarized results of multiannual deep soundings with the use of powerful controlled sources, it is suggested to subdivide the Earth’s crust, which is traditionally identified by seismic data, into two parts, namely, upper and lower. The upper crust of 10–15 km thick is more conductive and is the most actively involved in geologic processes. Its principal peculiarities are sharp horizontal heterogeneity and a wide range of variations of specific electric resistance for rocks (from 1 to 10⁵ Ohm m), a higher brittleness, and the presence of fluids that drain the suprastructure from the day surface owing to the supply of meteor waters to depths. The lower crust (in the depth interval from 10–15 to 35–45 km) is distinctive by the high specific electric resistance (10⁵–10⁶ Ohm m) and horizontal homogeneity of electric properties. Electric conductivity of the lower crust is mostly determined by the influence of planetary physical-chemical parameters (pressure, temperature, viscosity), phase transitions of substances, and geodynamic peculiarities of evolution for different segments of the Earth, rather than by geologic processes observed near the day surface.

Static distortions are known abroad by the term “static shift distortions.” They have a strong influence on the results of deep electromagnetic