Findings from Deep Magnetotelluric Studies in the Sloboda Geodynamic Intersection (East European Platform)

Abstract

The Sloboda Geodynamic Intersection is considered an convergence zone for major segments, aulacogens, faults, and suture zones of the East European Platform. Between 2020 and 2022, researchers of the Geological Faculty of Moscow State University and the Geoelectromagnetic Research Center of Branch of the Schmidt Institute of Physics of the Earth, Russian Academy of Sciences (GEMRC IPE RAS) conducted deep magnetotelluric surveys in this region, performed along the Pushkinskiye Gory–Andreapol (PA), Sebezh–Velikiye Luki–Rzhev (SVR), and Ostrov–Ostashkov (OO) profiles. Qualitative analysis of the data made it possible to assess the dimensionality of the studied medium, the total longitudinal conductivity of the sedimentary cover, and the dominant strike of the conductive structures. Quantitative interpretation using 1D, 2D, and 3D inversions resulted in geoelectric models comprising a conductive sedimentary cover and a highly resistive basement. Transcrustal zones of enhanced electrical conductivity interpreted as the southwest extension of the Ilmen–Ladoga anomaly were consistently identified within the depth range of 10–40 km. These conductivity anomalies are attributed to the deep subsidence of heavily tectonized and metamorphosed sedimentary rocks initially saturated with organic and carbonate matter.