Geoelectric model of the Earth’s crust and upper mantle of the Dniester-Bug megablock of the Ukrainian Shield

A network of long-period magnetotelluric and magnetovariational data (124 sites) in the period range 9—16 to 2500—6400 s made it possible explore geoelectric structure Erth’s crust upper mantle most Dniester-Bug adjacent megablocks Ukrainian shield. Based on resistivity cross-sections along profiles (with 2D inversion), a three-dimensional matrix was created for territory limited by coordinates 27.7—30.4° E 47.7—49.4° N, which included spatial each grid node profile, power model cells, resistance value cell. As result, geoelectrical anomalous structures were identified at different depths from 3 100 km.
 The entire block rocks 200×200 km down depth is characterized high resistivity, against objects reduced (LRO) are identified.
 resulting distribution high-resistivity over good agreement with laboratory dependencies obtained both Shield other data. Model show significant difference resistivities 14—16 (above 105 ohm), lower (about 104 (103 ohm). Against general decrease Earth’s crust, three regions anomalously (for given depth) resistances extend thickness crust. These consistent positive Bouguer anomalies.
 background rocks, LROs stand out, does not exceed 120 ohm·m. dimensions LRO zones indicate their locality do form continuous layer. An analysis space suggests genetic relationship between crustal LROs. Comparison Beltska zone modern activation Ukraine shows vertically horizontally. To explain mantle, overheating solidus 2—3 % melting and/or presence fluids necessary [Gordienko, 2017]. In recent studies discussing influence thermobaric conditions fluid content increased conductivity authors [Blatter et al., 2022] concluded that an large amount volatiles needed small amounts melt. assumption related has been tested comparing fault zones.
 vertical extent, connection rejuvenated systems can serve as basis deep migration enriched volatiles.