Geoelectric Characteristics of the Lithosphere in the Southern Sikhote-Alin Orogenic Belt from Magnetotelluric Sounding Data

A 3D model of electrical resistance to a depth of 130 km for an approximately 100 000 km2 area was obtained for the southern Sikhote-Alin orogenic belt using data from magnetotelluric soundings carried out along seven meridional and latitudinal crossing profiles. The model accounts for coastal effects and incorporates a layer with a resistance of 0.3 Ω m with bottom morphology based on the bathymetry of the Sea of Japan. The model was used to compute depth slices. Geoelectrical heterogeneities were analyzed, and a geological interpretation of electrical resistance anomalies in the crust and mantle was proposed. Regional features of electrical resistance distribution were found to correspond to the main tectonic units in the territory: the Khanka massif and terranes of the Sikhote-Alin orogenic belt. Magmatic bodies in the crust are demonstrated to increase the level of electrical resistance of the model. The latitudinal orientation of upper mantle electrical resistance zones predominates in the southern area.