Deep Structure of the Junction Zones of the Chuya Tectonic Depression and Its Mountainous Frame in Gorny Altai according to Magnetotelluric Studies

Abstract

Abstract ––Results of magnetotelluric studies (MTS) carried out along the SW–NE and W–E profiles across the Chuya depression are used to demonstrate the deep geoelectric structure of its internal field and the zones of transition to the northern (Kurai Ridge) and southern (South Chuya Ridge) mountainous frames. The Chuya depression is an area with small-block structure, with its axial part comprised of the thinnest sedimentary deposits (450–650 m). The key sites of the zones of transition from this depression to the Kurai and the South Chuya ridges manifest a complete geoelectric section of sedimentary deposits with a total thickness of 1000–1200 m. Subvertical conductive heterogeneous beds of abnormally low (<5 Ohm∙m) specific resistivity are mapped in the section of the sedimentary cover and the Paleozoic basement. They mark neotectonic faults and nodes of their intersection with the Paleozoic and Mesozoic faults. The kinematic parameters of the faults determined from the magnetotelluric data are generally consistent with the data of morphotectonic and geological studies.