DEEP STRUCTURE OF THE ZONES OF JUNCTION OF THE CHUYA TECTONIC DEPRESSION AND ITS MOUNTAINOUS FRAME IN GORNY ALTAI ACCORDING TO RESULTS OF MAGNETOTELLURIC STUDIES
E.V. Pospeeva, V.V. Potapov
Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
Keywords: Magnetotelluric studies, geoelectric horizons, neotectonic faults, conductive heterogeneous beds, electrical resistivity, Gorny Altai
Abstract
Results of magnetotelluric studies (MTS) carried out along SW-NE and W-E profiles across the Chuya depression are used to demonstrate the deep geoelectric structure of its internal field and the transition zones to 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 (450-650 m) sedimentary deposits. The key sites of the transition zones from this depression to the Kurai Ridge and the South Chuya Ridge 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 the their intersection nodes 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.
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