DEEP GEOELECTRIC MODEL OF THE TUNKA BASIN SYSTEM OF THE BAIKAL RIFT ZONE BASED ON MTS DATA

We report the results of deep magnetotelluric sounding, conducted for the first time within the Tunka basin system, which belongs to the southwestern flank of the Baikal Rift Zone. Despite the regional scope of the study, electrical conductivity anomalies were identified at virtually all intervals of the geoelectric section constructed to depths of 70 km. In the western part of the Tunka Rift, at the lower lithosphere level, there is an area of rocks that were presumably heated by a mantle plume, which was identified in previous studies in northern Mongolia. The position of the crustal conductive layer, which likely is a mineralized reservoir of planetary scale, is atypical: its thickness increases, and its roof rises towards the central part of the Tunka Basin. In the upper part of the Earth’s crust, subvertical conductive zones have been distinguished, which can be traced from the crustal conductive layer to sedimentary deposits. These zones are associated with fluid migration channels transporting geotherms of mantle origin. A correlation has been noted between these subvertical conductive anomalies and known thermal and/or mineral groundwater outlets, including “Nilova Pustyn”, “Arshan”, and “Zhemchug”. Additionally, one of the subvertical conductive zones in the eastern Tunka Rift, associated with a fluid migration channel, has been detected within sedimentary deposits (or does not reach them) near the Tibel’ti village, where the presence of geothermal waters had not been previously documented.