DEEP GEOELECTRIC MODEL OF THE TUNKINSKAYA SYSTEM OF BASINS OF THE BAIKAL RIFT ZONE BASED ON MTS DATA
Seminskiy I.K.1, Kuklina F.R.2, Nemtseva D.B.2, Kuvshinov A.V.1
1Institute of Solar-Terrestrial Physics SB RAS, Irkutsk, Russia
2OOO "SIGMA-GEO", Irkutsk, Russia
Keywords: magnetotelluric sounding, Baikal rift zone, Tunka rift, crustal conductive layer, geothermal and mineral waters.
Abstract
The article presents the results of a deep
magnetotelluric survey, conducted for the first time within the Tunka system of
depressions, which belongs to the southwestern flank of the Baikal rift zone.
Despite the fact that the studies were of a regional nature, conductivity
anomalies were identified in virtually all intervals of the geoelectric
section, constructed to depths of 70 km. In the western part of the Tunka rift,
at the level of the lower lithosphere, there is an area of distribution of
rocks presumably heated by a plume, which was identified for the territory of
northern Mongolia according to previous studies. The position of the crustal
conductive layer, probably a mineralized collector of a planetary scale, is
atypical: an increase in its thickness and an uplift of the roof to the central
part of the Tunka depression were established. In the upper part of the earth's
crust, subvertical conductive zones are distinguished, which are traced from
the crustal conductive layer to sedimentary deposits and are associated with
channels of fluid migration of geotherms of mantle genesis. A connection is
noted between these subvertical conductivity anomalies and known outlets of
thermal and/or mineral groundwater - "Nilova Pustyn", "Arshan",
"Zhemchug". In addition, one of the subvertical conductive zones in
the east of the Tunka rift, associated with a channel of fluid migration, is
distinguished in sediments (or does not reach them) in the area of the
village of Tibelti, where the presence of geothermal waters was previously
unknown
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