The separation of information on deep layers and shallow geological noise i
s an important point of the Russian-Chinese study of the crustal electrical
conductivity in Tien Shan. This work analyzes the magnetotelluric impedanc
e in terms of a quasi-3D thin-sheet model in order to improve results of th
e previous 2-D interpretation of magnetotelluric soundings. The numerical m
odeling was based on a composite map of the sedimentary cover thickness in
the Tien Shan region, constructed from Russian and Chinese geological-geoph
ysical data. The map was converted to a scheme of electrical conductance us
ing the average resistivity of the sedimentary cover, which was derived Fro
m the results of magnetotelluric studies conducted by Russian and Chinese g
eophysicists in western and eastern Tien Shan, respectively. The model impe
dance diagrams reveal 3-D effects of the Tarim, Dzungar, Chu, and Iii basin
s.