MAGNETOTELLURIC EVIDENCE OF DEEP GEODYNAMIC SETTINGS AT THE JUNCTION ZONE OF THE SOUTHERN TIEN SHAN AND TARIM BASIN

Detailed magnetotelluric and magnetovariation profiling was conducted (40 broadband stations) at the southern 140 km segment of geophysical transect MANAS with the help of MT instruments: MTU-5 (produced by "Phoenix Geophysics Ltd") and MT-24 (produced by EMI Center). MANAS transect extended from south of Kashgar, China, to just south of Bishkek, Kyrgyzstan and crossing the whole Tien Shan orogenic belt in transverse direction of its main ranges strike. We constructed 2D geoelectric model to characterize block-fracture structure at the junction zone of the Southern Tien Shan. There is low resistive inclined zone in the obtained cross-section imaging the underthrusting process of Tarim tectonic sheets under the Tien Shan mountains. Also there are some electrical heterogeneities as indications that young deformations inside Tarim lithospheric block have the whole crust scale.