Electrical structure of the crust in South Eastern Tibet

As part of the Sino-French earth science programme in Tibet, magnetotelluric and geomagnetic soundings were carried out in the southwestern part of Tibet. Eight magnetotelluric sounding sites and nineteen geomagnetic stations were occupied along roughly north-south profiles. The magnetotelluric profile runs from Lhozag to the south of Yangbajain to the north. The geomagnetic profile runs from Lang Kartse to Gulu. These experiments indicate a conductive layer at about 25 km in depth. This layer corresponds to the isotherm 1100°C. Shallow conductive structures related to the presence of significant partial melting were evidenced to the south of the Zangbo suture. A conductive structure was also evidenced at about 15 km in depth below the Nyainquentanglha range. This structure may correspond to partial melting due to the presence of fluids at the dipping plane between two overthrusting crustal blocks.