The features of the faults in the central and northern Tibetan plateau are discussed, based on two super-wide band magnetotelluric (MT) sounding profiles belonging to the INDEPTH (III)-MT project, which were finished between 1998 and 1999: one is from Deqing to Longweicuo (named line 500), the other is from Naqu to Golmud (line 600). This work assists research on the collision and subduction mode between the India and Asia plates. The MT results show that there is a series of deep faults, F1 to F10, in the central and northern Tibetan plateau. Of these faults, F2 is an earlier main fault which leans to the north, and F1 is a later main overriding fault. The Jiali deep fault zone, which has a very complex space structure, is composed of these two faults. F3, F4 and F5 are super-deep faults. They are high-angle faults and lean a little to the south. The main fault zone of the Bangong-Nujiang suture is composed of these three faults. Because of later activity in the structure, several shallow faults formed in the upper crust within the Bangong-Nujiang suture. The Tanggula fault zone is composed of two main faults, F6 and F7, and a series of sub-faults. The shallow segments of the main faults are in high angles and the deep segments of main faults are in low angles. These two faults generally lean to the south and extend into the lower crust. The Jinshajiang suture is composed of the Jinshajiang fault (F8) and the Kekexili fault (F9), and there is a series of sub-faults in the upper crust between these two faults. The Jinshajiang suture is a very wide suture caused by continent-continent collision. The Middle Kunlun fault (F10), which is the main structure of the Kunlun fault zone, is a high angle, super-deep fault. It is the north boundary of the Songpan-Ganzi-Kekexili block. Based on the conductive structure of the profile, the southern part of the Middle Kunlun fault belongs to the Tibetan plateau, but it is not certain whether the northern part of the Middle Kunlun fault belongs to the Tibetan plateau. There are conductive bodies stretching from the crust into the upper mantle below the Bangong-Nujiang suture and Jinshajiang suture. This may suggest heat exchange between the crust and mantle.
- Fault features
- Heat exchange between crust and mantle
- Magnetotelluric sounding