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THE GEOLOGICAL INTERPRETATION OF THE FORMING AND EV0LUTION OF LOP NUR, NW CHINA

Guo Zhaojie, Zhang Zhicheng   

  1. Department of geology, Beijing University, Beijing 100871
  • Received:1995-06-20 Revised:1995-06-20 Online:1995-12-20 Published:1995-12-20

Abstract: The main rivers in the Tarim basin flow towards the Lop Nur area, the lowest part of the basin. This phenomenon is resulted from the special geological background around Lop Nur. Because of the Himalaya collision orogenic event, there are Kuluktag dextral strike-slip fault zones on the northeast margin and Altyn sinistral strike-slip fault zones on the southeast margin of the Tarim basin. There are a few subsequent faults in both above-mentioned fault zones. Resulting from the sinistral displacement of the Ruoqiang fault(RF)and the dextral displacement of the Kongquehe fault(KF), there is an E- W extensional tectonic region setting in the Lop Nur area. The Lop Nur lake sag is a half- graben resulted from this extension. The distribution of rivers around Lop Nur is controlled by that of the fault structures. The later activity of the Tarim river dextral strike- slip fault(TF)and the Qiemo sinistral strike- slip fault (QF)resulted in the Luobuzhuang- Algan fault depression. The forming mechanism of the Algan sag is similar to that of the Lo p Nut fault depression. The generation of the Algan fault depression caused the diversion of some rivers in the northeast Tarim basin. For example, the Tarim river is now flowing through the Algan sag and then towards the Lop Nur lake. The diversion of rivers caused the changes of environment in this area. Therfore, the special structural background is one of the factors controlling the distribution of drainage system and development of Lop Nur.