罗布泊形成及演化的地质新说

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

位于塔里木盆地东北端的罗布泊是现今塔里木盆地的最低点，其形成受新生代以来塔里木盆地东南缘阿尔金走滑断裂系及东北缘库鲁克塔格走滑断裂系的控制。由于若羌断层的左行走滑及孔雀河断层的右行走滑，在罗布泊一带产生近东西向的拉张背景，罗布泊即是产生于这一拉张背景的一个箕状凹陷。罗布泊周缘及塔里木河下游水系的分布，均受控于该地区新生代以来的断裂构造。

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 strikeslip 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 (oF) resulted in the Luobuzhuang-Algan fault depression. The forming mechanism of the Algan sag is similar to that of the Lop Nur 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 tile Algan sag and then towards the Lop Nur lake. The diversion of rivers caused the changes of environment in this area. Ther fore, the special structural background is one of the factors controlling the distribution of drainage system and development of Lop Nur.