关键词: 阿奇克谷地, 阿尔金山左旋滑动, 羽毛状断裂谷群, 雅丹地貌, 库姆塔格羽毛状沙丘

Abstract: The Aqik Valley is located between the Lop-Nor depression and longitude 93°E. It is about 150 km long and 20~30 km wide. It is a part of the Neogene graben depression between the Aljin Mountains and the Baishan Hill. Its east end is adjoined to the Hexi Corridor depression. Based on the ESR dating of the Yarding strata and regional geomorphological features, the evolution history of the Aqik Valley and the Kumtagh Desert can be divide into four stages:(1) The big lake stage of Lop-Nor. This stage is from early Pleistocene to middle Pleistocene. The east side of the lake is at about longitude 93°15′E or more far, and the east part of the lake had 50~60 km wide.(2) The mountain uplift and lake retreat stage. During late middle Pleistocene(about 300 ka BP), the strong uplift of the Qinghai-Tibetan Plateau formed a barrier for the maritime air mass, and this caused the climate of Central Asia to be drier. In the north of the Aljin Mountains, plumetic fault valley group occurred in the strata of old lakes. The reason is that Aljin Mountains is moving eastward. In this region, there are two groups of faults(one EW direction, the other NE direction). So, the water of Shule River doesn't flow into the Lop-Nor. Its east lake valley is dried up gradually.(3) The rainstorm erosion and strong wind erosion stage. During the late Middle Pleistocene and the early Late Pleistocene, there are many Yardang groups at the branch river mouth of the north part of Aqik Valley. In the southern side of the valley, there are many NE direction, paralleled Yardang ranges and wind-eroded valleys. In the middle of the Aqik valley, there are seasonal salt marsh and isolated Yardang.(4) The expanding stage of Kumtagh Desert at the end of Late Pleistocene and Holocene. In this stage, the dunes expanded northward and covered up the plumetic fault valleys. Hence, wind erosion valleys and Yardang ranges became the most incredible plumetic sand dunes in the world.

Key words: Aqik Valley, the left-turn sliding of Aljin Mountains, plumetic fault valley groups, Yardang landform, Kumtagh plumetic dunes