Abstract: Fluvial-lacustrine deposit is a kind of consolidation sediments that is one important geological basis for erosion landform. The erosion landform developed on alluvial plains composed of fluvial-lacustrine deposits is widely distributed. But its relevant studies, especially about the development process of erosion landform are very less. Based on the field survey information, theoretical analysis and some relevant articles, this paper comprehensively analyzed the exogenic forces action mechanism in the development process of erosion landform on alluvial plains composed of fluvial-lacustrine deposits in the Taklimakan Desert. The results show as the following:(1) These main exogenic forces including weathering, running water, aeolian erosion and gravity drive the erosion landform development on alluvial plains composed of fluvial-lacustrine deposits in the Taklimakan Desert. (2) Because aeolian activities in the Taklimkan Desert occur very frequent, so aeolian erosion plays a leading role in erosion landform development. (3)At the same time, weathering, running water and gravity also play important roles. Some records of summer strong rainfall events in the Taklimakan Desert indicate that the function of running water in erosion landform development can't be neglected. Rain infiltration and soil cracks, main weathering forms, loosen the surface soil structure, smash sediments to pieces, and make soil be eroded easily. Moreover, all these exogenic forces have different importance in different stages of erosion landform development. But they work co-operatively and mutually reinforce. Wind erosion breakthroughs can develop under aeolian erosion together with weathering and running water in the initial stage. A series of erosion landforms, including deflation furrow, wind erosion groove, blowout pit, wind erosion depression, erosion platform, wind erosion residual pier, and wind erosion plain, can rapidly develop under aeolian erosion together with gravity and weathering in the rest of stages. Sand wedges, composed of sand particles deposited in the wedge-shaped space of soil cracks, are of great importance in erosion landform development. Rainwater flows into sand wedges and is adsorbed by sand. Due to good penetrability of sand deposits, water can infiltrate quickly without evaporation loss and reach the bottoms of cracks. The deep soil can be destroyed by soil expansion of wetting and unfreezing; soil cracks widen and extend into deep soil further. Lateral erosion and undercutting are the main forms of wind erosion as well as sheet erosion, they make the sediments hang up. Lateral erosion, undercutting and sand wedges provide good conditions for gravity collapse and accelerate the negative erosion landform development on the sediments with nonhomogeneous texture. Collapse diluvium also can slow down the speed of wind erosion landform development.(4) The morphological characteristics of erosion landform depend on the special exogenic forces combination and the interbedded sedimentary structure of alluvial plains, namely, compact sediment and soft sediments are distributed in turn in vertical profile.

Key words: Erosion landform, Exogenic forces, Fluviallacustrine deposits, Taklimakan Desert