Analysis Of The Formation Of The Present Sand Desert Iandscape In The Alxa Plateau, Northern China

Alxa Plateau which has always been attracted widespread attention was considered to be one of the major sources of dust storms in East Asia. Sand accumulation become the most major environmental issues in Alxa Plateau, seriously affected the lives and activities of the local population and agricultural production. Therefore, the developmental time of Alxa Plateau modern sand landscape has important scientific significance in sandstorm prevention, desertification control and resource protection.In this paper, we researched the modern sand landscape in the Alxa Plateau, focusing on the near north-northwest trending Mengen sand belt, the Zhongquanzi sand belt and Jilantai Basin, Minqin Basin by Stratum analysising and OSL dating method. Stratum structure shows that the modern sand landscape of Alxa Plateau developed on the lacustrine sediments and piedmont alluvial material. OSL dating result shows the time of sand accumulation in Alxa Plateau mainly focused on six time intervals:～19ka,～15ka,13-9ka,7-5ka,-2ka and0.1ka. However, desert landscape characterized by a large scale of sand dunes/hills started during the latest2ka.Compared with adjacent areas, the sandstorm activity in～19ka,～15ka,13-9ka and7-5ka is not limited to Alxa Plateau. In the margin of the Eastern Asian Monsoon domain and area of East Asian Monsoon have the homochronous sand activity. Thus, sand accumulation in～19ka,～15ka,13-9ka and7-5ka is a response to the climate background.Alxa Plateau developed desert landsacape since2ka,especially since0.1ka. However, the fluctuation of climate could not give a full interpretation for the expanding of sand activity. For example, the monsoon is strong in2ka and0.8, however, it have developed sand belt in Wuliji and Mengen.In fact, large scale human activities in the study area began the Han Dynasty. Over-cultivation, overgrazing, firewood collection transition, war, improper use of water resources, transportation, mining, population growth, and other human factors led to the desertification since2ka. Although certain human activities, such as arid desert oasis, etc. also cause varying degrees of partial reversal of desertification process, but large range of aeolian accumulation in Alxa Pleatu since2ka, especially since0.1ka BP and the formation of sand dunes dominated the landscape, is likely to be warmer and drier climate background, exacerbated by human industrial and agricultural activity. This conclusion indicates that we must give more consideration to the impact of human activities on desertification, and give more support in terms of policy.