Paleoclimate Changes Of Deserts Of Eastern China Recorded By Sandy Paleosol

China has vast loess, deserts and sandy-lands, these areas are also the significant distribution area of paleosol. Aeolian deposite extensively developed in sandy Desert of East China, it is through the reaction of drought aeolian sand sediments and reaction conditions of sandy paleosol sediments appear alternately, in response to climate change. The deposition of aeolian sand is the response of a period of dry and cold climate vegetation, then sand activation; while, the layer of sandy paleosol means relatively warm climate and vegetation growth well. On the basis of the original eolian sand soil pathogenesis, the sandy paleosol developed, and the dunes relatively fixed and shifting sand area decreases.The desert of Eastern China belongs to the monsoon sand area; there are mainly the Hulun Buir Desert, Otindag Desert and Horqin Desert. Based on12profiles in the field of sand in the area of ancient soil sample collection and indoor sample analyzed, and combined susceptibility, TOC, stable organic carbon isotope, the OSL chronology of relatively continued profiles, the writer study its paleoclimate changes. The conclusions are as follows:1. The environmental indicators such as stability of the organic carbon isotope, total organic carbon content and magnetic susceptibility of partial profiles in this three sandy land roughly reflect the palaeoclimate and palaeoenvironment of sedimentary sandy profile, and the three indicators present consistency in environmental implications of most profile.During the sedimentary period of eolian sand, the climate is relatively dry period. The magnetic susceptibility value of the profile is relatively low, the stability of organic carbon isotope value is low, either, namely the proportion of C4plants which is xerophilous increased in sandy land, which means the environment relatively drought and the vegetation growth less. At the same time, total organic carbon content of TOC value is also low. While, during the development period of sandy paleosol, the climate is relatively warm and wet. The magnetic susceptibility value of the profile relatively increases. And the deeper color of sandy paleosol layer, the higher the magnetic susceptibility values.13C value is relatively higher, that is, the rates of C3plants rise, which reflects the climate is pretty good, vegetation growth situation improved markedly, therefore, TOC value increases either.2. Comprehensive analysis of the chronostratigraphy and environmental indicators of the three sandy lands, it is concluded that China Eastern sand area has experienced four stages of evolution:①Eolian sand (15-10Ka);②Sandy soil (10-4Ka);③Alternation of black sand and yellow sand;④Reworking of LGM sand as destroy of soil.3. The latitudinal development and changes of sandy area in Eastern China is mainly controlled by the adjustable amplitude of the frontal margin of moonsoon. Under the Glaciation and interglaciation cycle, hydrothermal configuration changes resulting from Southeast Asia monsoon changes, which back to south or into north in the frontal edge, controlled the scope of Eastern sandy spreading south and north. The development period of sandy paleosol in Eastern China is varied, and there are some differences in different profiles of the same sandy land. The reason may be related to natural factors such as their latitude location, topography, and climate and so on, while the human factors within the region are also significant.