CLIMATIC CHANGE AND EVOLUTION OF HUNSHANDAKE DESERT IN CHINA SINCE MIDDLE HOLOCENE

The Hunshandake Desert, which locates in the eastern part of Inner Mongolia of China, has the shape of ellipse that prolongs in latitudinal direction. The longest axis has extended for 1260 km, its width ranges from 30 to 100 km, and the calculated area of the desert is about 1.8~{!A~}104 km2. This study focuses on the climatic change processes since the middle Holocene and its relation with the evolution of Hunshandake Desert. Magnetic Susceptibility (Ms), the ratio of humid-implied chemical elements to arid-implied chemical elements and the stratigraphical deposition phases and granularity are used as the proxies to indicate the degree of summer monsoon, the humidity and desert evolution respectively. The results show that the study region has experienced seven strong summer monsoon stages, during which the humidity and the vegetation coverage increased; and six weak summer monsoon stages, during which the humidity and the vegetation coverage decreased. Influenced by the climatic change, the Hunshandake Desert has underwent seven stabilizing (or area reducing) stages, during which paleosol developed, depositional particles became fine, the content of silt and clay increased; and five desert extending stages, during which Aeolian sand deposited, depositional particles became coarse and the content of fine sand increased. Suggested by the correlation analyses, we get to the conclusion that climatic humidity, vegetation coverage and the degree of desert stabilization has good positive correlation with the degree of summer monsoon, namely that the degree of summer monsoon is one of the controlling factors that influenced the climatic change and the desert evolution.