Climate Change Revealed by Magnetic Susceptibility and Organic Matter during the Holocene in Hunshandak Desert
LI Ming-qi1 JIN He-ling 1,2 ZHANG Hong1 SU Zhi-zhu3 SUN Zhong 1 1( Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000) 2( School of Resources and Environment, Lanzhou University, Lanzhou 730000)3 (Institute of Loess Plateau Research, Shanxi University , Taiyuan 030006)
Hunshandak desert is located in the west of Inner Mongolia, China. This region is sensitive to climate change with annual temperature between 0.9～5.5℃ and annual precipitation between 240.3～422.6mm. The samples were gotten at 5-cm intervals in Xilinhaote section(N43°52′36.6″,E116°05′34.1″)which is 2.8m high and lies in Hunshandak desert. In the laboratory the character of magnetic susceptibility and organic matter were analyzed. The trend that magnetic susceptibility changes is very similar to organic matter. The climate is warm and humid when the values of magnetic susceptibility and organic matter are big, while the climate is cold and arid when they are small. According to the character of the magnetic susceptibility and organic matter, the climate changes can be divided into 5 stages: 10.7~8.5 cal kaBP, cold and arid, the winter monsoon is stronger than the summer monsoon, but the summer monsoon is much stronger; 8.5~5.8 cal kaBP, warm and humid, the summer monsoon is much stronger than the winter monsoon and the period is consistent with the Holocene Optimum; 5.8~3.5 cal kaBP, fluctuated frequently between cold/arid and warm/humid, and the winter and summer monsoon both are weak; 3.5~1.9 cal kaBP, warm and humid, but the summer monsoon is weaker than the Holocene Optimum; 1.9cal kaBP to present, the climate becomes colder and colder and arider and arider, the summer monsoon gets weaker and weaker. The climate changes in Hunshandak desert are similar with other regions in China and in the world.