Preliminary Study On Climate Change Since The Late Pleistocene Of The Earth-forest Scenic In Datong

Since the formation of Datong Basin, the climate has been changing in this area. The alternating of warm-wet and cold-dry appears frequently. Landform types of the Datong earth-forest is special. The material composition of earth-forest is eolian loess and lacustrine deposition. The deposits is a joint product of endogenic and exogenic force of the earth. The exogenic forces of climate change is the main influence factor. Revealing climate change since the late Pleistocene of the Datong earth-forest area, which has important significance for the understanding of tectonic process, climate change in the Datong basin and the Asian monsoon evolution since the late Pleistocene.The Datong earth-forest scenic is located in Datong County of Shanxi Province. In this article the typical profile, DT profile is located in the northwest corner of the Datong earth-forest scenic. The geographical coordinates is:113°28.407’E,39°56.904’N, and the ground elevation is 996m. The deep of the entire profile is 463cm. There are 61 samples were collected, the sample number is:DT18-DT78. The DT profile has four layers. It includes Loess, Brown-yellow fine sandy silt layer, Gray green lacustrine silty fine sand layer, Red-brown lacustrine tine sand silt layer. Measure age of the key layers with ESR dating method, then using the deposition rate mode to establish time series of DT profile; Reconstructed the regional climatic change since the late Pleistocene, according to the variation of climatic proxies which consist of magnetic susceptibility, the average of the grain size and geochemical elements; On this basis, the consistency and difference between Datong earth-forest area and global environmental changes were also discussed.Research shows that:in this area climate evolution since the late Pleistocene can be divided into 4 stages:221.8 ka BP-190 ka BP, the late stage of second last interglacial period, in this period the climate is warm and wet, it basically corresponds with the seventh stage of deep-sea oxygen isotope; 190 ka BP-138 ka BP, the second last glaciation, the climate is the lowest in the whole profile, and the level of lake is low, this period corresponds with the sixth stage of deep-sea oxygen isotope; 138 ka BP-71.2 ka BP, Rees Wurm interglacial, the climate is warm and wet, the East Asian summer monsoon is stronger, this period corresponds with the fifth stage of deep-sea oxygen isotope, it includes 3 warm-wet and 2 cold-dry sub climate fluctuation; 72.1 ka BP to close to the surface, it’s W.G. deposition, the climate is cold and dry, and the East Asian winter monsoon is stronger.