The Paleoenvironment Research On Loess Susceptibility And Particle Size Characteristics Since Middle Pleistocene In Ning Cheng County Inner Mongolia

Under the background of human closely being attending the environment problem, we urgently need to foresee the future status of environment changes. Studying the environment changes in geology history period can provide a method and reference to forecast the whole world change, especially the climate cycle from the Quaternary period. Ning Cheng County is in the south of Chi Feng City, south in Inner Monggolia Autonomous Region, and is the connection of Hebei Province, Liaoning province and Inner Monggolia Autonomous Region. As the dividing line of East and West, Northeast and North China in China, it becomes the sensitive range which is effected because of the environment changes. Loess-Paleosol sequence records the characteristic of climate gyration, so taking samples of loess section plane in the region is a good way to study the environment change from the Quaternary period and to predict the future situateion.The thesis is completed on the basis of geological mapping project to Ning Cheng county in Inner Mongolia. The author carries out the experiment of magnetic susceptibility and granularity, and analyzes the result using the specimen of DaMaLianTu and AnJiaWoPu section plane, the work mainly makes the following conclusions and achievements:During the period of Medio-Pleistocene in Ning Cheng county, climate was very warm and moist. although with a wavy motion, it should be warmer and wetter than which in Late Pleistocene epoch. The climate in S5 and S4 stage was the best state, in which air temperature should be 2-5℃higher than the present stage, and the amount of precipitation was also slightly higher. In the beginning period of the last interglacial stage or called S1 stage, the climate still was warm and wet. But up to the Last Glaciation especially in postglacial period, An extreme climatic deterioration occurred. compared with the present stage climate, the air temperature has been 1-5℃lower, the amount of annual precipitation has been dropped to 400 mm. Turn into Holocene epoch, the climate took a turn for the better, both the air temperature and precipitation began to rise again, and to be commensurate to the present stage climate.1. Tt is thought that the original deposit was primarily aeolian phase after we carried out a testing on the sample, analysed the result of magnetic susceptibility and granularity.2. It is considered that area has experienced 10 great climate gyration from Middle Pleistocene. Among them, climate was especially warmest and wettest in S5 and S4 stage and driest and coldest in L1 stage.3. The content curve lower than 5μm well reflects the variations of the grain size of the region, Moreover, contrastively analysized with the Luo Chuan section, it is indicated the identity between the two. Therefore, the content curve lower than 5μm is looked on as the effective substitute indication of the paleoclimate.