Study On The Environmental Change In The Mianchi Basin And Its Influence Upon The Development Of Ancient Culture During 16ka And 2.3ka

Mianchi Basin is a canyon of the Middle Yellow River which is located in west of Henan Province. It is on the transitional belt of Loess Plateau and North China Plain; meanwhile it is also on the transitional belt of humid region and semi-humid region. The region around the Yellow River is one of the birthplaces of the Chinese nation. The author selects the environmental change between 16000yrBP and 2300yrBP in the Mianchi Basin and its influence on human culture as the topic of the thesis。It can be observed that the profile is continuous and thus it reflects the environmental change and its influence on human culture during 16000yrBP and 2300yrBP Because paleolake sediments can avoid artificial disturbance, the profile is a perfect one for environmental change research and man-land relationship study since Holocene.On the basis of indoor experimental analysis, the author selects proxy substitute indexes such as grain-size, TOC, geochemical elements. Through the comparison study of these climatic substitute indexes, the thesis reveals the process of the evolution of climatic environment and human culture in the Mianchi Basin. Finally, the thesis investigates the relationship between the evolution of environment and that of human culture.The thesis draws the following conclusion:(1)During 16000～8200yrBP, the soil weathering and eluviation process was weak and climate was dry. The lake was not formed by deduction;(2) 8200～7200yrBP was transition period of climate. It was the beginning of the Holocene megathermal; the climate was much warmer and humid than earlier. So the intensity of the soil weathering and eluviation was stronger, lake environment was formed;(3) 7200～5000yrBP,this period climate turned to warm and humid. It corresponded to the peak of Holocene megathermal, Lake Basin was warm and moist, and water level of the paleolake was higher than before(;4)5000～3200yrBP. This period was also warm-humid climate type, but the temperature and humidity were lower then before. Water level of the paleolake decreased. (5)3200～2300yrBP, proxy climatic substitute indexes indicates: this was a dry and cold period of lower temperature and less precipitation, the paleolake gradually dried up.There is close relationship between the environmental change of the Holocene and human cultural development. In the beginning of Holocene, it was the shifting period from Old Stone Age to the New Stone Age. 7000～5000yrBP was the Holocene climatic optimum. This was warm and humid period, Yangshao Culture appeared because of great environmental conditions. Then Longshan culture developed in Holocene sub-warm period between 5000～4000yrBP, then entered into the period of Xiashang civilization. Especially abrupt climate change events in the two periods, i.e. 5000yrBP and 4000yrBP have facilitated the emergence of ancient Chinese civilization.