Environmental Evolution And Human Activities In The Section Of Guanzhou Since The Holocene Under The Background Of The Quaternary Tectonic Activity

In the 21st century,the global environmental change is affecting the human survival environment.The study of past environment evolution mechanism is not only conducive to the present harmonious human-earth relationship but also to that of future.The middle reaches of Yangtze river is one of the origin of the Chinese culture,but flood disasters are frequent in this area since the prehistoric times and history period.Evolutions of the Guanzhou river and the landscape change have made a significant impact on the life of ancient ancestors.So this study is helpful for us to better understand the past environmental change and it lays the foundation for people to further study the evolution of civilization in the middle reaches of the Yangtze River and the contemporary economic and ecological construction.Selecting guanzhou site in Zhicheng city,Hubei province as the research object,multidisciplinary approach such as the AMS¹⁴C,grain size,magnetic susceptibility and geochemistry are used to research palaeofloods and human activities during the Holocene.Then,based on the integrated study with the sedimentary characteristics of the archaeological stratigraphy and relative literature data,river evolution of Guanzhou reach during Ming and Qing dynasties and before has been preliminary discussed.The four conclusions are concluded as follows:?1?The channel of Guanzhou reach has undergone many evolutions.The position of the shoals has changed or even vanished under the long period influence of the Yangtze river water flow and palaeofloods,during the Ming and Qing Dynasties.Just because shoals distributed at Guanzhou reach,it evolved into a two-branch river pattern.The south branch played as the main river and the marginal bank developed on the north shore.?2?In the early time,Guanzhou was connected to the riverbank and human beings inhabited here and developed a culture of Chengbeixi.Under the effect of palaeofloods in the later period of Chengbeixi Culture,Guanzhou gradually moved northward and even vanished for a period of time,and the intensity of human activity declined.During the Ming and Qing Dynasties,multiple palaeoflood events occurred in the middle reaches of the Yangtze river constantly shaped the evolution of the river.?3?During the early-middle period of Chengbeixi Culture,stratigraphic lithology was characterized by the alternative variation of coarse silt and fine silt,indicating multiple palaeofloods occurred at about 7760 a BP.?4?Magnetic susceptibility and geochemistry data show that in the early period of Chengbeixi Culture and the late of Daxi Culture,human activity was stronger than that in the other periods of Chengbeixi Culture and Daxi Culture due to the effect of palaeofloods.