The Geochemistry And Provenance Of The Sediments Of Liangzhu Sites And Their Implications On The Collapse Of Liangzhu Civilization

As a highly advanced civilization in the late Neolithic Age, the Liangzhu Culture is an important component of the research on the origin of Chinese civilization. The abrupt collapse of Liangzhu Culture has implications for the disscussions about the relationship between the human being and nature. We found that the yellow silty soil overlying the Liangzhu cultural layer of the Liangzhu sites had significant connections with the collapse of the Liangzhu Culture through literature investigations and communications with the archaeological workers at the sites.To find the provenance of the yellow silty soil, we collected samples at the sites of western wall、Yujiashan、ancient riverway. Meanwhile, we collected sediment samples of Dongtiaoxi River、Dazhe Mountain and the Qiantang River referring to the surroundings of the Liangzhu ancient city. We analyzed the content of major elements, trace elements and Sr-Nd isotopic compositions. The result of major elements indicates that the weathering intensity of the yellow silty soil is weaker than the materials from the Liangzhu cultural layer. The provenance of the materials from Dongtiaoxi River and Dazheshan is similar to the Taihu Lake and much different from the Liangzhu cultural layer and the overlying yellow silty soil. While the provenance of sediments in the lower reaches of Qiantang River is close to the East China Sea and the Yangtze River. The analyzation of trace elements shows that the materials of the Liangzhu cultural layer and the yellow silty soil may come from the same soure which is similar to the Qiantang River, the East China Sea, the Yangtze River, and the Taihu Lake, but is much different from Dongtiaoxi River and Dazheshan catchments. The trace elements also indicate that the sedimentary environment of both yellow silty soil and the materials of the Liangzhu cultural layer are marine-continental transitional facies. The Sr-Nd isotopic compositions of the Liangzhu cultural layer from different sites have a little difference, while the yellow silty soil’s isotopic compositions from different sites are very homogeneous which means that the yellow silty soil from different sites may have the same provenance. There is a more different between the sediments from the downstream and middle-upper stream of the Qiantang River. The former is similar to the East China Sea and the Yangtze River. The Sr-Nd isotopic compositions of yellow silty soil are similar to the downstream sediments of Qiantang River and both of them are close to the values of the Yangtze River and the East China Sea. While the isotope compositions of the sediments from the Dazheshan catchments and Dongtiaoxi River are obviously different from the yellow silty soil and the Liangzhu cultural layer which means that their provenances are different.Through the geochemical analyzation above we propose that the yellow silty soil overlying the Liangzhu cultural layer are not from the Dazheshan catchments and Dongtiaoxi River. In other words, collapse of the Liangzu Culture did not resulted by the flash floods from the Dazhe Mountains and Tiaoxi River. Considering the similarity of geochemical charcateristics of the Liangzu cultural layer and overlying yellow silty soil with the lower reaches of the Qiantang River, Yangtze River, and the East China Sea, We suppose that the collapse of Liangzhu civilization may be the results of the heavy flood from the Yangtze River or the transgression of the East China Sea caused by the sea level rise.