长江三角洲7000年来的环境变迁

Environmental Changes in the Yangtze Delta since 7000 aBP

上海马桥遗址14C测年、环境地球化学、孢粉与环境磁学分析,结合搜集的研究区部分考古地层与自然地层分析,结果表明,7 200 aBP^5 300 aBP研究区经历一次海退过程,大面积土地裸露,为良渚时期人类活动提供了广阔空间。该期适宜的气候使当时人类活动频繁,文化发达,出现前所未有的玉器文化。良渚文化后期气候向干冷转化,导致一次大范围的洪泛期,使良渚文化衰落。考古地层、自然洪积层以及与建湖庆丰剖面气候曲线分析表明,研究区洪泛期与气候转型期相一致。考古地层与自然地层对比研究认为,洪水事件是研究区存在多期文化断层的重要原因。

C dating, geochemical analysis, pollen analysis and environmental magnetism analysis are performed on samples from the Maqiao site, Shanghai. Comparitive study was conducted on the large amount of the collections from the archaeological sites and natural sedimentary stratum in the Yangtze Delta. The research results indicate that ocean degression happened 7200 aBP-5300 aBP, which made large area of land exposed, and offered good space for human activities during the Liangzhu Culture epoch. In the Liangzhu Culture epoch, suitable climatic conditions accelerated human activities, leading to the developed culture and unprecedented jade-article culture. At the late Liangzhu Culture, climatic transition from warm/wet climate to cold/dry climate occurred. This climatic transition resulted in large scale flooding periods, leading to the collapse of the Liangzhu Culture, followed by the relatively backward Maqiao Culture. Single archaeological section is not enough in reconstruction of paleo-climatic change and therefore, natural sections and archaeological sections are widely collected for further research. Comparitive research results between natural deposition sections, archaeological sections and climatic curves reconstructed from pollen analysis on samples taken from Qingfeng section, Jianhu Lake, Jiangsu Province indicate that the flooding periods in the Yangtze Delta matched well the climatic transition periods, which are also corresponding well to the strong changing fluctuations of the climatic conditions. Comprehensive research on the archaeological sections and natural sedimentary sections suggests that the cultural interruptions at the archaeological sites are the results of the flood events in the Yangtze Delta. Climatic changes, flood events and water changes play the important parts in influencing the development of human civilization in the Yangtze Delta. The research results are meaningful in further research on the climatic changes in the Yangtze Delta, esp. in research methodology.