湖北天门谭家岭遗址全新世中晚期气候变化及其对人类活动的影响

Impact of Middle to Late Holocene Climate Changes on Human Activities at Tanjialing Site,Tianmen,Hubei Province

石家河文化是长江中游地区早期文明演化进程中的重要阶段,然而目前对于石家河文化的绝对年代尚存有分歧,对该时期环境特征与人类文明相互关系的研究也较少.选择石家河文化典型遗址——谭家岭遗址为研究对象,经美国NSFArizona AMS实验室对该遗址剖面AMS 14C年龄的测定,并结合石家河文化的相对年代,可知石家河文化的绝对年代定在4800-4100cal.a BP比较合适;通过对该遗址剖面的地球化学元素分析,借助主成分分析、环境C值等统计分析方法,结果表明：本区在4850-4300 cal.a BP间,元素的第二主成分、环境C值和Mg/Ca比值处于高值段,反映气候相对温暖湿润,同时反映人类活动的指标F1和F3得分也处于高值段,表明人类活动较强;在4300-4124 cal.a BP间,元素的第二主成分、环境C值和Mg/Ca比值处于低值段,揭示气候进入相对寒冷干旱时期,同时F1和F3得分显著降低,指示人类活动减弱,石家河文化走向衰败.本文研究结果表明距今4300a暖湿转为干冷气候背景下的洪水事件可能促使石家河文化走向衰败.

The Shijiahe culture is a milestone in Chinese civilization development.However,there are still disputes as to the absolute age of the Shijiahe culture and the interaction between climate changes and human activities during this epoch.Sample profile from the Tanjialing site,i.e.a typical site of Shijiahe culture,was analyzed based on AMS 14C dating and geochemical elements,combined with the methods of principle component analysis（PCA）and ratio of elements（C value）.The results show that the absolute age of the Shijiahe culture is around 4800-4100 cal.a BP based on three AMS 14C dating measured in the America NSF-Arizona AMS Laboratory,consistent with the relative age of Shijiahe culture.Between 4850 and 4300 cal.a BP,high value of the second principle component（F2）,C value and Mg/Ca ratio indicate that the environment might be relatively warm and wet.Meanwhile,high values of the first and third principle components（F1 and F3）reflect strong human disturbances.For the period from 4300 to 4124 cal.a BP,low value of F2,C value and Mg/Ca ratio are indicative of cold and drought conditions.Meanwhile,low values of F1 and F3 might be related to weak human disturbances and the collapse of the Shijiahe culture.This study reveals that the flood events in the climate changes from warm and wet to cold and drought back-ground could be one potential trigger of the collapse of the Shijiahe Culture.