通过巢湖西岸湖泊钻孔的植硅体分析,结合AMS~(14)C年代测定,识别了5个植硅体组合带。根据各组合带主要植硅体类型变化特征,重建了该地区13.7-7.5 cal ka BP的气候环境演变史,共分为4个阶段:1)13.7-12.9 cal ka BP阶段,气候呈现温暖湿润的特点,降水量较大,其中晚期阶段(13.1-12.9 cal ka BP)气候开始逐渐变凉变干;2)12.9-11.5 cal ka BP阶段,降温幅度较大,降水量减少,可能对应全球性新仙女木降温事件;3)11.5-9.8 cal ka BP阶段,气温有所回升,降水量增加,气候总体表现为温凉湿润;4)9.8-7.5 cal ka BP阶段,气温进一步回升,降水量略有减少,并存在多次波动。其中8.4-8.2 cal ka BP期间发生了一次明显的变冷变干事件,可能代表了全球8.2 ka的降温事件。上述结果很好地响应了区域性与全球性的气候变化,填补了该地区之前更新世末至全新世初古环境演变研究的不足。此外,13.7-7.5 cal ka BP期间,水稻植硅体的连续出现表明该地区可能一直存在水稻生长,表明更新世末至全新世中期我国野生稻资源分布的北界至少已经到达巢湖流域。这一结果为研究我国史前野生稻资源的分布,以及长江流域及其以北地区稻作农业起源与发展等相关问题提供了实证和新线索。
英文摘要:
Based on systematic research on the phytolith fossils and the AMS~(14)C dating from core sediments drilled in the west bank of the Chaohu Lake,Anhui Province, China, 5 Phytolith zones are derived from bottom to top (depth: 170-1 082 cm). On the basis of the phytolith records, this paper tries to reconstruct the sequence of environmental evolution during 13.7-7.5 cal ka BP in the Lake Chaohu region, which mainly contains four stages: 1) The paleoclimatic environment had a warm and humid climate during 13.7 and 12.9 cal ka BP with high rainfall, however, it began to be a little cooler and drier later (13.1-12.9 cal ka BP); 2) The cold and dry paleoclimate was unstable during 12.9-11.5 cal ka BP with low rainfall, which might correspond to Younger Dryas event (YD); 3) The temperature and rainfall rose a little during 11.5-9.8 cal ka BP. The paleoclimatic environment presented a cool and moist climate at this stage; 4) The temperature increased, while the rainfall reduced slightly between 9.8 and 7.5 cal ka BP with some fluctuations. The environment (8.408.2 cal ka BP) was characterized by slightly shifting from warm-moist to cool-dry, possibly corresponding to the 8.2 ka cooling event. The above results show that the climate changes in this region are synchronous in a certain extent with global characteristics. In addition, according to the results of the phytolith analysis from lacustrine deposits of the Chaohu Lake, rice has already existed in this area since 13.7-7.5 cal ka BP. The discovery indicates that the northern boundary of distribution of wild rice reached the Chaohu Lake Basin since the Late Pleistocene. The results provide evidence and new clues for the study on the distribution range of wild rice in prehistoric times in China, and the origin and development of rice agriculture in the Yangtze River and its neighbouring northern region.