Climatic and Environmental Changes from the Sediment Record of Erhai Lake over the Past 10000 Years

Abstract

根据对洱海北部10.8m深水区ES孔沉积物高分辨率的孢粉、粒度、碳屑、藻类分析,结合AMS¹⁴C测年数据,划分了11个阶段,恢复了一万多年以来云南洱海地区气候环境演化序列.全球性的降温事件在该地区都有明显的反映,包括9900aBP(Younger Dryas)、8500aBP、7100aBP、5100aBP左右的四次冷事件,6800-5500aBP为全新世水热配置最佳期,距今2400年开始该地区出现较为明显的人类活动.;Erhai Lake, formed by faults, is the second largest freshwater lake on the northwestern Yunnan Plateau, southwestern of China. The area is influenced by southeast monsoon (from Bengal Gulf), the precipitation between March and October accounted for 70%-90% of a year. A nnual average temperature is 15.1℃. ES core with a length of 6.62m was taken from the deep-water area in the northern part of the lake basin in April, 2001. Based on the analysis of high resolution and multi-environmental proxies of this core, including AMS dating, pollen-spore, grain size, alga and carbon fragment, eleven phases of climatic and environmental changes have been identified. As a result, the regional paleoclimate and paleoenvironment are reconstructed over the past 10000 years. Four global cold events were well recorded, which happened in 9.9kaBP, 8.5kaBP, 7.1kaBP and 5.1kaBP. These cold events can be compared to those happened in different parts of the world. The period from 6.8kaBP to 5.5kaBP was the optimum period with wet and warm climate in Holocene. Obvious human activities began from 2.4kaBP in this region.