晚更新世以来呼伦湖地区孢粉植物群发展与环境变迁

VEGETATIONAL DEVELOPMENT AND ENVIRONMENTAL CHANGES IN HULUN LAKE SINCE LATE PLEISTOCENE

呼伦湖是我国纬度最高的湖泊。晚更新世以来，由于气候冷暧干湿的多次波动，湖相及河流、风成为主的水上沉积交替变化。通过对该区东露天煤矿沉积剖面１１３块样品进行系统孢粉百分比及浓度分析，划分出８个孢粉组合带。结合１４Ｃ测年数据，确定了该区２００００年以来的气候演变序列。其中１３０００—１０９００ａＢ．Ｐ．的温凉湿润期相当于北欧的Ｂｏｌｌｉｎｇ—Ａｌｌｅｒｏｄ暖期，ＹｏｕｎｇｅｒＤｒｙａｓ冷期大约在１０９００—１０６００ａＢ．Ｐ，约１０６００—１００００ａＢ．Ｐ．为全新世初期升温期。全新世中期（７２００—５０００ａＢ．Ｐ．），气候温暖湿润，年均温可能比目前高３℃左右。此后气候开始向干凉化方向发展。孢粉组合可以与北欧及邻区孢粉资料相比较，并为我国气候地层学的研究提供了新的背景材料。

The Hulun Lake is the northernmost lake in China. Since late Pleistocene, lacustrine and terrestrial environments dominated by fluvial factes and wind action alternate with each other because of climatic fluctuation. According to the systematic sporo-pollen percentage and concentration analysis on 113 samples from the Quaternary profile of theDonglutian Coal-mine, 8 pollen zones have been distinguished. Based on 14C dating date.the authors have reconstructed the different phases of climatic changes over the past 20 000 years,in which the cool and wet period of 13 000-10 900 aB. P. corresponds to the Bolting - Allerod the'rmomers, Younger Dryas kryomer occurring in 10 900-10 600 aB.P., 10 600-10 000 aB. P. to the Anathermal of the beginning of Holocene. It was warmer and wet in the middle of Holocenc (7 200-5 000 aB. P. ),with the mean annual temperature being 3 C higher than today;after that it became cool and drier. The pollen assemblagestudied in this paper also can be compared with those from other parts of China and from Europe,providing new background data for research on climatostratigraphy in this country.