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文章编号：16726561（2016）06085910
摘要：通过对新疆喀纳斯湖沉积物进行粒度分析，结合放射性同位素210Pb、137Cs定年，研究了喀纳斯湖沉积物粒度敏感组分特征及其环境意义。喀纳斯湖沉积物以细颗粒组分（粒径小于16 μm）为主，但1814～1830年（32～35 cm深度处）和1893～1903 年（18～20 cm深度处）这两个时期的沉积物粒度特征发生了突变，粗颗粒组分（粒径大于16 μm）尤其是粒径大于63 μm组分含量迅速升高。对沉积物粒度频率曲线的分析表明，这两个时期的沉积物来源或沉积动力过程发生了显著变化。基于此，首先运用粒径标准偏差法提取了沉积物中的敏感粒度组分C2（粒径为15～238 μm），进而通过敏感粒度组分与器测气象数据的相关性分析和沉积物粗粒径（C）中值粒径（M）图分析，研究了喀纳斯湖沉积物沉积时的动力条件。组分C2的含量大小与区域春季、夏季温度有关，反映了山地春季和夏季雪、冰融水入湖的强度，组分C2含量在1814～1830年和1893～1903年这两个时期的快速增大与水动力异常偏大有关，据此识别了两次显著的洪水事件。与区域树轮、冰芯记录及文献记载的对比分析表明，洪水事件的发生与对应时期内暖湿的气候特征有关。
关键词：环境演化；沉积物；粒度；敏感组分；环境意义；洪水事件；喀纳斯湖；新疆
中图分类号：P512.2文献标志码：A
Environmental Characteristics Inferred from Sediment Sensitive Grainsize Component Records in Kanas Lake of Xinjiang
ZHOU Jianchao1，2， WU Jinglu1， ZENG Haiao1
（1. State Key Laboratory of Lake Science and Environment， Nanjing Institute of Geography and Limnology，
Chinese Academy of Sciences， Nanjing 210008， Jiangsu， China； 2. University of Chinese Academy of Sciences， Beijing 100049， China）
Abstract： Based on the analysis of a sediment core from Kanas Lake of Xinjiang， compared with the dating of radioactive 210Pb and 137Cs isotopes， the characteristics and environmental significance of sensitive grainsize components of sediments in Kanas Lake were studied. The sediments mainly consist of fine particle components （grain size is less than 16 μm）； however， during 18141830 AD （the depth of 3235 cm） and 18931903 AD （the depth of 3235 cm）， the grainsize displays a sudden shift， which is the significant increase of the coarse particle components （grain size is more than 16 μm， especially more than 63 μm）. The analysis of grainsize frequency curves of sediments indicates that the sediment provenances or dynamic processes have changed significantly during 18141830 AD and 18931903 AD. And then， the sensitive grainsize component C2 （grain size is 15238 μm） of sediment is extracted by the method of grain sizestandard deviation. Based on the correlation analysis of sensitive grainsize component and meteorological data measured by apparatus， the dynamic conditions of sediments in Kanas Lake were studied with the CM diagram analysis of sediments. The content of sensitive grainsize component C2 is related to the regional spring and summer average temperature， and reflect the intensity of the meltwater from spring， summer snow and ice into the lake in mountainous； the significant increases of content of component C2 during 18141830 AD and 18931903 AD are related to the unusual increase of hydrodynamic force， thus two significant flood events are identified. Compared with the historical literatures and the records of tree ring and ice core， the flood events are related to warmer and wetter climate conditions during 18141830 and 18931903.