新疆博斯腾湖沉积物粒度的古环境意义初探  

Primary study on the environmental significances of grain-size changes of the Lake Bosten sediments

作　　者：黄小忠[1] 陈发虎[1] 肖舜[1] 吕雁斌[1] 陈建徽[1] 周爱锋[1] 

机构地区：[1]兰州大学西部环境教育部重点实验室兰州大学资源环境学院,兰州730000

出　　处：《湖泊科学》2008年第3期291-297,共7页Journal of Lake Sciences

基　　金：国家自然科学基金(40701192);西部环境创新群体项目(40421101);国家自然科学基金重点项目(90502008)联合资助.

摘　　要：湖泊沉积物的粒度分析是一种研究古环境变化常用的手段,但是其环境意义具有多解性,尤其是沙(荒)漠干旱区的湖泊沉积物粒度变化,代表的是沙尘天气的多寡强弱还是其它环境因素的变化值得细致研究.在对我国最大的内陆淡水湖——新疆博斯腾湖的沉积物短岩芯进行了210Pbex,137Cs定年的基础上,对近50多年沉积物的粒度进行分析,结果表明平均粒径与粗颗粒含量与区域最大河流——开都河大山口站的最大一天洪量、洪峰流量、天山巴音布鲁克站年降水量、湖泊水位变化以及湖泊附近焉耆站3-6月风力强度变化记录等环境因素对比发现,湖泊中部沉积物中粗颗粒含量变化主要反映的是入湖河流径流量、区域洪水强度及频率、山地降水,而并不反映大风天气或者湖泊水位的变化.对其近千年沉积岩芯的多指标分析结果表明,即使在数百年时间尺度上,博斯腾湖沉积物粒度的环境意义依然与十年时间尺度上一致.Grain size analysis is a conventional method to explore paleo-environmental changes, but its environment significance has various explanations. Especially for the lake sediments preserved in dry-land area close to Gobi and desert, it is still unclear if the grain size represents the intensity and frequency of the dust weather or the other environmental indicators. Based on the ^137Cs and ^210Pbex activities from a short-length Glew core drilling from the center of Lake Bosten, the largest inland freshwater lake in China, grain size analysis of the past 50 years of lake sediments suggests that the average grain size and coarse grains content coincide with the maximum one-day runoff and the flood peak runoff at Dashakou station of Kaidu River, and with the annual precipitation of Bayinbuluke Station in the Tianshan Mts. However, the peaks of grain size curves were not consistent with lake level variations or wind speed changes （from March to June） of the Yanqi Station near to Lake Bosten. Therefore, the coarse grains content and average grain size can generally represent intensity and frequency of flood events of the Kaidu River and strong precipitation in the surrounding Tianshan mountainous area, but do not indicate lake level variations nor wind speed changes. A millennial multi-proxy record of Lake Bosten also suggests that the environmental significance from grain size at centennial or multi-centennial timescales is the same as that at annual to decadal timescales.

关 键 词：博斯腾湖 粒度 古环境 洪水事件 开都河 

分 类 号：P512.2[天文地球—地质学] P343.3