摘要
青藏高原现代气候与环境存在着明显的区域差异．高原西北部的西昆仑山甜水海地区是高原上气候最干旱的区域．作者于1995年6月在该区海拔4840m的湖盆首次打钻取芯（TS95孔）．获得57m湖泊岩芯,经对样品的实验室测年和多项环境指标分析，表明，TS95孔岩芯覆盖了距今240－17ka间的时间尺度．期间，经历了倒数第二次冰期，末次间冰期．末次冰期早期，末次冰期间冰阶和末次冰盛期几个气候变化阶段．岩芯中碳酸盐含量变化可明显划分出两个大的环境阶段：在孔深30m以下，为河流沉积环境和开口型湖泊沉积环境，之上为封闭湖泊沉积环境，这种突然变化是由发生于距今150ka前的强烈构造运动事件造成的．在孔深30m以上，碳酸盐含量变化记录着古甜水海封闭湖泊的扩、缩变化历史，可借以作为区域气候与环境变化的指示器．结合其它环境指标的分析：指出西昆仑山甜水海地区在距今240－17ka期间的气候与环境变化特征表现为间冰期暖期的季风型气候和冰期的西风型气候交替作用、中间穿插过渡类型的模式．
Tianshuihai Lake basin is located in the northwest of the Qinghai-Xizang (Tibet) Plateau.where the modern climate is very dry. with an annual mean precipitation of only 21 mm. Thelake level in the basin has gradually declined stage by stage since the Last Glacial Maximum,leaving several terraces and 44 rows of sand and gravel palaeo-shorelines surrounding the lakebasin and vast area of lacustrine deposit plain in the basin.A 57-m-deep-lacustrine core (TS95 ) (35°21'N, 79°30'E ) was drilled at the elevation of 4840 ma. s. l. in the basin in 1995. The age of the core bottom is ca. 240 kaBP based on U-se-ries dating in the Geochemistry Lab. of University of Southern Cali fornia, and the top. ca. 17kaBP according to 14C dating. Therefore, it can provide valuable palaeo-climate and environment records of the Last Interglacial/Glacial cycle and the penultimate glacial period thoroughly. Variations of the carbonate content in the core TS95 can be divided into two parts on the boundary of 3om in depth. The lower part manifests fluvial and open lake environment, and the upper closed lake environment. This kind of abrupt alternation resulted from the strong tectonic movement event occurring around 150 kaBP The variations of carbonate content above 30 m of depth have recorded the history of the enlargement and shrinkage of the palaeo-Tianshuihai closed lake, indicating the behavior of the regional climate and environment changes. With the analyses on the other proxies, it is also suggested that the history of climate and environment changes dur1ng the period of 240-17 kaBP in the Tianshuihai area of west Kunlun Mountains was characterized by the monsoon-type in warmer stage of interglaciation alternation with the westile-type in colder period of gIaciation. and transitional type among them.
出处
《湖泊科学》
EI
CAS
CSCD
1998年第2期58-65,共8页
Journal of Lake Sciences
基金
中国科学院重大项目!KZ951-A1-202-02
"九五"国家攀登计划项目
关键词
青藏高原
湖泊
钻孔岩芯
碳酸盐含量
古气候
Northwestern Tibetan Plateau, lacustrine core, carbonate content, environment change
