末次冰期以来夏藏滩滑坡湖湖相沉积粒度特征及古气候意义  

THE GRAIN SIZE CHARACTERISTICS OF LACUSTRINE SEDIMENTS OF XIAZANGTAN LANDSLIDE LAKE AND ITS PALAEOCLIMATIC SIGNIFICANCE IN THE NORTHEASTERN TIBET PLATEAU SINCE THE LAST GLACIAL

作　　者：殷志强[1] 秦小光[2] 魏刚 武新宁 魏占玺 

机构地区：[1]中国地质环境监测院,北京100081 [2]中国科学院地质与地球物理研究所,新生代地质与环境重点实验室,北京100029 [3]青海省环境地质勘查局,西宁810007

出　　处：《第四纪研究》2017年第3期624-632,共9页Quaternary Sciences

基　　金：国家自然科学基金项目（批准号：41372333、41372187和41172158）资助 y

摘　　要：青藏高原东北缘末次冰期以来气候波动反映的干湿变化存在争议，传统观点认为该地区与全球气候变化趋势相同，即氧同位素偶数阶段气候表现为冷干、奇数阶段表现为暖湿，但有学者持与此相反的观点。笔者在对区内积石山和拉脊山围限的尖扎盆地内夏藏滩滑坡湖中深25.1m的湖相-黄土沉积剖面开展了研究，主要取得了以下认识：1）夏藏滩滑坡湖剖面沉积始于72±7.2ka B.P.，在8.0±0.9ka B.P.结束，沉积物主要由粉砂和粘土构成；2）湖相沉积物粒度大小反映了水动力条件强弱，粒度组分指示青藏高原东北缘在58～50ka B.P.和30～15ka B.P.两个时期为多雨湿润期，这两个时期也是该区巨型滑坡的频发期；3）湖水水位浅-深-浅-深的周期性波动，可能反映了青藏高原东北缘气候周期性的干-湿变化；4）从时间对应关系看，本文研究结果可能指示了在传统的冷阶段该区较湿的气候条件。There are some controversies on understanding the climate changes since the Last Glacial in the northeastern of Tibetan Plateau（TP）, and some traditional views pointed out that climate change in the region responded to the global climate in trend, closing to the Marine oxygen isotope stage（MIS）, in other words, the MIS even stages performance for cold, dry climate and the odd stages represent warm and humid environment. However, some scientists hold the opposite opinions. In 2007, the authors surveyed in the Xiazangtan super large scale landslide mass in the Qunke-Jianzha Basin of upper reaches of Yellow River, where confined by Lajishan Mountain and Jishishan Mountain, located at the summer and winter monsoon transition zone, and found a lacustrine-loess sediments profile（35°58＇49. 52″N, 101°59＇24. 25″E; 2316m a.s.l.） in the middle of landslide mass, which depth is about 25. 1m, then collected 208 grain size and magnetic susceptibility samples as indicators to test, and used the component separation method of grain size for fractionation. In this paper, the chorology, grain size and magnetic susceptibility of lacustrine and loess sediments profile was studied in detail since the Last Glacial, and mainly achieved the following conclusions：（1）The lacustrine profile of Xiazangtan landslide lake was formed after 72±7.2ka B.P. and ended about 8.0±0.9ka B.P., the sediments are mainly composed of silt and clay. （2）The grain size of lacustrine-loess sediments reflected the hydrodynamic conditions, which indicated there are two wet periods 58～50ka B.P. and 30～15ka B.P., and these two periods are also the super large landslides occurred periods. （3）The water level of the Xiazangtan landslide lake are during shallow and depth of cyclical fluctuations since Last Glacial, which reflected the climate change in the northeast margin of the Tibet Plateau represented a dry and wet cyclical change. （4）From the temporal correspondence, the results of this paper may indicate the more hum

关 键 词：末次冰期 黄河上游夏藏滩 滑坡湖 湖相沉积 粒度特征 

分 类 号：P931[天文地球—自然地理学] P546