澜沧江云南德钦古水一带第四纪堰塞湖的沉积特征及其环境意义  

Sedimentary Characteristics of the Quatenery Dammed Lake in the Lancang River near the Dêqên-Gushui Area,Yunnan,and Its Environmental Significance

作　　者：张永双[1] 赵希涛[2] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地质学报》2008年第2期262-268,I0008,共8页Acta Geologica Sinica

基　　金：中国地质调查局国土资源大调查项目(编号1212010541404);地质力学所基本科研业务费项目(编号DZLXJK200708)资助成果

摘　　要：在云南省西北部德钦县古水一带深切的澜沧江河谷中,发现了一套第四纪湖相沉积物,以纹层状粘土、粉砂质粘土和粉砂的互层组合为特征,构成了第三和第四级阶地的基座。笔者对该湖相剖面进行了U系、孢粉和若干地球化学指标的分析测试,并以这些结果讨论了古湖的形成时代和成因,以及古湖堆积时期的古植被和古气候。剖面顶部、中部和中下部粘土的U系法年龄测定结果分别为52.3±3.4ka、64.2±5.6ka和81.9±6.5ka,说明古水古湖形成于晚更新世早中期的末次间冰期晚期和末次冰期的早冰阶与间冰阶早期,很可能是大型冰川(如下游的明永冰川等)或巨量的冰水沉积物堰塞了澜沧江河谷而造成的结果。In the valley of the Lancang River near the Gushui area northwest to Dêqên county of Yunnan province one set of Quaternary dammed lacustrine sediments were discovered. The lacustrine sediments are composed of fine-layered clay, silty clay and silt, which form the basement of the third and fourth terraces. Based on the U-series dating, sporo-pollen analysis and soil-chemical test, this paper discussed the formation time and genesis of the paleo-lake, as well as the paleovegetation and paleoclimate during the lacustrine deposition. The U-series dating of clays collected from the top, mid and mid-bottom parts of one cross-section are 52.3±3.4 ka BP, 64.2±5.6 ka BP and 81.9±6.5 ka BP, respectively, which indicate that the Gushui paleo-dammed lake was formed during the later period of the last interglaciation to the early glaciation and interglaciation stage of the last glaciation at the early and middle stages of late Pleistocene. The lake was most probably caused by large glacier （such as the Mingyong glacier in downstream） or a large amount of ice-water deposits damming the valley of the Lancang River.

关 键 词：堰塞湖 澜沧江 滇西北 古气候 冰川作用 孢粉 

分 类 号：P512.2[天文地球—地质学]