摘要
在川滇交界的云南德钦奔子栏一带的金沙江河谷两岸,发现了发育于第四级阶地之下的湖相纹层状粘土层,其下为边坡碎屑流堆积,表明该湖相层为滑坡碎屑流堵江所形成的。采用U系法测年,获得金沙江右岸湖相粘土层上部和下部的年龄分别为55.4ka±3.5kaBP和82.1ka±6.6kaBP,左岸湖相粘土层为122.0ka±12.4kaBP,表明该古湖发育于晚更新世早中期。孢粉分析结果显示,该湖相粘土沉积期间的古植被为以松为主的常绿针叶林,气候温和较湿。该古堰塞湖的发现不仅对于研究金沙江的河流发育史具有指导意义,而且对了解现代大江大河灾难性地质灾害的形成演化具有重要的参考价值。
A lacustrine varved clay bed below terrace Ⅳ has been found on both sides of the Jinsha River valley near Benzilan, Deqen, Yunnan, on the Sichuan-Yunnan border. Below this lacustrine clay bed fie slope debris-flow deposits, indicting that the lacustrine deposits formed by damming of the Jinsha River by landslide debris flows. U-series dating yields ages of 55.4±3.5 -and 82.1±6.6 ka for the upper and lower parts of the lacustrine clay bed on the fight bank of the fiver respectively and 122.0±12.4 ka for the lacustrine clay bed on the left bank, which shows that the paleolake was developed in the early and middle parts of the late Pleistocene. The sporopollen analysis indicates that the paleovegetation was evergreen conifers dominated by pines, and paleoclimate was mild and humid. The discovery of the ancient landslide dammed lake not only has great significance for the study of development history of the Jinsha River but also is of reference value for the understanding of the formation and evolution of calamitous geological hazards of today＇s large rivers.
出处
《地质通报》
CAS
CSCD
北大核心
2007年第8期970-975,共6页
Geological Bulletin of China
基金
中国地质调查局项目<滇藏铁路沿线地壳稳定性调查评价>(编号:1212010541404)
"十一五"国家科技支撑计划项目(编号:2006BAC04B05)资助。
关键词
堰塞湖
金沙江
滇西北
地质灾害
古气候
dammed lake
Jinsha River
northwestern Yunnan
geological hazard
paleoclimate
作者简介
张永双（1968-）,男,研究员,从事工程地质与环境地质研究工作.E-mail：zhys100@sohu.com
