雅鲁藏布江大拐弯典型泥石流全新世以来发育历史及活动特征  

Development history and activity characteristics of typical debris flows in the Grand Bend of the Yarlung Zangbo River since the Holocene

作　　者：龚凌枫 张运达 铁永波[1,2,3] 高延超 刘文[5] 李青春 张斌[4] 杨洪 李光辉 卢佳燕 鲁拓 GONG Lingfeng;ZHANG Yunda;TIE Yongbo;GAO Yanchao;LIU Wen;LI Qingchun;ZHANG Bin;YANG Hong;LI Guanghui;LU Jiayan;LU Tuo(Chengdu Center,China Geological Survey,Chengdu 610081,Sichuan,China;Technology Innovation Center for Risk Prevention and Mitigation of Geohazard,Ministry of Natural Resources,Chengdu 611734,Sichuan,China;Observation and Research Station of Chengdu Geological Hazards,Ministry of Natural Resources,Chengdu 610000,Sichuan,China;Chengdu Engineering Corporation Limited of Power China,Chengdu 610072,Sichuan,China;Key Laboratory of Evaluation and Utilization of Strategic Rare Metals and Rare Earth Resource of Sichuan Province,Sichuan Geological Survey,Chengdu 610081,Sichuan,China;Institute of Geophysics&Geomatics,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081 [2]自然资源部地质灾害风险防控工程技术创新中心,四川成都611734 [3]自然资源部成都地质灾害野外科学观测研究站,四川成都610000 [4]中国电建集团成都勘测设计研究院有限公司,四川成都610072 [5]稀有稀土战略资源评价与利用四川省重点实验室,四川省地质调查院,四川成都610081 [6]中国地质大学(武汉)地球物理与空间信息学院,湖北武汉430074 [7]中国地质大学(北京),北京100083

出　　处：《地质力学学报》2022年第6期1024-1034,共11页Journal of Geomechanics

基　　金：国家自然科学基金项目(U20A20110-01);中国地质调查局地质调查项目(DD20221746)。

摘　　要：雅鲁藏布江大拐弯附近晚更新世末次冰期—全新世发育多期次泥石流,组合形成了现代大规模扇形堆积体。以派镇蹦嘎沟泥石流为例,采用地面调查、钻孔及14 C测年等方法,研究泥石流形成年代序列、堆积深度、冲出范围等特征,分析结果表明:现代蹦嘎沟依然有小规模的支沟泥石流发育且广泛堆积于沟道内,现存堆积扇区域尚未发现泥石流堆积;距今8500年左右为蹦噶沟全新世泥石流活跃期,单期次累积堆积深度约10.9 m;滨湖浅水相沉积(河流相)形成的浅灰色粉细砂中的两处碳样表明雅鲁藏布江现代河床在40~100年左右沉积深度约0.4 m,年平均沉积速率4~10 mm;海拔2906.1~2896.7 m及2849.4~2848.2 m处钻孔依次揭露厚度为9.4 m和1.2 m饼状青灰色粉质黏土,推测发生两次堵江事件。上述结果可为该区域全新世以来泥石流活动性特征研究提供参考。Multi-period debris flows have been developed in the last glacial period of the late Pleistocene-Holocene near the Grand Bend of the Yarlung Zangbo River in southeast Tibet,which combined to form a modern large-scale fan-shaped accumulation.The debris flows in the Bangga gully,Pai Town,were explored by ground survey,borehole,and 14 C dating methods to investigate the chronological sequence of formation,accumulation depth,and outrush range.The analysis results show that there are still small-scale debris flows in the tributaries of the Bengga gully,and they are widely accumulated in the channel,but no debris flow accumulation has been found in the existing accumulation fan area.The Holocene debris flows in the Bunga gully were active around 8500 years ago,and the cumulative accumulation depth of a single period is about 10.9 m.The two carbon samples in the light gray silt sand formed by the shallow lake facies(fluvial facies)show that the modern riverbed of the Yarlung Zangbo River was deposited at a depth of about 0.4 m in 40 to 100 years,and the annual average deposition rate was about 4~10 mm.The boreholes at 2906.1~2896.7 m and 2849.4~2848.2 m above sea level reveal a thickness of 9.4 m and 1.2 m cake-like bluish-gray clay in turn.It is assumed that two river-blocking events occurred.The above results could provide a reference for the study of the debris flow activity characteristics since the Holocene in this region.

关 键 词：雅鲁藏布江大拐弯 全新世 泥石流 发育历史 活动特性 

分 类 号：P642.22[天文地球—工程地质学]