| 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 |
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| 引用本文： | 龚凌枫,张运达,铁永波,高延超,刘文,李青春,张斌,杨洪,李光辉,卢佳燕,鲁拓.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[J].地质力学学报,2022,28(6):1024-1034. |
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| 作者姓名： | 龚凌枫 张运达 铁永波 高延超 刘文 李青春 张斌 杨洪 李光辉 卢佳燕 鲁拓 |
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| 作者单位： | 1.中国地质调查局成都地质调查中心, 四川 成都 610081 |
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| 基金项目： | 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 |
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| 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14C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。
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| 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 |
| 收稿时间： | 2022-06-21 |
Development history and activity characteristics of typical debris flows in the Grand Bend of the Yarlung Zangbo River since the Holocene |
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| Abstract: | 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 14C 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. |
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