地震地质 ›› 2015, Vol. 37 ›› Issue (4): 1136-1146.DOI: 10.3969/j.issn.0253-4967.2015.04.016

• 研究论文 • 上一篇    下一篇

雅鲁藏布江大峡谷入口河段最近两期古堰塞湖事件的年龄

李翠平1, 王萍1, 钱达1,2, 唐茂云1   

  1. 1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029;
    2. 中国地质大学, 北京 100029
  • 收稿日期:2015-09-15 出版日期:2015-12-20 发布日期:2016-01-28
  • 通讯作者: 王萍
  • 作者简介:李翠平, 女, 2015年于中国地震局地质研究所获构造地质学专业硕士学位, 电话: 010-62009041, E-mail: wulicuiping@126.com。
  • 基金资助:

    国家自然科学基金(41372211)与地震动力学国家重点实验室自主研究课题(LED2013A07)共同资助。

ages of the recent two episodes of glacially dammed lakes along the upstream of the yarlung zangbo gorge

LI Cui-ping1, WANG Ping1, QIAN Da1,2, TANG Mao-yun1   

  1. 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
    2. China University of Geosciences, Beijing 100029, China
  • Received:2015-09-15 Online:2015-12-20 Published:2016-01-28

摘要:

在雅鲁藏布江大峡谷入口河段, 分布着多级含湖相沉积的阶地, 在河床下还埋藏有巨厚的河湖相覆盖层。通过对阶地沉积和河床覆盖层浅部沉积物的光释光和14C测年, 初步建立了河谷上部沉积的地层年代学框架, 揭示出雅鲁藏布江大峡谷入口河段在末次盛冰期以来至少发育2期古堰塞湖(古堰塞湖Ⅰ, 古堰塞湖Ⅱ), 其沉积年龄分别为7~9ka、20~30ka, 并形成2级连续的海拔高度分别为2 906~2 956m、3 100~3 060m的堆积阶地(T1, T2)。古堰塞湖的沉积时间与青藏高原地区末次冰期冰盛期和全新世早期低温事件相对应, 推测是南迦巴瓦峰西坡的则隆弄冰川活动形成冰川堰塞坝堵塞河道的结果。古堰塞湖Ⅰ分布范围较小, 在大渡卡—米瑞发育湖相沉积, 湖尾大致在米林县城附近, 沉积厚度5~8m。古堰塞湖Ⅱ发育范围较广, 湖相沉积在大渡卡—卧龙均有出露, 湖尾大致在朗县附近, 最大沉积厚度超过100m。古堰塞湖Ⅱ被后期河流冲刷, 可形成1~3级次级阶地。

关键词: 雅鲁藏布江, 阶地, 光释光测年, 古堰塞湖, 冰川堵江

Abstract:

There are many episodes of multiple-level lacustrine terraces along the entrance of the Yarlung Zangbo Great Canyon. Besides, very thick fluvio-lacustrine sediments are buried beneath the cover of the riverbed. Optically stimulated luminescence and radiocarbon dating provide an approximate timeline of upper valley deposits and reveal at least two glacially dammed lake events (Ⅰ and Ⅱ) which have deposition ages of 7~9ka (Ⅰ) and 20~30ka(Ⅱ), respectively. The recent two episodes of glacially dammed lakes produced two steps of lacustrine terraces (T1, T2) correspondingly, which are of elevations 2906~2 956m and 3100~3 060m. The formation of paleo-dammed lakes reflects that the Zelunglung Glacier in the west slope of Mt. Namche Barwa had progressively advanced to block the Yarlung Tsangpo River during the early Holocene and the Last Glacial Maximum. The glacially dammed lake I has a relatively smaller extent. Its lacustrine sediments are distributed mainly from Datuoka to Mirui with maximum thickness about 5~8m. Its end is roughly at the south of Milin County. The glacially dammed lake Ⅱ occupies a large area with the end roughly nearby Lang County. Its sediments are exposed from Datuoka to Wolong with maximum thickness about 100m. After the later fluvial erosion, the lacustrine sediments of this lake formed 1~3 levels of secondary terraces.

Key words: Yarlung Zangbo Great Canyon, lacustrine terraces, glacially dammed lakes, OSL, glacier blocking

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