云南怒江河谷新近纪砾石层与堰塞湖相沉积的发现及其意义
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中国地质调查局“泛亚铁路大理至瑞丽沿线地质构造综合研究”(1212010814054),云南1:5万马厂、道街坝幅区调(1212010784004)和“西南地区活动构造与应力场模拟”(1212010911049)等项目联合资助


Neogene gravels and dammed-lake sediments newly discovered in Nujiang(Salween) River valleys, Yunnan Province,China and their implications
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    摘要:

    作者在怒江道街-惠通桥段考察研究中,填绘了道街盆地的晚新生代地质图,测量了多条河谷横剖面,不仅重新厘定了河谷中拔河150m以下的多级低阶地,而且在拔河180~380m的高度上发现了多级由磨圆良好、成分复杂的厚层冲积砾石层所组成的高阶地,及厚近100m的堰塞湖成因的砂层及其下伏厚约100m的砾石层。本文采集并测试了低阶地冲积物的OSL、U系与ESR样品的年龄,并对湖相砂层进行了磁性地层学研究。研究表明,6级低阶地形成于中更新世以来;在组成相当于第九级阶地上部的湖相砂层剖面的磁性地层柱中,上部以正极性为主含两次短期的负极性,下部则为负极性。与标准磁性地层柱对比表明,该湖相地层形成于4.2~2.6MaBP中-晚上新世, 湖相地层之下的埋藏阶地与高阶地则应形成于上新世早期至中新世晚期。据此,本文初步进行了区域地层对比,并认为:伴随青藏高原在中新世中晚期开始阶段性隆升,怒江已开始形成并下切,至上新世早期已下切至现今河床之下。

    Abstract:

    In Our field survey in the Daojie Basin segment through which the Nujiang River passes, lower terraces below 150m above river level were re-identified and re-divided into nineeight levels(T1~T8). At the same time, there are four levels of higher terrace 180~380m above river level (T10~T13)and a suit of dammed-lake sediments burial to be newly discovered. Lower terraces were dated by OSL, U-series and ESR methods,whereas the dammed-lake sediments were paleomagnetically analyzed. The results show that six lower terraces are formed since the Middle Pleistocene and that the upper part of the dammed-lake sediments is dominated by normal polarity but contains two short times of negative polarity, whereas the lower part is negative polarity. According to correlation with the standard magnetic polarity time scale, the formation age of the dammed-lake sediments should be 4.2~2.6Ma, i.e. the Middle-Late Pliocene. Thus, the higher terraces and burial terrace below the dammed-lake sediments should form in the early of Pliocene to the late of Miocene. On the basis of the results in the paper and our preliminary regional stratigraphic correlation, it can be believed that accompanied with intermittent uplift of the Tibetan Plateau since the middle and late of Miocene, the Nujiang River occurred and cut down and by the early of Pliocene cut down into below today’s river beds.

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赵希涛,吴中海,叶培盛,仝亚博,胡道功.2011.云南怒江河谷新近纪砾石层与堰塞湖相沉积的发现及其意义[J].地质学报,85(12):1963-1976.
zhao xi tao, Wu Zhonghai, Ye Peisheng, Tong Yabo, Hu Daogong.2011. Neogene gravels and dammed-lake sediments newly discovered in Nujiang(Salween) River valleys, Yunnan Province,China and their implications[J]. Acta Geologica Sinica,85(12):1963-1976.

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  • 收稿日期:2011-09-05
  • 最后修改日期:2011-11-01
  • 录用日期:2011-11-08
  • 在线发布日期: 2011-12-09
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