| 四川龙门山南段青衣江河流阶地形成时代及其构造地貌意义 |
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| 引用本文： | 王继龙,吴中海,张克旗,孙玉军,周游.四川龙门山南段青衣江河流阶地形成时代及其构造地貌意义[J].地质通报,2018,37(6):996-1005. |
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| 作者姓名： | 王继龙 吴中海 张克旗 孙玉军 周游 |
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| 作者单位： | 国土资源部新构造运动与地质灾害重点实验室/中国地质科学院地质力学研究所;中国地质大学(北京)地球科学与资源学院 |
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| 基金项目： | 中国地质调查局项目《南北构造带活动构造体系综合调查与研究》（编号：12120114002101）、《长江经济带活动构造与区域地壳稳定性调查》（编号：DD20160268）和国家自然科学基金项目《藏北高原近南北向地堑群晚新生代正断层活动的时空特性与规律研究》（批准号：41571013） |
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| 摘 要： | 地表调查发现,横穿龙门山南段的青衣江具有上游以发育深切峡谷为主,而中下游段阶地发育较完整的特点。采用光释光测年方法对现今青衣江低阶地进行年代学测试分析,获得了低阶地的形成年代,并结合对前人资料的对比和对青衣江河流阶地已有年代学数据的分析,基本确定青衣江中下游地区的T1~T7阶地主要形成于距今7.7~9.0ka,40~50ka,75~85ka,129ka,149ka,270~300ka,740ka。结合地表调查结果进一步推断,现今青衣江主河道在中更新世及之前已经存在。因此,现今的青衣江究竟是因断块整体倾斜式改道还是后期河流袭夺而形成需进一步研究。另外,据青衣江低阶地地貌面的年龄数据估算,龙门山南段青衣江流域不同段落的晚第四纪河流下切速率不同,中更新世以来,芦山至大岗顶段的河流下切速率明显较大,很可能是芦山地震发震构造(盲逆断层)在晚第四纪期间存在持续活动的地貌响应。
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| 关 键 词： | 龙门山 青衣江 光释光测年 河流阶地 芦山地震发震构造 |
| 收稿时间： | 2017/11/20 0:00:00 |
| 修稿时间： | 2018/4/9 0:00:00 |
Formation age and its tectonic geomorphological significance of Qingyiji-ang River terraces in the southern of Longmenshan, Sichuan |
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| WANG Jilong,WU Zhonghai,ZHANG Keqi,SUN Yujun and ZHOU You.Formation age and its tectonic geomorphological significance of Qingyiji-ang River terraces in the southern of Longmenshan, Sichuan[J].Geologcal Bulletin OF China,2018,37(6):996-1005. |
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| Authors: | WANG Jilong WU Zhonghai ZHANG Keqi SUN Yujun and ZHOU You |
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| Institution: | Key Laboratory of Neotectonic Movement and Geohazards, Ministry of Land and Mineral Resources/Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;School of Earth Science and Resources, China University of Geosciences, Beijing 100083, China,Key Laboratory of Neotectonic Movement and Geohazards, Ministry of Land and Mineral Resources/Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China,Key Laboratory of Neotectonic Movement and Geohazards, Ministry of Land and Mineral Resources/Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China,Key Laboratory of Neotectonic Movement and Geohazards, Ministry of Land and Mineral Resources/Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China and Key Laboratory of Neotectonic Movement and Geohazards, Ministry of Land and Mineral Resources/Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China |
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| Abstract: | The earth''s surface survey found that, across the south part of the Longmen Mountain, Qingyijiang River has incised can-yon along the upstream section, and terrace development is more complete along the downstream section. The chronological test of low terrace in Qingyijiang River was carried out by the method of OSL dating, and the formation age of low terrace was obtained. In combination with the systematic arrangement, comparison and analysis of the previous data and an analysis of the existing chronologi-cal data of the Qingyijiang River terrace, the authors found that the T1-T7 terrace in the middle and lower reaches of the Qingyi River was mainly formed at about 7.3~8.0ka, 40~50ka, 75~85ka, 129ka, 149ka, 270~300ka, 740ka. According to further inference from the results of the surface investigation, it is found that the present Qingyijiang River main channel already existed in the Middle Pleistocene and earlier. Therefore, the formation of the present Qingyijiang River resulted from the broken block tilting diversion or late river capture, which needs further research. In addition, the estimation of the age results of the geomorphic surface of the lower terrace of the Qingyijiang River shows that the crustal uplift rates of the Late Quaternary in different sections of the Qingyijiang River Valley in the south of Longmen Mountain are different. Since the Middle Pleistocene, the river incision rate of Lushan to Dagang-ding section has been significantly larger, which can probably be attributed to the geomorphic response of the Lushan seismogenic tec-tonics in the late Quaternary period. |
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| Keywords: | Longmen Mountain Qingyijiang River optically stimulated luminescence dating river terrace seismogenic structure of Lushan earthquake |
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