| 岷江演化讨论: 来自四川宜宾地区第四纪河流沉积物的重矿物证据* |
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| 引用本文： | 李磊,向芳,刘一鸣,台梓含.岷江演化讨论: 来自四川宜宾地区第四纪河流沉积物的重矿物证据*[J].古地理学报,2020,22(4):761-774. |
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| 作者姓名： | 李磊 向芳 刘一鸣 台梓含 |
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| 作者单位： | 1.成都理工大学地球科学学院,四川成都 610059;2.成都理工大学油气藏地质及开发工程国家重点实验室,四川成都 610059;3.成都理工大学沉积地质研究院,四川成都 610059;4.中国电建集团江西省电力设计院有限公司,江西南昌 330000 |
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| 基金项目： | *国家自然科学基金项目(编号: 41572093,41972101)资助 |
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| 摘 要： | 河流沉积的重矿物可以较为准确反映源区的母岩性质,进而揭示河流的演化过程。本研究以岷江下游河流阶地沉积与现代沉积的重矿物为主要研究对象,开展了古流向、重矿物组合特征、特征重矿物类型及重矿物特征指数分析。研究结果表明: 岷江下游Ⅴ级阶地至Ⅲ级阶地沉积中的重矿物以岩浆岩型重矿物为主,其物源来自龙门山构造带;现代沉积中的重矿物以变质岩型重矿物为主,其物源来自松潘—甘孜褶皱带。结合重矿物特征指数对比分析,认为造成这种重矿物类型差异的原因是青藏高原东缘阶段性隆升引起的岷江溯源侵蚀。受昆黄运动B幕影响,岷江于0.73—0.7 Ma下切至汶川附近,Ⅴ级阶地形成;受昆黄运动C幕影响,岷江于0.5—0.3 Ma强烈下切,Ⅳ级阶地形成;受共和运动影响,岷江在0.11—0.09 Ma下切至石大关,同时形成Ⅲ级阶地;此后岷江继续溯源侵蚀,在距今27 ka左右形成现代岷江。
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| 关 键 词： | 岷江演化 第四纪 物源分析 溯源侵蚀 重矿物 青藏高原东缘 |
| 收稿时间： | 2019-09-23 |
Discussion on evolution of Min Jiang River: Heavy mineral evidence from the Quaternary fluvial sediments in Yibin area,Sichuan Province |
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| Li Lei,Xiang Fang,Liu Yi-Ming,Tai Zi-Han.Discussion on evolution of Min Jiang River: Heavy mineral evidence from the Quaternary fluvial sediments in Yibin area,Sichuan Province[J].Journal of Palaeogeography,2020,22(4):761-774. |
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| Authors: | Li Lei Xiang Fang Liu Yi-Ming Tai Zi-Han |
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| Institution: | 1.College of Earth Sciences,Chengdu University of Technology, Chengdu 610059,China;2.State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059,China;3.Institute of Sedimentary Geology,Chengdu University of Technology, Chengdu 610059,China;4.Jiangxi Electric Power Design Institute, Nanchang 330000,China |
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| Abstract: | Heavy minerals deposited on river terraces can be used to reflect source rock properties and reveal river evolutionary processes. This study focused on the heavy minerals deposited in the lower Min Jiang River terraces and in the modern deposits. We studied paleo-current direction, characteristics of the heavy mineral assemblages, characteristic metamorphic minerals and heavy mineral characteristic indices. The results show that the lower reaches of the Min Jiang River Ⅴ- to Ⅲ-level terrace deposits consist dominantly of magmatic rock type, which mainly comes from the Longmen Shan mountain tectonic belt. The heavy minerals deposited in modern sediment come from the Songpan-Ganzi fold belt. The heavy mineral characteristic indices suggest that this change is due to headward erosion of the Min Jiang River. Affected by the phase B of the Kunhuang movement, the Min Jiang River was incised to the Wenchuan area at 0.73-0.7 Ma and the Ⅴ-level terrace formed. The Min Jiang River was strongly cut down at 0.5-0.3 Ma due to the phase C of the Kunhuang movement, and as a result the Ⅳ-level terrace formed. Influenced by Gonghe movement, the Min Jiang River was incised to the stone mark and Ⅲ-level terrace formed in 0.11-0.09 Ma. After that, the modern Min Jiang River was formed at around 27 ka. |
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| Keywords: | Min Jiang River evolution Quaternary provenance analysis headward erosion heavy mineral eastern margin of Tibetan Plateau |
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