| 引用本文: | 夏银珍，刘维明，赖忠平，胡凯衡，朱正峰，王 昊，张信宝，曹广超.2017.大渡河石广东古滑坡堰塞湖沉积物光释光年代研究[J].地球环境学报,8(5):419-426 |
| XIA Yinzhen, LIU Weiming, LAI Zhongping, HU Kaiheng, ZHU Zhengfeng, WANG Hao, ZHANG Xinbao, CAO guangchao.2017.Age of paleo-landslide-dammed lake at Shiguangdong in Dadu River[J].Journal of Earth Environment,8(5):419-426 |
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| 大渡河石广东古滑坡堰塞湖沉积物光释光年代研究 |
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夏银珍，刘维明，赖忠平，胡凯衡，朱正峰，王 昊，张信宝，曹广超
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1.青海师范大学 生命与地理科学学院，西宁 810008
2.中国科学院·水利部成都山地灾害与环境研究所 山地灾害与地表过程重点实验室，成都 610041
3.中国地质大学（武汉） 地球科学学院，武汉 430074
4.云南师范大学 旅游与地理科学学院，昆明 650500
5.中国科学院青藏高原研究所，北京 100101
6.中国科学院·水利部成都山地灾害与环境研究所，成都 610041
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| 摘要: |
| 堰塞是重要的极端地表过程之一，往往会造成灾难性的后果，对古堰塞湖的研究有助于对区域堰塞风险的认识。本文以青藏高原东缘大渡河上游石广东古滑坡堰塞湖为研究对象，地质证据显示该古堰塞湖的堵江高坝高约23 m，堵江滑坡的体积约1.6×107 m3，堰塞湖的最小蓄水量为2.0×107 m3。并选取两个湖相沉积剖面，采用单片再生法（single aliquot regeneration，SAR）与标准生长曲线法（standard growth curve，SGC）相结合的方法，测定了7个样品的光释光（optically stimulated luminescence，OSL）年龄，测年结果表明堰塞湖形成于距今约3.0 ka，结束于1.6 ka，即全新世晚期。初步推测堵江的古滑坡体可能由于地震诱发。 |
| 关键词: 大渡河 石广东 古堰塞湖 光释光测年 |
| DOI：10.7515/JEE201705005 |
| CSTR：32259.14.JEE201705005 |
| 分类号: |
| 基金项目:中国科学院·水利部成都山地灾害与环境研究所青年科学研究基金项目（SDS-QN-1602）；国家重点基础研究发展计划项目（2015CB452704）；国家自然科学基金项目（41661144028，41771023） |
| 英文基金项目:Youth Science Fund of Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, (SDS-QN-1602); National Key Basic Research Program of China (2015CB452704); National Natural Science Fundation of China (41661144028, 41771023) |
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| Age of paleo-landslide-dammed lake at Shiguangdong in Dadu River |
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XIA Yinzhen, LIU Weiming, LAI Zhongping, HU Kaiheng, ZHU Zhengfeng, WANG Hao, ZHANG Xinbao, CAO guangchao
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1. School of Life and Geographic Science, Qinghai Normal University, Xining 810008, China
2. CAS Key Laboratory of Mountain Hazards and Surface Process, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
3. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
4. School of Tourism and Geographical Sciences, Yunnan Normal University, Kunming 650500, China
5. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
6. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
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| Abstract: |
| Background, aim, and scope Dadu River is as one of the river in eastern fringe of the Tibetan Plateau. As it lies in the intersection of Xianshuihe, Anninghe and Longmenshan fault belt, thus the unique tectonic background and geomorphology have contributed to the formation of many landslide-dammed lakes. At present, the research on landslide dammed lake mainly reflects the two major aspects-mechanism of formation and disaster prevention and mitigation, and using the method of chronology is seldom discussed systematically. Damming is one of an important earth surface process, and always leads to disastrous results. The study of paleo-dammed lake contributes to the understanding of the regional risk of blocking river. In this paper, we study Shiguangdong (SGD) landslide dammed lake at the upstream of Dadu River in the eastern margin of the Tibetan Plateau. The sediment evidences show that the dam height is about 23 m, the volumes of landslide and minimum storage capacity are 16 million cubic metres and 20 million cubic metres. In recent years, more and more scholars have paid more attention to the relationship between the lake and the landscape. Materials and methods Two profiles were chosen and collected 7 optically stimulated luminescence (OSL) samples of which 4 samples from SGD1 profile and 3 samples from SGD2 profile, all the samples were kept from light in a dark place. First, the samples were processed chemically to remove carbonate and organic matter, then 38—63 μm quartz components were selected from the sample of purification, for the OSL dating experiment. The method of single aliquot regeneration (SAR) combined with standard growth curve (SGC) was adopted to study the optically stimulated luminescence dating of seven lacustrine samples, which were collected from these two profiles in Shiguangdong. Results The 7 effective OSL ages (1.8 ka, 10.6 ka, 2.6 ka, 3.0 ka, 2.0 ka, 1.6 ka, 1.7 ka, on the depth of 5.5 m, 6.7 m, 6.8 m, 7.7 m, 0.9 m, 1.4 m, 4.6 m) results showed that the Shiguangdong dammed lake was formed at around 3.0 ka and ended at 1.6 ka. Discussion The Longriba fault locates in the north of Shiguangdong dammed lake which is the thrust right strike-slip fault zone, fault motion rate of the north eastern is about 5.4 ± 2.0 mm ∙ a−1, vertical sliding rate is about 0.7 mm ∙ a−1, crustal shortening rate is about 0.55 mm ∙ a−1, showed a strong earthquake potential. In addition, landslides can also be triggered by extreme rainfall. The latest summary of ancient climate record shows 8—3 ka in the Holocene is one of the largest stage of summer monsoon rainfall/humidity rainfall began to decrease afterwards. Shiguangdong dammed lake formed at 3.0 ka, belongs to the climate transition stage, and the Loess Plateau of the ancient flood records show that during the transition stage of the climate system unstable, more extreme rainfall events occur frequently. Although climate conditions are one of the causes of the lake, it is speculated that the Shiguangdong landslide body may be induced by earthquake by analyzing. Conclusions The lake in the upper reaches of the Dadu River is confirmed by geological evidence through the field investigation. And the two lacustrine sedimentary section 7 samples of OSL test concluded that the formation of the ancient lake was about 3.0 ka, in the late Holocene. Preliminary speculation that the landslide was triggered by an earthquake, it is still necessary to guard against the risk of a similar incident in this area. Recommendations and perspectives So except to the study of disaster risk of the dammed lake, it has profound significance to combine the time scale reflected by ages data with the research for the dammed lake landscape evolution and formation mechanism. As we inferred that the ancient lake in Shiguangdong may have been triggered by an earthquake. However, the formation mechanism of the ancient landslide need further study for the model and the detailed characteristics for the ancient slide. In the next work can explore the relationship between Shiguangdong lake and other lake in Dadu River, it belongs to the same ancient lake or two ancient lake respectively, and what is the connection between them, these questions need to be further discussed and the research carried out by researchers. |
| Key words: Dadu River Shiguangdong paleo-dammed lake optically stimulated luminescence dating |
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