| 珠江口外海域滨海断裂带沿构造走向的变化特征 |
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| 引用本文： | 熊成,曹敬贺,孙金龙,夏少红,万奎元,范朝焰,杨碧峰.珠江口外海域滨海断裂带沿构造走向的变化特征[J].地球科学,2018,43(10):3682-3697. |
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| 作者姓名： | 熊成 曹敬贺 孙金龙 夏少红 万奎元 范朝焰 杨碧峰 |
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| 作者单位： | 1.中国科学院边缘海与大洋地质重点实验室, 中国科学院南海海洋研究所, 广东广州 510301 |
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| 基金项目： | 国家自然科学基金项目41376060中国科学院边缘海地质重点实验室开放基金项目MSGL15-05国家自然科学基金项目41576046国家自然科学基金项目41506046 |
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| 摘 要： | 珠江口外海域滨海断裂带是南海北部陆缘重要的控震和发震构造，其研究关系到区域防震抗震、地壳稳定性评价及对南海构造演化的认识.为探明滨海断裂带沿构造走向上的变化特征，对2015年珠江口海陆联测数据进行了处理，使用射线追踪、走时模拟等方法，获得了珠江口西侧的地壳纵波速度结构模型和滨海断裂带在珠江口地区的发育位置和构造形态等信息.结果显示，珠江口西侧滨海断裂带总体倾向SE，向下可能延伸至莫霍面；沉积层在断裂带陆侧较薄，在滨海断裂带处突然增厚；断裂带内地壳速度为5.3~6.7 km/s，相对两侧地壳表现出低速特征；莫霍面的埋深由断裂带陆侧的28.5 km抬升至其海侧的24.5 km；海陆两侧的地壳结构具有明显的非均一性.对比前人在珠江口东侧的研究成果，珠江口外滨海断裂带总体形态特征相似，但也表现出明显的差异，自东向西，断裂带内部的结构形态从简单变得复杂，逐渐发育明显的阶梯状断层；北界断裂从断距很大的陡崖式正断层逐渐转变为断距较小的低角度正断层，且北界断裂的位置向北错动了一段距离，断裂带内的低速异常则逐渐变弱.本研究不但可以加深对滨海断裂带浅、深部结构的认识，而且还能为研究南海北部陆缘的发震构造提供参考.
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| 关 键 词： | 珠江口 滨海断裂带 地壳结构 深地震探测 地球物理 |
| 收稿时间： | 2017-11-15 |
Variation Characteristics along the Strike of the Littoral Fault Zone in Offshore Pearl River Estuary |
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| Abstract: | The Littoral Fault Zone (LFZ) is an important seismic control and seismic structure in the northern continental margin of the South China Sea.The study of LFZ is related to regional seismic resistance, crustal stability evaluation and the understanding of tectonic evolution of the South China Sea. To find out the spatial variations along the strike of the LFZ, we processed the data of the onshore-offshore deep seismic experiment in Pearl River Estuary (PRE) area in 2015 and simulated a P-wave velocity model in the western PRE and detected the general location of LFZ. The results show that the LFZ dips southeast down to the Moho with a low velocity of 5.3-6.7 km/s in the crust. The basement fluctuates greatly and the depth of the Moho interface is decreases gradually from 28.5 km to 24.5 km from the onshore to offshore. Compared with previous studies in the eastern PRE, the general morphological characteristics of the LFZ on both sides of the PRE are similar. However they also show obvious differences. From east to west, the structure of the fault zone becomes more complex, with steped normal faults developed and the northern boundary fault moves northward a distance and changes into low angle normal fault with small fracture distance from steep normal fault with large break distance, and the low velocity anomaly in the fault zone gradually decreases. The results not only deepen the understanding of the shallow and deep structure of LFZ, but also provide a reference for the seismotectonics of the northern continental margin of South China Sea. |
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