| LIANG Chao,XIE Xinong,WANG Hua,ZHONG Guangjian,LIU Entao,SUN Ming,YI Hai,QIN Chunyu,CAO Haiyang,HE Jie,ZHAO Yanpu. 2019. Effects of igneous bodies on modification of modern slope morphology: Insights from the continental slope offshore Dongsha Islands, South China Sea. Acta Oceanologica Sinica, 38(5):109－117 |
| Effects of igneous bodies on modification of modern slope morphology: Insights from the continental slope offshore Dongsha Islands, South China Sea |
| 火成岩体在现今陆坡形态调整中的作用：来自南海东沙群岛近海陆坡的启示 |
| Received:November 24, 2017 |
| DOI：10.1007/s13131-019-1357-y |
| Key words:igneous bodies modern slope morphology Dongsha Islands South China Sea |
| 中文关键词: 火成岩体 现今陆坡形态 东沙群岛 南海 |
| 基金项目:The National Natural Science Foundation of China under contract Nos 91528301, 41702121, 41606074 and 41702114; the National Science and Technology Major Project under contract No. 2017ZX05026-005-002; the Survey of Oil and Gas Resources in the Northern South China Sea and Taiwan Strait under contract No. DD20160154. |
| Author Name | Affiliation | E-mail | | LIANG Chao | College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China
Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, China | | | XIE Xinong | College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China
Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, China | xnxie@cug.edu.cn | | WANG Hua | Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, China
Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China | | | ZHONG Guangjian | Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510760, China | | | LIU Entao | College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China
Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, China | | | SUN Ming | Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510760, China | | | YI Hai | Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510760, China | | | QIN Chunyu | Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China | | | CAO Haiyang | Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China | | | HE Jie | Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China | | | ZHAO Yanpu | Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China | |
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| Abstract: |
| A statistical analysis for the morphological parameters extracted from numerous seismic profiles, and a high-resolution seismic study of the southeastern slope of the Dongsha Islands (South China Sea) with water depth between approximately 500 and 3 100 m, has revealed the variation of morphological features due to the intrusion of igneous bodies and associated sedimentary processes. Three types of the continental slope are distinguished:(1) a rough and steep slope with multiple igneous bodies (Type 1), (2) a relatively smooth and gentle slope with the single igneous body (Type 2), and (3) a smooth and gentle slope without igneous bodies (Type 3). These igneous bodies, formed in the post-seafloor spreading of the South China Sea, are often characterized by high positive seismic amplitudes, and chaotic reflections with complex shapes. The igneous bodies in Type 1 separated the slope into two or more upper sub-sags and a lower main-sag, in which the sub-sags and main-sag could be filled with sediments transported by alongslope bottom currents at the same time. Whereas, the igneous body in Type 2 just separated the slope into an upper sub-sag and a lower main-sag, in which the sediments could be transported into the lower main-sag only after the upper sub-sag has been filled up. Type 3 represents a normal slope with common clinoform progradation. The modern slope morphologies in the study area are the results of adjustments of the continental slope due to the intrusion of igneous bodies and associated sedimentary processes. The distinctions among three types of modern slope morphologies indicate different depositional conditions and adjustments of slope morphologies. |
| 中文摘要: |
| 对从南海东沙群岛近海陆坡（水深约500-3100m）采集到的二维地震剖面提取地形数据后进行统计学分析，结合地震相研究，发现研究区陆坡形态的变化与火成岩体，以及与火成岩体相关联的沉积过程存在着紧密地联系。共识别出了3种陆坡类型：（a）发育多个火成岩体的粗糙、陡的陆坡（类型1）；（b）发育单个火成岩体的较为光滑、平缓的陆坡（类型2）；（c）无火成岩体发育的光滑并且平缓的陆坡（类型3）。这些火成岩体形成于南海海底扩张之后，具有较为复杂的形态，在地震剖面上多表现为强振幅的杂乱反射。在类型1中，多个火成岩体将陆坡分为上部的两个或者多个次凹和下部的一个主凹，这些凹陷可以同时被沿坡流带来的沉积物充填。然而在类型2中，单个火成岩体将陆坡为一个上部的次凹和一个下部的主凹，只有当上部的次凹被沉积物填满后，沉积物才可以开始充填主凹。类型3为发育斜坡沉积的正常陆坡。研究区现今的陆坡形态是由于火成岩体的侵入和与火成岩体相关的沉积过程所共同导致的陆坡形态调整的结果。三种陆坡类型现今陆坡形态间的差异指示不同的沉积条件和陆坡形态调整。 |
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