| 南海珠江口盆地恩平凹陷北带串沟河道沉积特征及其岩性圈闭发育潜力 |
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| 引用本文： | 江 标,卓海腾,李小平,丁 琳,吴宇翔,李智高,王英民,孙 珍,孙龙涛,王智娜.南海珠江口盆地恩平凹陷北带串沟河道沉积特征及其岩性圈闭发育潜力[J].高校地质学报,2022,28(5):735-746. |
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| 作者姓名： | 江 标 卓海腾 李小平 丁 琳 吴宇翔 李智高 王英民 孙 珍 孙龙涛 王智娜 |
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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； 南海海洋研究所，广州 510301；
2. 中国科学院大学，北京 100049； 3. 中山大学海洋科学学院，珠海 519082；
4. 中海石油（中国）有限公司深圳分公司，深圳 518054； 5. 浙江大学 海洋学院，舟山 316021 |
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| 摘 要： | 串沟河道是河流体系发育演变中的重要沉积单元，但目前对其沉积特征和沉积过程的系统报道较少。文章综合利用岩矿、测井和三维地震资料，在南海珠江口盆地恩平凹陷北带韩江组六段识别出了典型的串沟河道沉积。在地震剖面上，串沟河道呈相互孤立分布的中—强振幅反射，平面属性图和分频RGB融合切片显示其在平面上总体较为平直，具有北东窄南西宽的特征，且头部向北东侧逐渐尖灭。钻井显示，串沟河道岩性以含砾粗砂岩为主。通过与已有模式和现代实例的对比，发现恩平北带串沟河道发育的独特之处是其位于富泥的泛滥平原背景中，而不是富砂的坝体之上，且主要发育在低位体系域内。基于对沉积过程的综合分析，提出研究区内串沟河道主要遵循上游扩展的发育演变模式：低位期辫状主河道水体间歇性淹没河道间的先存泛滥平原区，触发串沟河道自下游低洼处的溯源侵蚀且逐渐向上游扩展。串沟河道砂体自身物性好且易于被后期海侵泥岩覆盖，具备良好的侧封、顶封条件，将可能成为盆地重要的岩性圈闭类型。文章的相关结论可为珠江口盆地岩性圈闭勘探提供新的思路。
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| 关 键 词： | 珠江口盆地 恩平凹陷 串沟河道 沉积模式 岩性圈闭 |
Seismic Sedimentology and Development Potential of Lithologic Traps ofChute Channels in the Northern Enping Sag,Pearl River Mouth Basin,South China Sea |
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| JIANG Biao,ZHUO Haiteng,LI Xiaoping,DING Lin,WU Yuxiang,LI Zhigao,Wang Yingmin,SUN Zhen,SUN Longtao,WANG Zhina.Seismic Sedimentology and Development Potential of Lithologic Traps ofChute Channels in the Northern Enping Sag,Pearl River Mouth Basin,South China Sea[J].Geological Journal of China Universities,2022,28(5):735-746. |
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| Authors: | JIANG Biao ZHUO Haiteng LI Xiaoping DING Lin WU Yuxiang LI Zhigao Wang Yingmin SUN Zhen SUN Longtao WANG Zhina |
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| Institution: | 1. CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology,;
Chinese Academy of Science, Guangzhou 510301, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China;
3. School of Marine Sciences, Sun Yat-sen University, Zhuhai, 519000, China;
4. Shenzhen Branch of CNOOC (China) Co., Ltd., Shenzhen 518054, China; |
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| Abstract: | Chute channel is an important depositional unit in the development of fluvial systems, but there are few systematic studies focusing on its sedimentary characteristics and processes. In this paper, a series of typical chute channel deposits have been identified in the lowstand systems tracts of the sixth member of the Hanjiang Formation in the northern Enping Sag using cores, well logs and 3D seismic data. On seismic profiles, chute channels are generally isolated high-amplitude anomalies. Seismic attributes and slices from frequency decomposition and RGB blending indicate that chute channels are general straight and widen from NE to SW. They gradually pinch out to the NE direction. Core data shows that the lithology of chute channels is mainly gravel bearing coarse sandstones. Compared with the existing models and modern examples, the chute channels developed in the northern Enping Sag is so unique that it is located in a background of mud-rich flood plain rather than braided bars. Based on the comprehensive analysis of the sedimentary processes, it is proposed that the chute channels within the study follow the upstream expansion model: episodic flooding can influence preexisted flood plain between the braided channels, triggering the headward erosion of the chute channels from the low-lying area downstream of the flood plain. Generally, the chute channels have good physical properties and can be further buried by transgressive mudstones, thus having excellent lateral and top sealing conditions. Consequently, chutes channels may form an important lithologic trap type within the whole basin. The finding of this study can provide new enlightenment for the exploration of lithologic traps in the Pearl River Mouth Basin. |
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| Keywords: | Pearl River Mouth Basin Enping Sag Chute channel depositional model lithologic trap |
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