珠江口盆地恩平凹陷恩平组物源体系分析及未来大洋钻探建议

2022,96(8):2788-2799
杜文波1,2, 朱荣伟1,2, 熊量莉1, 朱红涛3, 舒誉4, 黄众5
1) 中国地质调查局广州海洋地质调查局，自然资源部海底矿产资源重点实验室，广东广州，510075;2. 2) 南方海洋科学与工程广东省实验室(广州)，广东广州，511458;3) 中国地质大学(武汉)，湖北武汉，430074;4) 中海石油(中国)有限深圳分公司，广东深圳，518054;5) 中国海洋石油国际有限公司，北京，100028
摘要：物源体系分析是沉积盆地特征分析的重要内容，为进一步阐明珠江口盆地恩平凹陷恩平组的沉积特征和物源体系，本文拟利用恩平凹陷的三维地震资料和钻井数据，通过古生物环境分析和锆石U- Pb定年等方法，并借助地震剖面中古沟谷的识别、前积反射结构、地震多属性分析结果和沉积相带平面分布特征，对恩平凹陷恩平组物源体系特征进行综合分析。研究结果表明，恩平组PSQ1～PSQ2时期表现位明显的陆相湖盆特征，物源主要为珠江口盆地内隆起的古生代变质岩和中生代火成岩基底，少量来源于北部华南褶皱带的元古宙变质岩；随着PSQ3时期断层活动逐渐停止，湖平面不断上升，华南褶皱带物源供给能力明显增强，逐渐成为恩平凹陷主要物源。鉴于目前南海北部缺少陆相湖盆地层的完整岩芯剖面，制约了南海北部裂陷期构造- 沉积耦合研究并影响了该地区的油气勘探，建议下一步在南海北部陆相沉积盆地(如珠江口盆地)开展大洋钻探工作，以便获取更连续、时间精度更高，受风化作用影响更小的陆相湖盆地层的完整岩芯剖面。这不仅有利于指导下一步油气勘探，也可通过重建陆相沉积盆地不同地质历史时期的沉积变化过程，为了解古气候状态和预测未来气候变化提供重要依据。
关键词：恩平凹陷；恩平组；物源体系；沉积特征；大洋钻探

Analysis of provenance systems of Enping Formation in the Enping sag of Pearl River Mouth basin and future ocean drilling proposals

Du Wenbo1,2, Zhu Rongwei1,2, Xiong Liangli1, Zhu Hongtao3, Shu Yu4, Huang Zhong5
1) Key Laboratory of Marine Mineral Resources, Ministry of Natural Resources, Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou, Guangdong 510075, China;2) Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), China Geological Survey, Guangzhou, Guangdong 511458, China;3) China University of Geosciences, Wuhan, Hubei 430074, China;4) Shenzhen Branch, CNOOC China Limited,Shenzhen, Guangdong 518054, China;5) CNOOC International Limited, Beijing 100028, China
Abstract：Provenance systems analysis are important part of sedimentary basin characterisation. A comprehensive analysis of the provenance systems characteristics of the Enping Formation in the Enping sag was undertaken based on 3D seismic data and drilling data from the Enping sag, and paleontological environment analysis, zircon U- Pb dating, identification of ancient valleys, progradation reflection, seismic multi- attribute and characteristics of sedimentary facies. The research results show that the PSQ1- PSQ2 of the Enping Formation exhibits obvious lacustrine rift basin characteristics, and the provenance is dominated by Paleozoic metamorphic and Mesozoic igneous rocks in the uplift region of the Pearl River Mouth basin, and a small amount of Proterozoic metamorphic rocks in the northern South China fold belt.During the PSQ3, the fault activity gradually ceased, the lake level continued to rise, and the provenance supply capacity of the South China fold belt increased and gradually became the main provenance of the Enping sag. The lack of complete core profiles of continental basins in the northern South China Sea limits the structural- sedimentary coupling research during the rifting period and affects the next oil and gas exploration in this area. Therefore,it is suggested that ocean drilling should be carried out in continental sedimentary basins (such as the Pearl River Mouth basin) in the northern South China Sea,in order to obtain core section which are continuous, undisturbed and chronologically well constrained. This is not only beneficial to guide the next hydrocarbon exploration, but also provides an important basis for understanding the paleoclimate and predicting future climate change by reconstructing the sedimentary change process of the continental sedimentary basin in a different geological period.
Key words：Enping sag; Enping Formation; provenance systems;sedimentary characteristic; ocean drilling
收稿日期：2022-05-17
基金项目：本项目为南方海洋科学与工程广东省实验室（广州）人才团队引进重大专项（编号GML2019ZD0207，GML2019ZD0201）、中国地质调查局项目（编号 DD20221712，DD20221719）和国家自然科学基金项目（编号 42106079）联合资助的成果。
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