| 珠江口盆地白云凹陷壳幔拆离断裂活动对深层大型三角洲沉积体系的控制作用 |
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| 引用本文： | 柳保军,庞雄,谢世文,梅廉夫,郑金云,孙辉,颜晖,吴宇翔,向绪洪,冯轩.珠江口盆地白云凹陷壳幔拆离断裂活动对深层大型三角洲沉积体系的控制作用[J].地球科学,2022,47(7):2354-2373. |
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| 作者姓名： | 柳保军 庞雄 谢世文 梅廉夫 郑金云 孙辉 颜晖 吴宇翔 向绪洪 冯轩 |
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| 作者单位： | 1.中海石油深海开发有限公司, 广东深圳 518054 |
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| 基金项目： | 国家重大科技专项2016ZX05026-003-003中海石油深海开发有限公司科技项目CNOOC-KJ135ZDXM37SZ01SHENHAI |
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| 摘 要： | 壳幔拆离断裂活动与沉积体系响应为世界陆缘演变研究的热点，选取珠江口盆地白云凹陷壳幔拆离体系及其沉积响应开展系统性解剖.结合陆缘演变认识新进展、长电缆三维地震和钻井综合解释等揭示白云凹陷南部主控断裂带主要由4排NEE-NE向断至莫霍面的高角度铲式壳幔拆离断裂组成，裂陷期幕式活动使得白云凹陷经历了均一裂陷、拆离裂陷和断拗转换三阶段演化；均一裂陷期（下文昌组），控洼断裂未延伸至莫霍面，主要发育断裂转换带控制下的轴向陡坡辫状河三角洲/湖相沉积体系，缓坡物源体系不甚发育；拆离裂陷期（上文昌组），壳幔拆离断裂断至莫霍面，呈现强烈水平伸展和垂向落差，导致上盘远离断层一侧强烈旋转翘倾、抬升剥蚀成为最主要缓坡物源体系，靠近断层北侧沉降深陷成为深湖盆，上盘中段发育大型三角洲沉积；断拗转换期（恩平组），拆离作用减弱而沉降作用显著增强，控制了北部缓坡挠曲坡折和NW-SE向推进的大型三角洲/湖相沉积体系的发育.由此，主控断裂由均一伸展到壳幔拆离伸展的构造演变导致白云凹陷上文昌组至恩平组缓坡大型三角洲、下文昌组东西轴向转换带辫状河三角洲和洼陷周边陡坡带扇三角洲砂岩三类规模储集体与湖相泥岩满盆叠置的分布格局，使其成为深水勘探向中深层拓展的主要对象.
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| 关 键 词： | 白云凹陷 壳幔拆离断裂 壳幔拆离伸展 缓坡大型三角洲 深水勘探 石油地质学 |
| 收稿时间： | 2021-07-30 |
Control Effect of Crust-Mantle Detachment Fault Activity on Deep Large Delta Sedimentary System in Baiyun Sag,Pearl River Mouth Basin |
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| Abstract: | Crust-mantle detachment faults and its sedimentary system response are the hotspots of the study on continental margin evolution in the world. In this paper it focuses on the Baiyun Sag in the Pearl River Mouth Basin under a systematic dissection. Combined with the new progress in the evolution of continental margins, it is revealed through long cable three-dimensional seismic data and comprehensive drilling interpretation that the main control fault zone in the southern Baiyun Sag is mainly composed of 4 rows of NEE-NE trending high-angle shovel-type crust-mantle detachment faults, which reach to the Moho Surface. Three stages of tectonic activities were identified, as isostatic rifting, detachment rifting, and fault-depression transformation. During the isostatic rifting stage (Lower Wenchang Formation), when the depression-controlling fault had not extended to the Moho Surface, axial steep-slope braided river delta-lacustrine deposition systems were developed, while the gentle slope provenance system was not well developed. During the detachment rifting stage (Upper Wenchang Formation), crust-mantle detachment faulted to the Moho Surface, showing strong horizontal extension and vertical drop, which led to the strong rotation, warping, uplifting and denudation of the hanging wall, and became the main source system of gentle slopes where large delta system developed. At the meantime, the north downshrown side of the fault became deep lake. During the fault-depression transition stage (Enping Formation), the detachment effect weakened and the subsidence increased significantly, which controlled the development of the large delta-lacustrine sedimentary system advancing in the NW-SE direction and the flexure of the gentle slope in the north. As a result, the tectonic evolution of the main control fault in the Baiyun Sag led the depositional systems transferred from the east-west axial braided river deltas in Lower Wenchang Formation to large deltas developed in gentle slopes in the Enping Formation, and fan delta sandstone developed as well in the steep slope belts around the sags consistently. Three types of large-scale reservoirs and lacustrine mudstone combinations have been identified, so the deep-water exploration targets have expanded to the middle and deep layers. |
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