南大西洋西非岸盆地群构造、沉积演化对比  

A comparative study of tectonic and sedimentary evolution of West African coastal basins in the south Atlantic Ocean region

作　　者：洛怡 李江海[1] 杨梦莲 LUO Yi;LI Jianghai;YANG Menglian(Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871

出　　处：《中国地质》2021年第1期120-128,共9页Geology in China

基　　金：国家科技重大专项“南大西洋两岸盆地分析与油气资源评价”(2016ZX05033-002、2016ZX05033-001)资助。

摘　　要：非洲西部海岸盆地群经历了裂谷期、同裂谷期和漂移期构造演化阶段,构造演化和沉积充填有一定的相似性,但是由于后期局部构造和差异沉积的影响,现今盆地发育的构造样式和沉积建造有一定区别,导致勘探效果有较大的差异。本文通过对比南大西洋赤道段转换型、中段含泥型、中段含盐型和南段火山型盆地的综合柱状图,加上对尼日尔三角洲盆地和下刚果盆地进行平衡剖面恢复,探讨西非岸三段四类盆地的特征,以求对盆地的勘探工作有所帮助。赤道段转换型盆地在阿普特期和阿尔比期的裂谷阶段完成了湖泊、河流等陆相沉积到浅海碳酸盐岩沉积的转换,未发育盐岩。中段含泥盆地巨厚的新生代阿卡塔组泥岩为滑脱层,在差异负载作用下,泥岩层发生变形。中段含盐盆地在阿普特期,由陆相沉积过渡为浅海碳酸盐岩沉积。阿普特期盐岩层在差异负载和重力滑脱作用下流动变形,形成了伸展、底辟和挤压构造带。南段火山型盆地以裂谷期发育的溢流相玄武岩和凝灰岩为特征,发育典型的向海倾斜反射体。Basins along West African coast have certain similarities in structure and evolution since they have all experienced prerift,rift and drift period,but there also exist differences in present tectonic and sedimentary patterns due to the influence of local events,which leads to different exploration results.In order to summarize characteristics of these basins,the authors compared the comprehensive lithologic column diagrams and restored balanced cross-sections of Niger delta basin and lower Congo basin.The results are as follows.1)Basins in the equatorial segment have transferred from continental facies such as lacustrine facies and fluvial facies to neritic facies,and there exist no salt deposits in this kind of basins.2)Niger delta basin is characterized by thick Cenozoic Akata Formation,which is a detachment layer and has been deformed under differential load.3)The salt-bearing basins in central segment experienced a transition period in Aptian stage,within which sedimentary environment transferred from continent to marine environment.The Aptian salt rocks migrated under the differential load and gravity slippage and divided whole basin into three domains,i.e.,extensional domain,salt diapir and contractional domain.4)The volcanic type in the southern segment is characterized by intense volcanism and extensive development of SDRs.

关 键 词：南大西洋 构造沉积演化 被动大陆边缘 平衡剖面恢复 

分 类 号：TE121[石油与天然气工程—油气勘探]