【摘要】 尼日尔三角洲位于非洲大陆西海岸的几内亚湾,由尼日尔河注入大西洋形成的,是世界上最大的三角洲之一。它发育于冈瓦纳大陆裂解形成的中、西非裂谷系和大西洋被动大陆边缘交汇部位,主体位于大西洋洋壳之上,部分位于非洲前寒武纪结晶基底之上。中、西非中生代裂谷系通过控制贝努埃-尼日尔河系的发育,间接控制三角洲的形成演化。尼日尔三角洲是一个进积型三角洲,具有典型的进积三角洲沉积序列,自下而上依次是海相页岩(Akata组)、近海三角洲相砂岩-页岩互层(Agbada组)和陆相冲积砂岩(Benin组)。三个岩石地层单位均规律性穿时,向洋方向变新。尼日尔三角洲层序中发育一大型重力滑动构造。该重力滑动构造的主滑脱面位于Akata海相页岩中,可以划分出前缘挤压构造变形区和后缘拉张伸展构造变形区。挤压构造变形区发育褶皱冲断带,伸展构造变形区发育堑垒构造,两者之间的过渡带发育滑脱褶皱。尼日尔三角洲的重力构造伴生有广泛发育的泥构造。重力动构造的形成可能与新生代喀麦隆火山带(Cameroon volcanic line)有一定的关系。更多还原

【Abstract】 The Niger Delta,one of the largest delta in the world,is located on the eastern passive continental margin of the Atlantic Ocean. It was formed during the Niger River entering the Atlantic Ocean. The main part of the delta lies on the Atlantic oceanic crust,and the minor part on the African pre-Cambrian basement. The Central and West African Rift Systems indirectly control the formation of the Niger Delta through controlling the distribution and development of the Benue-Niger river system. It is a prograded delta with typical prograding sequence,i. e.,regressive sequence. The prograding sequence is constituted with the marine shale( Akata Formation),paralic sand and shale( Agbada Formation) and continental alluvial sands( Benin Formation) from the bottom to the top. These three lithostratigraphic units are diachronous. All of them are younger seaward. There is a large scale gravity gliding tectonics. The main detachment fault lies in the Akata marine shale. The gravity tectonics can be divided into the front compressional deformation province and the trail extensional deformation province. The front compressional deformation formed a fold-thrust belt. The trail extensional deformation formed horst-graben structures. The detachment folds are well developed in the transitional zone between these two deformation provinces. Accompanied with the gravity-gliding tectonics,shale tectonics are widely developed in the Niger Delta. There is possibly some formation-relation between the gravity-gliding tectonics and the Cenozoic volcanic activities of the Cameroon volcanic line.更多还原