西非被动大陆边缘重力滑脱构造发育演化及成因机制  

Tectonic Revolution and Forming Mechanism of Gravitational Décollement Structures in the Passive Continental Margin of West Africa

作　　者：胡望水[1] 李涛[1] 于水 吴婵[1] 何瑶瑶[3] 龙小军[3] 

机构地区：[1]长江大学油气资源与勘探技术教育部重点实验室,湖北荆州434023 [2]中海石油研究中心国际研究部,北京100027 [3]中国石化江汉油田分公司勘探研究院,湖北武汉430023

出　　处：《大地构造与成矿学》2012年第2期186-196,共11页Geotectonica et Metallogenia

基　　金：国家重大专项(2008ZX05030-003)"西非被动大陆边缘盆地海底扇等勘探目标评价与优选"部分成果

摘　　要：西非被动大陆边缘盆地在晚侏罗世伴随大西洋的裂开而形成,陆内裂陷构造旋回(晚侏罗世-早白垩世阿普特期(Aptian))主要发育陆内裂陷构造;过渡期构造旋回(阿普特期)沉积了一套潟湖相塑性层(盐岩);被动大陆边缘构造旋回(早白垩世阿尔布期(Albian)至今)共发育了两期重力滑脱构造,早白垩世阿尔布期-渐新世发育一期(早期)重力滑脱构造,中新世至今发育了另一期(晚期)重力滑脱构造。西非被动大陆边缘同一期重力滑脱构造具有从早到晚由陆向海的前展式发育规律,且多期重力滑脱构造具有从早到晚由陆向海迁移的进积叠加规律。西非被动大陆边缘重力滑脱构造发育的主要控制因素是大地构造背景、地层掀斜、滑脱面形态,其中大地构造背景控制重力滑脱构造体系类型,地层掀斜是引起地质体重力滑脱和变形的根本、控制构造变形的强度,滑脱面形态控制着重力滑脱构造类型和发育位置;次要控制因素是差异重力负载和塑性滑脱层等。并在此基础上建立了宽缓型凹面斜坡和窄陡型斜坡滑脱面下的西非被动大陆边缘重力滑脱构造成因发育模式。The passive continental margin of West African basin began to form when the Atlantic Ocean broke up in Late Jurasic, and based on the difference of geodynamic mechanism, the tectonic revolution of the basin could be divided into three epochs. The main style of tectonic development was intracontinental rift in Late Jurassic-Early Cretaceous Aptian stage, which was named as intracontinental rift tectonic cycle epoch. In transitional tectonic cy- cle epoch （ Aptian stage） , the lagoons ductile layer （salinastone） was deposited in the basin. The third tectonic de- formation stage is passive continental margin tectonic cycle one （Cenomanian-present） in which the gravitational d6eollement structure developed, then, the stage could be further divided into two phases： Early Cretaceous Albian period-Oligocene and Miocene-now. The tectonic evolution model of every phase gravitational decollement structure was advanced from land to sea, and there were prograding and superimposed deformation model of every phase from early to late. According to the analysis of the gravitational decollement structure formation mechanism, the main controlled factors included 1） tectonic background, which determined the gravitational decollement structure type, 2） stratum tilting, which induced gravity slipping and deforming and controlled the deformation degree, and 3） decollement shape, which controlled its type and forming location. Then, the secondary factors are different gravity loading and ductile deeollement layer. Based on the analysis of forming mechanism, this study establishes a gravita- tional decollement structure mechanism evolution model of wide-gentle type concave slope and narrow-steep type slope slip surface on the West African passive continental margin.

关 键 词：西非 重力滑脱构造 构造发育演化 成因机制 

分 类 号：P542[天文地球—构造地质学] TE121.1[天文地球—地质学]