中非裂谷盆地构造演化差异性与构造动力学机制

分析了不同空间位置盆地的构造演化差异性，并结合区域构造事件探讨了中非裂谷盆地的构造动力学成因机制。中非裂谷盆地包括两个分支体系：西非裂谷系主要呈左旋走滑双断式结构；中非裂谷系主要表现为单断式右旋走滑结构。研究区内有走滑盆地和伸展盆地两种类型：前者位于走滑断裂带内部，近似平行于走滑断裂带展布，走滑作用强，构造反转明显；后者位于走滑断裂带端部，与走滑断裂带斜交，伸展作用强，构造反转较弱。中非裂谷盆地发育3期裂陷—拗陷构造旋回：早白垩世，中非盆地同时发生强烈的裂陷作用；晚白垩世，不同空间位置盆地的裂谷作用强度差异明显并且经历构造反转；古近纪，只有近NW-SE向盆地发生第三期裂谷作用，而其他盆地处于拗陷期。中非裂谷盆地是非洲陆缘板块构造运动在非洲陆内3个块体差异应力作用的陆内响应，3期裂谷作用的构造动力来源不同：早白垩世中大西洋扩张、晚白垩世南大西洋快速扩张和印度洋扩张双重作用、古近纪非洲板块与欧洲板块主要碰撞及西北印度洋中脊扩张影响。

Differences in Tectonic Evolution and Mechanisms of Tectonic Dynamics of Rift Basins in Central Africa

In this study, differences in tectonic evolution of basins in various locations are analyzed. Based on these results and regional tectonic events, mechanisms for tectonic dynamics of rift basins in Central Africa are discussed. Rift basins in Central Africa include two systems:West African systems are dominated by dextral strike-slip double faults, whereas those in Central Africa are mainly single sinistral strike-slip faults. In the study area, there are two types of basins:strike-slip basins and extensional basins. The former is located within the strike-slip fault belt, and is roughly parallel to the fault belt. It shows strong strike-slip movement and tectonic inversion. The latter is located at the ends of the strike-slip fault belt and intersects obliquely with the fault belt. It has strong extensional movement but relatively weak tectonic inversion. Rift basins in Central Africa experienced three episodes of rifting-depression tectonic cycles. In the Early Cretaceous, basins in Central Africa all underwent intense rifting. In the Late Cretaceous, basins at different locations experienced rifting of varying intensities and tectonic inversion. In the Paleogene, only roughly NW-SE striking basins underwent the third rifting episode, while other basins were subjected to depression. Rift basins in Central Africa resulted from terrestrial responses to stress differences between the three blocks in mainland Africa during tectonic movements of the African continental plate. The dynamic tectonic sources were different for the three rifting episodes, the expansion of the Mid-Atlantic Ocean in the Early Cretaceous, the rapid expansion of the South Atlantic Ocean and expansion of the Indian Ocean in the Late Cretaceous, and the major collision between the African and Eurasian Plates and spreading of the mid-ocean ridge in the Northwest Indian Ocean in the Paleogene.