走滑—拉分盆地构造特征及盆地成因模式探讨: 以中非多赛奥盆地为例

立足于中非剪切带的构造演化，文章分析了中非剪切带对多赛奥盆地形成与演化的控制作用，明确了多赛奥盆地的 构造演化阶段，并从盆地结构和构造样式分析入手，探讨了多赛奥盆地的成因机制。研究表明，受中非剪切带“强—弱” 两期走滑作用控制，多赛奥盆地经历了扭张期、压扭期、拗陷期三期的构造演化阶段，扭张期为盆地的主要形成期，压扭 期为盆地构造定型期。在晚白垩世压扭期，盆地东、西部遭受不同程度的压扭作用，形成东部主坳区和西部压扭区，东部 主坳区遭受后期压扭作用较弱，表现为不对称的双断结构特征，而西部压扭区遭受强烈的后期压扭作用，地层发生弯曲变 形，Borogop II断裂发生正反转作用，形成大型正花状构造区。受早期扭张作用和后期压扭作用双重控制，多赛奥盆地发育 两类五种构造样式。右阶右旋作用机制形成的扭张作用控制了多赛奥和塞拉迈特走滑—拉分盆地的形成。

Discussion on the Structural Features and Formation Mechanism of Strike-Slip Pull-Apart Basin: A Case Study in the Doseo Basin,Central Africa

Based on the tectonics of the Central African Shear Zone (CASZ), how the CASZ controlled the formation and evolution of the Doseo Basin was analyzed in this paper. The evolutional stages of the basin were divided, the basin structure was analyzed, and the formation mechanism of the basin was discussed. Results show that the CASZ developed two periods of strike-slip processes which were strong and weak, respectively. The strike-slip strength controlled the evolutional stages of the basin, i.e., transtensional, transpressional and depression stages, The transtensional stage was the main formation stage of the Doseo Basin; in contrast, the transpressional stage was the structural setting stage of the basin. The eastern and western parts of the basin developed different strength transpression in the transpressional stage. As such, the basin was formed to a division of eastern main depression and western transpression zone. The eastern main depression developed weak transpression, and it had asymmetric double-fault structure. In contrast, the western transpression zone developed strong transpression, stratigraphic deformation, inversion of the Borogop II fault, and formation of large positive flower structural area. Transtensional and transpressional activities controlled the structural styles of the Doseo Basin in two types of structural styles and five sub-types. Transtension which was formed in right step-dextral controlled the formation of strike-slip pull-apart basin.