苏丹-南苏丹穆格菜德盆地苏夫焉凹陷构造特征及演化

Structural features and evolution of the Sufyan depression, Muglad Basin in Sudan-South Sudan

通过识别地震剖面构造样式、恢复骨干剖面构造演化历史，研究了苏丹-南苏丹穆格莱德盆地苏夫焉凹陷构造特征及其构造演化。结果表明：苏夫焉凹陷整体为南陡北缓的地堑结构，构造格局呈现东西分区、南北分带，正断层相关构造样式可识别出“两类五种”，其中以基底卷入型铲式正断层、沉积盖层旋转型平面正断层为主。伴随中非剪切带以及周缘板块的构造演化，凹陷经历了早白垩世巴雷姆期-晚白垩世土伦期、晚白垩世末期-古近纪古新世、新近纪至今3期强-弱-弱断坳演化阶段，其中在第一演化阶段的早期-AbuGabra组第四段、第五段沉积时期，沉积中心位于凹陷中南部，而之后的演化阶段，沉积中心位于紧邻南部边界断层的洼陷带，并由此推测凹陷中部将是深层系（AbuGabra4段）油气勘探的有利区。

The structural characteristics and evolution of Sufyan depression, Muglad Basin has been studied by identifying the structural patterns on seismic profile and restoring the tectonic evolution history of the major profile. The results show the Sufyan depression is a graben that is steep in the south and gentle in the north as a whole, and the tectonic framework presents ＂west-east differentiation and north-south dissimilitude＂. Normal faults can be classified into two major categories and five types, of which the basement-involved listric normal fault and sedimentary cover-rotary plain normal fault are the main type. As the tectonic evolution of central Africa shear zone and the periphery plates progressed, the Sufyan depression experienced three stages of fault-depression evolution： The first stage in the Early Creatace Barremian to Late Creatace Turonian is very intense, the second in the end of Late Cretaceous to Paleocene and the third in the Neogene until present are quite weak. In addition, during the depositional stage of the fourth and fifth member of the Abu Gabra Formation, which is also the early period of the first evolution stage, the depocenter is located in the central and southern Sufyan depression; during the last two stages, however, the depocenter is located in the subsag which is adjacent to the southern boundary fault. Thus, it is predicted that the central sag will be favorable exploration area of the fourth member of the Abu Gabra Formation （the deep strata）.