Geometry and Forming Mechanism of Synsedimentary Structures in Northern Melut Sub-Basin, South Sudan

The Melut Basin is a rift basin elongated in NW-SE direction located in south Sudan. Under the influence of Intracratonic extensional forces that resulted from the opening of the Atlantic, and associated left-lateral strike-slip, a series of synsedimentary structures are developed in Melut Basin. On the basis of different features of structure development continuous, late deformation and drive mechanism, there are mainly three types of synsedimentary structures developed, i.e. inherited structures, fault-related structures and differential compaction-related structures, respectively. Inherited structures are inherited from paleo-uplift and reformed by later-stage faulting. Fault-related structures form as a result of displacement decreases with distance from the fault surface caused by low dip angle listric fault. The origins for the listric fault include listric basin-bounding fault caused by adjacent titled block and strike-slip fault involved into shale formation. The main two types of differential compaction-related structures are caused by intense differential compaction within intervals of sandy conglomerate of alluvial fan and the original sediments are inclined to collapse into depression during sedimentary compaction, respectively. The synsedimentary fault and its assemble pattern controlled the distribution of sedimentary facies, the synsedimentary structures has great influence for the generation, migration, accumulation and preservation of oil and gas.