同沉积生长断层的控砂作用研究——以北部湾福山凹陷永安—白莲地区流沙港组一段为例

以高精度层序地层学、沉积学、构造地质学为指导,对福山凹陷流沙港组一段进行了沉积体系的精细研究以及同沉积断层的综合分析。总结出研究区流沙港组一段主要发育3种沉积体系类型:辫状河三角洲、扇三角洲和湖泊沉积体系,包括9种沉积微相。福山凹陷永安—白莲地区流沙港组一段同沉积断裂可划分为西部伸展调节断裂系、东部走滑调节断裂系和中部变换调节断裂系。中央调节断裂带两侧断层在流沙港组一段的差异性活动,导致地层厚度中心从早期到晚期具有一个自西向东迁移的过程。通过沉积体系时空演化规律分析得出,三角洲砂体展布范围在流沙港组一段也具有明显的自西向东迁移的过程。研究表明,同沉积断层对沉积体系展布具明显的控制性,并提出了3种断层控砂模式。

Controls of synsedimentary faults on sedimentary filling of 1st member of Liushagang Formation in Yongan-Bailian areas in Fushan Sag,Beibuwan Basin

The comprehensive analyses of the sedimentary systems and synsedimentary faults in the 1st member of the Liushagang Formation in the Fushan Sag were made based on high-resolution sequence stratigraphy, sedimentology and structural geology. 3 sedimentary systems were concluded including braided river delta, fan delta and lacustrine sedimentary system. 9 sedimentary microfacies were classified. The synsedimentary systems in the 1st member of the Liushagang Formation in the Yongan-Bailian areas of the Fushan Sag were divided into the western extending accommodation fault system, the eastern strike-slip accommodation fault system and the central transfer fault system. The differential activities of the faults on each side of the central transfer fault system resulted in the migration of formation thickness center, migrating from west to east in the 1st member of the Liusha-gang Formation. The space-time evolution regularities of sedimentary systems indicated that the main delta sand body also migrated from west to east in the 1st member of the Liushagang Formation. The development of synsedimentary faults controlled the distribution of sedimentary systems and 3 controlling patterns were concluded.