北部湾盆地北部坳陷构造——沉积特征及其演化

在二维和三维地震资料解释基础上,对北部湾盆地北部坳陷地层分布及断裂系统进行了研究,建立了坳陷断裂分布格局及构造样式;结合地层和钻井资料分析了断裂活动期次和特征,揭示古近纪坳陷构造演化经历了三期幕式断陷活动：古新世,初期拉张裂陷阶段,形成狭小的半地堑;始新世早中期,第二期强烈拉张裂陷阶段,形成统一的湖盆,发育两个沉积中心;渐新世,断坳转换期,涠西南低凸起和3号断裂强烈活动,沉积中心迁移至海中凹陷.这为进一步油气勘探工作提供了有价值的参考.

Characteristics of Tectonic Sedimentary Evolution in Northern Depression of Beibuwan Basin

Based on the 2D and 3D seismic data interpretation, study on stratigraphy distribution and fault systems has been conducted for Beibuwan basin, and the distribution framework of depression fault systems and structural styles of this study area have been built. On the basis of stratigraphy and logging data, the faulting evolution history has been analyzed. It is revealed that three episodes of rifling phases had occurred in Paleogene in northern depression. The first was initial extensional rifling phase in Palaeocene, resulting in the development of narrow half-graben; the second was intense extensional rifting phase in the early to middle Eocene, a unified lake basin formed, and two depocenters occurred; the third was transforming stage from rifting to sagging in Oligocene, the Weixinan low uplift and No.3 fault activitied intensely, and the depocenters shifted to Haizhong sag. This study has provided basis for further work of petroleum exploration.