中国近海裂陷盆地始新世构造变革的厘定及地质意义:以北部湾盆地涠西南凹陷为例

为明确始新世构造变革事件在中国近海盆地的表现形式和空间展布范围，揭示其动力学成因，以北部湾盆地涠西南凹陷为例，利用最新的地质资料，对始新世构造变革界面进行了精细厘定.结果表明:盆地在始新世中、晚期经历了裂陷作用南北转变、断裂体系转型、地层挠曲变形和沉积-沉降中心迁移等构造转换过程；始新世构造变革的发生与周缘板块重组所诱导的区域应力场南北向转变有密切的动力学成因联系，尤其是与太平洋板块俯冲方向转变和印度-欧亚板块强烈碰撞紧密相关；该构造事件的发生，揭示了中国近海裂陷盆地演化具有统一性与差异性共存、继承性与改造性同在、伸展性和走滑性叠加的特点，其深刻影响了成藏要素的耦合匹配关系，深部优质烃源岩与浅部走滑相关构造的配置决定了油气优势成藏部位. 

Identification of Eocene Tectonic Transition and Its Geological Significance of Rift Basins Offshore China:A Case Study in Weixi'nan Sag,Beibu Bay Basin

In order to identify the expression and spatial distribution of Eocene tectonic transition event in petroliferous basins offshore China, and reveal the geodynamic origin ultimately, based on the new released geological data, investigation on interface was carried out from a case study of Weixi'nan sag. The results show that the basin experienced the rifting change to N-S-directed, transformation of fault system, flexural deformation of strata and the migration of the depocenters. The Eocene tectonic transition is closely related to the stress change due to the reorganization of neighboring plates, especially to the orientation change of Pacific plate subduction and collision of Indian plate and Eurasian plate. The occurrence of this tectonic event reveals the coexistence of consistency and diversity, inheritance and reworked structures, extension and strike-slip deformation. It deeply influences the coupling between different accumulation elements. The configuration of the high-quality source rocks and the shallower strike-slip structures determines the advantageous section of hydrocarbon accumulation.