渤海海域古近系湖盆边缘构造样式及其对沉积层序的控制作用

Structural styles of the Paleogene lacustrine basin margin and their control on sedimentary sequences in Bohai Sea area

陆相断陷湖盆边缘构造带是湖盆的重要组成部分,它们通常紧邻生油中心,是陆相断陷湖盆的油气主要富集带之一。渤海海域古近系湖盆边缘构造样式可划分为伸展型湖盆边缘和走滑型湖盆边缘两大类,伸展型湖盆边缘又可划分为陡坡断裂型湖盆边缘、缓坡断裂型湖盆边缘、简单缓坡带型湖盆边缘和轴向斜坡型湖盆边缘。伸展型湖盆边缘在全区各大凹陷均可见,走滑型湖盆边缘仅发育在盆地的东部地区,主要受郯庐断裂带的控制。不同类型湖盆边缘的构造活动方式和构造演化过程各不相同,因而其所形成的地貌形态有较大的差别,可容空间和沉积基准面的变化各具特色,从而导致不同构造样式的湖盆边缘具有不同的沉积层序构成模式。湖盆边缘构造样式对层序构成的控制作用的分析对储集层预测和岩性圈闭预测具有重要的指导意义。

As an important part of continental rift lacustrine basin, the structural zones of the basin margin which are usually located close to the hydrocarbon-generating center, are important petroliferous belts in the continental rift lacustrine basin. In the Bohai Sea area, the structural styles of the Paleogene lacustrine basin margin can be divided into two types： extensional lacustrine basin margin and strike slipping lacustrine basin margin and the former one is further subdivided into the steep slope faulted lacustrine basin margin, the gentle slope faulted lacustrine basin margin, the simple gentle slope lacustrine basin margin and the axial slope lacustrine basin margin. The extensional lacustrine basin margin is widely distributed in the large sags of the study area, while the strike slipping one is developed in the eastern area of the basin and is mainly controlled by the Tancheng-Lujiang faulted belt. Due to the differences of the structural movements, the structural evolution of different lacustrine basin margins, the palaeogeomorphology, the accommodation variation and the sedimentary base level changes are different. As a result, different lacustrine basin margins with different structural styles have different sedimentary sequence filling models. The analyses of the control of lacustrine basin margin structural styles on sequence filling are very important for reservoir delineation and prediction of lithologic traps.