渤海海域渤东地区断裂体系与盆地结构

The Development Characteristics of the Fault System and Basin Structures of the Bodong Sag, East China

以渤东地区为研究对象,运用丰富的三维地震资料,文中将剖面特征分析与水平相干切片特征分析相结合,在对断裂体系精细刻画的基础上,建立了不同类型断裂的结构模式,分析了断裂的展布特征,并就断裂体系对盆地结构的控制作用进行了研究,结果表明:渤东地区新生代断裂体系发育特征吻合于郯庐断裂新生代右旋应力场,表现为以NNE向走滑断裂为主枝、以NE向拉张断裂为侧枝、近EW向断裂为细脉的特点,可以划分为走滑断裂、拉张-走滑断裂、走滑-拉张断裂和拉张断裂四种基本类型,受断裂性质和活动强度的影响,不同类型断裂的空间结构存在明显差异;受郯庐断裂左旋到右旋的转变、拉张作用与走滑作用强弱的转变、地幔上涌水平拉张到热沉降的转变等因素的影响,不同时期的断裂体系存在明显差异,依据断裂对盆地结构的控制作用,可将新生代盆地发育划分为左旋-右旋转换、走滑-拉张断陷、拉张-走滑断陷和走滑-拗陷4个不同的演化阶段。明确断裂的时空差异性对于渤东地区油气勘探具有重要指导意义。

Based on the detailed description of fault system, this paper established different types of fault structure patterns and analyzed the distribution characteristics of faults in the study area of Bodong by using abundant seismic data and combined analyses of sections and time slice characteristics. Furthermore, we carried out studies of the controlling role that fault system played on basin structures. It is concluded that the development characteristics of fault system in Cenozoic age was in accordance with the right lateral stress-field of Tanlu fault which is expressed as NNE-trending strike-slip faults for main branches, NE- trending tensional faults for secondary ones and near EW-trending faults for the least abundant ones. Also, faults can be subdivided into slip typed, tensional-slip, slip-tensional, and tensional types. Besides, different types of faults have different structures due to the effects of property and activity intensity. Fault system in different ages showed tremendous differences because of stress transition of Tanlu fault from left lateral to right lateral and intensity transition between tension and slip. According to the dominant impact that fault acted on basin structures, Cenozoic basin can be classified into four revolutionary stages, i.e., transitional stage from left lateral to right lateral, slip-tension faulted stage, tension-slip faulted stage, and slip- depression stage. Therefore, the identification of temporal and spatial differences of faults could be used as an important guideline for the oil and gas exploration in Dodong area.