Abstract:

Based on the data of three seismic work areas in the Lower Congo Basin, nine typical salt-related tectonic patterns are summarized in the basin and the distribution pattern of salt structures is confirmed. Established with the base tilt angle as a single variable based on the discrete element numerical simulation method, and evolution results of the structure and motion vectors are obtained. With the increase of the basement inclination angle, the flow velocity of salt rock and its overlying sediments gradually increases, and the subsequent terrigenous sediment transport distance is also longer. The basement inclination mainly has three kinds of control effects on the salt rock flow: differential compaction as the master control, differential compaction and gravity gliding combined, gravity gliding as master control. These three control effects are all affected by the basement inclination angle and appear in turn with the change of the angle. Based on the analysis results above, control pattern of basement inclination on salt rock flow in the passive margin basin of the South Atlantic is established.

Key words: Lower Congo Basin, salt structure, numerical simulation of discrete element method, structure inclination, control pattern

摘要：

基于下刚果盆地3个工区的地震数据, 总结盆地内9种典型的盐相关构造样式, 并基于离散元数值模拟方法, 以构造倾斜角度为单一控制变量建立模型, 对比分析盐岩的运动矢量演化。模拟结果表明, 随着构造倾斜角度的增加, 盐岩及其上覆岩层的流动速度逐渐增大, 后续陆源沉积物的搬运距离也越远, 更易形成盐构造; 盐岩流动主要有3种控制机制: 差异压实作用控制、差异压实作用和重力滑脱作用共同控制以及重力滑脱作用控制, 这3种控制作用均受坡度的影响, 随着坡度的改变, 3种控制作用依次出现, 控制着盐构造的形成。在上述分析结果的基础上, 建立被动陆缘盆地构造倾斜角度对盐岩流动的控制模式。

关键词: 下刚果盆地, 盐构造, 离散元数值模拟, 构造倾斜角度, 控制模式