膝褶带构造及其地球物理正演

通过构建一系列理想的膝褶带地质模型, 利用四阶有限差分法单炮记录正演模拟方法, 对各类型膝褶带在地震反射剖面上的图像几何学特征进行了正演。正演结果分析表明: 1) 在地震剖面上, 膝褶带变形样式不同于断层构造样式, 膝褶带在地震剖面上具有一定宽度, 带内地震信息呈低振幅、信息模糊或空白带; 2) 膝褶带内外角之间的变化, 即膝褶带内地层产状的倾角变化, 对地震反射信息影响巨大; 3) 在膝褶带内地层陡立或近于直立的情况下, 地震反射界面从膝褶带外向内追踪困难, 且发生反射界面信息假象。这些地球物理正演结果为实际地震剖面的构造解释、膝褶与断裂构造的区分提供基本的参考。

Kink-Band Structure and Its Geophysical Forward Modeling

Finite-difference method-single-shot record method is applied to forward-model kink-band models.Based on the analysis of forward modeling results and the features of seismic images response to the various kink-band belt models,the conclusions are summarized as follow.1) In the seismic profile,kink-band belt is characterized by the substantial width of low-reflectivity,low-signal-to-noise zone and their sub-parallel edges in cross section,which are different from the features of the fault structure.2) Their orientations at a high angle to layering can impact on the seismic imaging efforts.3) Steeply or nearly vertical dipping bedding in the kink-band belt often misguide the reflection interface tracking by some overvalued and other false information.These results can provide first references for interpretation of the seismic profiles,such as identifying structural type,and distinguishing the fault from the kink-band.