Development of branching brittle and ductile shear zones: A numerical study
Development of branching brittle and ductile shear zones: A numerical study
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DOI：
10.1002/2016gc006793
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发表时间：
2017-06
期刊：
影响因子：
3.7
通讯作者：
Sven Erik Meyer;B. Kaus;C. Passchier
中科院分区：
文献类型：
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作者：
Sven Erik Meyer;B. Kaus;C. Passchier
大陆碰撞带通常与大规模走滑剪切带相关。在大多数情况下，这些剪切区很复杂，由多股组成，宽度、长度和总位移各不相同。在这里，我们提出了二维数值模型来模拟在脆性（摩擦/塑性）或延性条件下地壳内不同深度水平上此类剪切带的形成。剪切带的局部化是由材料参数的材料对比（异质性）引发的。我们系统地测试了脆性和韧性状态下的应变弱化率，以了解其对剪切带网络发展的影响。我们的模拟表明，脆性剪切带系统中对立断层的发展与变形过程中摩擦角的减小密切相关。一般来说，应变弱化的变化对延性剪切区也有显着影响。数值结果表明，局部高应变区的几何形状和厚度尤其受到变形过程中弱化机制的影响。此外，剪切线的互连和相互作用导致更复杂的运动学模式，从而导致最大主应力轴的局部变化。剪切束的这些相互作用可以解释剪切相关结构（例如褶皱）的出现或剪切带的不同特征，例如剪切带的厚度或断层相对于应力场的方向，这与现场观察一致。
Continental collision zones are usually associated with large‐scale strike‐slip shear zones. In most cases, these shear zones are complex and consist of multiple strands, varying in width, length, and total displacement. Here we present 2‐D numerical models to simulate the formation of such shear zones at different depth levels within the crust, under either brittle (frictional/plastic) or ductile conditions. Localization of shear zones is initiated by a material contrast (heterogeneity) of the material parameters. We systematically test the rate of strain weakening in brittle and in ductile regimes to understand its influence on the development of shear zone networks. Our simulations suggest that the development of antithetic faults in a brittle shear zone system is closely linked to a decrease in the angle of friction during deformation. In general, variation of the strain weakening also has a significant influence on ductile shear zones. Numerical results show that the geometry and thickness of the localized high strain zone are especially affected by weakening mechanisms during deformation. Furthermore, the interconnection and interaction of the shear strands lead to a more complex kinematic pattern, which lead to a local change in the maximum principal stress axis. These interaction of shear strands may explain the occurrence of shear‐related structures (e.g., folds) or differing characteristics of shear zones, such as the thickness of shear zones or the orientation of the faults to the stress field, which are consistent with field observations.