In many mountain belts, deformation concentrates along mechanically weak fault zones inherited from earlier tectonic events. This work investigates the effects of two modes of structural weakening on the orientation of rifting and later tectonic inversion with respect to the imposed divergence/convergence direction in a high-resolution 3D finite difference model with a viscous-frictional rheology. In the first set of experiments, weakening consists in a decrease in frictional strength with increasing shear strain. The generated normal faults strike orthogonal to the imposed divergence direction. These faults are reactivated during tectonic inversion and absorb 50 to 70 percent of accumulated strain. In the second set of experiments, frictional strength is a decreasing function of shear strain rate. The generated faults are oblique to the divergence direction, implying oblique fault slip. Fault reactivation depends on the obliquity of the inverted rift to convergence direction, where larger obliquity leads to more intense fault reactivation. These new numerical results are compared to previous analogue and numerical models on the one hand, and natural examples of intracontinental mountain ranges due to tectonic inversion on the other hand. These comparisons demonstrate that both modes of frictional weakening should be taken into account when seeking to understand large-scale rifting and inversion tectonics.

中文翻译：

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断层弱化过程对陆内斜裂谷及随后的构造反转的影响

在许多山带中，变形集中在从早期构造事件继承的机械薄弱断层带。这项工作在具有粘性摩擦流变学的高分辨率 3D 有限差分模型中研究了两种结构弱化模式对裂谷和后期构造反演方向的影响。在第一组实验中，弱化包括随着剪切应变的增加摩擦强度的降低。生成的正断层走向与强加的发散方向正交。这些断层在构造反转期间重新激活并吸收 50% 到 70% 的累积应变。在第二组实验中，摩擦强度是剪切应变率的递减函数。生成的断层与发散方向成斜向，暗示断层倾斜滑动。断层再活化取决于逆裂谷对收敛方向的倾斜度，其中较大的倾斜度导致更强烈的断层再活化。这些新的数值结果一方面与以前的模拟和数值模型进行了比较，另一方面与由于构造反转而导致的大陆内山脉的自然例子进行了比较。这些比较表明，在寻求了解大规模裂谷和反转构造时，应考虑两种摩擦减弱模式。这些新的数值结果一方面与以前的模拟和数值模型进行了比较，另一方面与由于构造反转而导致的大陆内山脉的自然例子进行了比较。这些比较表明，在寻求了解大规模裂谷和反转构造时，应考虑两种摩擦减弱模式。这些新的数值结果一方面与以前的模拟和数值模型进行了比较，另一方面与由于构造反转而导致的大陆内山脉的自然例子进行了比较。这些比较表明，在寻求了解大规模裂谷和反转构造时，应考虑两种摩擦减弱模式。