Within a low-grade ductile shear zone, we investigated exceptionally well exposed brittle faults, which accumulated antithetic slip and rotated into the shearing direction. The foliation planes of the mylonitic host rock intersect the faults approximately at their centre and exhibit ductile reverse drag. Three types of brittle faults can be distinguished: (i) Faults developing on pre-existing K-feldspar/mica veins that are oblique to the shear direction. These faults have triclinic flanking structures. (ii) Wing cracks opening as mode I fractures at the tips of the triclinic flanking structures, perpendicular to the shear direction. These cracks are reactivated as faults with antithetic shear, extend from the parent K-feldspar/mica veins and form a complex linked flanking structure system. (iii) Joints forming perpendicular to the shearing direction are deformed to form monoclinic flanking structures. Triclinic and monoclinic flanking structures record elliptical displacement–distance profiles with steep displacement gradients at the fault tips by ductile flow in the host rocks, resulting in reverse drag of the foliation planes. These structures record one of the greatest maximum displacement/length ratios reported from natural fault structures. These exceptionally high ratios can be explained by localized antithetic displacement along brittle slip surfaces, which did not propagate during their rotation during surrounding ductile flow.

中文翻译：

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韧性剪切脆性断层位移-长度标度

在低等级韧性剪切带内，我们研究了异常暴露的脆性断层，这些断层积累了反向滑动并旋转到剪切方向。糜棱质主岩的叶理面大约在断层的中心与断层相交，并表现出韧性反向阻力。可以区分三种类型的脆性断层： (i) 在与剪切方向倾斜的预先存在的钾长石/云母脉上发育的断层。这些断层具有三斜侧翼结构。（ii）翼裂纹在三斜侧翼结构的尖端作为 I 型断裂打开，垂直于剪切方向。这些裂缝被重新激活为具有对立剪切的断层，从母钾长石/云母脉延伸，形成复杂的连接侧翼结构系统。(iii) 垂直于剪切方向形成的接头变形以形成单斜侧翼结构。三斜和单斜侧翼结构记录了椭圆位移-距离剖面，断层尖端的位移梯度由主岩中的延展性流动引起的陡峭位移梯度，导致叶理平面的反向拖动。这些结构记录了从天然断层结构报告的最大最大位移/长度比之一。这些异常高的比率可以通过沿脆性滑动表面的局部对立位移来解释，这些位移在周围延展性流动期间的旋转过程中没有传播。三斜和单斜侧翼结构记录了椭圆位移-距离剖面，断层尖端的位移梯度由主岩中的延展性流动引起的陡峭位移梯度，导致叶理平面的反向拖动。这些结构记录了从天然断层结构报告的最大位移/长度比之一。这些异常高的比率可以通过沿脆性滑动表面的局部对立位移来解释，这些位移在周围延展性流动期间的旋转过程中没有传播。三斜和单斜侧翼结构记录了椭圆位移-距离剖面，断层尖端的位移梯度由主岩中的延展性流动引起的陡峭位移梯度，导致叶理平面的反向拖动。这些结构记录了从天然断层结构报告的最大位移/长度比之一。这些异常高的比率可以通过沿脆性滑动表面的局部对立位移来解释，这些位移在周围延展性流动期间的旋转过程中没有传播。