Fault architecture and fracture network evolution (and resulting bulk hydraulic properties) are highly dependent on the mechanical properties of the rocks at the time the structures developed. This paper investigates the role of mechanical layering and pre-existing structures on the evolution of strike–slip faults and fracture networks. Detailed mapping of exceptionally well exposed fluvial–deltaic lithologies at Spireslack Surface Coal Mine, Scotland, reveals two phases of faulting with an initial sinistral and later dextral sense of shear with ongoing pre-faulting, syn-faulting, and post-faulting joint sets. We find fault zone internal structure depends on whether the fault is self-juxtaposing or cuts multiple lithologies, the presence of shale layers that promote bed-rotation and fault-core lens formation, and the orientation of joints and coal cleats at the time of faulting. During ongoing deformation, cementation of fractures is concentrated where the fracture network is most connected. This leads to the counter-intuitive result that the highest-fracture-density part of the network often has the lowest open fracture connectivity. To evaluate the final bulk hydraulic properties of a deformed rock mass, it is crucial to appreciate the relative timing of deformation events, concurrent or subsequent cementation, and the interlinked effects on overall network connectivity.

中文翻译：

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机械演化的机械分层岩体中断层和裂隙网络的生长：以苏格兰Spireslack露天煤矿为例

断层构造和裂隙网络演化（以及由此产生的整体水力特性）在很大程度上取决于结构发展时岩石的机械特性。本文研究了机械分层和既有结构在走滑断层和断裂网络演化中的作用。对苏格兰Spireslack露天煤矿异常暴露的河流-三角岩性进行了详细的测绘，揭示了断层的两个阶段，即初始的左旋断层和后来的右旋剪切感，以及持续的断层前，同断层和断层后联合组。我们发现断层带的内部结构取决于断层是自并置还是切割多种岩性，是否存在促进床层旋转和断层核心透镜形成的页岩层，断裂时节理和煤理岩的方向。在正在进行的变形过程中，裂缝的胶结作用集中在裂缝网络最紧密的地方。这导致与直觉相反的结果，即网络的最高裂缝密度部分通常具有最低的开放裂缝连通性。为了评估变形岩体的最终整体水力特性，至关重要的是要了解变形事件，同时发生或随后发生的胶结作用的相对时机，以及对整体网络连通性的相互影响。这导致与直觉相反的结果，即网络的最高裂缝密度部分通常具有最低的开放裂缝连通性。为了评估变形岩体的最终整体水力特性，至关重要的是要了解变形事件，同时发生或随后发生的胶结作用的相对时机，以及对整体网络连通性的相互影响。这导致与直觉相反的结果，即网络的最高裂缝密度部分通常具有最低的开放裂缝连通性。为了评估变形岩体的最终整体水力特性，至关重要的是要了解变形事件，同时发生或随后发生的胶结作用的相对时机，以及对整体网络连通性的相互影响。