Abstarct Faults vary in structural style, from simple planes to complex systems composed of fault cores and damage zones. Increased fault complexity results from the interaction of mechanical and chemical processes, including fracture growth, shear, and linkage, and mineral dissolution and precipitation. Although water-rock interaction is traditionally associated with fault rock weakening and shear localization, we investigate processes of fault core widening by water-rock interactions that resulted in quartz precipitation. We combine field and petrographic observations with prior mechanical characterization to assess the impact of alteration and cementation on fault architecture at the Dixie Comstock epithermal gold deposit, Nevada, USA. Mineralized portions of the fault contain strong, thick, silicified fault cores and wide, weak damage zones, with evidence for widening of the core through entrainment of damage zone material and repeated cycles of embrittlement, dilation, and cementation. We present a model of fault zone evolution in which the hydrothermal regimes favoring either alteration-weakening or precipitation-strengthening result in distinct fault zone architecture and mechanical and flow properties of fault systems. Alteration-weakening favors localization of the fault into thinner, clay-rich, low permeability fault cores. Precipitation-strengthening promotes thick, strong, and low permeability fault cores, with mineralization-embrittlement enhancing transient permeability following coseismic failure.

中文翻译：

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矿物沉淀作为断层核心生长的机制

抽象断层的构造风格各不相同，从简单的平面到由断层核心和破坏带组成的复杂系统。断层复杂性的增加是机械和化学过程相互作用的结果，包括裂缝生长、剪切和连接，以及矿物溶解和沉淀。尽管水岩相互作用传统上与断层岩弱化和剪切定位有关，但我们研究了导致石英沉淀的水岩相互作用导致断层核扩大的过程。我们将现场和岩相观察与先前的力学表征相结合，以评估蚀变和胶结作用对美国内华达州迪克西康斯托克低温热液金矿床断层结构的影响。断层的矿化部分包含强、厚、硅化的断层核和宽、弱的破坏带，有证据表明通过夹带损伤区材料和脆化、膨胀和胶结的重复循环使岩心变宽。我们提出了一个断层带演化模型，其中有利于蚀变减弱或降水强化的热液状态导致断层带结构和断层系统的机械和流动特性不同。蚀变减弱有利于将断层定位为更薄、富含粘土、低渗透率的断层岩心。降水强化促进了厚、强和低渗透率的断层核，矿化脆化增强了同震破坏后的瞬时渗透率。我们提出了一个断层带演化模型，其中有利于蚀变减弱或降水强化的热液状态导致断层带结构和断层系统的机械和流动特性不同。蚀变减弱有利于将断层定位为更薄、富含粘土、低渗透率的断层岩心。降水强化促进了厚、强和低渗透率的断层核，矿化脆化增强了同震破坏后的瞬时渗透率。我们提出了一个断层带演化模型，其中有利于蚀变减弱或降水强化的热液状态导致断层带结构和断层系统的机械和流动特性不同。蚀变减弱有利于将断层定位为更薄、富含粘土、低渗透率的断层岩心。降水强化促进了厚、强和低渗透率的断层核，矿化脆化增强了同震破坏后的瞬时渗透率。