The Cigar Lake uranium deposit in the Athabasca Basin is the world’s second largest high-grade unconformity-related uranium deposit. Its distinct geological architecture includes heterogeneous basement lithologies, a local basement high and sub-vertical faults. The sub-vertical faults are classified further into two sub-types: faults that are restricted to the basement, termed ‘basement faults’, and faults that are distinctly related to post-Athabasca fault reactivation, in that they extend upward into the sandstone, termed ‘extended basement faults’. This study aims to evaluate the effects of the aforementioned geological factors on the fluid flow patterns under two different driving forces, buoyancy due to variation of fluid density or ‘thermal convection’ and deformation or a combination of them, and to determine the most probable fluid flow scenarios for the formation of the deposit. The numerical results show that fluid flow is strongly affected by the two types of faults. While the basement faults represent fluid paths with complex fluid flow patterns, depending on the driving forces, providing favourable physical conditions for different chemical processes, such as fluid-fluid and fluid-rock interactions, the extended basement faults enhance the permeability of an E-W corridor within the sandstone and significantly strengthen the overall upwelling flow above the basement faults, promoting sandstone-hosted mineralization. The numerical results also suggest that the main deposit likely formed via fluid convection during tectonically quiet periods, although faulting played a critical role in increasing permeability, in turn, enhancing thermal convection.

中文翻译：

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来自加拿大阿萨巴斯卡盆地东部世界级雪茄湖铀矿床的流体流动机制和地质因素的 2-D 和 3-D 数值模拟的新见解

阿萨巴斯卡盆地的雪茄湖铀矿床是世界第二大高品位不整合面铀矿床。其独特的地质结构包括不均匀的基底岩性、局部基底高和亚垂直断层。次垂直断层进一步分为两个子类型：局限于基底的断层，称为“基底断层”，以及与后阿萨巴斯卡断层再激活明显相关的断层，因为它们向上延伸到砂岩中，称为“扩展地下室断层”。本研究旨在评估上述地质因素对两种不同驱动力下流体流动模式的影响，浮力是由于流体密度变化或“热对流”和变形或它们的组合，并确定最可能形成矿床的流体流动情况。数值结果表明流体流动受到两种类型的断层的强烈影响。虽然基底断层代表具有复杂流体流动模式的流体路径，但取决于驱动力，为不同的化学过程（如流体-流体和流体-岩石相互作用）提供了有利的物理条件，而延伸的基底断层增强了 EW 走廊的渗透率并显着加强基底断层上方的整体上升流，促进砂岩成矿。数值结果还表明，主要矿床可能在构造安静时期通过流体对流形成，尽管断层作用在增加渗透率方面发挥了关键作用，反过来，