Fluid percolation conditions in fault zones are often inferred in geologic studies, but the porosity and permeability of rocks are rarely tested during mineral exploration drilling. Routine permeability and porosity tests on drill core, with adequate detection limits and accuracy, can provide new insights into present- and paleo-fluid flow processes and deposit formation in sedimentary basins and permeable fault zones (e.g. uranium deposits, sub-sea hydrothermal ore deposits). In this study, geological and hydrogeological observations were combined with results of over a thousand permeability tests at spot-on unconfined drill core, extracted along transects through the Gryphon U deposit and fault zone, using a pressure-decay N₂ gas probe with adequate seal to the rock surface. The new seal method allowed a wide range of permeability determinations under field conditions (over 5 × 10^–20 to 10^–12 m²). The penetrative macropore networks were observed directly from gas discharge patterns on drill core surfaces. For the tested crystalline basement rocks below the Athabasca Basin, we inferred that the matrix permeability and porosity distribution appear to be preserved since the late Paleoproterozoic/Mesoproterozoic, under the cover of a sedimentary basin. The permeability values at the present time, and the patterns of rock alteration and deformation, offer insights to paleo-hydrogeological conditions. The gneissic and pegmatitic host rocks have relatively low permeability at present time, except fractured (discrete flow channels) and/or intensely altered to a more porous rock. The alternating zones of silicification and desilicification appear to pre-date the intense argillic alteration, and it may have been a result of earlier hydrothermal activity. The Gryphon U deposit occurs in elongated narrow “lenses” along several fault strands of a fault zone (below the unconformity surface and within basement rocks). U-ore is a cementing mineral in fault-related fractures and fault rocks, but remnant flow channels in fractures in U-ore are still preserved. The most permeable and porous fault rocks are coarse gouges (~ 40% porosity, ~ 10^–15 m² permeability) with approximately three orders of magnitude higher rock matrix permeability than the gneissic host rocks. Such fault rocks locally contain carbonaceous matter, and similar fault rocks may have been preferentially mineralized by U to form the U ore lenses, but the role of brittle-ductile and ductile fault and shear zone rocks in U mineralization is not yet clear at Gryphon. Our review of U–Pb uraninite ages at Gryphon suggests a protracted faulting and U-mineralization history. In response to numerous episodic events of brittle deformation and hydrothermal alteration, the permeability and porosity of the host rocks and U-ores have evolved, as observed by multiple cross-cutting reaction fronts. We inferred from the test results and the alteration halo at the U deposit, affecting a wide part of the fault zone, that the permeability and porosity increased by the downward ingress of U-rich acidic basinal brine that percolated into the basement-hosted (rooted) shear/fault zone and nearby crystalline basement rocks. However, the younger prominent U roll/redox-fronts caused local-scale reduction in porosity and permeability by hematite cementation.

在地质学研究中通常可以推断断层带的渗流条件，但是在矿物勘探钻井过程中很少测试岩石的孔隙率和渗透率。在钻芯上进行常规渗透率和孔隙度测试，具有足够的检测限和准确度，可以提供对当前和古流体流动过程以及沉积盆地和渗透性断层带中的沉积物形成的新见解（例如铀矿床，海底热液矿床） ）。在这项研究中，将地质和水文地质观测结果与点上无限制钻头岩心的一千多个渗透性测试结果相结合，并使用压力衰减N ₂沿横断面通过Gryphon U矿床和断层带提取。气体探头，对岩石表面具有足够的密封性。新的密封方法可在野外条件下（5×10 ^–20至10 ^–12 m ²范围内）进行多种渗透率测定）。穿透性大孔网络直接从钻芯表面的气体排放模式观察到。对于阿萨巴斯卡盆地下方的经测试的晶体基底岩石，我们推断，自晚古元古代/中元古代以来，在沉积盆地的掩盖下，基质渗透率和孔隙度分布似乎得以保留。目前的渗透率值，以及岩石蚀变和变形的模式，为了解古水文地质条件提供了见识。除断裂（离散的流体通道）和/或强烈地改变为孔隙度较大的岩石外，片麻岩和古卷岩主岩目前的渗透率较低。硅化和反硅化的交替区域似乎早于强烈的泥质蚀变，可能是早期热液活动的结果。狮ry U沉积物沿着断层带的几条断层带（在不整合面以下和基底岩石内）出现在细长的“透镜”中。U型矿石是与断层有关的裂缝和断层岩石中的胶结矿物，但仍保留了U型矿石裂缝中的残余流道。渗透性和多孔性最强的断层岩石是粗凿（〜40％孔隙度，〜10^–15 m ²渗透率）比片麻岩主岩高出大约三个数量级。这种断层岩局部含有碳质物质，类似的断层岩可能已经被U优先矿化以形成U矿石晶状体，但是在Gryphon，脆韧性延性断层和剪切带岩石在U矿化中的作用尚不清楚。我们对Gryphon的U–Pb铀矿年龄的回顾表明，长期的断层和U矿化历史。响应多个脆性变形和热液蚀变的事件，从多个横切反应前沿观察到，宿主岩和U型矿石的渗透性和孔隙度已经演化。我们从测试结果和U矿床的晕圈变化中推断出，该断层影响了整个断层带，渗透率和孔隙度的增加是由于富铀的酸性盆地盐水向下渗入，渗入了基底层（根状）剪切/断层带和附近的结晶基底岩中。但是，较年轻的显着的U辊/氧化还原锋通过赤铁矿胶结作用导致孔隙度和渗透率局部降低。