The significance of the silicification zones for the formation of unconformity-related uranium deposits in the Athabasca basin, Saskatchewan

由于未发现的矿化深度不断增加，在阿萨巴斯卡盆地发现新的铀矿床变得越来越困难，这就需要更好地了解它们的形成条件和环境。这些矿床的一个从未被系统研究过的特征是，在阿萨巴斯卡组砂岩矿床的正上方存在着硅化带，或称“盖层”。该项目的目的是确定这种硅化作用在与不整合面有关的铀矿床的形成中所起的作用（如果有的话），并确定它如何影响勘探工作。为了实现这些目标，本项目将重点关注两个主要主题：(1)建立硅化带的三维空间范围。这将使用AREVA和公共领域的钻井日志来完成。两种主要的可能性是：硅化带严格来说是局部的，位于矿床的正上方，或者它发生在区域范围内，与矿床没有直接关系。(2)建立了硅化带形成的物理化学条件以及硅化带与矿床形成的时间关系。这将主要使用矿物学和地球化学方法，特别是石英过度生长和石英填充孔隙空间的稳定同位素，使用二次离子质谱（SIMS）和流体包裹体来实现。预计该项目的研究结果将有助于在空间和时间上将硅化带与蚀变、脱硅化、构造背景、岩石学以及最重要的铀沉积的风格和强度联系起来。研究区主要为Martin Lake U远景区，该区具有发育良好的硅化带，并可能延伸至McArthur河2区和Centennial矿床。一旦确定了硅化作用对铀沉积的重要性，将与阿海珐地质学家一道，就提高勘探效率的问题对结果进行评估。

It is becoming increasingly difficult to discover new uranium deposits in the Athabasca Basin due to the increasing depth of undiscovered mineralization, which necessitates an even better understanding of their formation conditions and setting. One feature of these deposits that has never been systematically studied is the silicification zone, or "cap", present immediately above the deposits in the Athabasca Group sandstones. The purpose of this project is to ascertain what the role, if any, this silicification played in the formation of the unconformity-related uranium deposits and to establish how it can affect exploration efforts. To achieve these goals, the project will focus on two main topics: (1) Establishing the three-dimensional spatial extent of the silicification zone. This will be done using drill logs available at AREVA and in the public domain. Two main possibilities are: the silicification zone is strictly local and situated directly above a deposit, or it occurs on a regional scale and is not directly related to a deposit. (2) Establishing the physical and chemical conditions of formation and the temporal relationship between the silicification zone and the deposits' formation. This will be achieved using mostly mineralogical and geochemical methods, in particular stable isotopes on quartz overgrowths and quartz filling pore space, using Secondary Ion Mass Spectrometry (SIMS), and fluid inclusions. It is anticipated that the findings of this project will help relate, spatially and temporally, the silicification zone with style and intensity of alteration, desilicification, structural setting, petrology, and most importantly, uranium deposition. The area studied will primarily be the Martin Lake U prospect, which exhibits well-developed silicification zones, with possible extension to the McArthur River Zone 2 and Centennial deposits. Once the significance of the silicification for uranium deposition has been established, the results will be assessed, in conjunction with AREVA geologists, in terms of increased exploration efficiency.