Iron oxides/hydroxides from the Athabasca Basin (Saskatchewan) and Kiggavik Camp (Nunavut) unconformity-related deposits as indictors for uranium mineralization

本研究的目的是表征与不整合相关的铀环境中存在的不同类型的铁氧化物，并识别与铀矿化密切相关的铁氧化物。铁是造岩矿物结构中的一种丰富的化学成分。在富铀环境中，Fe和U氧化物共沉淀，并且/或者U将被吸附在Fe氧化物表面，然后逐渐被纳入Fe氧化物结构中，从而导致U的沉积。Fe氧化物在很大的氧逸度范围内都是稳定的。这种稳定性使它们能够保存从地层环境中继承的微量元素组成。不同地质因素（如冰川和/或河流）对风化和侵蚀寄主岩石中富铀铁氧化物的分散可以在铀矿床周围形成特征分散晕。探测这些光晕可以指导勘探地质学家找到未发现的铀矿床。由于铁氧化物不局限于特定的矿床类型或岩性，为了将其作为找铀的指示物，本研究提出在富铀环境中对铁氧化物进行表征，然后利用与铀成矿密切相关的物理、化学和同位素特征对松散沉积物中铁氧化物颗粒的来源进行分类。为了建立利用铁氧化物勘探铀矿床的标准，本研究建议：1)从加拿大已知的代表性铀矿床（如阿萨巴斯卡盆地的雪茄湖）、其基岩和这些矿床周围的贫瘠岩性中收集样品作为背景；2)利用最先进的分析技术，如扫描电子显微镜（SEM）、矿物解解分析（MLA）和激光烧蚀电感耦合等离子体质谱（LA-ICP-MS），表征所收集样品中铁氧化物的颜色、粒度、质地、矿物组合、微量元素组成和Fe和O同位素地球化学；3)数据整合，利用多元统计技术对数据进行分析，构建识别U矿化指示铁氧化物的判别模型；4)建立利用氧化铁找铀标准。

The goal of this research is to characterize different types of Fe oxides present in unconformity-related U settings, and identify those closely associated with U mineralization. Iron is an abundant chemical component in the structure of rock-forming minerals. In U-rich settings, Fe and U oxides co-precipitate and/or U will be adsorbed on the surface of Fe oxides, and then will gradually be incorporated into the Fe Oxides structure that results in deposition of U. Fe oxides are stable over a wide range of oxygen fugacity. This stability enables them to preserve their trace element compositions inherited from formation environments. Dispersion of U-rich Fe oxides from weathered and eroded host rocks by different geologic agents such as glaciers and/or rivers can form a characteristics dispersal halos around U deposits. Detecting these halos can guide exploration geologists to undiscovered U deposits. As Fe oxides are not limited to a specific mineral deposit type or lithology, to use them as indicators for U exploration, this research proposes to characterize Fe oxides in targeted U-rich settings, and then use physical, chemical, and isotopic signatures of those closely associated with U mineralization for classification of the source of Fe oxide grains in unconsolidated sediments. To establish criteria for using Fe oxides in exploration for U deposits, this study proposes 1) collecting samples from a representative number of known Canadian U deposits such as Cigar Lake in the Athabasca Basin, their bedrocks, and barren lithologies surrounding these deposits as background; 2) characterizing color, grain size, textures, mineral associations, trace element compositions, and Fe and O isotope geochemistry of Fe oxides in collected samples using state of the art analytical techniques such as scanning electron microscopy (SEM), mineral liberation analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS); 3) data integration, and data analysis using multivariate statistical techniques to construct discrimination models identifying Fe oxides indicating U mineralization; and 4) establish criteria for using Fe oxides in exploration for U deposits.