On the genesis of Rabbit Lake and other unconformity-type uranium deposits in northern Saskatchewan, Canada
On the genesis of Rabbit Lake and other unconformity-type uranium deposits in northern Saskatchewan, Canada
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加拿大萨斯喀彻温省北部 Rabbit Lake 及其他不整合型铀矿床的成因
DOI：
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发表时间：
1978
期刊：
影响因子：
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通讯作者：
T. Sibbald
中科院分区：
文献类型：
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作者：
J. Hoeve;T. Sibbald
描述了兔子湖存款的地质学、矿物学和地球化学，该存款位于Aphebian/太古代变质基底和Helikian Athabasca组的上覆未变质砂岩之间的不整合面附近。在存款的几个阶段的蚀变，矿化，再活化，再沉积，间歇角砾岩分离，被确认。蚀变主要是绿泥石化，伴有一些电气石化、硅化和硅化，伴随着H2 O、MgO（可能还有B）的引入，以及SiO2、Na 2 O、K2 O、CaO和Sigma Fe 2 O3的沥滤。该存款矿物学特征复杂，以U、Ni、Co、Cu、Pb、Zn、Fe、Mn、As、S、Se等多种元素为代表。和成矿期次表明了氧化还原反应在形成该存款中的重要性。通过与阿萨巴斯卡盆地其他不整合型矿床的比较，提出了成岩-热液成矿模式。该模型调用了阿萨巴斯卡地层中氧化成岩溶液的渗透，在地热梯度的影响下被加热，最终在盆地底部达到约200摄氏度的温度。加热的成岩溶液与石墨质基底岩石反应生成甲烷，甲烷充当移动的还原剂。成矿作用是含甲烷还原性溶液和氧化性成岩溶液相互作用的结果。后者将矿石成分带到还原地点，从而沉积，矿石成分可能是在层内风化和氧化过程中通过淋滤从阿萨巴斯卡组中提取的。因此，从广义上讲，萨斯喀彻温省不整合型矿床的形成过程可能与砂岩型卷状前缘矿床的形成过程相似。
A description is given of the geology, mineralogy, and geochemistry of the Rabbit Lake deposit, located in the immediate vicinity of the unconformity between an Aphebian/Archean metamorphosed basement and overlying unmetamorphosed sandstones of the Helikian Athabasca Formation. In the deposit several stages of alteration, mineralization, remobilization, and redeposition, separated by intermittent brecciation, are recognized. The alterations, predominantly chloritization with some tourmalinization, silicification, and dolomitization, are accompanied by introduction of H 2 O, MgO, probably also B, and by leaching of SiO 2 , Na 2 O, K 2 O, CaO, and Sigma Fe 2 O 3 . The deposit is of complex mineralogy and typified by a broad suite of elements including U, Ni, Co, Cu, Pb, Zn, Fe, Mn, As, S, and Se.In the history of the deposit conditions have repeatedly oscillated between oxidizing and reducing, and the temporal relationships between oxidizing, reducing, and mineralizing episodes indicate the importance of redox reactions in shaping the deposit.After comparison with other unconformity-type deposits in the Athabasca Basin, a diagenetic-hydrothermal metallogenetic model is presented. The model invokes percolation of oxidizing diagenetic solutions in the Athabasca Formation, which, being heated under the influence of the geothermal gradient, eventually attained temperatures of around 200 degrees C at the floor of the basin. Reaction of the heated diagenetic solutions with graphitic basement rocks generated methane, which acted as a mobile reductant. Mineralization resulted from interaction of flows of the methane-bearing reducing solutions and the oxidizing diagenetic solutions. The latter have carried the ore constituents to the site of reduction and, hence, of deposition.The ore constituents may have been derived from the Athabasca Formation by leaching during a process of intrastratal weathering and oxidation. Thus, in a broad sense, processes governing the formation of the Saskatchewan unconformity-type deposits may have been similar to those that give rise to sandstone-type roll-front deposits.