Reactivation mechanisms and related-porosity enhancement of shear zones in the context of basement-hosted uranium mineralization: case of the Spitfire discovery in the Patterson Lake corridor, Canada

IF 1 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Geochemistry-Exploration Environment Analysis Pub Date : 2021-07-28 DOI:10.1144/geochem2020-082

M. Abdelrazek, A. Benedicto, Olivier Gerbeaud, P. Ledru

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引用次数: 4

Abstract

Uranium mineralization in the Patterson Lake corridor (southwestern Churchill province, Canada) is hosted in the metamorphosed Paleoproterozoic basement covered to the north by the flat-lying sandstone formations of the Athabasca Basin. The mineralization is exclusively contained within inherited ductile structures that were reactivated under a brittle regime. Petrographic and micro-structural studies of drill core samples from the Spitfire discovery (Hook Lake project) reveal the linkages between structural evolution of the basement, alteration and mineralization. During basement exhumation, localization of non-coaxial deformation led to the formation of a large anastomosing shear zone system made of mylonitic rocks. Strain localization associated with fluid circulation induced strong mineralogical and rheological changes, forming discontinuities in mechanical anisotropy. During and post-deposition of the Athabasca Basin after 1.80 Ga, these zones of anisotropy localized brittle reactivation, expressed by a network of micro-fractures later amplified by dissolution processes which enhanced porosity later filled with phyllosilicates and uranium oxides. Cross-cutting relationships between alteration minerals and structures indicate that fluid circulation was active after the basement exhumation. Uranium-bearing fluids moved through the network of micro-fractures. As shown for the Spitfire prospect, fertile structures in the basement below the Athabasca Basin have a combined poly-phase structural and alteration history during which development of ductile shear zones followed by brittle reactivation and dissolution processes led to the formation of superimposed shear and damaged zones in which uranium orebodies are located. Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways

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基底型铀矿化背景下剪切带的活化机制及相关孔隙度增强:以加拿大Patterson Lake走廊Spitfire油田发现为例

帕特森湖走廊（加拿大丘吉尔省西南部）的铀矿化位于变质的古元古代基底中，该基底北部被阿萨巴斯卡盆地平坦的砂岩地层覆盖。矿化仅包含在继承的韧性结构中，这些结构在脆性状态下被重新激活。喷火发现（胡克湖项目）岩芯样本的岩石学和微观结构研究揭示了基底结构演化、蚀变和矿化之间的联系。在基底剥露过程中，非共轴变形的局部化导致了由糜棱岩组成的大型网状剪切带系统的形成。与流体循环相关的应变局部化引起了强烈的矿物学和流变学变化，形成了机械各向异性的不连续性。1.80年后阿萨巴斯卡盆地沉积期间和沉积后 Ga，这些各向异性区域局部脆性再活化，表现为微裂缝网络，后来通过溶解过程放大，增强了后来填充有层状硅酸盐和铀氧化物的孔隙率。蚀变矿物与构造之间的交叉关系表明，基底剥露后流体循环活跃。含铀流体在微裂缝网络中流动。如喷火式勘探所示，阿萨巴斯卡盆地下方基底的肥沃构造具有多相结构和蚀变历史，在此期间，韧性剪切带的发育以及脆性再活化和溶解过程导致铀矿体所在的叠加剪切带和损伤带的形成。主题收藏：本文是铀流体通道收藏的一部分，可在以下网站获取：https://www.lyellcollection.org/cc/uranium-fluid-pathways

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来源期刊

Geochemistry-Exploration Environment Analysis 地学-地球化学与地球物理

CiteScore

3.60

自引率

16.70%

发文量

审稿时长

1 months

期刊介绍： Geochemistry: Exploration, Environment, Analysis (GEEA) is a co-owned journal of the Geological Society of London and the Association of Applied Geochemists (AAG). GEEA focuses on mineral exploration using geochemistry; related fields also covered include geoanalysis, the development of methods and techniques used to analyse geochemical materials such as rocks, soils, sediments, waters and vegetation, and environmental issues associated with mining and source apportionment. GEEA is well-known for its thematic sets on hot topics and regularly publishes papers from the biennial International Applied Geochemistry Symposium (IAGS). Papers that seek to integrate geological, geochemical and geophysical methods of exploration are particularly welcome, as are those that concern geochemical mapping and those that comprise case histories. Given the many links between exploration and environmental geochemistry, the journal encourages the exchange of concepts and data; in particular, to differentiate various sources of elements. GEEA publishes research articles; discussion papers; book reviews; editorial content and thematic sets.