Magmatism, sedimentation and the uranium mineral system in the Paleoproterozoic core of Canada

加拿大古元古代核心的岩浆作用、沉积作用和铀矿物系统

• 批准号: RGPIN-2017-04427
• 负责人: Ansdell, Kevin
• 金额: $ 2.84万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711035
• 关键词: Magmatism; sedimentation; uranium; mineral; system

The Precambrian Shield makes up a significant portion of the crust in Canada, and many of the Archean (>2.5 billion years old) components were joined together about 1.8 billion years ago during a cataclysmic collision, called the Trans-Hudson orogeny, that is preserved in a linear belt that extends from Saskatchewan to Baffin Island. The collision, which was related to the motion of lithospheric plates, formed a mountain range that was probably of the same scale as the present-day Himalayas. In the lead up to the collision, there were complex interactions between different crustal elements which generated magmas, sediments, and structures. The aim of part of this research, which involves mapping and sampling in the field by a number of graduate and undergraduate students, and the application of modern analytical techniques for the analysis of trace elements and isotopes is to unravel the interaction between different crustal blocks just prior to the major collision 1.8 billion years ago, with a focus on the well-exposed rocks in northern Saskatchewan and Manitoba. It will be necessary to define the composition of different parts of the crust and mantle in order to understand how they interacted. In addition the Precambrian rocks in central Canada host world-class hydrothermal deposits of copper, zinc, gold, uranium, and rare earth elements, and their formation is intimately related to the evolution of the mountain belt. The research will focus on the youngest igneous rocks (about 1.85 to 1.82 billion years old) that formed during this mountain-building event, partly because this represents the most complex part of this event, and will provide a chemical and isotopic “fingerprint” of the parts of the crust and mantle that might have been involved in the formation of these rocks. In addition, the sedimentary rocks that formed in basins as continental collisions were occurring preserve zircons as detrital minerals, and they record the age and character of the source regions for these sediments. The mountain belt was then eroded, and sediments were deposited in the uranium-rich Athabasca Basin, under which is a zone of alteration that may represent an ancient weathered profile. This will be examined to determine its origin, and whether this might be an important source of metals, including uranium, for the younger mineral deposits. Direct outcomes of all this work will be student theses and journal papers, and well-trained new geoscientists to work in academia, government or the Canadian minerals industry.

前寒武纪地盾构成了加拿大地壳的重要部分，许多太古代（> 25亿年）的组成部分在大约18亿年前的一次灾难性碰撞中结合在一起，称为跨哈德逊造山带，该造山带保存在从萨斯喀彻温省延伸到巴芬岛的线性带中。这次碰撞与岩石圈板块的运动有关，形成了一个可能与今天的喜马拉雅山脉规模相同的山脉。在碰撞之前，不同的地壳元素之间发生了复杂的相互作用，产生了岩浆、沉积物和构造。这项研究的一部分涉及由一些研究生和本科生在实地进行绘图和取样，并应用现代分析技术分析微量元素和同位素，其目的是揭示18亿年前发生重大碰撞之前不同地壳块体之间的相互作用，重点是北方萨斯喀彻温省和马尼托巴省暴露良好的岩石。有必要确定地壳和地幔不同部分的组成，以便了解它们如何相互作用。此外，加拿大中部的前寒武纪岩石还蕴藏着世界级的铜、锌、金、铀和稀土元素热液矿床，它们的形成与山脉带的演化密切相关。 这项研究将集中在最年轻的火成岩（约18.5至18.2亿年），形成于这一造山事件中，部分原因是这代表了这一事件中最复杂的部分，并将提供可能参与这些岩石形成的地壳和地幔部分的化学和同位素“指纹”。此外，在大陆碰撞发生时在盆地中形成的沉积岩保存了锆石作为碎屑矿物，它们记录了这些沉积物源区的年龄和特征。山脉带随后被侵蚀，沉积物沉积在富含铀的阿萨巴斯卡盆地，在该盆地之下是一个可能代表古代风化剖面的蚀变带。将对此进行研究，以确定其来源，以及这是否可能是较年轻矿床的金属（包括铀）的重要来源。所有这些工作的直接成果将是学生论文和期刊论文，以及训练有素的新地球科学家在学术界，政府或加拿大矿业工作。