Faults and fluids in accretionary orogens

增生造山带的断层和流体

• 批准号: RGPIN-2021-03318
• 负责人: Kellett, Dawn
• 金额: $ 2.62万
• 依托单位: Saint Mary's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742494
• 关键词: Faults; fluids; accretionary; orogens

Accretionary orogens (mountain belts) form over tens to hundreds of millions of years as continental and oceanic fragments (terranes) carried on a subducting oceanic plate accrete to a continental plate margin. These multiple collisions produce a complex network of faults (breaks in the Earth's otherwise largely impermeable crust) in the resulting mountain belts, that can be prone to later slip (reactivation). The faults can be efficient pathways for the transfer of rock melt (magma), fluids and heat, which facilitate the flux and concentration of metals. Many ore-deposit settings (e.g. deformation zones, intrusions, basins) occur within or proximal to accretionary orogen fault systems, and host metals, many of which are considered essential for Canada's future society (e.g., Sn, W, Mo, In, Au, Bi, Co, U). The long-term objective of my research program is to document the fault, fluid and thermal records of orogenic upper crust and relate them to geodynamic processes and ore-deposit formation. My recent work has focused on coeval geological, structural and ore-system records in Canada's flanking accretionary orogens, the east coast Canadian Appalachians and the west coast Canadian Cordillera. These studies suggest that ore-relevant processes may have been triggered by perturbations of the Earth's lithospheric mantle (the layer of the Earth that underlies the crust) beneath accreted terranes. My short term objectives (O1-3) are focused around testing that hypothesis in these two orogens. Over the next five years, I will (O1) reconstruct the temperature-time and structural evolution of the upper crust during post-accretionary reactivation of orogenic fault zones using field mapping, analysis of rock microstructures, and petrochronology and thermochronology rock dating methods. I will (O2) determine the fault-fluid-critical metal mineralization relationships during these periods using novel methods including U-Pb dating of slickenfibres and veins, K-Ar dating of fault gouge clay and stable and clumped isotopes. Finally, I will (O3) explore how lithospheric perturbations such as subducted slab break-off and delamination may influence the temperature-time evolution of the upper crust in a post-accretionary orogenic setting via numerical modeling. This work will result in a refined framework for long-term fault behaviour in accretionary orogens, particularly in the contexts of orogen lithosphere evolution and ore-deposit formation. Results will contribute to Canada's ability to search for its critical mineral resources. HQP involved in conducting this research will collaborate with world-class laboratories, industry, and government, and will develop transferable skills in analytical research, data management, common structural geology and ore deposits field and laboratory research methods, and science communication.

增生造山带（山带）的形成需要数千万至数亿年的时间，因为俯冲洋板块携带的大陆和大洋碎片（碎屑）增生到大陆板块边缘。这些多次碰撞在由此产生的山脉带中产生了复杂的断层网络（地球基本上不渗透的地壳中的断裂），这些断层可能倾向于后期滑动（重新激活）。断裂是岩浆、流体和热传递的有效通道，促进了金属的流动和富集。许多矿床环境（如变形带、侵入体、盆地）发生在增生造山带断层系统内或其附近，其中许多被认为对加拿大未来社会至关重要（如，Sn、W、Mo、In、Au、Bi、Co、U）。我的研究计划的长期目标是记录造山上地壳的断层、流体和热记录，并将它们与地球动力学过程和矿床形成联系起来。我最近的工作主要集中在加拿大的侧翼增生造山带，东海岸加拿大阿巴拉契亚山脉和西海岸加拿大科迪勒拉同时代的地质，结构和矿石系统的记录。这些研究表明，与矿石有关的过程可能是由地球岩石圈地幔（地壳之下的地球层）在增生地幔之下的扰动触发的。我的短期目标（O 1 -3）是围绕测试这两个造山带的假设。在今后五年中，我将（O 1）重建温度-时间和结构演化的造山断裂带增生后的再活化过程中使用现场绘图，岩石显微结构分析，岩石年代学和热年代学岩石测年方法。我将利用新的方法，包括光滑纤维和脉的U-Pb年龄，断层泥粘土的K-Ar年龄和稳定的和聚集的同位素，确定这些时期的断层-流体-临界金属成矿关系。最后，我将（O3）探讨如何岩石圈扰动，如俯冲板片断裂和拆沉可能会影响温度-时间演化的上地壳在后增生造山环境通过数值模拟。这项工作将导致在增生造山带，特别是在造山带岩石圈演化和矿床形成的背景下的长期故障行为的一个细化的框架。 调查结果将有助于提高加拿大寻找其重要矿产资源的能力。参与这项研究的HQP将与世界一流的实验室，行业和政府合作，并将在分析研究，数据管理，共同结构地质学和矿床领域和实验室研究方法以及科学交流方面发展可转移的技能。