Faults and fluids in accretionary orogens

随着大陆和海洋碎片(地体)在俯冲的大洋板块上附着到大陆板块边缘，在数千万到数亿年的时间里形成了增生造山带(山脉带)。这些多重碰撞在由此形成的山脉带中产生了一个复杂的断层网络(地球上基本不透水的地壳中的断裂)，这可能容易在以后滑动(重新激活)。断裂是岩石熔体(岩浆)、流体和热量转移的有效途径，有利于金属的流动和聚集。许多矿床环境(如变形带、侵入体、盆地)赋存在增生的造山带断裂系统和宿主金属内或附近，其中许多被认为对加拿大未来的社会是必不可少的(如：锡、钨、钼、铟、金、铋、钴、铀)。我的研究计划的长期目标是记录造山带上地壳的断层、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两侧的增生造山带、东海岸加拿大阿巴拉契亚山脉和西海岸加拿大科迪莱拉地区的同时代地质、构造和成矿系统记录。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(地壳下方的地球层)的扰动触发的。我的短期目标(O1-3)专注于在这两个造山带检验这一假设。在接下来的五年里，我将(O1)利用野外测绘、岩石微结构分析以及岩石年代学和热年代学的岩石测年方法，重建造山断裂带后增生再活动过程中上地壳的温度-时间和结构演化。我将(O2)使用新的方法确定这些时期的断层-流体-临界金属成矿关系，包括滑石纤维和矿脉的U-Pb定年，断层泥粘土的K-Ar定年，以及稳定和成团的同位素。最后，我将通过数值模拟来探索岩石圈扰动(如俯冲板块断裂和剥离)如何影响后增生造山环境中上地壳的温度-时间演化。这项工作将为增生造山带的长期断层行为提供一个完善的框架，特别是在造山带岩石圈演化和矿床形成的背景下。结果将有助于加拿大寻找其关键矿产资源的能力。参与这项研究的总部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、常见构造地质和矿藏野外和实验室研究方法以及科学交流方面发展可移植的技能。

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.