Detrital Zircon geochronology applied to Cordilleran Tectonics

碎屑锆石地质年代学应用于科迪勒拉构造

• 批准号: RGPIN-2017-04848
• 负责人: Guest, Bernard
• 金额: $ 0.53万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633784
• 关键词: Detrital; Zircon; geochronology; applied; Cordilleran

This 5 year research program is part of a long-term effort to unravel the complex tectonic history of the mountains of western North America (N.A. Cordillera). The N.A. Cordillera is one of the most intensively studied mountain belts on earth and a key natural laboratory for studying feedback relationships between the deep mantle, lithosphere, hydrosphere and atmosphere. Although much is known about the evolution of the N.A. Cordillera, and many workers are focused on its genesis, there are still important fundamental questions and contradictions that remain unresolved or poorly explained. Resolving these, is important to the international earth science community because of North America’s important role as a natural laboratory for research into continental plate tectonics. If we do not understand the best-studied continent on earth then how do we extrapolate to other parts of the world that are less well understood? The most important problems remaining in North American tectonics: 1. The Baja - BC controversy, 2. Terrane processes: How and where are terranes made, transported and accreted? 3. Orogenic and magmatic cyclicity: Why do magmatic arcs shut down and flare up and how is this related to terrane processes 4. Subduction initiation: How does subduction initiate and propagate, what are the rates, and how does this process relate to the terrane processes? These unresolved questions are all central to our understanding of the last half a billion years of western North America’s tectonic evolution. In addition, the answers to theses questions impacts how scientists view continental tectonics in general, at the global scale. A key outcome of the next five years of research by my group is the resolution of the The Baja-BC controversy, which is centered on paleomagnetic data and basic geologic observations. The paleomagnetic data require large-scale south to north transport of terranes whereas the geologic observations are seen as precluding such lateral displacements. We are reconciling the geological and paleomagnetic data via the use of high-resolution detrital zircon geochronology as an independent constraint on the lateral movement of crustal fragments. Success in this area will change the tectonic history of western North America and contribute to resolving questions 2 and 3 above. Another important outcome of this program will be to establish Haida Gwaii as North America’s natural laboratory for subduction initiation. Our research program will provide the first data that records the uplift and erosion associated with the initiation of Pacific plate subduction beneath western North America. We will know when subduction initiated, propagation rate and what the effects on the overriding plate are. This research program is important to Canada because it raises Canada’s profile as a transformative agent in the earth sciences while training Canadian HQP who will transfer knowledge and skills.

这项为期5年的研究计划是一项长期努力的一部分，旨在揭开北美西部山脉复杂的构造历史。安第斯山脉）。这个疏证科迪勒拉山脉是地球上研究最集中的山脉带之一，也是研究深部地幔、岩石圈、水圈和大气之间反馈关系的重要天然实验室。尽管我们对N.A.的演变了解很多。尽管许多工作者都在关注它的起源，但仍然有一些重要的基本问题和矛盾尚未解决或解释不清。解决这些问题对国际地球科学界很重要，因为北美是研究大陆板块构造的天然实验室。如果我们不了解地球上研究得最好的大陆，那么我们如何推断世界上其他不太了解的地方？北美大地构造学中最重要的问题：1。巴哈-公元前争议，2。地体过程：地体是如何和在哪里形成、运输和增生的？3.造山和岩浆旋回性：为什么岩浆弧关闭和爆发，这是如何与火山喷发过程4。俯冲起始：俯冲是如何起始和传播的，速率是多少，这个过程与俯冲过程有什么关系？这些未解决的问题都是我们理解北美西部过去5亿年构造演化的核心。此外，这些问题的答案影响了科学家如何看待全球范围内的大陆构造。我的团队在接下来五年的研究中的一个关键成果是解决了Baja-BC争议，该争议的核心是古地磁数据和基础地质观测。古地磁数据需要大规模的南向北运输的岩石，而地质观测被视为排除这种横向位移。我们正在通过使用高分辨率碎屑锆石地质年代学作为对地壳碎片横向运动的独立约束来协调地质和古地磁数据。这一地区的成功将改变北美西部的构造历史，并有助于解决上述问题2和3。该计划的另一个重要成果将是将海达冰川建立为北美俯冲起始的天然实验室。我们的研究计划将提供第一个数据，记录与太平洋板块俯冲在北美西部之下的开始有关的隆起和侵蚀。我们将知道俯冲何时开始，传播速度以及对覆盖板块的影响。该研究计划对加拿大很重要，因为它提高了加拿大作为地球科学变革推动者的形象，同时培训了将传授知识和技能的加拿大HQP。