Structural and magmatic evolution of rifts and passive margins: implications for continental breakup and natural resources in Canada

裂谷和被动边缘的构造和岩浆演化：对加拿大大陆破裂和自然资源的影响

• 批准号: RGPIN-2021-04011
• 负责人: Peace, Alexander
• 金额: $ 2.55万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=754860
• 关键词: Structural; magmatic; evolution; rifts; passive

The solid outermost layer of the Earth, known as the lithosphere, is classified as either continental or oceanic depending on its origin and composition. Continental lithosphere can be stretched and eventually torn apart opening a new ocean creating a transition from continental to oceanic lithosphere called a passive margin. Passive margins related to the opening of the Atlantic Ocean characterize Eastern Canada from the Arctic to Nova Scotia, and older examples are also preserved onshore. Using a highly original and innovative onshore-offshore approach integrating both geological and geophysical methods, my research examines how extensional tectonic processes shaped the geology of Canada, and their importance in the formation and preservation of natural resources that are relevant to Canadian environmental and economic needs. Passive margins are classified as magma-rich or magma-poor, based on the volume of rift- and breakup-related magmatism (molten rock). Canada is the ideal research location as both types occur. Magma-rich margins are postulated to relate to elevated temperatures (e.g. mantle plumes) and `active' rifting, whereas magma-poor margins are suggested to be driven by `passive' far-field extension. However, ambiguity of evidence for mantle plumes and magmatism on magma-poor margins suggests the end-member classification is an oversimplification as it fails to account for structural inheritance (the role of older structures) or explain phenomena such as rift obliquity (non-orthogonal extension). As such, whether continental rifting and breakup is driven by active or passive processes, the role of structural inheritance, rift obliquity, and the relationship of these mechanisms to rift-related magmatism are unresolved and will be the focus of this groundbreaking research program. The long-term goal of this research program is to advance the understanding of the drivers and controls of continental rifting and breakup by answering the presently unresolved question: To what extent is passive margin structure and evolution controlled by magmatism versus structural inheritance? The innovative, integrated, and comprehensive approach will involve geological and geophysical mapping of rift-related deformation and magmatism in Eastern Canada followed by modelling and plate reconstructions. Most previous work studies either only the onshore or the offshore region. Here however, both onshore and offshore regions will be studied to provide an innovative insight and therefore lead to impactful advancements.The impact of this will be realised by advancements in the offshore exploration industry who will benefit from enhanced sub surface knowledge which will translate into more successful and environmentally responsible exploration. Wider Canadian society will also reap economic benefits as a result of these industrial advances, and the academic community will benefit from increases in the fundamental understanding of global tectonic processes.

地球最外层（称为岩石圈）被归类为大陆或海洋，具体取决于其起源和成分。大陆岩石圈可以伸展，并最终撕裂打开一个新的海洋，从而从大陆岩石圈转变为被动边缘。与大西洋开放有关的被动边缘是加拿大东部从北极到新斯科舍省的特征，旧例子也被保存在陆上。我的研究使用了一种综合地质和地球物理方法的高度原始和创新的陆上岸方法，研究了扩展的构造过程如何影响加拿大的地质，以及它们在与加拿大环境和经济需求相关的自然资源中的重要性。被动边缘根据裂谷和分裂相关的岩浆作用（Molten Rock）的体积分类为岩浆富或岩浆贫困。随着两种类型的发生，加拿大是理想的研究地点。假定岩浆富含岩浆的边缘与温度升高（例如地幔李子）和“主动”裂缝有关，而岩浆贫穷的边缘建议由“被动”远场延长驱动。然而，岩浆贫困边缘的地幔羽和岩浆作用的证据的歧义表明，最终成员的分类是过度简化的，因为它无法说明结构遗传（旧结构的作用）或解释诸如裂谷（非正交扩展）之类的现象。因此，无论是主动或被动过程，大陆裂谷和破裂是否驱动，结构遗传，裂谷倾斜的作用以及这些机制与裂谷相关的岩浆作用的关系尚未解决，这将是该突破性研究计划的重点。该研究计划的长期目标是通过回答目前尚未解决的问题来提高对大陆裂谷和分裂的驱动因素的理解和控制：在多大程度上，被岩浆主义与结构遗传控制的是在多大程度上被动利润结构和进化？创新，综合和全面的方法将涉及加拿大东部与裂谷相关的变形和岩浆作用的地质和地球物理映射，然后进行建模和板块重建。以前的大多数工作研究都只能在陆上或近海地区。但是，在这里，将研究陆上和近海地区，以提供创新的见解，从而导致有影响力的进步。这将通过在海上勘探行业的进步来实现的影响，他们将从增强的次级表面知识中受益，这将转化为更成功和负责任的勘探。加拿大社会还将由于这些工业发展而获得经济利益，学术界将受益于对全球构造过程的基本了解的提高。