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: 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=742816
• 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.

地球最外层的固体，称为岩石圈，根据其起源和组成分为大陆或海洋。大陆岩石圈可以被拉伸并最终被撕裂，形成一个新的海洋，形成一个从大陆岩石圈到海洋岩石圈的过渡，称为被动边缘。从北极到新斯科舍省的加拿大东部地区，与大西洋开放有关的被动边缘是其特征，更古老的例子也保存在岸上。使用一个高度原创性和创新的陆上-海上方法，结合地质和地球物理方法，我的研究探讨了伸展构造过程如何塑造加拿大的地质，以及它们在形成和保护与加拿大环境和经济需求相关的自然资源方面的重要性。被动边缘根据与裂谷和裂解有关的岩浆活动（熔融岩）的量分为岩浆丰富或岩浆贫乏。加拿大是理想的研究地点，因为这两种类型都有。据推测，富含岩浆的边缘与温度升高（如地幔柱）和“主动”裂谷有关，而贫岩浆的边缘则被认为是由“被动”远场延伸驱动的。然而，缺乏岩浆边缘的地幔柱和岩浆活动证据的模糊性表明，端元分类是一种过度简化，因为它不能解释结构遗传（旧结构的作用）或解释裂谷的不均匀性（非正交延伸）等现象。因此，无论大陆裂谷和分裂是由主动还是被动过程驱动的，结构继承的作用，裂谷的韧性，以及这些机制与裂谷相关的岩浆活动的关系尚未解决，将是这个开创性的研究计划的重点。本研究计划的长期目标是通过回答目前尚未解决的问题来促进对大陆裂谷和分裂的驱动力和控制的理解：被动边缘结构和演化在多大程度上受岩浆活动与结构继承的控制？这种创新、综合和全面的方法将涉及加拿大东部与裂谷有关的变形和岩浆活动的地质和地球物理测绘，然后是建模和板块重建。大多数以前的工作要么只研究陆上或海上区域。然而，在这里，我们将研究陆上和海上地区，以提供创新的见解，从而带来有影响力的进步。这一影响将通过海上勘探行业的进步来实现，海上勘探行业将受益于增强的地下知识，这将转化为更成功和对环境负责的勘探。更广泛的加拿大社会也将因这些工业进步而获得经济利益，学术界将因对全球构造过程的基本理解的增加而受益。