Finding the fingerprint of mantle dynamics on plate tectonic processes

寻找板块构造过程中地幔动力学的指纹

• 批准号: RGPIN-2022-03084
• 负责人: Heron, Philip
• 金额: $ 2.19万
• 依托单位: University of Toronto
• 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=762167
• 关键词: Finding; fingerprint; mantle; dynamics; plate

Whether plate tectonic activity is primarily driven by crustal (`top--down') or mantle (`bottom--up') processes is an enduring challenge in geodynamics. My research program investigates plate tectonic processes using high performance computing to identify the potential fingerprint of the mantle in such mechanisms. For this grant cycle, I'll focus on four interlinked areas that work towards this long term goal.  The Arctic is a region where repeated episodes of continental breakup have been documented but an understanding of the processes is limited. A goal will be to produce detailed numerical models of the tectonic evolution of the Arctic Ocean from first principles. The models will incorporate knowledge created by decades of regional geological mapping and will build on my research expertise in identifying the fingerprint of top-down or bottom-up processes in episodes of continental breakup (rifting). Repeated episodes of rifting as seen in the Arctic region commonly produce `terranes', which are small fragments of the Earth's continents that become isolated from their principal domain. Despite global ubiquity, the processes involved in the generation of such fragments are not well understood, with previous work mainly focusing on their provenance rather than how they originated. The work here aims to deduce the relative importance of top--down and bottom--up processes in the creation of terranes. On a global scale, the evolution of the Arctic Ocean also spans the final breakup of supercontinent Rodinia and the amalgamation and breakup of Pangea. Given the long timeframe, a deeper understanding of the relationship between mantle convection and the supercontinent cycle is critical in understanding the role of mantle processes in the evolution of the Arctic Ocean. Through 3D numerical modelling, we will investigate the size of a supercontinent required to produce an impact on bottom--up dynamics from the convective mantle. Moving closer the present-day, instances of deep (>30 km) intraplate earthquakes have occurred over the past 50 years in Eastern Canada, the United States, Africa, and Eurasia. The potential impact of these deep earthquakes on shallower tectonics is rarely investigated. Modern data science techniques are well suited to evaluate the response of the crust to intraplate deep earthquakes. By building a potential fingerprint of a bottom--up impact on crustal tectonics from historical events, the research program can apply this testable framework to future events. The novelty of this multi-scale program includes the use of state--of--the--art computational models to add a fourth dimension (time) to available data. By modelling regional tectonics (e.g., Arctic dynamics and deep earthquakes) and global--scale features (e.g., supercontinents and terranes), the proposed research will work towards the long--term goal of understanding which plate processes are initiated from the mantle (bottom-up) or the crust (top-down).

板块构造活动主要是由地壳(“自上而下”)还是地幔(“自下而上”)过程驱动的，这是地球动力学中一个持久的挑战。我的研究项目使用高性能计算来研究板块构造过程，以识别这种机制中地幔的潜在指纹。在这个赠款周期中，我将重点关注四个相互关联的地区，它们致力于实现这一长期目标。北极是一个记录了多次大陆分裂事件的地区，但对其过程的了解有限。一个目标是从基本原理出发，制作北冰洋构造演化的详细数值模型。这些模型将结合几十年区域地质填图所创造的知识，并将基于我在识别大陆分裂(裂谷)事件中自上而下或自下而上过程的指纹方面的研究专长。在北极地区看到的反复裂谷事件通常会产生“地体”，即地球各大洲与其主要领域隔绝的小碎片。尽管这种碎片在全球普遍存在，但人们对这些碎片的产生过程还没有很好的了解，以前的工作主要集中在它们的起源上，而不是它们是如何起源的。这里的工作旨在推断自上而下和自下而上过程在地体形成中的相对重要性。在全球范围内，北冰洋的演化也跨越了罗迪尼亚超大陆的最终解体和盘古大陆的合并和解体。鉴于时间很长，深入了解地幔对流和超大陆循环之间的关系对于理解地幔过程在北冰洋演化中的作用至关重要。通过3D数值模拟，我们将调查从对流地幔对自下而上的动力学产生影响所需的超级大陆的大小。走近今天，在过去的50年里，加拿大东部、美国、非洲和欧亚大陆都发生了深部(30公里)板内地震。这些深部地震对浅层构造的潜在影响很少被研究。现代数据科学技术非常适合于评估地壳对板内深部地震的响应。通过建立历史事件对地壳构造的自下而上影响的潜在指纹，该研究计划可以将这个可测试的框架应用于未来的事件。这个多尺度计划的新颖性包括使用最先进的计算模型来为可用数据增加第四个维度(时间)。通过模拟区域构造(如北极动力学和深部地震)和全球尺度特征(如超大陆和地体)，拟议的研究将朝着了解哪些板块过程是从地幔(自下而上)或地壳(自上而下)开始的长期目标努力。