Finding the fingerprint of mantle dynamics on plate tectonic processes

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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).