Geodynamics of the continental mantle lithosphere: Investigations into active and ancient evolution of continental plate boundaries and interiors

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The proposed research will investigate the dynamics of the continental mantle lithosphere and its relationship to crustal tectonics. The mantle lithosphere is the sub-crustal portion of the Earth’s lithosphere and makes up the largest component member of the continental tectonic plates. Compared to the overlying crust and fluid mantle below, its evolution is little studied and poorly understood. The research program will make tangible advancements in our understanding of this part of the Earth by answering important outstanding questions in three targeted environments where continental mantle lithosphere is/was tectonically active: (1). How and why does mantle lithosphere get completely/partially removal in some regions and what are consequences at the surface?; (2) What happens when continental mantle lithosphere collides at a plate boundary zone?; (3) What causes episodes of “intraplate” tectonics where plate deformation occurs distant from plate boundaries? The research will explore these questions in tectonically strategic field areas including the Eurekan Orogeny in Canada’s high arctic, the alpine plate boundary zone of the South Island of New Zealand, the plateaus of Anatolia, and the Apennine orogen of Italy. We use computational geodynamics for research and are developing advanced new 4-dimensional tools for this work, where we consider evolution of the models through time and in three spatial dimensions. The modelling tools are distinguished from others used for global tectonics as they incorporate viscous-plastic rheologies, multi-component systems, and boundary conditions that allow for the thermomechanical exploration of the complex coupled mantle-mantle lithosphere-crust-surface. The research will also be innovative and distinct among geodynamics studies by using a multidisciplinary top-down methodology where observational constraints--geological, geophysical, geodetic--are integrated directly into the computational analyses. With the new geodynamics tools and methodology and the targeted field studies, the research will make significant progress in our knowledge of lithospheric dynamics and how continental tectonics works. The proposed research is significant for exploring what is a fundamental gap in our understanding of plate tectonic processes—how and why continental plates are geologically active. The mantle lithosphere is the bridge between the mantle thermal engine and tectonically active crust and this research will help reveal what drives plate tectonics on our active Earth. Also, as the site for the genesis of diamond bearing volcanic kimberlite pipes, the study of the evolution of the continental mantle lithosphere has direct implications for understanding the development of important resources within Canada’s mineral industry. Across a broader frontier, the research will help decipher the geologic evolution of terrestrial bodies such as Venus, Mars, Io, and Europa that display much different surface tectonic activity compared to Earth.