Earth’s codependent siblings: studying dynamic interactions between crust and mantle in ancient and modern continents

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The continental crust is the cradle of our modern ecosystem, and the cornerstone of Earth’s present day geochemical and plate-tectonic cycles. Over the course of its 4.0-4.5 billion-year lifetime, the continental crust has changed shape and volume through addition of new material to its roots and margins, and removal by erosion and subduction. The chemical and physical interactions between the crust and sub-continental lithospheric mantle (SCLM) are by far the most important in controlling the way continents develop. The strong mutual influence between these reservoirs causes their fate to be intimately tied together; they are truly co-dependent siblings. My research focusses on critical interface regions where the crust and mantle are in direct contact: subduction zones, and the roots of cratons and mountain belts. Through analytical geochemistry, petrology and fabric analysis, I provided new constraints on how, when and how fast geochemical and tectonic processes occur in these regions. In addition, I developed new methods for constraining these aspects. This new research program builds on these advances and investigates 5 key topics: 1) the stabilization of ancient cratonic roots, 2) orogenesis and plateau formation in the Himalaya-Tibet orogen; 3) the role of subduction in Earth’s earliest tectonics; 4) eclogitization of the crust buried to mantle depth; and 5) the magmatic processes leading to kimberlite eruption. Each topic forms the basis for a clearly defined research stream, each with clear research questions, adequate approaches to answer these, and well-defined projects for training highly qualified personnel (HQP). The overall program is heavily analysis-based and particularly distinguishes itself through the breadth of methods used, which will allow broad insight and impact. The HQP will greatly benefit from this, as it will allow them to get hands-on training in cutting-edge analytical methods and develop the skills to creatively use these in answering fundamental geological questions. To ensure analytical and educational success, the project relies on a combination between my personal analytical expertise, and the leading analytical infrastructure and excellent research staff at the Pacific Centre for Isotopic and Geochemical Research (PCIGR). The program thus provides a solid and coherent framework for advancing the knowledge of our lithosphere and for fostering future research excellence.