Slab Plume Interactions in Deep Earth Regions

Understanding mantle dynamics requires deep knowledge of plumes and slabs. Seismic tomography images reveal the existence of interacting slabs and plumes with very intricate shapes. This wide diversity of interacting slab-plume morphologies is indicative of their properties (strength, rheology, composition) and dynamics, although we still lack strong quantitative studies, most numerical models address slab or plume dynamics in isolation. The SPIDER project proposes to focus on slab-plume interactions, in order to decipher the effects of plume and slab properties on their geometry and dynamics. To do so, SPIDER will 1/ numerically model complex slab-plume interactions within a vigorously convecting mantle using the state-of-the-art code StagYY. The applicant will develop topological tools to automatically detect and time-track the plume and slab morphologies and properties; 2/ rigorously explore the effects of the rheological contrasts between slabs and plumes, magmatic-geochemical evolution and mantle melting on slab-plume interaction patterns; and 3/ systematically compare seismic tomography, magmatism and climatic observations in the very distinct Tonga-Samoa and Farallon-Yellowstone slab/plume systems with the characteristics and dynamics of model slab/plume interactions. This unprecedented effort to explain the diversity of observed slab-plume interactions will ultimately help to constrain mantle rheology and dynamics. The applicant will bring his experience in numerical modeling of subduction zone and plume dynamics to the Laboratoire de Géologie de Lyon, Terre, Planètes et Environnement (LGL-TPE, UCBL, France) and University College London, UK, where he will benefit from and contribute to world-leading expertise on the Earth’s mantle-lithosphere evolution in a stimulating intellectual environment. This project will reinforce his professional independence and knowledge diversity as he will become a key player in the geodynamic modeling domain.