Project Title: Analogue and numerical modelling of topographic response of subduction initiation at passive margins.

Supervisor: Ernst Willingshofer & Dimitrios Sokoutis

Objectives: The initiation of subduction remains a major unresolved question in geodynamics. Theoretical studies have highlighted the complexity of the processes involved. Critical parameters resulting in subduction are debated, but it is commonly accepted that zones of lithospheric weakness are required. This project aims at: understanding the role of (a) rheology, (b) lithosphere structure and (c) angle of convergence at passive (hyper-extended) margins, in the initiation of subduction, through analogue and numerical modelling. Particular attention will be paid to the topographic response during and after the onset of subduction as it provides means for validating modelling results through the rock record of uplift, erosion, and sedimentation, and current topography.

Expected Results: Identification of favourable parameter combinations (rheologic, geometric and kinematic) for subduction initiation at continent-ocean boundaries. Prediction of preferred sites for subduction initiation in the Mediterranean realm.

Academic secondment: ESR visit T. Gerya at ETH Z├╝rich, M24-30, for numerical experiments, to investigate the role of changes in temperature and fluid flow in subduction initiation. J.P. Brun to visit Utrecht for interpretation of modelling results and application to Mediterranean subduction systems.  Industrial secondment: Kalkulo AS, will provide numerical solutions and expertise of fluid flow and tectonics on the reservoir to basin scale, complementing lithosphere scale numerical contribution by ETH.

Links to other projects: Detailed analysis of topography associated with subduction systems through observations and models: ESR1,4,15; assessment of vertical motions at sites of potential subduction initiation and mature subduction systems: ESR8,11,13.