Project Title: Erosion and the localisation of crustal deformation in extensional roll-back systems.

Supervisor: Fred Beekman, Ernst Willingshofer

Objectives: It is generally accepted that in convergent settings like collisional mountain belts, surface processes are key for controlling the locus of deformation and hence the architecture of the evolving orogen as well as the efficiency of exhumation of (high pressure) rocks. In contrast, in parts of subduction systems that are under extension, the influence of surface processes on the localisation of crustal deformation and high heat flow is less well understood. In this project analogue and numerical modelling methods will be employed to assess the potential of erosion to control the localisation of core-complex formation and increased heat flow in extensional roll-back systems (Pannonian Basin, Aegean, Basin & Range). This will be tested against the conventional idea that rheological heterogeneities within the thickened crust are the controlling parameter.

Expected Results: The project will discriminate between surface erosion and intra-crustal rheological heterogeneities as the main controlling factor in localising structural and thermal heterogeneities in thickened crust under extension. Coupled analogue-numerical modelling will yield quantitative constraints on the amount of erosion needed to trigger and localise deformation in such systems and to allow for the assessment of the geothermal potential of these areas.

Academic secondment: ICTJA Barcelona, Garcia-Castellanos & Fernandez, 2 x 3 months, analogue modelling of topography and structure. Durham, van Hunen, numerical modelling of thermal evolution of deforming crust in extensional subduction system. Industry secondment: TNO, The Netherlands, constraining link of backarc extension to geothermal systems.

Links to other projects: Comparison of uplift mechanisms in forearc and backarc systems ESR12,13; evaluating the influence of structural grain and crustal architecture on later subduction related extension ESR4,9.