How does overriding plate crust impact convergence zone dynamics?

International audienceOverriding plates in convergence zones exhibit contrasted unit sizes, morphologies, thermal structures, thicknessesand rheologies of the different structural levels. Some overriding plates show very localized deformation (e.g.,in the Alps) while other show distributed deformation over thousands of kilometers (e.g., in the Himalayasthrough the Tibetan plateau). Several studies (Heuret et al., 2007; Guillaume et al., 2009; Yamato et al., 2009;Rodriguez-Gonzalez et al., 2012; Butterworth et al., 2012; Meyer and Schellart, 2013) have already highlightedthe important role played by the overriding lithosphere as a whole on the subduction zone dynamics. However,these studies were performed at the mantle scale and did not specifically included a crust in the overriding plate,whose role remains poorly understood.In this study, we use a 2D thermo-mechanical numerical model of oceanic subduction followed by continentalsubduction/collision, in which the rheological properties of both the lithosphere and the crust of theoverriding plate are systematically varied. We investigate the effects of parameters controlling the rheologicalstructure (i.e. initial thermal structure of the lithosphere, thickness and nature of the material for both the crustand the lithospheric mantle) on the whole convergence zone dynamics