Taiwan mountain building: insights from 2-D thermomechanical modelling of a rheologically stratified lithosphere

International audienceThe Taiwan orogen has long been regarded as a case example for studying mountain building in association with subduction processes. In this paper, we present a fully coupled thermomechanical modelling of the Taiwan collision based on a realistic viscous-elastic­plastic rheology. It satisfactorily reproduces available thermochronometric data, long-/short-term deformation patterns, heat flux and erosion/sedimentation distribution across the Taiwan orogeny. We found that a deep seated flux of Asian crustal material into the orogenic wedge should be invoked to counter-balance observed exhumation and erosion in the Central Range. However, in contrast with recent thermokinematic models of exhumation and deformation suggesting that underplating plays a significant role, we show that most constraints on exhumation and deformation can be more straightforwardly interpreted by the frontal accretion of the rheologically layered Asian crust. We finally infer that such a model is in better agreement with the basic expectation that the hot/young and buoyant Chinese continental margin should hardly be subducted beneath the cold/old and dense oceanic plate of the Philippines Sea