Physical controls of magmatic productivity at Pacific-type convergent margins: Numerical modelling

摘要: Abstract We use a coupled petrological–thermomechanical model of subduction with spontaneous slab bending to investigate magmatic productivity at active continental margins. The is designed simulate fossil Pacific-type margins that have broad well-developed fore-arc accretionary wedge system. degree plate coupling strongly depends on the dimensionless ratio ( R H 2 O ) between convergence rate and water propagation velocity. Delamination from overriding followed by trench retreat common for models relatively slow rates 4 ). In contrast, higher > result in continuous coupling. curvature increases length subducted plate. Periodic variations angle time are observed later stages become more conspicuous depth. These favoured slower stronger oceanic crust. Two fundamentally different regimes melt numerical experiments correlated natural observations: (1) during plates (as Late Paleozoic margin central Chile) largest occurs onset due temporary steepening slab, then decays rapidly flattening inclination angle, thereby precluding further formation partially molten mantle plumes. (2) Highest obtained simulations associated delamination retreat. As an extension decoupling finally leads pronounced back-arc basin (similar Mesozoic southernmost Chile). this case production stabilization upward asthenospheric flow toward spreading centre, favouring generation hydrous plumes slab.