Dynamics and numerical modeling of deep-seated accretionary prisms in the Chilean Coastal Cordillera

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Objectives: Our proposal focusses on HP/LT rocks along the Coastal Cordillera of Chile. These represent short periods of growth of the convergent margin. Preserved accretionary systems in central Chile reveal cyclic mass flow over ~ 100 Ma, whereas arc granitoids matk stable retrowedge areas. N of 34°S and S of 48°S similar accretionary prisms are destroyed by subduction erosion. Our goal is to understand the principal causes for the formation, subduction, exhumation and destruction histories of fossil Chilean accretionary prisms in relation to concomitant magmatic arcs. Methodology. We will (1) test current conceptual models and acqired PTtd-paths by numerical thermomechanical 2D-modeling with constraints from the deformational, thermal and exhumational histories; (2) elucidate the evolution of passive-to-active continental margins by establishing early time markers in central Chile via detrital zircon (U/Pb) and white mica (Ar/Ar) dating; (3) study the different mechanisms of destruction of accretionary prisms N of 34°S and S of 48°S in cooperation with partner projects providing petrological and geochronological support; (4) to refine tectono-metamorphic models by compiling all information about the Chilean basement.