Dynamische Modellierung der Andenorogenesek eingebettet in ein 3D Kugelschalenmodell des Erdmantels

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Some essential features of Andean orogenesis cannot be explained only by a dynamic regional model since there are essential influences across its vertical boundaries. A dynamic regional model of the Andes should be embedded in a 3-D spherical-shell model. Because of the energy distribution on the poloidal and toroidal parts of the creeping velocity and because of geologically determined mass transport alongside the Andes, both models have to be 3-D. We developed a new viscosity profile of the mantle with jumps at the lithospheric-asthenospheric boundary and at a depth of 410, 520 and 660 km. Therefore, the challenges to the code Terra are now essentially larger. In the last three years we have resolved these problems in an international cooperation (see 2.2 b)). Based on the new viscosity profile and on the improved Terra, we computed a new forward spherical-shell model [103, 104]. Papers on the improvement of Terra [56, 70] have been submitted. We conceived a regional model of the Andean orogenesis (3.2 b)) with the same new viscosity profile. We want to investigate why there is flat-slab subduction in some segments of the Andes and why deformation of the crust and volcanism migrate eastward. The evolution of the abundances of incompatible elements indicate a cycle which was finished by a fast process, perhaps by a large-scale delamination of the lower plate, perhaps also by another type of delamination. In connection with another spherical-shell model (with prescribed plate boundaries), the regional model should numerically explain why a plateau-type orogen evolved at an oceanic-continental plate boundary.