Dalla convergenza Varisica all'estensione permo-triassica: confronto fra dati naturali e modellizzazione numerica

The Permian-Triassic igneous activity, associated with regional scale deformation developed under HTLP metamorphic conditions and widely recorded in the pre-Alpine crust of the European Alps, can result from late-orogenic collapse of a collisional belt or from lithospheric thinning leading to a continental rifting process. In order to reduce this ambiguity, we use a 2D finite element model to give new insights on the sequence of mechanisms operating during active ocean-continent convergence, followed by continental collision and pure gravitational evolution and on the regional geodynamic interpretation of the Paleozoic-Mesozoic evolution of the Alpine area. The modeling predictions are compared with the P-T climax conditions of Variscan and Permian-Triassic metamorphism affecting the continental crust of the Helvetic to Southalpine Domains. The good agreement between model predictions and natural data realized for the Early to Neo Variscan evolution indicates that, during Paleozoic, the pre-Alpine crust of the Alps was part of an active ocean-continent convergent margin and an intra-continental suture zone.