INTEGRATION OF NATURAL DATA WITHIN NUMERICAL MODEL TO THE GEODYNAMICS RECONSTRUCTION OF AN INNER PART OF THE ALPINE BELT.

The need to understand and evaluate the mutual influence of the various involved factors promoted the development of numerical models that are able to analyze the contemporaneous interaction of numerous physical and geological variables, in order to simulate the processes working along ac- tive margins in a way, as more as possible, similar to the natural one. In this context a numerical modeling approach is used to validate the physical and geological reliability of the geodynamic evolution of an inner portion of the Alpine belt: the Austroalpine domain. A previous numerical model (SubMar original code) has been implemented to refine the modeling setting and to extend the comparison with the natural data to the entire Austroalpine Domain in terms of: (i) P-T peak setting, (ii) prograde and retrograde thermal gradients, (iii) exhumation rates, (iv) P-T-t-paths, (v) peak and exhumation timing. Several parametrical simulations of an ocean-continent convergent system are performed to obtain the better configuration to apply for the Alpine subduction. Dur- ing these analysis some original results regarding general geodynamics observation are obtained. Model predictions pointed out that a direct relationship exists between mantle rheology and the amount of recycled crustal material: the larger the viscosity contrast between hydrated and dry mantle, the larger the percentage of recycled material into the mantle wedge. Slab dip variation has an impact on the amount of the continental recycling and the metamorphic evolution of the exhumed material. Moreover, the model results suggest that the slab dip is influenced by the thermal state of the overriding plate, and, in particular, for the cold overriding plate configura- tion, a shallower slab dip setting occurs; in contrast, in the hot overriding plate configuration, a steeper subduction occurs. Furthermore, a thickness increase of the subducting plate decreases the variability of the slab geometry, disregarding the thermal state of the overriding plate. For what concern the comparison between the model predictions and the natural data belonging to Austroalpine domain a very good agreement is obtained in terms of P-T peak assemblages, ther- mal gradients, exhumation rates, peak and exhumation timing, thermo-barometric and lithology mixing and P-T-t paths for the Austroalpine of the Western Alps. All the above analysis suggest that a pre-collisional evolution of this domain, with the burial of the continental rocks (induced by ablative subduction of the overriding plate - Adria plate) and their exhumation (driven by up- welling flow generated in a hydrated mantle wedge) could be a valid mechanism for this part of the Alps. The results are less comparable with the thermal state suggested by the natural data of the Austroalpine of the Eastern Alps.