Thermo-mechanical approach to validation of deep crustal and lithospheric structures inferred from multidisciplinary data: application to the Westernand Northern Alps

Current multidisciplinary studies confront the difficult problem of validat ion and verification of internal compatibility of geophysical and geologica l data of different nature, quality and origin. Our 'geodynamic' approach e xploits the natural interdependence between the data related to different p hysical properties of geological structures (density, rheology, temperature , stress). Using the latter as input for a thermomechanical finite-element model, we can verify whether the inferred properties and geometries (i) are mechanically stable, (ii) require theologically consistent stresses, strai ns, realistic thermal conditions, etc., and (3) will evolve in a geological ly realistic way in the future. This 'mechanically balanced' approach is te sted on the Alpine orogen (ECORS and NFP20 profiles) in the framework of th e GeoFrance 3D programme. The results suggest a number of corrections and a djustments that tan be made to existing seismically-and gravity-predicted g eometries of structures such as the Ivrea body and those of the depleted su bducted crust.