STRUCTURAL SYNTHESIS OF THE EASTERN ALPS: A LITHOSFERE SCENARIO OF THE ALPS: A COLLISIONAL OROGENIC CHAIN

In this paper the Alpine evolution of the Eastern Alps, southern side, is outlined starting from the early and oldest stages of the rifting predating the opening of the Alpine oceanic Tethys . We refer to the early Permian and mid Triassic huge magmatic e occurrences which affected the Dolomites strongly reinforcing their upper crust which controlled, with their more rigid behaviour, the further convergence evolution of the Eastern Alps southern sector. The N Giudicarie fault is the divide between the Central and the Eastern Alps along the western border of the stronger upper crust of the Dolomites. To the S this structure (presently mostly buried under the Adamello intrusion) acted as a part in a transfer zone separation between the Orobie-Presolana-Val Camonica. eoalpine to mesoalpine, structural belt (late Cretaceous- Lower Eocene) and the eastern zone (Giudicarie and Western Dolomites structures) unaffected by deformations of similar age. The structural evolution of the Eastern Alps, mostly in their southern sector, occurred during the neoalpine convergence (late Oligocene-Neogene up to Pleistocene). Here, several compressional events originate strong indentation of the more rigid Adriatic lithosphere between the nappe building of the Tauern structure and the European lower crustal units descending to the S under the Adriatic indenter, as documented by deep seismic reflectors of the Transalp Profile and their interpretations here proposed.