ALPS versus APENNINES: structure and evolution of the orogenic belt(s?) in northwestern Italy.
IGG-CNR, Torino, Italy
Alps and Apennines are two orogenic belts on which the geological community performed analysis, models and theories during a couple of centuries. Since the ophiolites were considered a proof for the existence of the Western Tethyan oceanic domain interposed between Eurasia and Africa plates, a number of models for the formation of the alpine and apenninic collisional belts flourished.
Units outcropping in both belts display strongly different metamorphic and structural evolution; this witnesses for the various stages of ripening of the crustal levels presently at the surface. The position of the ophiolites in the belt and their metamorphic and structural evolution reflect thus the fate of the surrounding basement units.
The image of the two belts at crustal scale, based on deep seismic sounding and geophysical investigations, allows to correlate the surface geology to the deep structures and poses constraints for the kinematic of the two belts. These interplay at crustal scale to form the present day complex configuration in which deep crustal levels and sedimentary basins are juxtaposed at surface.
Taking into account both surface geology, metamorphism and geophysical data, an attempt of the evolution of the region from Early Cenozoic to Present will be illustrated and discussed in the frame of the kinematic of the western Mediterranean area.