Tectonic model for the evolution of the western Alps

Both European and Adriatic continental margins of the Alpine Piemont ocean were deformed and metamorphosed in the eclogite facies at ~ 100 Ma, prior to the main stage of continental collision in the Eocene. It is proposed that the precollision (Eoalpine) high-pressure metamorphism in the internal crystalline nappes of the western Alps was a result of the subduction of the European continental margin below the lithosphere of the Piemont ocean. Concurrent oceanic subduction and tectonic erosion on the Adriatic side resulted in the Eoalpine high-pressure metamorphism of the Sesia-Dent-Blanche system. The precollisional setting proposed for the western Alps is comparable to the tectonic configuration around the Gulf of Oman, where continent-continent collision has not yet occurred. -from Authors