Paleo-European crust of the Italian Western Alps: Geological history of the Argentera Massif and comparison with Mont Blanc-Aiguilles Rouges and Maures-Tanneron Massifs

Roberto Compagnoni, Simona Ferrando, Bruno Lombardo, Nicholas Radulesco, and Daniela Rubatto

The “External Crystalline Massifs” of the Western Alps (Mont Blanc, Aiguilles Rouges, Grandes Rousses, Belledonne, Pelvoux, and Argentera) consist of a polymetamorphic Variscan basement, which was only marginally reworked during the Alpine tectonometamorphic cycle. These massifs experienced an early subduction event at peak metamorphic conditions of ~700°C and 1.5 GPa, followed by continental collision coupled with amphibolite-facies metamorphism, anatexis and exhumation to shallow crustal levels in the Carboniferous (see von Raumer et al., 1999 for a review).

This contribution focuses on the magmatic and metamorphic history of the Argentera Massif, the southernmost and largest of the External Crystalline Massifs exposed in Italy. Its evolution from Ordovician to Early Permian is compared to that recorded in the Mont Blanc-Aiguilles Rouges Massif, the other External Crystalline Massif extensively exposed in the Italian Alps. Further comparison is drawn between these large massifs and the Maures-Tanneron Massif of Provence, France, the area of Variscan Europe nearest to Argentera.