Geological map of the upper Gressoney Valley, Western Italian Alps.

Detailed geological mapping of the upper Gressoney Valley in the Western Italian Alps has permitted us to reconstruct the lithostratigraphy and the structural evolution of three different tectonic units: the Monte Rosa Massif and the Zermatt-Saas Zone and The Combin Zone. The studied nappes can be grouped into a Lower Tectonic Element which underwent eclogite facies metamorphism (Monte Rosa Massif and Zermatt-Saas Zone) and an Upper Tectonic Element (Combin Zone) pervasively equilibrated under greenschist facies conditions and lacking mesoscale evidence of high pressure metamorphism. The reconstruction of the lithostratigraphy and the mapping of the different generations of tectonic contacts between the different units allowed us to infer the presence of different generations of tectonic contacts separating oceanic and continental crust units.