Fig. 3

a Tectonic sketch of the area studied, showing the Internal and External Complexes and internal sub-units of the Sesia Zone. Tectonic boundaries are shown as continuous lines where outcropping; dashed lines are interpretive boundaries. The red colour indicates the tectonic contact between the Internal and External Complexes. b Map of the main metamorphic imprint of the studied area: in the Internal Complex only areas close to the contact with the External Complex are affected by a greenschist facies overprint. c Map of the pre-Alpine metamorphism and magmatism: pre-Alpine metamorphic relics are found in the Internal Complex, whereas in the External Complex they were found only in the Nery-Torché and Aquila-Lago slices and in few amphibolites in the Crabun Sheet. d Map showing the distribution of HP minerals. They were found exclusively in the Internal Complex and in the Barmet SZ