Pogallo Line, South Alps, northern Italy: an intermediate crustal level, low-angle normal fault?

The Pogallo Line is a major crustal shear zone in the crystalline S Alps of N Italy which separates middle amphibolite-granulite facies rocks of the Ivrea zone from lower-middle amphibolite facies rocks of the Strona-Ceneri zone. U-Pb, Rb-Sr, and K-Ar whole-rock and mineral ages for samples from this region indicate that the two zones pursued different time-temperature paths after Caledonian peak metamorphism. We suggest that the Pogallo Line may represent a low-angle normal fault that developed at intermediate crustal levels during a Late Triassic-Early Jurassic extension and attained its present subvertical orientation during Alpine deformation.-after Authors