Evidence of Early Permian extension during the post-Variscan evolution of the central Southern Alps (N Italy)

Abstract In the central Southern Alps (N Italy) some well-preserved Permian extensional structures, that exceptionally escaped Alpine deformation, have been recently identified. Their analysis offers important insights for interpretation of post-Variscan tectonics affecting during Permian. We describe here a previously unknown fault system related to development Early Orobic Basin, where large exposures Variscan basement preserve their original tectonic contacts with overlying Lower cover. The consists Low-Angle Normal Faults (LANFs) accompanied by High-Angle faults (HANFs), these last entirely developed within volcanic, volcaniclastic and terrigenous deposits. studied structures occurring in upper part Gerola Valley, share several features normal already recognized other areas Alps. low-angle planes are characterized continuous layer coarse-grained breccias, locally impregnated tourmalinites. rocks invariably observed along surface at basement-cover contact all across study area. This newly identified its characteristic combination low- high-angle suggests regime pure extension Alps, rather than transtensional provided data give new into geodynamic scenario, which is discussed light transition from Pangea B A configuration.