Miocene to present major fault linkages through the Adriatic indenter and the Austroalpine-Penninic collisional wedge (Alps of NE Italy)

From the Miocene onwards, the Alpine and South Alpine domains have been closely coupled within the framework of fault kinematics and geodynamic processes related to the continuing indentation of the Adria plate against Europe. In this study, the post-Oligocene evolution of a wide sector of the North Adriatic indenter border and nearby areas is re-examined in an extensive regional context by means of structural, geochronological and seismotectonic data. The Adria northern edge roughly corresponds to the Periadriatic lineament which is characterized in the central-eastern Alps by an abrupt change of orientation from east-west to NNE-SSW at the North Giudicarie line. Several strike-slip fault linkages have developed along the northern and southern sections of this major fault since the Miocene. In the Alpine domain, fault connections facilitated tectonic unroofing of the deeper nappes (Penninic units) in the Tauern window and a westward crustal stretching of the upper nappes (Austroalpine units) in the Brenner detachment hanging wall. In the Southern Alps, several fault linkages are observed, which are related to reactivation of inherited faults by the indentation process. These processes began during the early Miocene, were fully developed in the latest Miocene-early Pliocene, and are very probably still continuing. The final result is a complex shear zone of 250 km length, that in the southern part is considered as an incipient divide between the nearly stationary westernmost part of the North Adriatic indenter and the still northward-pushing main body of the Adria plate.