Polyphase Tertiary fault kinematics and Quaternary reactivation in the central-eastern Alps (western Trentino)

The network of faults and morphotectonic lineaments at the hanging wall of the North Giudicarie fault (western Trentino, NE Italy) is examinated to investigate the Alpine kinematics from Neogene to Quaternary times. The faults display an average trend parallel to the North Giudicarie line and are characterised by mylonites, ultramylonites, cohesive and uncohesive cataclasites and associated pseudotachylytes indicating a long tectonic activity in a contractional regime. Calculations of the stress distributions (P–T–B axes method, numerical dynamical analysis, direct inversion methods, dihedra calculations) have yielded stress fields which may be attributed to different tectonic steps of the Alpine contraction along the Giudicarie lineament. The NNE- to NE-trending faults (e.g. Val Clapa, Val dellʹAcqua, Val Burlini and Rumo faults) and the ENE-trending faults (Malga Preghena and Passo Paluʹ faults) at the hanging wall of the North Giudicarie line indicate a NW- and WNW-oriented compression during Neogene. Some morphological features suggest a possible quaternary activity of the NW and NE to ENE faults.