Plio-Pleistocene structural inversion around the Catanzaro Trough (Calabria, South Italy): change from transcurrent to extensional kinematics?

The Catanzaro Trough basin (Calabria, South Italy), extending from the Tyrrhenian to the Ionian Sea, filled by up to 2000 m of Neogene- Quaternary sedimentary succession, represents a key zone to understand the evolution of entire Calabrian Arc. This basin is characterized by multi-phases tectonics that have acted in the study area since the Upper Miocene. To gain knowledge about this area, we focused the study on the fieldwork survey, which allowed to acquire more than 700 fault planes, classified on the base of kinematics and fault direction, evenly distributed throughout the area. These data were used to obtain the stress fields that have controlled the evolution of the Catanzaro Trough. Indeed the collected data analysis supplies information about three main structural events: Upper Miocene-Zanclean, Piacezian-Lower Pleistocene, and Middle-Upper? Pleistocene phases, alternatively controlled by the activity of NW-SE and NE-SW oriented fault systems. The selected major NW-SE oriented faults showing left lateral kinematics, together with secondary fault systems represented by E-W oblique and NE-SW transcurrent faults are the result of a paleo-stress with ca. E-W-trending maximum principal ? 1 axis (P-axis) and a horizontal NNW-SSE extensional ? 3 axis (T- axis), responsible for the Upper Miocene-Zanclean opening of a WNW-ESE fault bounded basin. During Piacezian-Lower Pleistocene, a change of stress field seems to yield inversion of major left-lateral faults, suggesting a new stress regime, with a ca. N-S oriented maximum principal axis (? 1 ), and a ca. NW-SE oriented minimum principal axis (? 3 ), compatible with the right-lateral motion of the same fault system This structural stage, in turn, was replaced by extensional phase, with a (? 3 ), ca. WNW-ESE oriented, controlled mainly by NE-SW and subordinately N- S oriented normal faults, which split obliquely the Catanzaro Trough, producing up-faulted and down-faulted blocks, arranged as graben-type systems (i.e. Lamezia Basin, Brutto et al., 2016). These last two fault systems give also indication of recent (post Middle-Upper? Pleistocene) faults activity of an area historically considered with the highest probability of occurrence of major earthquakes throughout the whole Italy.