Kinematics and dynamics of the Late Quaternary rift-flank deformation in the Hyblean Plateau (SE Sicily)

Abstract

The southernmost branch of the Siculo–Calabrian Rift Zone (SCRZ), in SE Sicily, is flanked by an actively uplifting, 31 km wide and 40 km-long, rectangular-shaped crustal block (Siracusa Domain; SD), whose Late Quaternary tectonic evolution has been controlled by the active NW-verging thrusting along its northwestern margin, accompanied by an extension on the opposite side. Within the mobile block, a local extensional stress-field has produced two N140 oriented Late Quaternary collapsed basins, which opened roughly perpendicular to the direction of stretching along the SCRZ. Some tectonic peculiarities of the SD, such as the occurrence of shortening in absence of a crustal back-stop, the coexistence of local extensional and contractional stress-field and the primary role played by fluids in the deformational processes, suggest a possible connection between the shallower crustal dynamics with a deep-seated Mantle intrusion, beneath the region, as it is commonly documented to occur along the rift-zones, where the rift-flank volcanism develops. Similar dynamics and kinematics have been, in fact, described in the adjacent areas of the western flank of SCRZ, which are affected by volcanism (e.g. Eolian Islands and Mt. Etna). The results of our study in the Hyblean region give, thus, the opportunity to detail on the mode and the mechanics of faulting, that can be significant to interpret the seismicity and active deformation in the adjacent volcanic areas of Sicily.