Tectonics and sedimentation of the Lower and Middle Pleistocene mixed siliciclastic/bioclastic sedimentary successions of the Ionian Peloritani Mts (NE Sicily, Southern Italy): the onset of opening of the Messina Strait

Biostratigraphic analyses carried out on siliciclastic/bioclastic deposits discontinuously cropping out along the Ionian flank of NE Sicily, indicate that they form two sedimentary events of Early and Middle Pleistocene, respectively. Vertical facies successions, showing transgressive trends, suggest that sedimentation occurred within semi-enclosed marine embayments, where sublittoral coastal wedges developed on steep ramp-type shelves. Sediments accumulated in shoreface to offshore transitions along steep bottom profiles. This depositional scenario was strongly conditioned by the tectonic activity of the rift zone linking Western Calabria and Eastern Sicily. The effects of glacio-eustatism were also recognized. According to our reconstruction, the study area was controlled by a transfer fault system which affected the coastal margin producing major episodes of uplift and subsidence. Block-faulting was responsible for significant cannibalization and recycling of older deposits during the Middle Pleistocene. Such a tectonic setting can be considered the precursor scenario for the formation of the Messina Strait between Calabria and Sicily. This narrow, linear basin influences the hydrodynamic setting of sublittoral deposits along the Ionian coast of Sicily, giving rise to strong flood/ebb tidal currents. The uppermost part of the Middle Pleistocene succession recognized in the study area is indeed dominated by tide-influenced associations of sedimentary structures which most likely record the first stage of the opening of this 'seaway' of the central Mediterranean Sea.