Plio-quaternary tectonic evolution and structure of the Catania foredeep, the northern Hyblean Plateau and the Ionian shelf (SE Sicily)

Available multi- and single-channel seismic reflection profiles, calibrated by onshore borehole data, have been used for defining the structural style s in the shelf and slope of the Ionian Sea between Catania and Augusta (SE Sicily). The geological and geophysical data suggest that this area represe nts a segment of the foredeep-foreland system which collapsed after Late Pl iocene times. The foundering was controlled by normal faults trending NE-SW , which flank the southern margin of the Catania foredeep. Onland, in outcr op, these faults appear largely to be post-dated by Lower Pleistocene sedim ents, nearshore carbonates passing laterally into basinal clays, which lie unconformably upon older substrata. Offshore, close to the southern edge of the foredeep, seismic lines allow recognition of two distinct units: a syn -rift wedge (Upper Pliocene submarine tholeiites and sediments), and a post -rift sequence which can be correlated with Lower Pleistocene carbonates, s ands and clays recognisable on land, both in outcrop and by borehole data. The true frontal part of the thrust belt, as detected by the seismic lines, occupies the inner part of the area investigated and is buried by Upper Pl iocene and Lower Pleistocene sediments. However, the compressive deformatio n seems to propagate toward the south-southeast by means of growing detachm ent levels developing at depth within Pleistocene marine clays, for a lengt h of about 10 km, ahead of the present-day thrust front. Offshore, the faul ts trending NE-SW are dissected towards the east by faults trending NNW-SSE , subparallel to the Malta Escarpment, which flank the edge of the submerge d Messina Rise. These faults, originating in a steep scarp which drops east wards to the deep Ionian basin, have triggered submarine slides and affecte d the present-day seafloor sediments. As shown by seismic lines and as stre ssed by the modern seismicity of the area, some of the faults alone the Mal ta Escarpment could be still active. (C) 1998 Elsevier Science B.V. All rig hts reserved.