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Variability of depositional setting along the north-western Sicily continental shelf (Italy) ... 143
ty has no considerable variation between summer and while in the eastern sector extensional and strike-slip
winter, remaining between 37.6‰ and 38.2‰ (Demirov mechanisms prevail. Shallow (<25 km) seismic events
& Pinardi, 2002). of low to moderate magnitude (max Md 5.6 on Septem-
ber 2002) occur along an E-W trending belt located
Along the shelf and the upper slope, the Quater- northward. The focal mechanisms related to the main
nary deposits consist of seawards dipping clastic and seismic shocks are in agreement with a dominant NE-
terrigenous deposits coming from the northern Sicily SW fault trend coupled with a NW-SE compressive off-
(Pepe et al., 2003; Agate et al., 2005), whereas in the set direction (Agate et al., 2000; Giunta et al., 2009).
basinal areas hemipelagic sediments are locally interca-
lated with volcanoclastic sediments (Baghi et al., 1980). The highest uplift rates during the last 125 ky in
northern Sicily (Ferranti et al., 2010) were found on the
In the continental shelf, the Pleistocene deposits inner margin-terraces in the eastern coast (0.8-1.63
are truncated by an erosional surface formed during the mm/y), whilst the Holocene rates are between 20% and
last glacio-eustatic oscillation. Local uplift caused the 70% higher than those calculated for the Tyrrhenian
systematic non-preservation of portions of the oldest terraces. The vertical tectonic rates show a decrease
sequences (Pepe et al., 2003). Prograding sedimentary from E to W. In the Tindari promontory the rate of MIS
wedges of coastal deposits formed during the Last Gla- 5.5 is 0.67 mm/y (Bonfiglio et al., 2010). The Holocene
cial Maximum (LGM, about 18 ka) are present along the rate is higher, as suggested by Bottari et al., (2009)
shelf margin. The prograding wedges are absent where from the presence of a Holocene tidal notch at 4 m
the heads of the canyons or failure scars have indented a.s.l.. West of the headland of Tindari, Holocene mark-
the outer shelf (Lo Iacono et al., 2011). Integrated high ers showing increasing rate are not found, presumably
resolution study based both on seismic reflection data due to the coseismic activity of main structural features
and on micropaleontological-sedimentological analisys active during the Pleistocene in northern Sicily: the Kabil-
of a core collected in the outer shelf of the Gulf of Ter- ianeCalabrian Thrust Front (west of Acquedolci) and the
mini, allowed the recognition of two drastic sea-level Vulcano-Tindari Fault (east of Patti) (Sulli et al., 2012).
falls during the Last Glacial Maximum and the Younger Further on, both coastal geomorphological and marine
Dryas, and provided the different position of sea level geology data between Acquedolci and Capo d’Orlando
during the last 41 ky. demonstrate that while the mainland sector is uplifted,
with the same rates both during MIS 5.5 (0.34 mm/y) and
The Northern Sicily continental margin originated the Holocene (0.36 mm/y), contemporaneously the off-
as a consequence of a complex interaction of compres- shore area is subsiding, suggesting the existence of fault
sional events, crustal thinning and strike-slip faulting. systems parallel to the coastline, separating the inner
Following the early-middle Miocene deformation and from outer sector of the continental shelf, causing differ-
thrusting of the Kabilian-Calabrian units and the most ent vertical movements (subsidence vs. uplift) (Sulli et al.,
internal units of the Sicilian-Maghrebian chain (Catalano 2012). Westwards, near Cefalù, some fossil-bearing de-
et al., 1985; Pepe et al., 2005), the opening of the Tyr- posits, dated to MIS 5, at relatively low altitude (29 m, An-
rhenian Sea led to the subsidence of the northern Sicili- tonioli et al., 2006) indicated vertical movement rates low-
an margin since the Late Tortonian (Baghi et al., 1980; er than 0.2 mm/y. Westward, between Palermo and the
Fabbri et al., 1981). Late Miocene-early Pliocene north- Egadi islands, many MIS 5.5 markers show a substantial
dipping high-angle reverse faults, involving mainly deep stability, except for small and local vertical movements
seated, carbonate platform units, produced structural (Gulf of Castellammare, Mauz et al., 1997 and Castel-
highs (Avellone et al., 2010), among which those sea- luzzo Plain), due to the action of transcurrent faults where
ward bounding the intraslope basins (Pepe et al., 2003), uplift rates reach 0.1 mm/y (Antonioli et al., 2006).
termed peri-Tyrrhenian basins by Selli (1970), filled with
Late Neogene to Quaternary evaporitic, hemipelagic, 3. MATERIALS AND METHODS
siliciclastic and volcaniclastic deposits, up to 1200 m
thick (Baghi et al., 1980). Later, normal faults partly dis- The morphological features of the area were stud-
sected the back- and fore-limb of the structural high. ied by MultiBeam Echo Sounder (MBES) data, acquired
Middle-upper Pliocene reflectors clearly diverge towards in different oceanographic cruises, by using both the
the normal fault bordering the basin, thereby demon- Reson SeaBat 8111, generating 105 beams at a fre-
strating syn-extensional deposition (Pepe et al., 2003). quency of 100 kHz with depth range of 35-800 m, and
E-W- to NE-SW-trending normal faults exerted during the Reson SeaBat 8160, which generates 126 beams
the Pleistocene a control on the morphology of the pre- with depth range of 30-3,000 m. Bathymetric data were
sent day shelf and coastal areas. acquired and stored using the PDS2000 acquisition
software. Sound velocity profiles were collected with the
As a consequence two types of basins formed in Navitronic Systems AS-SVP-25. Post-processing of Mul-
the North Sicily continental margin (Pepe et al., 2005): ti Beam data was accomplished with the PDS-2000 sys-
(1) minor intra-slope basins (e.g. Palermo and Termini tem and included the graphic removal of erroneous
basins) whose origin is related to the (?) late Miocene - beams, noise filtering, processing of navigation data and
early Pliocene shortening and thrusting of the Sicilian- correction for sound velocity. Gridding of the filtered
Maghrebian Chain, and (2) major extensional basins soundings was carried out to obtain the final DEM
(e.g. Cefalù Basin) whose origin is connected to the (Fig. 2), which provided high resolution 3D views of the
continental rifting which affected the internal side of the sea-floor, shaded relief maps, slope maps and bathy-
margin during the middle (?) -late Pliocene, as demon- metric cross sections.
strated by synextensional deposition.
Various sets of CHIRP and multi- and single-
The tectonic activity of the northern Sicily conti-
nental margin is outlined by a large upper plate seismici-
ty (Fig. 1), producing a seismogenic region character-
ized by compressional focal mechanisms to the west,