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Fig. 1 - Physiography of the northern Sicily continental margin, with location of earthquake epicentres in northern Sicily mainland and
offshore. Isobath interval: 0-200 m each 50 m; from 500 upward each 500 m. In the bottom left corner: simplified tectonic map of the
central Mediterranean region.
es, regional factors, as tectonic processes and nature of processes and highlighting the specific factors related to
sedimentary supply, affect the geological evolution of more local control, with the aim to propose a geological
the continental shelf. Sedimentation along the shelves is model able to explain the evolution of this physiographic
dominated by sand deposition together with organogen- units in the context of the central Mediterranean region.
ic carbonates and marine fossils-bearing pelites, in dif-
ferent percentages depending on the climatic zones, the 2. GEOLOGICAL BACKGROUND
prevailing type of coastline (high or low) and the pres-
ence or absence of large river mouths, as well as the The northern Sicily continental margin (Fig. 1) is
distance from coast and the water depth. The activity of located in the southern Tyrrhenian Sea, from the north
benthic organisms and of various types of traction cur- Sicily coastal belt to the Marsili Abyssal Plain, in the
rents (waves, tides, coastal currents, etc.) characterizes transitional area between the Sicilian-Maghrebian chain
the sediments that accumulate in shallow marine envi- to the south and the Tyrrhenian Basin to the north
ronments. Even the presence of special biocenosis (ma- (Nicolich, 1985; Scarascia et al., 1994).
rine phanerogams grasslands, platform coralligenous,
etc.), if sufficiently wide, may be relevant. This continental margin is composed of: (1) a nar-
row (<8 km) and steep (up to 2.5°) continental shelf, with
Northern Sicily continental shelf is a part of the the edge between -95 m and -140 m. Around 40 m water
continental margin that links the Sicily chain to the Tyr- depth the external sector of the shelf, mainly character-
rhenian back-arc basin (Fig. 1), so it’s a key area to un- ized by hemipelagic sedimentation, is separated by an
derstand the processes that occurred in this part of the internal sector with higher hydrodynamics where mainly
central Mediterranean, built up mainly during the Neo- terrigenous and locally biogenic sedimentation prevails;
gene-Quaternary. (2) a very steep (7-8°) upper continental slope ranging in
depth from 150 to 1000 m; (3) a flat intra-slope basin
The scientific interest, connected with the high and plain at a depth of 1500 m; (4) a lower continental slope
variable seismicity of the area, the neotectonic activity, that is wider and gentler than the upper slope, and (5) a
the high and variable uplift/subsidence rate, the occur- bathyal plain from a depth of 3000 m.
rence of depositional sequence generated by the inter-
action between relative sea level changes and sediment The wave regime (Gulf of Palermo and Termini) is
supply, and the economic interest, due to the occur- characterized by NW, NE and E directions (Astraldi et
rence of bio- and geo-resources, are at the base of the al, 2002). The storm waves reach usually 3-4 m in
large availability of geological data. height, have a period of 6 s and an annual frequency of
3% (Istituto Idrografico della Marina, 1982). The tidal
This work describes the geomorphological, strati- excursion indicate a microtidal regime with a tide height
graphic and sedimentological features in selected areas varying between 0.37 and 0.60 m a.s.l. The water salini-
of the north-western Sicily continental shelf, summariz-
ing the common features associated with large-scale