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