Page 5 - 15 New data on the Holocenic sea-level
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F. Antonioli et al. / Global and Planetary Change 34 (2002) 121–140 127
of the assessment of post-Tyrrhenian vertical mobi- clastic deposits, overlain in discordance by late oro-
lity. By studying the present vertical distribution and genic clastic deposits (Abate et al., 1991, 1996b,c).
by sampling and dating, with absolute-age techni-
ques, Vermetid reefs and a submerged speleothem, Several orders of subhorizontal abrasion surfaces,
sea-level rise data were obtained for San Vito Lo interpreted as raised marine terraces, are present at
Capo (last 500 years BP) and for Marettimo Island different heights (up to 160 m) along wide coastal
(last 9 ka BP). These results have been compared tracts of the W Sicily, including Marettimo island and
with similar data from the Tyrrhenian Sea (Alessio et Capo San Vito peninsula. Their formation has been
al., 1998) and from extra-Mediterranean areas (Bard considered to be of Middle – Upper Pleistocenic age,
et al., 1996). The new data have also been compared since they cut not only carbonatic rocks and marl-
with predicted sea-level curve based on glacial – stones of Mesozoic age but also terrigenous, evaporitic
isostatic models applied to the same coastal areas and calcarenitic formations of Late Miocene to Lower
(Kurt Lambeck, unpublished data). Pleistocenic age (D’Angelo and Vernuccio, 1996).
2. Geological framework of NW Sicily Extensive outcrops of Quaternary deposits occur in
the coastal plains and along the coastal belt; they are
The NW sector of Sicily and the Egadi Archipe- represented by bioclastic calcarenites, conglomerates
lago represent the emerged western edge of the with sandy matrix, lacustrine sands and gravels and
Sicilian – Maghrebid Chain, which originated from aeolian calcarenites. Particularly, littoral calcarenites
the deformation of the Meso-Cenozoic Northern Afri- and conglomerates, associated with the lowermost
can continental margin. The geological setting of the marine terrace, outcrop in lenses along the western
area is characterized by the overthrusting of tectonic coastal tract of the Capo San Vito Promontory and on
units referable to the Panormid carbonatic platform the coasts of Marettimo. They have been ascribed to
and its margins on units belonging to other palae- the Eutyrrhenian substage on the base of the presence
ogeographic domains (such as the Trapanese basin; of a typical warm molluscan fauna (with Strombus
Giunta and Liguori, 1972; Abate et al., 1991, 1993; bubonius and other Senegalese taxon; Malatesta,
Catalano and D’Argenio, 1982); the piling up of SE- 1957; Ruggeri et al., 1968; Abate et al., 1993,
verging thrust sheets in the Middle – Upper Miocene 1996a; Antonioli et al., 1994b; Mauz et al., 1997).
and in the Middle Pliocene tectonic phases determined On the base of their present-day height (verified only
the overlying of brittle rocks over more ductile rocks. in one sampling site for the W side of the Capo San
Further (Pleistocenic) disjunctive and strike-slip tec- Vito Promontory and in three sites for Marettimo),
tonics, occurred mainly along NW – SE, NE –SO, N – previous authors pointed out respectively, for the two
S and E – W oriented normal fault systems, caused the areas, a relative stability and a limited, differential
splintering up into blocks with differential raising and uplift during the last 125 ka (Abate et al., 1996a;
the formation of structural highs alternated to basins Mauz et al., 1997).
(D’Angelo et al., 1997). In the Capo San Vito Prom-
ontory, this is reflected by the occurrence of lowered 3. Quaternary marine terraces
sectors, presently occupied by coastal plains (Castel-
luzzo and Cornino Plains; Abate et al., 1991). More- A geological survey was performed in a coastal
over, the recent tectonics created favorable conditions sector including three coastal plains (San Vito, Cas-
for the onset of both deep-seated and surficial gravita- telluzzo and Cornino Plains) nearby to San Vito
tional slope deformations, which are particularly Promontory and the submerged area in front of these,
widespread along the eastern flank of the peninsula with the aim to study the Upper Quaternary tectonic
(Agnesi et al., 1995). trends. The morphological evidences of the seven
marine terrace (from + 90 to about À 18 m) surveyed
The Capo San Vito Promontory and the Island of consist in a subhorizontal erosional platforms, with a
Marettimo are characterized by Mesozoic – Tertiary remarkable lateral continuity (Fig. 2), and locally
units composed of carbonatic, evaporitic and silico- well-preserved marine deposits lenses. Marine
notches (at 2, 6, 15, 45, 60 and 70 m above the
