Page 10 - 15 New data on the Holocenic sea-level

132 F. Antonioli et al. / Global and Planetary Change 34 (2002) 121–140
Late Quaternary tectonic stability (i.e. Eastern coast of and of about 0.024 mm/year (sector F). From the
Sardinia). In these areas the Eutyrrhenian notch
(Antonioli et al., 1999a) is extended for tens of kilo-
meters, at a level ranging from 7.1 to 8.2 m a.s.l.
(maximum semidiurnal tide 12 cm). We can consider
this height (about 7 F 1 m a.s.l.,) as a reference level
for the quite-stable West Mediterranean coastal zones.
In the Capo San Vito Promontory, we identified six
sectors, characterized by different post-Eutyrrhenian
neotectonic deformation and uplift (Fig. 2, inset):
sector A (Cornino Plain), where the inner margins
of Eutyrrhenian terraces and notches lie at about 16 m
a.s.l.; sector B (Monte Cofano), where the notches
occur at 11 m a.s.l. and the inner margins at 12 m
a.s.l.; sector C (southern Castelluzzo Plain), where
these features are at heights between 14 and 15 m
a.s.l.; sector D (northern Castelluzzo Plain), where the
Eutyrrhenian inner margins range from 11 to 12 m
a.s.l.; sector E (Piana di Sopra), where the Eutyrrhe-
nian inner margin is decreasing from south to north
(ranging from 9 to 6 m a.s.l.); sector F (San Vito
Plain), where the Eutyrrhenian morphological features
occur at a height between 9 and 10 m a.s.l. (Fig. 5).
The vertical dislocation of these sectors from 125 ka
to the present day highlights the presence of a differ-
ential neotectonic component that displaced sector A
of about 8 m, sectors B and D of about 4 m, sector C
of over 6 m and sector F of about 2 –4 m. On the
contrary, the data suggest relatively stable conditions
for the sector E or a slight lowering in the northern-
most area of the San Vito Promontory. Considering
these data, the gathered average magnitude of post-
Tyrrhenian differential vertical movement is of about
0.064 mm/year (sector A), of about 0.032 mm/year
(sectors B e D), of about 0.048 mm/year (sector C)
Fig. 8. Section of the submerged cave of Punta Martini Cape in the SE coast of Marettimo (see location in Fig. 7). The entrance to the cave lies
at 27 m of depth; the dated speleothem has been sampled around the middle of the cave at À 24 m.
consideration that the submerged shallower marine
terrace (VII order) shows a vertical distribution pat-
tern very similar to the one derived for the Eutyr-
rhenian forms (VI order; Fig. 6), it seems that a rather
constant tectonic behavior might have occurred in
each sector since the Upper Pleistocene. Moreover,
it is interesting to note that in all the sectors the whole
uplifted sequence of marine terraces shows a tectonic
deformation which is coherent with the gathered uplift
rates for the last 125 ka (Fig. 6). Differential behavior
between contiguous sectors seems to be in strong
relation with the N – S and NE – SW aligned regional
tectonic lineaments.
A similar geological survey has been performed
also on Marettimo Island to verify the vertical tectonic
mobility of the area in recent times and to evaluate the
consistency of the indicators of palaeo-sea level. In
Marettimo the Eutyrrhenian deposits (represented by
calcarenites, breccias and conglomerates with a red-
dish sandy matrix, overlaid by aeolic and continental
sediments, Abate et al., 1996a,c) are present, along
some coastal tracts, in limited patches at heights
between 2 and 10 m a.s.l. The present-day vertical
distribution of the Eutyrrhenian notches along the
coasts of Marettimo shows a height range from 5 to
8.20 m (Fig. 7); these values are affected by a degree
of accuracy of F 25 cm in the height estimation. A
speleothem was observed at depth of À 23/24 m b.s.l.
during the scuba diving exploration of the ‘‘Punta
Martini Cape’’ submerged cave (Fig. 8). It has been
sampled and dated with absolute age techniques (14C
and U/Th, Table 2).
The notches found at Capo San Vito (Fig. 4) and
Marettimo present structural and morphological traits