Page 4 - 36 Elevation of the last interglacial highstand in Sicily

ARTICLE IN PRESS
6 F. Antonioli et al. / Quaternary International 145– 146 (2006) 3–18
Tyrrhenian age, and therefore is in a zone of minor
tectonic activity.
2.2. Sector 2—southern coastline
In contrast to the tectonic controls that operate in
northern and northeastern Sicily, with southward thrust
progradation, the southern region apparently does not
record tectonic uplift. The southern coastline west of the
Hyblean Block consists of low cliffs composed of poorly
resistant lithologies that do not preserve evidence of
previous sea-level positions. However, because MIS5.5
sea level was higher than modern sea level, terraces
should be preserved inland of the low cliffs in some
localities. Therefore either the poor resistance of the
rock has led to erosion of any uplifted remains, or
alternatively it is possible that MIS 5.5 record is
submerged below modern sea level.
2.3. Sector 3—SE coastline
Sector 3, the Hyblean Plateau is part of the Pelagian
Block and forms the northern margin of the African
Plate, therefore experienced a different tectonic history
from the rest of Sicily. The area underwent collision with
northern Sicily in Early Miocene to Pliocene times
(Grasso and Pedley, 1990), but because the Pelagian
Block is essentially a rigid mass, it has suffered brittle
deformation, but has not developed the complex thrust
system of the Maghrebian region to the north. Thus the
tectonic background has led to reduced rates of vertical
tectonic motion, and this is reflected in the limited uplift
recorded in coastal sites, that are described in this paper. (Lanzafame and Bousquet, 1997).
2.4. Sector 4—northeastern area
Northeastern Sicily including Calabria is situated at
the southern margin of the Tyrrhenian microplate
(Gvirtzman and Nur, 1999). The area, called the
Appennine–Maghrebian Chain, is composed of sedimen-
tary and metamorphic rocks within a southward-verging
system of thrusted nappes developed above the north-
ward-dipping African plate. The resulting tectonic
depression has created a foredeep along the northern
margin of the African continental crust that is occupied
by early Quaternary marine clays. These clays form the
substrate for much of the eastern and southern flanks of
the Mount Etna volcanic edifice and are known as the
sub-Etnean clays. Farther to the south, the African crust
is represented at the surface by the platform carbonates
and clastics of the Hyblean plateau which make up
southeastern Sicily. In the Tyrrhenian Sea north of Sicily,
a subducted margin is marked by the Aeolian Islands
volcanic arc. Overall, this tectonic regime imposes
north–south compression to the northeastern Sicily
region (Lanzafame and Bousquet, 1997). Field relation-
ships between rocks of the Appenine–Maghrebian Chain
and the early Quaternary marine clays indicate that
thrusting in this compressional regime continued until at
least mid-Pleistocene times (Lanzafame and Bousquet,
1997), while active regional uplift is indicated by several
lines of evidence. In particular, the early Quaternary
marine clays are now found several hundred metres
above sea level (Romano, 1979), and well-developed
uplifted Tyrrhenian marine erosional platforms occur at
about 130 m at Taormina in Sicly, as well as in Calabria
on the eastern side of the Messina Straits.
This compressional framework is transected by a
number of seismogenic structures of regional tectonic
importance. Of these, the largest is the Malta Escarp-
ment, a structure that intersects the African margin on
the southern side of the Mediterranean at a high angle.
It strikes NNW–SSE and defines the eastern and
southeastern edge of the Sicilian continental shelf,
marking the boundary with the oceanic-affinity crust
of the Ionian Sea to the east. Dip-slip displacement on
the Malta Escarpment amounts to some 3 km, and
where it intersects the coast of Sicily on the eastern side
of Mount Etna a series of active faults (the Timpe fault
system) produce scarps up to 200 m and fault planes
displaying both dip-slip and right oblique slip kinematic
indicators (Lanzafame and Bousquet, 1997; Monaco et
al., 1997). This major structure, although its continuity
is disrupted by interactions with other faults, has been
interpreted as passing through northeastern Sicily as a
series of structures which ultimately displace the Aeolian
arc by approximately 6 km in a right-lateral sense
The most important structure which intersects the
faulting associated with the Malta Escarpment is the
NNE–SSW striking Messina fault system. The 1908
Messina earthquake was attributed to a blind fault in the
Messina area (Valensise and Pantosti, 1992), and
although there is uncertain linkage between the faults
along the linear NE Sicily coast north of Etna, the
uniform strike of these faults provides good reason to
consider them as a group. This system defines the
northeastern coastline of Sicily bordering the Straits of
Messina, and produces fault scarps in the mid-Holocene
age surface of the Chiancone deposits on the eastern side
of Mount Etna and coast-bounding faults in the
Taormina area. These faults are thought to meet the
onshore expression of the Malta Escarpment (Timpe
faults) in the eastern Etnean area (Lanzafame et al.,
1997), but we stress that the Malta Escarpment-Timpe
faults and Messina fault system are different fault groups.
3. Data
The first four authors of this paper have together
examined the coastline of all Sicily, to re-evaluate