Page 14 - 36 Elevation of the last interglacial highstand in Sicily
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ARTICLE IN PRESS
16 F. Antonioli et al. / Quaternary International 145– 146 (2006) 3–18
Pleistocene terraces that are visible in the Marsala area Sicilian coastline into four sectors, each characterized by
above the MIS 5.5 terrace occurring at 34 m. different MIS 5.5 heights and uplift rates:
The inner margin of the GTS is found at an elevation Sector 1: NW Sicily: here we calculate a mean uplift
of 200 m in the Marsala coastal area and at about 400 m rate of 37 mm/ka, with a maximum of 224 and a
on the southern coast (Fig. 2). Notably, in the Marsala minimum of À40 mm/ka, leading us to regard this as a
area the younger terraces are cut into and below the quasi-stable area. Nevertheless, some dislocations in this
outer edge of the GTS, while in the south the GTS sector probably result from recently identified post MIS
surface appears to descend beneath the sea. It may be 5.5 strike-slip faulting that in some places continues into
that a Tyrrhenian terrace was formed in this area the late Holocene, for example at St. Vito where
(between Trifontane and Agrigento, Fig. 2) but has since Dendropoma platforms dated at only 650–400 years are
been drowned. Such subsidence could be linked, at least displaced (Fig. 3B).
in part to tectonic loading beneath the Gela frontal
thrust system. This suggestion is consistent with the Sector 2: S Sicily: along this coastline, some 350 km in
Quaternary depression of the Gela–Catania foredeep length, there appear to be no MIS 5.5 outcrops. The
farther east, while the emergence of the Hyblean inferred subsidence may be due to tectonic loading at
Plateau, unrepresented along the southern coast, may the Gela frontal thrust system.
be primarily related to the presence of major lower plate
structures such as the Malta Escarpment and the Scicli Sector 3: SE Sicily: in this area, dominated by the
fault zone (Fig. 2). Such speculations also appear Hyblean Plateau, we estimate a mean uplift rate of
consistent with the appreciable Tyrrhenian uplift along 85 mm/ka, with a maximum of 216 and a minimum of
the Monte Tauro–Augusta coast closest to the Malta À24 mm/ka. As with the NW sector we accordingly
Escarpment and with the Lampedusa data indicating regard this as a quasi-stable coast, based on the low
essentially no uplift southwards away from the thrust elevations of MIS 5.5 deposits, although affected by the
belt. proximity of the Malta Escarpment offshore. Adjacent
to this structure the MIS 5.5 terrace reaches its
The highest uplift rates occur north of the thrust front maximum elevation of about +32 m. Farther south
on Mt. Etna near Catania and at Taormina, places also along the coast near Siracusa, another terrace at 105 m
adjacent to major coast-bounding structures (Malta has also been proposed as MIS 5.5 (Bianca et al., 1999)
Escarpment and Messina fault system; Fig. 2). This although, in our view, this interpretation is not well
region is affected by north–south compression and supported by the available evidence.
east–west extension as well as possibly being influenced
by slab rollback and detachment and thermal inputs Sector 4: NE Sicily: here we estimate a mean uplift
from asthenopheric upwelling (Lanzafame and Bous- rate of 924 mm/ka, with a maximum of 1344 (corre-
quet, 1997; Gvirtzman and Nur, 1999). sponding to the eastern flank of Etna in close proximity
to the coast-bounding Malta Escarpment) and a
Finally, the overall main displacements in the minimum of 704 mm/ka. Regional north–south com-
Tyrrhenian coastal areas can be viewed as controlled pression results in east–west extension and rifting,
by overlapping mechanisms that can be summarized as possibly coupled with slab rollback and detachment
follows: large-scale regional uplift, subsidence and with associated isostatic uplift and asthenospheric
transcurrent processes, triggered by the evolution of upwelling. Within this framework, comparisons between
the Tyrrhenian basin. Localized uplift and subsidence MIS 5.5 and Holocene uplift indicators suggest a mean
are responsible for fault-bounded headlands and asso- acceleration in uplift of about 100%.
ciated coastal plains.
Acknowledgments
6. Conclusions We thank journal reviewers Paul Hearty and Carlo
Bartolini for insightful advice which helped to clarify the
In addition to compiling and evaluating all published contents of this paper.
Tyrrhenian shoreline data for the Sicily region, we have
discovered and dated two important new Tyrrhenian References
sections: a terrace outcrop at Taormina (with an ESR
age) and shoreline deposits at Cefalu` (with an AAR Abate, B., Di Maggio, C., Incandela, A., Renda, P., 1991. Nuovi dati
age). A new continuous survey of the Tyrrhenian inner sulla geologia della penisola di Capo San Vito (Sicilia NW).
margin has also been carried out over a distance of Memorie Societa` Geologica Italiana 47, 15–25 (in Italian).
about 85 km between E S. Vito and Trapani, involving
re-measuring elevations and establishing error bars at Abate, B., Ferruzza, G., Incandela, A., Renda, P., 1992. Ritrovamento
many sites. Overall, these data lead us to divide the di depositi a Strombus bubonius. nell’isola di Favignana. Rivista
Mineraria Siciliana 162, 37–46 (in Italian).
