Page 1 - Torelli2000

AFRICAN CONTINENTAL MARGINS OF THE MEDITERRANEAN SEA – Djerba, 22 - 25 November 2000

Cenozoic collisional and extensional structures among
Sardinia, Sicily and Tunisia (Central Mediterranean) : examples

and constraints from seismic reflection profiles

L. Torelli1, G. Carrara1, R. Sartori2 and N. Zitellini3

1 Dip. di Scienze della Terra, Univ. Parma, Italy
2 Dip. di Scienze della Terra e Geologico-Ambientali, Univ. Bologna, Italy

3 Istituto di Geologia Marina CNR, Bologna, Italy

INTRODUCTION
Within the Central Mediterranean the geology of the south-western Tyrrhenian Sea and of the
western end of the Strait of Sicily is still relatively poorly known. However, this marine area pre-
sents several aspects that may be relevant to the comprehension of the geologic evolution of the
entire Central Mediterranean.
Among the aspects worthy of interest are the following: i) the relationship between the
Tunisian and the Sicilian segments of the Maghrebian fold-and-thrust belt, ii) the distribution of
the Kabylo-Calabrian terranes, iii) the collision of the Sardinia-Corsica block, during its Neogene
rotation, with the African margin, and iv) the nature and evolution of extensional tectonics in the
Tyrrhenian basin, in the Strait of Sicily and in the Sardinia Channel, where the previous two areas
merge.
In order to understand the geology of the south-western Tyrrhenian Sea/western Strait of
Sicily, the acquisition of deep seismic profiles and a reprocessing of existing seismic data were
undertaken. In addition sampling and Well data available along the seismic profiles have been
taken in account. The results are here summarized as a geologic cross section derived from one
of these crustal scale seismic profiles (Fig. 1).
GEOLOGIC SETTING
The study area (inset of Fig 1) presents a complex arrangements of tectonic units derived from
both the European (internal massifs) and African domains. Its evolution was accomplished most-
ly during the Tertiary in relation to the the collision between Africa and Europe.
In this area, as in the whole of the Mediterranean basin, contraction and extension often
occurred at the same time. In particular, the opening of the Balearic basin, from Oligocene to
Early Miocene, and the ensuing rotation of Corsica-Sardinia, gave rise to a southeastward prop-
agating fold-and-thrust belt that involved internal terranes (Kabylo-Calabrian units) and part of
the African continental margin. Apparently, the shortening continued after the rotation of
Corsica-Sardinia stopped.

53 CIESM Workshop Series n°13