Page 3 - Torelli2000

P. 3

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

The domain of the fold-and-thrust belt can be further subdivided into three sub-domains: i)
the Adventure foredeep, ii) the Egadi fold-and-thrust belt, and iii) the Kabylo-Calabrian units.

The foredeep basin is ﬁlled with Serravallian-lower Messinian sediments that were later short-
ened and partially detached from their substrate during the Messinian. Towards the northern
shoulder of Pantelleria trough some extensional faults, likely related to the above mentioned rift-
ing, cut the foredeep sediments and along a few of them volcanic bodies were emplaced.

In the Egadi fold-and-thrust belt a few shallow-dipping south-facing reﬂections can be
observed. They are Interpreted as thrust faults bounding the units of the African continental mar-
gin piled up southward during the Miocene.

Farther to the north, the terranes piled up belong to the Kabylo-Calabrian units. Following the
contraction, some of these thrust faults were reutilised in extension and gave rise to basins ﬁIled
with Plio-Quaternary sediments. Roughly at the boundary between the African and the Kabylo-
Calbrian units one of these Plio-Quaternary basin shows contractional structures. Such structures
are thought to be indicative of a recent episode of inversion tectonics.

In the area of the Kabylo-Calabrian units the reﬂectivity is very poor; however, short south-
dipping reﬂections can be observed. These reﬂections are interpreted as deﬁning rotated fault
blocks originated during the opening of the Tyrrhenlan basin.

This structural style becomes more evident moving towards the Tyrrhenian basin domain
where fault blocks and also syn-rift sediments can be recognised along the southern Tyrrhenian
slope. In the Tyrrhenian plain it is not possible to deﬁne a particular structural style but a
depocentre of Messinian evaporites shows up quite weIl. At the very end of the cross section
some faulted blocks, tilted northward, are bounded to the north by the Selli Fault. lt is worthy of
note that in the Tyrrhenian domain the PIio-Quaternary sediments, and in the Tyrrhenian plain
even the Messinian evaporites, are not affected by extensional faulting. Therefore, in this part of
the Tyrrhenian basin, the stretching occurred mostly in the early phase of opening. The PIio-
Quaternary extensional basins superposed onto the fold-and-thrust belt prove that extension
migrated southward in time (In some way keeping up with the southward migration of the thrust
front).

Using this cross-section and other deep regional seismic images we try to reconstruct the
Neogene kinematics of this sector of the Central Mediterranean, comparing the main deforma-
tive events of the area with the tectonic and sedimentary evolution of adjacent regions, namely
the Kabylo-Calabrian and Maghrebian units in Sicily and Tunisia.

55 CIESM Workshop Series n°13

1 2 3