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330 A. Sulli / Tectonophysics 324 (2000) 321–336
overlying Tertiary deep-sea arkosic turbidites of
Aquitanian–Early Burdigalian age are here interpre-
ted as the roof thrust of the duplex systems.
Seismic profiles do not reveal prominent exten-
sional structures related to negative tectonic inver- Pleistocene basin filling is deformed in the lower
sion (as claimed by Tricart et al., 1990; Torelli
et al., 1992). Neither listric normal faults nor
thrust plane inversion in normal faults are visible
in our seismic lines. Furthermore growth struc-
tures, as well as large basins, are absent in the
Neogene–Quaternary successions. Crustal thin-
ning therefore appears to be mostly an inherited
geometry, which predates the orogenic stage.
The Drepano thrust front (Fig. 3) is the tectonic
boundary between Kabilian–Calabrian units and
Apenninic–Maghrebian units. It is traceable at
depth, where it also displaces some crustal reflectors lateral strike–slip movements cut off the main front
(Fig. 9), accounting for the partial overlap of the
‘Sardinian’ crust on the ‘Alpine’ crust. This front,
considered to be Middle Miocene in age (Beccaluva
Fig. 11. Geological structural map of the study area.
et al., 1986), underwent a reactivation, according
to a ‘thrust envelopment’ geometry, which involved
the basement after the Messinian. Fig. 9 shows how
the Messinian reflector plunges under the Kabilian–
Calabrian tectonic wedge, whilst the Plio-
part, where inversion tectonic structures occur. The
progression of the deformation is ‘in sequence’, as
deeper levels are involved in more internal areas
(Bally et al., 1985). This peculiarity is common to
other areas near the Sicilian mainland (Catalano
et al., 1998a) and seems to be linked to post-
Miocene tectonics that modified the morphotectonic
setting of the area. On the whole the pre-Messinian
tectonic transport exhibits a SE vergency, as pointed
out by the NE–SW-trending thrust fronts (Fig. 11).
The compressional post-Messinian features have a
general SSE transport direction. NW–SE right-
in several discrete portions (Fig. 11).