Page 5 - CatalanoInfuso&Sulli_1995

TECTONIC HISTORY OF THE SUBMERGED MAGHREBIAN CHAIN OF SICILY

ESE the Gela Thrust front (Sciacca offshore,
Fig. 2) and appears as a crostai salient
PalonnoMos. showing pre--late Miocene to middle
Pliocene compressional (or transpres-
- 1 D2 !S3S] D4 D5 - 6 IF4 km sional?) deformation. Structures con-
tinue southeastwards below the Gela
Fig. 5. Geologica/ cross-section along the Northern Sicily offshore constructed on the basis of Thrust System (Gela TS; Fig. 6A).
available reflection seismic lines. The geologica/ section runs from the Drepano Seamount According to Argnani (1989), Argnani
southeastwards to the Palermo Mts. offshore. 1, Plio-Pleistocene deposits; 2, Knbilian- et al., (1989), Antonelli et al., (1988),
Calabrian Units; 3, deformed Miocene clastic deposits; 4, Cretaceous-Palaeogene imbricates; Torelli et al., (1991) the area experi-
(? )basinal carbonates thrust units; (6) 5, platform carbonates thrust units. enced transcurrent deformation.

Mesozoic-Tertiary rocks of more mount-type deposits (i.e. Ammonitico The Gela Thrust System and its
northerly derived units are tectoni- Rosso), pelagic marly carbonates and foredeep
cally sandwiched between the Lower earliest Miocene open-shelf clastic car-
and Upper Miocene rocks (Fig. 3). bonates. These beds are known to crop The Gela TS ('Gela Nappe'; Ogniben,
(b) The carbonate substratum consists of a out in western Sicily as the Trapanese 1969) is a thin-skinned accretionary
wedge of Mesozoic ramp units, with and Saccense palaeogeographical units wedge (Figs 6, 7), which overthrusts its
internai duplex geometry (Fig. 3). (Catalano, 1987; Antonelli et al., 1988). foreland marine sediments (Catalano,
Transport direction appears to have 1987; Antonelli et al., 1988; Argnani,
been eastward and southeastward, 'Deformed foreland' 1989). It extends laterally into onland
with shortening decreasing southeast- southern Sicily where its thickness
ward. The internai stratigraphy includes The third area shows the character of a increases and widespread back-thrust
Triassic-Liassic carbonate platform de- deformed foreland. It is developed features are exposed (Grasso et al., 1991;
posits, overlain by Jurassic-Eocene sea- from the Adventure Thrust Front to Catalano et al., 1993b).

The Gela TS is formed of repeated
packages of folded and faulted deposits,
that are complexly thrust, mostly show-

NNE Gela Thrust Front ssw

l..eane we/1 iiiiiiiiii;;:::::=::::=====:::n o

2 NNE Pelagian Foreland

4 q10 + •

~~~~~ 6 12
B

o 2km 10 I

Pelagian Foreland ...13' 15'
cpSS\\6 ,..
Malto Graben Linosa ploreou Linosa Graben

..++++++++++++++++++ o '" "
2
12km

CJ
1

Fig. 6. Simplified geologica/ section across the Gela tectonic wedge and the rifted Pelagian foreland in its eastern sector. 1, Plio-Pleistocene
deposits; 2, Gela Thrust System; 3, Carbonate substrate of the Hyblean and Pelagian foreland (from the bottom: pre-Triassic, Mesozoic-
Palaeogene, Miocene); 4, basement (inferred).

© 1995 Blackwell Science Ltd, Terra Nova, 7, 179-188. 183