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RHEGMATIC-LIKE BASINS IN SICILY 5

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Fig. 3. Crustal sections across Eastern (A) and Western Sicily (B). A. l - Plio-Pleistocene clastic units; 2 - "Gela Nappe"; 3 -
Peloritani crystalline units; 4 - Sicilide Monte Soro units; 5 - Panormide units; 6- Sicilide Troina units; 7 - Numidian Flysch; 8 -
Sicanian units; 9- I-Iyblean foreland; l O- crust. B. l - Panormide units; 2- Imerese units; 3 - Trapanese units; 4- Sicanian units; 5-
Saccense units; 6- crust. <)>-main out-of-sequence low angle reverse faults. The thick lines are the main high-angle buried and emergent

regional-trending transpressional faults

tachment surfaces along the originai Sicilian multilayer. NEOTECTONIC FIELD DATA OF THE
During this kinematic stage disharmonic folding occurred, SICILY MAINLAND
which is generally represented by isoclinal geometries in the
less competent Liassic to Tertiary basinal sequences, and The neotectonic structural grain of Sicily mainland is
more gentle (mostly ramp anticlines) in the Triassic to Lias- represented by different geometries related to compres-
sic carbonate platfonn sequences. During a later kinematic sional, transcurrent and extensional deformational stages.
stage, another and deeper piggy-back thrust sequence cut the
previous multiduplex, producing more and more cut-off re- THRUST TECTONICS
lations.
Plio-Pleistocene thrust geometries characterise the
During the Africa-Europe collision, the occurrence of Northern and Centrai Sicily mainland. In Northern Sicily,
back-stop-like processes might be supposed (see Fig. 3). the thrusting is expressed by enveloped-like geometries in-
Field evidences in eastern Sicily are the regional back- volving Messinian-Early Pliocene deposits (Figs. 5 and 6),
thrusting ofthe "Antisicilide Nappe" overthe previously de- while in Centrai Sicily the thrust pile is represented by the
formed Peloritani element during the Early Langhian, as "Gela Thrust System" auctorum (Fig. l OB). The Plio-Pleis-
well as the Sicilide Nappe over the Oligo-Miocene Nu- tocene thrust sheets are cut by more recent dip- and strike-
midian Flysch in north-central Sicily. With this interpreta- slip fault systems.
tion, the Sicilide and Antisicilide sequences can be regarded
as the Cretaceous to Paleogene filling deposits of the Si- STRIKE-SLIP TECTONICS
canian basin and its eastward prolongation.
It is possible to define many of the most recent struc-
The crustal doubling (delamination) and the vertical tures characterising the Sicily mainland as the result of
discontinuities, as supported by the deep geophysical data large-scale strike-slip motions. These structures, at length
from the Baglio Inclusa and Alcamo areas (Colombi et al., recognisable in the island, express a regional, prevalently
1973; Giese & Reutter, 1978), and surrounding areas (Cass- E-W trending strike-slip dextral system with associated
inis et al., 1969; Morelli et al., 1975; Schutte, 1978), might mega-riedels (Fig. 13). The recognised associated structures
have determined unti! the Pleistocene the emplacement of are prevalently brittle and subordinately ductile structures
the Gela Thrust System (in this paper, it is northward ex- (Figs. 8-1 0).
tended versus the buried Sicanian wedge and its detached
Cretaceous to Miocene covers) ofthe Sicanian Thrust Sys- Severa! field observations indicate that the outcropping
tem over the gently deformed foreland (Hyblean and Sac- neotectonic brittle structures consist mostly of fault systems
cense domains).