GEOLOGICA CARPATHICA, JUNE 2005, 56, 3, 255271
Transtensional/extensional fault activity from the Mesozoic
rifting to Tertiary chain building in Northern Sicily
and PIETRO RENDA
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via U. La Malfa n. 153, 90146 Palermo, Italy; email@example.com
Dipartimento di Geologia e Geodesia dellUniversità, C.so Tukory n. 131, 90134 Palermo, Italy; firstname.lastname@example.org
(Manuscript received February 25, 2004; accepted in revised form September 29, 2004)
Abstract: Extensional structures of different ages characterize the Sicilian fold-and-thrust belt. Normal faults ranging in
geometry from stepped to listric and formed in different geodynamic settings significantly controlled the pattern of syn-
tectonic deposits. Since Mesozoic times Sicily has experienced deformation related to the opening of the Tethys Ocean.
Between the Upper Triassic and the Cretaceous normal, strike- and oblique-slip faults, developed in northern Sicily, in
the framework of a transtensional deformation regime induced by the oblique rifting of the African and European conti-
nental passive margins. Since Tertiary times a reversal in the general relative plate motion induced convergence, fol-
lowed by collision of the European and African margins. Neogene compressional deformations were locally associated
to extensional structures related to the orogenic wedge taper and to the Pliocene-Pleistocene Tyrrhenian Basin evolution.
The persistent activity of extensional structures at different times and within different tectonic pictures is magnificently
preserved in the following Triassic-to-Recent stratigraphic record: (i) carbonates were deposited on the Jurassic passive
margin, formed by neritic platforms and intervening pelagic basins; (ii) the Cretaceous extension in the Africa plate
boundary followed Late Triassic-Early Jurassic transtension due to Neotethys stretching; (iii) clastic deposition occurred
during Neogene chain building ahead of the advancing thrust front (foredeep deposition) and in the inner sectors of the
orogenic wedge (perched deposition in extensional setting); (iv) the perched-basin deposition at the rear of the wedge
was probably related to the extensional collapse of the taper during the Late Miocene and (v) the attenuation of previ-
ously thickened lithosphere corresponds to the onset of the Tyrrhenian stretching.
Key words: MesozoicTertiary, Sicilian Maghrebian Chain, modes of extension, basin formation, normal faults.
Introduction and objectives
Tectonic inversion, that is the switch from extensional to con-
tractional deformation regimes or vice versa, is an important
process in the evolution of collision mountain belts (e.g. Will-
iams et al. 1989). The early rift-basin history of many orogen-
ic systems is clearly preserved within their stratigraphic record
(e.g. the Alps: Gillcrist et al. 1987; Butler 1989) and, in turn,
mountain belts may be subject of late/or post orogenic col-
lapse (e.g. the Western Cordillera in North AmericaConste-
nius 1996). The effects of extensional deformations recog-
nized within orogenic systems generally subdivided into pre-
or post-thrusting events, the successive modifications of pre-
thrusting extensional structures during orogenic events and
their eventual reactivation during the onset of late or post-oro-
genic extension (Tavarnelli 1996) are not well documented.
The goal of this paper is to underline that the Sicilian Maghre-
bian Chain is characterized by a long history of extension,
starting with the formation of a passive margin and active
through the evolution of the fold-and-thrust belt up to its col-
lapse and to the consequent post-orogenic deformations.
In fact, carbonate platforms, belonging to the African pas-
sive margin and characterizing the Sicilian Maghrebian Chain,
developed during Mesozoic times under the crustal attenua-
tion regime which led to the opening of the Tethys Ocean
(Dercourt et al. 1986). From the Oligocene onwards, as a con-
sequence of the convergence of the African and European
plates, these platforms suffered contractional deformations
and were affected by folding and thrusting during the con-
struction of the Apenninic-Maghrebian Chain. Syn-orogenic
extensional strains, intense at shallow crustal levels, induced
the formation of basins in several domains of the evolving
chainforedeepforeland system, namely in the foreland, in
the foredeep and in the back of the chain (Oldow et al. 1993;
Keller et al. 1994; Tricart et al. 1994).
At shallow crustal levels of the Sicilian Maghrebian Chain
extensional tectonics mainly gave rise to syn-sedimentary nor-
mal faults recognized within the Mesozoicearly Tertiary pre-
orogenic successions and the upper Tertiary syn-orogenic and
post-orogenic successions. Syn-sedimentary normal faults are
also overprinted by Neogene thrust-related deformations.
The evidence of transtensional structures of different ages
and the stratigraphic record of Mesozoic extension has been
described by many authors (Truillet 1966, 1970; Wendt 1965,
1971; Bernoulli & Jenkins 1974; Catalano & DArgenio 1982;
Bouillin et al. 1992; Martire et al. 2000), and related to the
opening of the Neotethys Ocean. A younger episode of exten-
sional tectonics, connected to the evolution of the orogenic
256 NIGRO and RENDA
Fig. 1. A Tectonic sketch of the Central Mediterranean. 1 Front of the Apenninic-Maghrebian Chain (in the Ionian Sea: front of the
Calabrian Ridge); 2 front of the Kabilides units and Calabrian Arc borders. B Tectonic sketch of Sicily. 1 Etna volcano; 2 Up-
per Pliocene-Pleistocene deposits (foredeep in Southern Sicily); 3 deformed Miocene-Upper Pliocene foredeep (Gela Nappe p.p. in the
Caltanissetta Basin); 4 Peloritani units and related Oligocene-Miocene syn-tectonic deposits; 5 Sicilidi Units and related Oligocene-
Miocene syn-tectonic deposits; 6 carbonates of the Panormide Units and related Oligocene-Miocene syn-tectonic deposits; 7 pelagic
carbonates Imerese-Sicani Units and related Oligocene-Miocene syn-tectonic deposits; 8 units derived from the Western sector of the
Hyblean-Pelagian Block of Sicily (compressional deformation inside) and related Oligocene-Miocene syn-tectonic deposits; 9 South-
eastern sector of the Hyblean-Pelagian Block of Sicily (foreland, extensional deformation inside). C Schematic crustal section across the
Sicily belt, showing the structural style of the extended orogen. Cross-section only shows the main Pliocene-Pleistocene strike-slip struc-
tures. The crustal and sub-crustal thinning factors (McKenzie 1978; Royden & Keen 1980) have been calculated; for their computation we
assumed an initial crustal thickness ranging from 30 km in the foreland areas to 35 km in the inner sector of the chain (Pepe et al. 2000). The
lithospheric initial thickness ranges from 100 km in the external areas to about 200 km in the chain roots. In the strong subsiding sectors of
the analysed transect the δ factor is about 3, the β factor is equal to 5, whereas the necking level is located at about 10 km (Pepe et al. 2000).
The water depth and thickness of the submerged late TortonianPleistocene basin fill deposits related to the stretching factors fit the theoret-
ical values proposed by McKenzie (1978).
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 257
wedge taper (Kezirian et al. 1994; Giunta et al. 2000) and to
large-scale rotations (Oldow et al. 1990), has affected this
chain since Miocene times.
In this paper we analyse the extensional tectonics along the
Sicilian Maghrebian Chain, from pre-orogenic to orogenic
processes by using several examples and we propose an at-
tempt to extrapolate the role of these tectonics in the formation
of Mesozoic-Tertiary basins for the Western Mediterranean
orogens. The Mesozoic transtensional/extensional tectonics
was produced during the rifting processes leading to the open-
ing and evolution of the Neotethys Ocean. The activity of
transcurrent/normal faults induced basin formation and con-
trolled facies and thickness distribution of the rift-basin depos-
its. The Tertiary syn-collisional extensional tectonics con-
trolled the basin formation in the orogenic wedge. Normal
faults developed ahead of the advancing thrust front deter-
mined the accommodation space for foredeep sedimentation.
Structural setting of Sicily
Sicily, located between the Apennines and North-Africa, is
the easternmost sector of the Maghrebian fold-thrust belt,
formed during the Neogene (Fig. 1A). In the mainland, a
southward-tapering orogenic wedge is exposed and the thrust
front forms an arcuate salient in Southern Sicily and in the
Sicily Channel and Ionian Sea (Fig. 1A).
The Sicilian Maghrebian Chain, corresponding to a thrust
beltforedeepforeland system (Ogniben 1960; Broquet et al.
1966; Grandjacquet & Mascle 1978; Catalano & DArgenio
1978, 1982), extends with a dominant WE trend from the
Trapani Mts to the Peloritani Mts (Fig. 1B) and it is formed by
a stack of imbricate foreland-verging folds and related thrust
sheets (Grandjacquet & Mascle 1978; Bianchi et al. 1987;
Roure et al. 1990; Catalano et al. 2000). The north-eastern
corner of Sicily (Peloritani Mts), composed of sedimentary
and crystalline terrains, is a belt of controversial origin, inter-
preted as a microplate interposed between the African and Eu-
ropean margins during the Mesozoicearly Tertiary times
(Amodio Morelli et al. 1979), or as a segment of the European
margin (Bouillin 1986; Bouillin et al. 1992).
The tectonic units were piled along shallow thrusts and
were transported southwards during the construction of the
Neogene Apenninic-Maghrebian fold-thrust system (Ogniben
1960; Broquet et al. 1966; Scandone et al. 1974; Catalano et
al. 1979; Catalano & DArgenio 1982).
The syn-tectonic deposits lying on the stacked chain units
are progressively younger toward the foreland, and were af-
fected by contractional deformations acquired during the
southward migration of the thrust front (Caire et al. 1960; Bro-
quet et al. 1984; Roure et al. 1990; Nigro & Renda 2000).
These deposits are widespread in central Sicily, in the Nebrodi
Mts and in the southern slopes of the Madonie Mts (Fig. 1).
The south-eastern portion of the island is occupied by the
Hyblean Foreland representing the emergent sector of the Pe-
lagian Block (Winnock 1981) which extends from Tunisia
through to the Sicily Channel.
Compressional tectonics linked to the chain building mainly
developed through crustal block rotations and oblique-slip
thrusting (see Ben-Avraham & Grasso 1990, 1991; Oldow et
al. 1990; Reuther et al. 1993; Lickorish et al. 1999; Nigro &
Renda 2001a for field and paleomagnetic evidence).
Starting from the Northern Sicily coast, a process of crustal
attenuation and subsidence has affected the chain since Late
Tortonian times (Kezirian et al. 1994; Giunta et al. 2000;
Fig. 1C). Repeated failure of the orogenic wedge also oc-
curred during the PliocenePleistocene times (Nigro & Renda
The stratigraphic successions of Sicily indicate a deposition
onto differently subsiding and fault-controlled blocks (Scan-
done et al. 1974; Biju-Duval et al. 1977; Catalano &
DArgenio 1978, 1982), displaying a facies distribution with
carbonate platforms and intervening pelagic basin during Me-
sozoicearly Tertiary times (Fig. 2).
Palinspastic restorations of the Sicilian Maghrebian Chain
(Catalano & DArgenio 1978, 1982; Catalano et al. 1979;
Dercourt et al. 1986; Casero & Roure 1994) indicate a physio-
graphically sinuous continental shelf margin, represented by
Fig. 2. Stratigraphic sketch of Sicily. Carbonate sedimentation
represents the pre-orogenic strata. Mesozoic-lower Tertiary plat-
forms are known as Peloritani (partly), Panormide and Hyblean-
Pelagian, while the intervening pelagic basins are known as Sicilide
and Imerese-Sicano. The Sicilide Basin was characterized by tur-
biditic deposition. Clastic deposits represent the Tertiary syn-tec-
tonic strata filling the basins located inner and outer with respect
to the thrust front.
258 NIGRO and RENDA
salients and recesses (Scandone et al. 1974; Catalano &
Structural pattern of the extensional structures
within the Sicilian strata
Various scale normal faults, recognized in Sicily and pro-
duced by extension of the crust, are here ascribed to four main
We focused mostly on the north-western part of the island
featuring many tectonic units (sites A to F; Figs. 310).
Late TriassicEarly Jurassic
Normal/transcurrent fault systems displace the Upper Trias-
sic-Lower Jurassic strata of the Western-Northern Sicily car-
bonate platforms, showing a mostly NS or EW orientation
(Trapani and Eastern Madonie Mts; sites A and B in Fig. 3, re-
spectively). Locally preserved slickensides, with pitch indicat-
ing a gently-dipping slip vector, allowed us to recognize later-
al displacements for strike-slip deformation mechanism.
Slickensides and calcite fibres show left-lateral and, to a
smaller extent, right-lateral displacements.
Dip-slip faults (dipping 30° to 60°) are also present, with
not always well preserved kinematic indicators and locally
showing extensional displacements.
Transcurrent faults are characterized by damage zones in
which strike-slip horses developed (Fig. 3B), with associated
joints and spaced cleavage.
Facies and thickness distribution of the Lower Jurassic-
Lower Cretaceous pelagic deposits and the stratal relation-
ships with their substrate (Wendt 1965; Mascle 1979; Tri-
maille 1982) suggest tilting of faulted blocks along the
carbonate platform-basin boundaries. In several sites (Fig. 3A)
Middle Jurassic pelagic strata onlap and lie on the carbonate
platform faulted strata. The lithofacies of the pelagic strata in-
volved in the strike-slip faulting range from hemipelagic
(Fig. 3A) to condensed (Figs. 4A, 5E).
Carbonate or dolomitic breccias, ranging in thickness from
a few centimeters up to several hundred of meters (Trapani
and Palermo Mts, respectively), are present within the pelagic
strata near the transcurrent fault strands.
The faults with lateral displacements locally exhibit oppo-
site dips forming flower structures (Fig. 3A) with widespread
Fig. 3. Mesozoic strike-slip deformations in Western Sicily (faults are plotted in the stereonets). A Negative flowers affecting the Up-
per Triassic carbonate platform strata and the Lower Liassic pelagic strata (left side of photo) in the Trapani Mts (site A). The Liassic de-
posits overlay the platform during faulting. The Dogger-Malm unfaulted strata post-date deformation in the site. B Transcurrent fault
displacing carbonate platform strata in the Eastern Madonie Mts (site B). Erosion occurred before the Upper Cretaceous unconformable
deposition of the pelagic deposits. See text for further explanations.
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 259
Fault breccias are also present with thickness decreasing
eastwards from a few meters (Trapani Mts) to many tens of
meters (Palermo Mts), where tilted blocks of carbonate plat-
form strata are affected by paleokarst structures (Ferla & Bom-
Fig. 4. Examples of Jurassic and Cretaceous tectonics (faults are plotted in the stereonets). A Extensional-transtensional faults affect-
ing the Upper Triassic-Lower Liassic carbonate platform-condensed pelagic deposits in the Southern Trapani Mts (site C). Normal fault
activity reveals the wedge geometry of the Dogger growth deep-water strata overlying the carbonate platform. B Extensional tectonics
during the DoggerMalm is represented by extensional fractures filled by pelagic deposit of this age. C Extensional tectonics occurred
during the Cretaceous. Widespread small-scale structures, corresponding to sub-vertical extension veins truncated by bedding-parallel
stylolites, indicate extensional deformation. D Syn-sedimentary normal fault affecting the Cretaceous pelagic strata are characterized
by upwards decreasing of displacement and are truncated by load stylolites.
The present-day orientation of these faults is mostly NS in
site A (Trapani Mts). Instead, in site B (Eastern Madonie Mts)
the orientation of the faults affecting the carbonate platform
deposits is on average WE and Upper Cretaceous basin de-
posits lie over the fault zones (Fig. 3B).
260 NIGRO and RENDA
The Lias-Dogger pelagic (locally condensed) beds overly-
ing the Triassic carbonate platform strata (Fig. 4A) define a
typical wedge growth pattern. These strata are mildly folded
and unconformably covered by the Middle Jurassic deep-wa-
ter deposits. These elements, in combination with observed
block-tilting phenomena, may result from the development of
roll-over structures during deformation.
Extensional fracture systems, locally filled by Dogger-
Malm deposits (Fig. 4B), are present in the hanging-walls of
the faulted blocks, with spectacular examples in the hinge re-
gions of roll-over anticlines (Southern Trapani Mts).
In Western Sicily (Trapani Mts), Cretaceous extensional
tectonics are mainly represented by various scale normal
Fig. 5. Example of Cretaceous extensional tectonics in the Southern Trapani Mts (site C). (A) 100 m-in-scale listric normal fault affecting
the basin-plain deposits. Listric normal faults fade out upsection within the Cretaceous strata, exhibit various relationships with bedding, and
are characterized by stepped geometry defined by alternating, wide (up to 100 m) sub-horizontal flats connected by low-angle extensional
ramps. The Upper Cretaceous strata post-date faulting. Associated mesoscopic structures are abundant, and mainly consist of fault fans, in
which antithetic normal faults are widely associated with the synthetic master faults. Syn-sedimentary meso-scale structures are recorded in
the footwall. These are represented by extensional fans, with master and antithetic fault sets (B), conjugate set of planar faults (C) and exten-
sional duplexes (D). These sets were probably generated prior to bed tilting during Miocene deformation, because their obtuse bisectors are
normal to the bedding in both hinge regions and limbs of the compression-induced gentle anticlines. The Cretaceous extensional tectonics
followed the Early Jurassic transtension. In photo E (orthogonal to photo A) the flat of the Cretaceous listric normal fault cuts a transtension-
al fault sheaf. The Early Jurassic tectonics induced rapid drowning of the Lower Lias carbonate platform, as shown by the thin condensed
horizons over the neritic carbonates. Faults are plotted in the stereonets. See text for further explanations.
faults, mainly with a trend at low angles to a mean WE direc-
tion, that is normally to the Middle Jurassic transtensional
faults (see stereonets of Figs. 4 and 5).
Bedding-parallel stylolites and bedding-normal en-échelon
calcite veins (Fig. 4C), the most representative syn-sedimenta-
ry extensional structures, show evidence of a simultaneous de-
velopment during the same deformation.
Syn-sedimentary normal faults, characterized by an upward
decrease of displacement along their surfaces, pre-date the di-
agenetic stylolites (Fig. 4D). Soft-sediment deformation is
also suggested by fault tips accommodated downwards by
folding (Fig. 4D).
Examples of syn-sedimentary Cretaceous extensional struc-
tures are also shown in Fig. 5. Cretaceous normal faults have
locally experienced deflection or folding as a consequence of
the superimposed Neogene contraction (see Fig. 5A).
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 261
Fig. 6. Miocene extension during folding and thrusting in the Trapani Mts, followed by Late Miocene (?)-Pliocene extension (site D). Com-
pressional structures are represented by south-verging folds and reverse faults, subsequently northwards tilted due to the activity of a north-
dipping listric normal fault. 1 kilometer-in-scale contractional structure is represented by a ramp-anticline in which the forelimb is over-
turned (A). The thrusting provided the geometric superposition of the slope/basinal deposits over the Western extent of the carbonate
platform. Metric-in-scale structures indicate extension during folding/thrusting (as in photo D) and after compression (photos B and C).
Post-folding extension is represented by innerward-dipping normal faults, which cut folds and cleavage (photos B and C). Locally, previous
shear zones have been re-utilized and negatively inverted. Intra-folding extension (photo D) is already represented by foreland-dipping nor-
mal small faults, generally located in the hinges of the drag folds. These faults may represent the effect of the activation of synthetic struc-
tures during thrusting coupled by shearing. See text for further explanations.
In Fig. 5E a Cretaceous normal fault parallel to bedding de-
fines an extensional flat truncating older faults which affect
the carbonate platform and the Jurassic condensed strata.
Several vertical faults with oblique-slip kinematics offset
beds or slump horizons at the outcrop-scale, act as transfer
zones from one decollement horizon to another, accommodat-
262 NIGRO and RENDA
ing both flexural shear and producing significant variations in
Oligocene-Miocene interplay between compression and ex-
Since Oligocene times, the Sicilian passive margin has ex-
perienced contraction and was affected by thin-skinned, pig-
gy-back thrusting (terminology after Butler 1987) that pro-
duced significant displacements towards the southern foreland
(Broquet et al. 1966, 1984; Catalano et al. 1979; Nigro & Ren-
Stepped thrust faults with ramp-flat geometries and with ki-
lometric spacing of the ramps are recognized.
Due to the occurrence of detachments within the multilayer,
thrust-related folding produced multi-harmonic structures,
splays and duplexes. In particular, folding (one to several hun-
dred meters in size, related to the rheology of the local strati-
graphic sequence) was accommodated by flexural-slip and
buckling mechanisms. The normal limbs dip shallowly north-
to-northeastward, whereas the forelimbs are steeply dipping
southwards, or overturned northwards, defining a clear south-
ern vergence (Fig. 6A). These structures generally nucleated
by steeply N-dipping thrusts.
Faulting and folding developed under simple shear. Flex-
ural shear related structures (such as striae on bed surfaces)
orthogonal to the fold axes have been observed, mostly with-
in the Cretaceous pelagic strata. The simple shear strain in
the thrust hanging-walls may result in a reduction in the rate
of displacement near the base of the asymmetric ramp anti-
clines and permits us to identify overturned thrust-related
folds (Fig. 6A). Minor structures related to shear consist of
layer-normal pressure-solution cleavage and layer-parallel
shear planes. The spacing of the cleavage domains is gener-
ally 1 cm or less in the Upper Cretaceous deposits overlying
the Jurassic basins (see Fig. 6). The mean bedding cleavage
intersection lineation trends WE. No axial-plane cleavage is
recorded in the Upper Cretaceous strata overlying the slight-
ly deformed carbonate platform in the Southern Trapani Mts
(see Figs. 5 and 9). Folding-related cleavage is more and
more developed northwards, in the Trapani Mts between
Trapani and the S. Vito Peninsula, where the Western Sicily
chain units are exposed.
Extensional strains locally form within contractional fold-
ing. Intra-folding extension is represented by small normal
faults located near the hinge of the minor drag folds along the
100 m scale limbs (Fig. 6D). The high ratio of simple shear
may have induced vertical thinning coupled to fold amplifica-
tion and asymmetry.
In the fold outer arcs, the strong mechanically competent
horizons are broken by extensional faults and fractures. Small-
scale extensional faults located in the overturned fold limbs
could result from fold amplification and/or fold-hinge collapse
Extensional structures, corresponding to foreland-dipping nor-
mal faults (Fig. 7), in the forelimbs of the thrust-related folds,
such as asymmetric ramp anticlines, have also been observed.
Fig. 7. Foreland-dipping normal faults in the forelimb of a metric-
scale blind thrust (Southern Trapani Mts; site E). See text for further
Normal faults have also been recognized in the foreland de-
The abrupt change in thickness near the hinterland-dipping
reverse faults has been commonly observed and interpreted by
Giunta et al. (2002) as the result of normal fault positive inver-
sion during contraction (Fig. 8).
Late Miocene extensional tectonics
Post-folding extension is mainly represented by normal
faults with stepped geometry, generally northwards dipping,
towards the Tyrrhenian Sea.
Stepped normal faults widely affect the Northern Sicily suc-
cessions, where the lower terminations are generally isolated
fault surfaces defining extensional fans. Sometimes, they are
observed to merge within upper detachments to define exten-
sional duplexes (Fig. 9B)
Steeply-dipping normal faults affect the back-limbs of the
thrust-ramp anticlines with geometries which led to elimina-
tion of the effects of extensional deformation through passive
back-tilting of the hanging-walls, and permit to reconstruct the
original contractional architecture of the stacked thrust pile
The extensional detachments are mainly located at the base
of the Mesozoic carbonates, Cretaceous basin-plain deposits,
and Oligocene-Miocene foredeep deposits.
Tilting and repeated faulting during extension are suggested
by development of lozenge-shaped, fault-bounded basins
(Fig. 10B). Mesoscopic normal faults are arranged to form
two or more variously dipping fault systems, where fault over-
printing relationships are common. Both systems of mesos-
copic faults appear tilted and displaced by steeply dipping
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 263
Fig. 8. Examples of inverted structures in Western Sicily. The two cross-sections show positive inversion of normal faults, foreland-dipping
in example A, and chain-dipping in example B. 1 Pliocene-Pleistocene deposits; 2 undifferentiated Upper Tortonian-Messinian de-
posits (a); distinguished in cross-section A in Tortonian deposits (b) and Lower Messinian sandstones (c); 3 Serravallian-Lower Torto-
nian deposits; 4 Oligocene-Lower Miocene deposits; 5 Mesozoic carbonate platform deposits. GI in the right-hand side is the growth
index, defined as (hangingwall thicknessfootwall thickness)/footwall thickness. See text for further explanations.
normal faults, particularly developed in the Palermo-Madonie
Mts towards the Tyrrhenian coast.
Cataclastic zones several meters thick are present at the base
of the Mesozoic carbonate platform deposits. These catacla-
sites consist of cemented breccia, with clasts ranging from
coarse- to medium grained.
Extensional faults are characterized by remarkable varia-
tions in strike, from WE in Western Sicily to NWSE in the
more easterly domains. Fault-slip data indicate a normal kine-
matics. Locally, two sets of calcite fibres are superposed along
the fault surfaces. The earlier kinematic indicators have a low
pitch, suggesting re-activation of pre-existing oblique-slip
faults under extensional deformation conditions.
The activity of these extensional detachments produced in
places tectonic superposition of younger rocks above older
ones, with cut-out of lithostratigraphic units present elsewhere
within the Sicilian successions (Fig. 10A).
High-angle fault strands truncate the Oligocene-Miocene
thrust faults, folds and the extensional detachments of the
Northern Sicily belt, locally also producing metric to kilomet-
ric deformations within the Pliocene-Pleistocene deposits.
The structural data summarized in the previous sections al-
low us to reconstruct the paleotectonic evolution of northern
Figure 11 shows the modes of extension recognized in
Northern Sicily since the Mesozoic.
Strike-slip mechanisms, active in the Maghrebian passive
margin during Late TriassicEarly Jurassic times (Fig. 11A),
connected with the plate margin rifting and consistent with a
general transtensional regime, controlled the development of
high subsidence sedimentary basins. Fragmentation of the tid-
al platform, increasing of the subsidence (see the abrupt facies
change in carbonates, from tidal to pelagic), local uplift and
emersion episodes (see the hard grounds and paleokarst struc-
tures within the platform carbonate succession; Ferla & Bom-
marito 1988) and presence of irregular tectonic depressions
within the carbonate platform (locally with deposition under
anoxic conditions Catalano & DArgenio 1982) testify to
these Late Triassic-Early Jurassic transtensional tectonics.
Fault escarpments around these tectonic-controlled platform
margins produced a progressive areal decrease of the neritic
depositional domain and the consequent re-sedimentation of
thick wedges of carbonate breccias (Fig. 2).
Transcurrent and orthogonal normal faulting developed
since the Jurassic, as the shallow expression of the passive
margin development. The orientation of these faults allow us
to reconstruct the pattern, which is summarized in Fig. 11A.
The Lias deformation acts through strike-slip faults
(Fig. 11A1), which determinate roughly tectonic depressions.
In Sicily the Upper Triassic-Jurassic extensional tectonics
(strike-slip faults trending perpendicular to coeval listric nor-
mal fault systems) could be related to the rifting of the African
margin induced by opening of the Neotethys Ocean. The
available paleomagnetic data (Nairn et al. 1985; Grasso et al.
1987; Oldow et al. 1990), indicating the Sicilian belt experi-
enced clockwise block rotations from 30° to up 120° during
264 NIGRO and RENDA
Neogene time, seem to support this hypothesis. The restored
Jurassic strike-slip and normal fault trending, from NS to
NWSE and from WE to NESW, respectively, and their
distribution indicate a WNWESE trending sinistral shear
The Dogger-Malm up to Cretaceous tectonic subsidence re-
lated to crustal attenuation also dominated the Sicilian Magh-
rebian Chain. Normal fault activity represents the main mode
of deformation in this time (Figs. 4 and 5) and roll-over anti-
clines developed around the edges of the carbonate platform,
characterized by extensive re-deposition processes (Bernoulli
& Jenkins 1974).
A high extension rate vs. subsidence rate is suggested by the
vertical facies trend of Jurassic pelagic carbonates, indicating
a progressive deepening of the pelagic sediments sharply su-
perposed onto shallow-water neritic carbonates and a further
drowning of relict, adjacent carbonate platform domains (Cat-
alano & DArgenio 1982; Casero & Roure 1994). This strati-
graphic relationship is indicative of a more uniform, high rate
of crustal attenuation.
Fig. 9. Post-thrusting extension in the Southern Trapani Mts (A and B; site C) and Palermo Mts. (C; site F). In the Southern Trapani Mts,
examples of normal faults are still well recorded in the Upper Cretaceous pelagic deposits of the Scaglia. Normal faults mostly have low-an-
gles, wide flats and displace both the Mesozoic strata and the Middle-Upper Miocene clays deposits (see geological cross-section). The Mi-
ocene normal faults post-date the extensional structures of Figs. 4 and 5 because they cut the load stylolites and displace the Upper Creta-
ceous extensional veins, faults and fractures. Miocene extensional flats run along different stratigraphic levels, to form extensional horses
(A) and duplexes (B). Local re-activation of previous compressional structures, such as roofs/floors bounding duplex, has been recognized
(lower-left side of photo B). Scale invariance is represented in photo C, where a listric normal fault displaces the back limb of an older ramp
anticline, determining the backslide of the tectonic unit, their passive rotation and in consequence roll-over geometries. See text for further
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 265
Fig. 10. Post-thrusting normal faults in places determined a high rate of stretching and chain decoupling. Low-angle normal faults (ex-
tensional detachments) are wide in length and are mostly located at the base or top of the less competent successions. Low-angle normal
faulting (see stereonet) and passive rotation during extensional tectonics development seem to have determined tectonic elisions of
lithostratigraphic members within the Sicilian successions and mechanical contacts with younger-on-older geometry (A). Along ramps,
repeated faulting and rotation may have determined lozenge geometries (chaos-like structures of Wernicke & Burchfiel 1982; photo B).
See text for further explanations.
The high extension rate also led to a sudden physiographic
uniformity of the passive margin during Cretaceousearly
Tertiary times. This tectonics could be interpreted as a shear
sense reversal of transform faults of the Neotethys Ocean.
The Cretaceous small extensional faults may represent the
shallow expression of the activity of the roll-over anticlines
which persisted from the Jurassic (Fig. 11A2).
Collisional tectonics and the consequent crustal asymmetri-
cal thickening (Channel & Mareschal 1989) initiated during
Oligocene times. The modes of extension during these colli-
sional deformations, in both the back and frontal sides of the
orogenic wedge (Figs. 6, 7, 9 and 10), controlled the deposi-
tional pattern of sediments within piggy-back and foredeep
basin setting. The normal faults, similar to the foreland-dip-
ping duplexes of Boyer & Elliott (1982) and particularly in-
tense in the frontal parts of the orogenic wedge during Oli-
goceneMiocene times, dip away from the local tectonic
transport (Fig. 7).
During the Neogene contraction, Mesozoic normal faults
were reactivated for the thrust front migration towards the
foreland (Fig. 11B) and the syn-depositional faulting is sug-
gested by the abrupt thickness change of the deposits near the
faults. The fold amplification under a simple shear allowed the
formation of normal faulting in the limbs of the ramp anti-
clines (Fig. 11C).
As depicted in Figs. 12 and 13, basin formation during the
Sicily chain building may be in part controlled by extension,
both in the inner sector and external to the thrust front. The
distribution of facies and thickness of Oligocene-Miocene
syn-tectonic deposits supports the model of Fig. 13, where a
266 NIGRO and RENDA
Fig. 11. Modes of extensional tectonics recognized in Sicily since the Mesozoic. (A) The scheme summarizes the fault pattern affecting the
passive margin during the Jurassic. It is represented by transcurrent faults orthogonal to dip-slip normal faults. The tectono-sedimentary his-
tory is depicted in the schemes A1 and A2. Syn-sedimentary transtension affect the Triassic-Liassic strata. Then Dogger-Malm deposits rep-
resent the post-tectonic deposition and a new extensional tectonics developed in the Cretaceous. The Mesozoic normal faults were in places
positively inverted during contraction, as depicted in (B). Extension due to normal faulting is suggested by growth strata inducing thickness
change near the faults. Folding of foreland-dipping normal faults may occur during positive inversion for thrust front migration toward the
foreland, as shown by the scheme in the lower part of the figure. The orientation of inherited structures with respect to the tectonic transport
direction permits some remarks on the concepts of re-activation and inversion. If the older fault is antithetically oriented with respect to the
new thrust faults, then it may be more easily rotated or folded (see scheme in the lower part of the Figure). Folding of the fault surface may
apparently change the geometrical position of the fault-blocks, where a folded pre-existing extensional footwall block may partly seem to be
a hangingwall during subsequent compressional tectonics. (C) Extension also occurred during contraction-related folding. The post-thrust-
ing extension is represented mostly by the negative inversion of the thrust faults (D). It allows us to determinate roll-over geometries and the
overall backsliding of the tectonic units. The stretching of the chain was realized through the repeated faulting and the passive rotation of
blocks, allowing the formation of lozenge-like geometries and local elision of stratigraphic sequences within the multilayer (E). See text for
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 267
Fig. 12. Shear mechanisms during thrusting may activate Riedel shears (like R-shears), some of these fitting well with the foreland-dip-
ping normal faults active outside the thrust front (upper part of the figure). Invariance scale of deformative mechanisms allow us to pro-
pose that normal faulting may occurs in the foredeep basin during emplacement (lower part of the figure). In an deforming wedge system,
lithospheric flexure of the lower plate for chain loading is mostly realized through normal fault activation. Normal fault domain is present
as far as toe region of the wedge, where extensional forces may propagate up into the foredeep deposits. Normal faulting produces ac-
commodation space for clastic filling and may be more easily developed if the thrusting occurs under non-zero vertical simple shear. Pos-
itive inversion of normal faults in the lower plate occurs due to the thrust front migration forelandwards.
mild lithospheric flexuring developed in response to the
thrust-induced loading. The scheme of Fig. 13A indicates the
thickness and facies distribution of foredeep deposits in Sicily.
These deposits are composed of rocks eroded from the evolv-
ing thrust belt. Their thickening towards the foreland, and the
vertical facies trends support the hypothesis of normal fault
activity in both the thrust front and in the peripheral bulge. As
shown in Figs. 7 and 8, foreland-dipping fault systems may
have created the depressions where clastic deposition oc-
curred. These faults are antithetic with respect to more con-
ventional hinterland-dipping faults that were developed in the
peripheral bulge. In Sicily, in domains located ahead of the ad-
vancing thrust fronts, the development of syn-thrusting nor-
mal faults occurred extensively. These structures (masters and
minor antithetic) dip both foreland and hinterland (Fig. 8),
leading to development of an asymmetric foredeep basin. The
reactivation of the Mesozoic normal faults probably contribut-
ed to the development of the foredeep basin, as described by
Scisciani et al. (2001) in the Apennines. These normal faults
were inverted during the migration of the thrust fronts toward
the foreland, as suggested by the data shown in Fig. 8.
The high crustal thickening due to thrust stacking
(Fig. 13B) exceeded the critical taper of the orogenic wedge.
The onset of Miocene extensional tectonics characterized by
low-angle normal faults (Figs. 9 and 10) results from the col-
lapse of the orogenic wedge related to excess of the critical
taper threshold, and led to restoration of an internal sub-criti-
cal taper condition. The flats of these fault are regionally de-
veloped, defining km-scale extensional detachments (sensu
Lister et al. 1991), usually forming low-angles with the bed-
ding and locally reactivating pre-existing mechanical anisotro-
pies, such as thrust surfaces (for example, lower-left sector of
Fig. 9). This extensional episode is manifested by hinterland-
dipping, low-angle detachments responsible for inducing a
hinterland glide of the uppermost Maghrebide tectonic units.
These normal faults cut downsection through the stratigraphic
268 NIGRO and RENDA
sequence of the tectonic pile towards the deepest parts of the
orogenic system, where they are imaged at crustal depths, as
shown by the crustal profile across the Sicilian belt (Fig. 1C).
In the Sicilian mainland the detachment fault systems develop
under brittle conditions, whereas in the Tyrrhenian offshore
the upper level of necking recognized by Pepe et al. (2000)
may represent the brittle-ductile transition zone.
Perched deposition (molasse) occurred within elongated de-
pressions during activity of the low-angle detachments
(Fig. 13C). The faulting development was accompanied by
block tilting since Tortonian time and is suggested by the fa-
cies distribution of the clastic deposits and by their relation-
ships to the mobile substratum. Upper Miocene deposits over-
lie the faulted back-limbs of thrust ramp anticlines (Giunta et
Fig. 13. A This scheme shows the Miocene foredeep deposits and their stratigraphic thickness distribution in Sicily. The provenance of
filling materials is mostly from the chain, allowing us to recognize extension outside the chain front by foreland-dipping normal faults. B
Foreland-dipping normal faults reduce flexure due to loading in the back of the wedge. Low deflection during thickening crust induces a rap-
id increase in the wedge slope, which becomes the main source area for sediment supply in the foredeep. C For attainment of high values
of the wedge slope angle, mechanical instability occurs, counterbalanced by extension in the inner sectors. The cyclical development of su-
percritical taper values in the Sicilian wedge occurred during the PliocenePleistocene (Nigro & Renda 2001b) and has been expressed by
extensional failure in its back and the coeval resedimentation processes in its toe region. See text for further explanations.
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 269
Fig. 14. Modes and sequence of extensional structures developed in Sicily from the Mesozoic. From top to bottom, extensional dynamics
occurred during the Mesozoic, allowing basin formation during the rift stage of the Neotethys and the drifting of the African passive con-
tinental margin. In particular, during the late Triassicearly Lias, the basin formation was dominated by transtensional tectonics, as a
consequence of the Maghrebides rifting stage. Transtensional tectonics continued during the Jurassic, when the passive margin had the
maximum rate of extension. During the Late Cretaceous the further extension may have been related to the Sicilide basin opening. This
tectonic episode may also represent the evolution of the Neotethys shear inversion. During the Neogene the Sicilian chain was built and
propagated forelandwards under thrust tectonics. The building Sicilian wedge experienced extension both in the foredeep and in its back,
reflecting collapse due to supercritical taper conditions. The wedge collapse during the Late Miocene (Giunta et al. 2000a) is represented
by low-angle extensional faults, which thinned the chain towards the Tyrrhenian. During the PliocenePleistocene, the different rates of
rotations of the African and European plates controlled the development of the southern Tyrrhenian margin. It was affected by a WE
trending deep-seated shear zone (Giunta et al. 2000b), which induced transtension in the northern Sicily submerged sectors and transpres-
sion in the central mainland. Transtension characterized the basin opening and the present-day morphostructural settlement of Northern
Sicily. See text for further explanations.
al. 2000). The facies distribution of these sediments of Upper
Miocene age implies that deposition was generally controlled
by syn-sedimentary extensional tectonics and by a northward
shift of the subsidence of the substratum made up of the piled
tectonic units subsequent to the backsliding of the upper tec-
tonic units. The tectono-sedimentary evolution of perched
deposition was controlled by mobility of hanging-wall blocks
during Tortonian extension. The age distribution of Upper
Tortonian deposits in northern Sicily (with younger rocks sys-
tematically outcropping in the northernmost domains) may be
interpreted as due to the interplay of detachment-bounded
blocks, footwall uplift and hanging-wall subsidence.
A synthetic model for the modes of onset, based on these
data (Fig. 14), shows the evolution of the extensional defor-
mations in northern Sicily since Mesozoic times from the pas-
sive margin stage to the syn-orogenic basin formation.
270 NIGRO and RENDA
Crustal attenuation during TriassicEarly Jurassic time, re-
lated to north Africa rifting, was associated with transtensional
faulting and great accommodation space filled by carbonate
deposition. Late JurassicCretaceous subsidence of the Afri-
can margin was still dominated by a high extension rate, ac-
commodated through activity of listric normal faults reflected
by a minor deposition rate.
The Early Miocene thrusting, induced by the Sardo-Corso
transpressional collision with the African continental margin,
shows extensional deformations accompanying the onset and
evolution of the Neogene orogenic belt, consisting mainly of
normal faults affecting also the foreland and foredeep do-
The Late Miocene extensional stage, induced by the exceed-
ed critical taper values, shows low-angle simple shear defor-
mations, in part represented by the backsliding of the Maghre-
bian tectonic units. In the back domains of the orogenic wedge
normal fault activity was induced by mechanical failure of the
critical wedge taper, and controlled clastic deposition within
satellite (piggy-back) basins.
Intra-thrusting attenuation affected the uplifted orogenic
belt favouring the opening of intramountain basins, where
high subsidence and deposition rates were reached within in-
tra-slope, fault-controlled basins.
Acknowledgments: Grateful thanks for the helpful sugges-
tions, the detailed and constructive comments and the support-
ive linguistic corrections, leading to the improvement of the
paper are due to D. Puglisi (University of Catania, Italy), L.
Csontos and to D. Plaienka (Editorial Board member). Work
supported with UNIPA (ex MURST 60 %) and COFIN 2003,
P. Renda funds.
Amodio Morelli L., Bonardi G., Colonna V., Dietrich D., Giunta G.,
Ippolito F., Lorenzoni S., Paglionico A., Piccarreta G., Russo
M., Scandone P., Zanettin-Lorenzoni E. & Zuppetta A. 1979:
The Calabrian-Peloritani Arc in the frame of the Apenninic-
Maghrebian Chain. Mém. Soc. Geol. Ital. 17, 16 (in Italian).
Ben-Avraham Z. & Grasso M. 1990: Collisional zone segmentation
in Sicily and surrounding areas in the Central Mediterranean.
Ann. Tectonicae 5, 131139.
Ben-Avraham Z. & Grasso M. 1991: Crustal structure variations and
transcurrent faulting at the eastern and western margins of the
eastern Mediterranean. Tectonophysics 196, 269277.
Bernoulli D. & Jenkyns H. 1974: Alpine, Mediterranean and central
Atlantic Mesozoic facies in relation to the early evolution of the
Tethys. Soc. Econ. Paleont. Miner., Spec. Publ. 19, 129160.
Bianchi F., Carbone S., Grasso M., Invernizzi G., Lentini F., Longa-
retti G., Merlini S. & Mostardini F. 1987: Sicilia orientale: pro-
filo geologico Nebrodi-Iblei. Mem. Soc. Geol. Ital. 38,
Biju-Duval B., Dercourt J. & Le Pichon X. 1977: From the Tethys
Ocean to the Mediterranean Seas: a plate tectonic model of the
evolution of the Western Alpine System. In: Biju-Duval B. &
Montadert L. (Eds.): Structural history of the Mediterranean
basins. Ed. Technip, Paris, 143164.
Bouillin J.P. 1986: Le bassin maghrébin: une ancienne limite entre
lEurope et lAfrique à lOuest des Alpes. Bull. Soc. Géol.
France s. 8, 2, 4, 547558.
Bouillin J.P., Dumont T. & Olivier P. 1992: Organisation structurale
et sédimentaire de la paléomarge nord téthysienne au Juras-
sique dans les monts Péloritains (Sicile, Italie). Bull. Soc. Géol.
France 163, 6, 761770.
Boyer S. & Elliot D. 1982: Thrust systems. A.A.P.G. Bull. 66, 9,
Broquet P., Caire A. & Mascle G. 1966: Structure et évolution de la
Sicile occidentale (Madonie et Sicani). Bull. Soc. Géol. France
s. 7, 8, 9941013.
Broquet P., Duée G., Mascle G. & Truillet R. 1984: Evolution struc-
turale alpine récente de la Sicile et sa signification géody-
namique. Rev. Géol. Dynam. Géogr. Phys. 25, 2, 7585.
Butler R.W.H. 1987: Thrust sequences. J. Geol. Soc. London 144,
Butler R.W.H. 1989: The influence of pre-existing basin structure
on thrust system evolution in the Western Alps. In: Cooper
M.A. & Williams G.D. (Eds.): Inversion Tectonics. Geol. Soc.
Spec. Publ. 44, 105122.
Caire A., Glangeaud L. & Grandjacquet C. 1960: Les grands traits
structuraux et lévolution du territoire Calabro-Sicilien (Italie
meridionale). Bull. Soc. Géol. France 7, 2, 915938.
Casero P. & Roure F. 1994: Neogene deformations at the Sicilian-
North Africa plate boundary. In: Roure F. (Ed.): Peri-Tethyan
Platforms. Ed. Technip, Paris, 2745.
Catalano R. & DArgenio B. 1978: An essay of palinspastic restora-
tion across the Western Sicily. Geol. Romana 17, 145159.
Catalano R. & DArgenio B. 1982: Geologic scheme of Sicily (in
Italian). In: Catalano R. & DArgenio B. (Eds.): Guida alla
Geologia della Sicilia Occidentale. Guide Geologiche Regiona-
li, Mem. Soc. Geol. Ital., Suppl. A., 24, 941.
Catalano R., DArgenio B., Montanari L., Renda P., Abate B., Mon-
teleone S., Macaluso T., Pipitone G., Di Stefano E., Lo Cicero
G., Di Stefano P. & Agnesi V. 1979: Contributo alla conoscen-
za della struttura della Sicilia Occidentale: Il profilo Palermo-
Sciacca. Boll. Soc. Geol. Ital. 19, 485493.
Catalano R., Franchino A., Merlini S. & Sulli A. 2000: Central west-
ern Sicily structural setting interpreted from seismic reflection
profiles. Mem. Soc. Geol. Ital. 55, 516.
Channel J.E.T. & Mareschal J.C. 1989: Delamination and asymmet-
ric lithospheric thickening in the development of the Tyrrhe-
nian Rift. In: Coward M.P., Dietrich D. & Park R.G. (Eds.):
Alpine Tectonics. Geol. Soc., Spec. Publ. 45, 285302.
Constenius K.N. 1996: Late Paleogene extensional collapse of the
Cordilleran foreland fold and thrust belt. Geol. Soc. Amer. Bull.
108, 1, 2039.
Dercourt J., Zonenshain L.P., Ricou L.E., Kazmin V.G., Le Pichon
X., Knipper A.L., Grandjacquet C., Sbortshikov I.M., Geyssant
J., Lepvrier C., Pechersky D.H., Boullin J.P., Sibuet J.C., Sa-
vostin L.A., Sorokhtin O., Westphal M., Bazhenov M.L., Lauer
J.P. & Biju-Duval B. 1986: Geological evolution of the Tethys
from the Atlantic to the Pamirs since the Lias. Tectonophysics
Ferla P. & Bommarito S. 1988: Bauxiti lateritiche medio-giurassiche
nei calcari della piattaforma carbonatica panormide di Monte
Gallo (Palermo). Boll. Soc. Geol. Ital. 107, 579591.
Gillcrist R., Coward M. & Mugnier J. 1987: Structural inversion and
its controls: examples from the Alpine foreland and the French
Alps. Geodinamica Acta 1, 534.
Giunta G., Nigro F. & Renda P. 2000: Extensional tectonics during
Maghrebides chain building since late Miocene: examples from
Northern Sicily. Ann. Soc. Geol. Pol. 70, 8198.
Giunta G., Nigro F. & Renda P. 2002: Inverted structures in Western
Sicily. Boll. Soc. Geol. Ital. 121, 1117.
Grandjacquet C. & Mascle G. 1978: The structures of the Ionian sea,
Sicily and Calabria-Lucania. In: Nairn A.E.M., Kanes W.H. &
Stheli F.G. (Eds.): The Western Mediterranean. Plenum Press,
TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY IN NORTHERN SICILY 271
New York, 4B, 257329.
Grasso M., Manzoni M. & Quintili A. 1987: Misure magnetiche sui
Trubi infrapliocenici della Sicilia Orientale: possibili implicazio-
ni stratigrafiche e strutturali. Mem. Soc. Geol. Ital. 38, 459474.
Kastens K., Mascle J., Auroux C., Bonatti E., Broglia C., Channel
J., Curzi P., Emeis K.C., Hasegawa S., Hieke W., Mascle G.,
McCoy F., McKenzie J., Mendelson J., Muller C., Rehault
J.P., Robertson A., Sartori R., Sprovieri R. & Torii M. 1988:
ODP leg 107 in the Tyrrhenian Sea: insights into passive mar-
gin and back-arc basin evolution. Bull. Geol. Soc. Amer. 100,
Keller J.V.A., Minelli G. & Pialli G. 1994: Anatomy of late orogenic
extension: the Northern Apennines case. Tectonophysics 238,
Kezirian F., Barrier P., Bouillin J.P. & Janin M.C. 1994: The Pelori-
tan Oligo-Miocene (Sicily) a remnant of the Algero-
Provençal Basin Rifting. C. R. Acad. Sci. Paris Ser. II, 319 2,
Lickorish W.H., Grasso M., Butler R.W.H., Argnani A. & Maniscal-
co R. 1999: Structural styles and regional tectonic setting of he
Gela Nappe and frontal part of the Maghrebian thrust belt in
Sicily. Tectonics 18, 4, 669685.
Lister G.S., Etheridge M.A. & Symonds P.A. 1991: Detachment
models for the formation of passive continental margins. Tec-
tonics 10, 10381064.
Martire L., Pavia G., Pochettino M. & Cecca F. 2000: The Middle-
Upper Jurassic of Montagna Grande (Trapani): age, facies and
depositional geometries. Mem. Soc. Geol. Ital. 55, 219225.
Mascle G. 1979: Etude géologique des Monts Sicani. Riv. Ital. Pale-
ont. Stratigr., Mem. 16, 1431.
Nairn A.E.M., Nardi G., Gregor C.B. & Incoronato A. 1985: Coher-
ence of the Trapanese units during tectonic emplacement in
Western Sicily. Boll. Soc. Geol. Ital. 104, 267272.
Nigro F. & Renda P. 2000: Un modello di evoluzione tettono-sedi-
mentaria dellavanfossa neogenica siciliana. Boll. Soc. Geol.
Ital. 119, 667686.
Nigro F. & Renda P. 2001a: Oblique-slip thrusting in the Maghre-
bide chain of Sicily. Boll. Soc. Geol. Ital. 120, 187200.
Nigro F. & Renda P. 2001b: Late Miocene-Quaternary stratigraphic
record in the Sicilian Belt (Central Mediterranean): tectonics
versus eustasy. Boll. Soc. Geol. Ital. 120, 151164.
Ogniben L. 1960: Geologic scheme of the northeastern Sicily Riv.
Min. Sic. 6465, 184212 (in Italian).
Oldow J.S., Channell J.E.T., Catalano R. & DArgenio B. 1990:
Contemporaneous thrusting and large-scale rotations in the
Western Sicilian fold and thrust belt. Tectonics 9, 661681.
Oldow J.S., DArgenio B., Ferranti L., Pappone G., Marsella E. &
Sacchi M. 1993: Large-scale longitudinal extension in the
Southern Apennines contractional belt, Italy. Geology 21,
Pepe F., Bertotti G., Cella F. & Marsella E. 2000: Rifted margin for-
mation in the south Tyrrhenian Sea: A high-resolution seismic
profile across the north Sicily passive continental margin. Tec-
tonics 19, 2, 241257.
Reuther C.D., Ben-Avraham Z. & Grasso M. 1993: Origin and role
of major strike-slip transfers during plate collision in the cen-
tral Mediterranean. Terra Nova 5, 249257.
Roure F., Howell D.G., Muller C. & Moretti I. 1990: Late Cenozoic
subduction complex of Sicily. J. Struct. Geol. 12, 2, 259266.
Royden L. & Keen C.E. 1980: Rifting process and thermal evolution
of the continental margin of eastern Canada determined from
subsidence curve. Earth Planet. Sci. Lett. 51, 343361.
Scandone P., Giunta G. & Liguori V. 1974: The connection between
Apulia and Sahara continental margins in the Southern Apen-
nines and in Sicily. Mem. Soc. Geol. Ital. 13, 317323.
Scisciani V., Calamita F., Tavarnelli E., Rusciardelli G., Ori G.G. &
Paltrinieri W. 2001: Foreland-dipping normal faults in the inner
edges of syn-orogenic basins: a case from the central Apen-
nines, Italy. Tectonophysics 330, 211224.
Tavarnelli E. 1996: Geol. Rdsch. 85, 363371.
Tricart P., Torelli L., Argnani A., Rekhiss F. & Zitellini N. 1994:
Extensional collapse related to compressional uplift in the Al-
pine Chain off northern Tunisia (Central Mediterranean). Tec-
tonophysics 238, 317329.
Trimaille H. 1982: Etude géologique du Bassin de Trapani (Sicile,
Italie). PhD. These, Univ. Franche-Comté, 1177.
Truillet R. 1966: Existence de filons sédimentaires homogènes et
granoclassés dans les environs de Taormina (monts Péloritains-
Sicile). C. R. Som. Soc. Géol. France 9, 354359.
Truillet R. 1970: Etude géologique des Péloritains orientaux (Si-
cile). Riv. Min. Sic. 115117, 1157.
Wendt J. 1965: Synsedimentäre Bruchtektonik im Jura Westsiz-
iliens. Neu. Jb. Geol. Paläont. Mh. 5, 286311.
Wendt J. 1971: Geologia del Monte Erice (Provincia di Trapani, Si-
cilia occidentale). Geol. Rom. 10, 5376.
Wernicke B. & Burchfiel B.C. 1982: Modes of extensional tecton-
ics. J. Struct. Geol. 4, 2, 105115.
Williams G.D., Powell C.M. & Cooper M.A. 1989: Geometry and
kinematics of inversion tectonics. In: Cooper M.A. & Williams
G.D. (Eds.): Inversion tectonics. Geol. Soc. London, Spec.
Publ. 44, 315.
Winnock E. 1981: Structure du Bloc Pelagien. In: Wezel F.C. (Ed.):
Sedimentary Basins of Mediterranean Margins. Technoprint,