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R. CATALANO ET AL.
Some beds in the large basin show of the Kabilo-Calabrian Unit. The nian tectonic history was recently out-
evidence of folding (Fig. 9D); deformed incompetent Cretaceous-Lower Mio- lined on the base of sequence
sediments are unconformably overlain cene cover of the northern (internai) stratigraphy and basin analysis (Agate
by undeformed layers, which in tum basinal, and related carbonate platform et al., 1993). The already imbricated
were affected by recent vertical faulting. units were detached during the Lan- substratum was eroded and block
The Linosa Plateau (Fig. 9C) is made up ghian-early Tortonian interval and then faulted along listric and growth norma!
of a mildly folded pre-Miocene sedi- thrust over progressively more south- faults. The extensional event opened
mentary body, overlain by a Messinian eastward domains, that at this time half grabens (hinterland basins) that
horizon, or Messinian erosional surface. acted as the foreland. Clastics of Numi- were progressively filled by dastic
An almost 300 m-thick, very recent NE- dian Flysch type and coeva! deposits wedges. Structural inversion of the
SW prograding wedge rests on a were stjicked to form the highest thrust half-graben deposits took piace subse-
prominent discontinuity of late Plio- sheets (Fig. 3). Synchronously, or soon quently between 2.4 and 1.2 Ma (Cat-
cene-Pleistocene age. This indicates afterwards, deep-water and shallow- alano et al., 1988). This deformation,
that the Linosa Plateau was near sea- water carbonate rocks forrning the described by Tricart et al., 1990, from the
level, probably by about l Ma. substratum were detached and ac- Eastern Sardinian area and known on
creted as thrust ramps and flats. land and in the Sicily Charme!, appears
PALAEOGEOGRAPHIC SETTING to be related to a change in the stress
ANO TECTONIC EVOLUTION Syntectonic late Tortonian-early Plio- field, implying compression along a N-
cene dastics, evaporites and pelagic 5 stress axis (Catalano and Milia, 1990).
A late Triassic to Pleistocene sedimen- chalks unconformably overlie this pre- Between 1.2 and 0.8 Ma extensional
tary cover can be recognized along a vious shortened substratum. These structures dissected the basins, fol-
NE-SW trend in the region studied. This deposits were later folded and thrust, lowed by further compressive deforma-
sedimentary body is represented by a in their frontal portions. Along the tion between 0.8 and 0.5 Ma. The last
widespread late Triassic-early Liassic advancing front of the chain deposits 0.5 Myr has involved strong vertical
shallow-water carbonate sequence, fol- of the same age filled the late Tortonian movement.
lowed by Jurassic-Palaeogene, slope to foreland basin formed on Adventure
basin marly and pelagic carbonates, Bank. Decollements progressively de- CONCLUSIONS
unconformably overlain by Neogene coupled the Upper Miocene to Pliocene
terrigenous and clastic carbonate depos- sedimentary cover, giving rise to the The tectonic evolution of the Centrai
its of foreland basin type (see strati- Gela thrust system at between 2.4 and Mediterranean region, extending from
graphic chart, in Catalano et al., 1989). 0.8 Ma. The most recent detachment the Western Bank across the Egadi
planes appear to involve deposits older Islands to the Southern Sicily offshore
The stratigraphy and palinspastic than 0.8 Ma (Fig. 7). Seismic analyses of and the Eastern side of the Pelagian
restorations of the Sicilian-Maghrebian the more recent stacking structures of Block, has been described using geolo-
chain reveal that the tectonically stacked the Gela TS front suggest an increase in gica! cross-sections, based on revised
Mesozoic rock units belonged essen- loading driven by thrusting of the Gela interpretations of seismic profiles and
tially to two main palaeogeographic foredeep (Fig. 8). new seismic reflection and stratigraphic
domains, a northern 'internai' trough data.
and a southern 'external' carbonate to The Malta-Linosa region was affected l The Sicilian-Maghrebian sector,
evaporitic platform, that developed on a by growth faulting and extensional mostly submerged in the Sicily Straits,
common deep-water Permian substra- tectonics during the early to late Plio- is represented by an eastward- and
tum (Catalano et al., 1991). These rocks cene. The stratigraphic signature and southeastward-verging thrust belt,
are believed to belong to palaeogeo- the structural pattern suggest a rifting 12 km thick, formed of Miocene flysch-
graphic domains that formed the Sici- mechanism for opening of the Sicily type thrust slices, stacked in an imbri-
lian continental margin, prior to Channel. Deformed beds appear to be cated pile of basin and carbonate plat-
collision with Sardinia. Some of the bounded above by an unconformity, form thrusts. These were derived from
rock sequences can be correlated with that can probably be correlated with a deformation of the Mesozoic-Palaeo-
those cropping out on land (Catalano tectonically enhanced 1.2 Ma sequence gene Sicilian continental margin. Dur-
1987; Antonelli et al., 1988). boundary. At the Pliocene-Pleistocene ing Early Miocene-Pleistocene, com-
boundary, folding was active. Uplift of pression resulted in progressively on-
A new and more complex palaeogeo- the islands (Malta, Lampedusa) could lapping foreland basins.
graphic setting was created after the have taken piace during this time
early Miocene collision betweeen Sardi- interval, simultaneously with the de- Since the Triassic, this area of the
nia and the Maghrebian-Sicilian con- position of a deltaic fan on the Linosa African margin is envisaged as having
tinental margin. Progressive foreland Plateau. Later, half-grabens again un- involved two main depositional areas: a
basins developed in front of an east- derwent strong vertical tectonics; rifting northern (internai) deep water basin
ward advancing chain, from the earliest was responsible for almost 1800 m of and a southern (external) carbonate to
Miocene to early Pleistocene. Tectonic vertical displacement during the Pleis- evaporitic platform.
analysis of the Sicilian-Maghrebian tocene. 2 The deformation of the more recent
region indicates that deformation be- thrust structures of the Gela Thrust
gan after earliest Miocene emplacement Further north in the belt (i.e. in the
south Tyrrhenian Sea) the post-Messi-
186 1995 Blackwell Science Ltd, Terra Nova, 7, 179-188.
