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Framed in the current geodynamics of the central Mediterranean, the Aeolian-Tindari-Letojanni fault system is part of a wider NW-SE oriented right-lateral wrench zone which accommodates diverging motion between regional-scale blocks located at the southern edge of the Calabrian Arc. In order to investigate the structural architecture and the active deformation pattern of the northern sector of this tectonic feature, structural observations on-land, high and very-high resolution seismic reflection data, swath bathymetry data and seismological and geodetic data were merged from the Lipari-Vulcano volcanic complex (central sector of the Aeolian Islands) to the Peloritani Mountains across the Gulf of Patti. Our interpretation shows that the active deformation pattern of the study area is currently expressed by NW-SE trending, right-transtensional én-echelon fault segments whose overla ing gives rise to releasing stepover and pull-a art structures. This structural architecture has favored magma and fluid ascent and the shaping of the Lipari-Vulcano volcanic complex. Similarly, the Gulf of Patti is interpreted as an extensional relay zone between two overlapping, right-lateral NW-SE trending master faults. The structural configuration we reconstruct is also supported by seismological and geodetic data which are consistent with kinematics of the mapped faults. Notably, most of the low-magnitude instrumental seismicity occurs within the relay zones, whilst the largest historical earthquakes (1786, Mw=6.2; 1978, Mw=6.1) are located along the major fault segments.

The 3D stratigraphic architecture and Late Neogene to Recent tectonic evolution of the Paola Basin (offshore western Calabria), a segment in the fore-arc of the Tyrrhenian‐Ionian subduction system, is reconstructed by using a grid of high-penetration reflection seismics. Oligocene to Messinian deposits are interpreted all along the profile. They tend to fossilize preexisting topography and reach the largest thicknesses between (fault controlled) basement highs. Plio‐ Quaternary deposits are found over the entire area and display variations in thickness and tectonic style. They are thicken up to 4.5 km in the depocenter of the basin, and decrease both in the east and west termination of the lines. The Paola Basin can be partitioned into two sectors with different tectonic deformation, separated by a NNW-SSE elongated area that coincides with the basin depocenter. Tectonic features associated with strike-slip restraining and releasing bends are widely spread over the western sector of the basin. Overall, they form an approximately NStrending and geomorphically prominent ridge separating the Paola Basin from the Marsili abyssal plain. A high-angle, NNE-trending, normal fault system develops on the south-west tip of the basin, where the faults offset the Messinian horizon of ca. 500 m. Data suggest that limited vertical slip occurs along reverse faults detected at the border and inside the sedimentary infilling of the Paola Basin, reaching thickness of more than 3.8s two way travel time. The reflection sequence pattern can be interpreted as a result of the infilling of the thrust-top basin related to a prograding system, located between a growth ramp-anticline to the west and a culmination of basement-thrust sheets to the East. We propose that the Paola Basin developed near the northern edge of the Ionian slab where tearing of the lithosphere is expected. Also, the strike-slip fault system is a kinematic consequence of obliquely convergent subduction settings, where interplate strain is partitioned into arc-parallel strike-slip zones within the fore-arc, arc or back-arc region.

High-resolution, single-channel seismic and multibeam bathymetry data collected at the Amendolara Ridge, a key submarine area marking the junction between the Apennine collision belt and the Calabrian subduction forearc, reveal active deformation in a supposedly stable crustal sector. New data, integrated with existing multichannel seismic profiles calibrated with oil-exploratory wells, show that middle to late Pleistocene sediments are deformed in growth folds above blind oblique-reverse faults that bound a regional pop-up. Data analysis indicates that similar to 10 to 20km long banks that top the similar to 80km long, NW-SE trending ridge are structural culminations above en echelon fault segments. Numeric modeling of bathymetry and stratigraphic markers suggests that three 45 degrees dipping upper crustal (2-10km) fault segments underlie the ridge, with slip rates up to similar to 0.5mm/yr. Segments may be capable with M similar to 6.1-6.3 earthquakes, although an unknown fraction of aseismic slip undoubtedly contributes to deformation. The fault array that bounds the southern flank of the ridge (Amendolara Fault System) parallels a belt of M-w

We present a seismotectonic model of the active thrust front in western Sicily, which includes the area hit by the 1968 Belice earthquake sequence. The ~40 km long South-WEstern Sicilian Thrust (SWEST) is formed by two aligned albeit non-parallel fault arrays, the Granitola-Castelevetrano Thrust System (GCTS) in the west and the Partanna- Poggioreale Thrust System (PPTS) in the east. The ~NE-SW trending, NW-dipping GCTS straddles from the Pelagian coastline to Castelvetrano, is ~18 km long and composed of two segments, with the northern, ~12 km long one showing geodetic and geologic evidence of active deformation (Barreca et al., 2014). The segment is marked by a sharp gradient in Differential SAR interferometry (DinSAR and STAMPs) and GPS velocity fields. Geologic evidence include an up to 60 m high, and up to 15° steep scarp, which is the fore-limb of a broad fold involving Lower Pleistocene shore calcarenites, and cm-scale reverse displacement of an ancient road dated as early Bronze-Hellenistic age. Inversion of fault slip-lineation data from structures displacing the archaeological remains yields a ~N110°E shortening axis, consistent with the geodetic shortening direction estimated from GPS differential velocities. The ~ENE-WSW trending PPTS stretches from Partanna to the macro-seismic area of the 1968 earthquake sequence and is composed of two ~10 km long segments limited by relay ramps. Although geologic and geodetic evidence of deformation are less clear than for the GCTS, we nonetheless observe a gradient in interferometry data for the western segment, and evidence of slow deformation (creep?) in historical to recent (last ~400 yr?) man-made structures. Integration of geologic, geodetic and seismology data suggests the active folds and thrusts are the uppermost expression of steep (45°) crustal ramps (Monaco et al., 1996) which upthrust the Saccense platform at depth. Based on macroseismic and seismological evidence (Monaco et al., 1996), we contend that the PPTS was partly activated during the 1968 sequence, and that rupture stopped at the junction with the GCTS. The current geodetic strain accumulation on the GCTS, on the other hand, suggests that the fault array has been significantly loaded, and that its last important co-seismic event could have been caused the 4th–5th century A.D. destruction of Selinunte (Bottari et al., 2009).

High-resolution bathymetry and a grid of single-channel reflection seismic profiles (Sparker and Chirp) were recently recorded in a sector of the upper slope of Capo Vaticano (CV) promontory (Tyrrhenian coast, W Calabria) where forward and inverse modeling of previously acquired aeromagnetic data highlight the presence of a WNW©\ESE elongated, 20 km long and 3¨C5 km wide, magnetized body extending from sea floor to about 3 km below sea level. Magnetic properties of this body are consistent with those of the medium to highly evolved volcanic rocks of the Aeolian Arc (De Ritis et al., 2010). Forthwith offshore promontory, the bathymetry highlights a complex-shape seamount that develops along a WNW direction, orthogonally interrupted by NE-trending ridges (Loreto et al., 2013), the largest of which shows major- and minor-axes of ca. 11 and 2 km, respectively. Summit elevation is ca. 70 m. Several vented fluids points were imaged on top of the seamount by chirp profiles. The largest of which rises from seafloor up to 6/7 m within water column, assuming the acoustic water velocity of 1500 m/s. Two faults systems associated with extensional faults are mainly observed on seismic profiles. High-angle NW-trending normal faults, SW-dipping, formed along the continental slope connecting the south-west continental shelf of the CV promontory to the Gioia Tauro basin (Pepe et al., 2013). These faults generally have small displacements, up to 40 m, and are sealed by Pleistocene deposits. A NE-trending normal fault, SE-dipping, is also observed on both chirp and sparker profiles. Its length is estimate to be more than 30 km, partially borders the NE-trending ridge intersecting the NW-trending fault. Landward, another NE-trending normal fault affects Pliocene and lower Pleistocene, and is sealed by upper Pleistocene. The described new geophysical data lead to a re-examination of the magnetic anomaly field interpretation. In fact, the revealed NE-trending ridge encounters the CV NW-SE ridge just where the peak value of the Reduced-to-the-Pole magnetic anomaly lies. Therefore, the inherent source body is emplaced where the maximum fracturing occurs. This suggests highly magnetized material crystallized in a vertical conduit that fed a volcanic system, likely fault-controlled, surrounded by the almost not magnetized rocks of the Gioia and the Paola sedimentary basins and of the Arco Calabro Peloritano units.

Ischia island develops at the edge of the shelf area and represents the sub-aerial section of a larger, E-W trending volcanic ridge including others submerged or buried volcanic edifices. In the past decade the island’s offshore has been the object of extensive hydrographic and marine geophysical surveys that have shown the structural complexity of the undersea sections and have overall shown the importance of gravity failures in island’s evolution. In this paper we report a previously unreported deep-seated slump structure and associated surficial mass wasting phenomena which occur off Ischia south-western flank. Recently acquired hydrological and geophysical data lead to identify the morphological features and the internal organization of the failed sediments which spread along the continental slope. The extent of this deep-seated deformations and the deep structural levels involved lead to investigate on the influence played by volcanic processes and regional tectonics on slope failure. The Ischia southern slope was explored through a multibeam survey and a single-channel seismic survey. Acquisition was carried out from aboard the R/V Urania at depths between 400 and 1200 m. The bathymetric data were collected using a hull mounted Reson 8160 multibeam sonar. Resolution resulted in a 20x20 m implemented with 50x50 gridded size provided by a previously collected data. Seismic survey consisted of 6 seismic lines run along the slope spaced 1 km between them and 5 cross lines. The acoustic source used was a 1Kjoule high-energy power supply system with a multi-tips (400) sparker array, fired at 2s time interval. The collected data show that a wide submerged area of 350 km2, between 400 to 1200 m depths is undergoing slow-moving deformation and associated secondary mass wasting phenomena. Morphological features include trenches, counterscarps, bulging and both extensional and contractional features while internal deformations show typical landward dipping reflectors with strong evidence of synsedimentary faulting and asymmetric anticlines. Deformation processes operate at various scales generating folds with wavelength ranging from hundreds meters to kilometers. Extensional and rotational rupture surfaces sole out at various low-angle detachment planes located at depths from few hundreds meters to 1 kilometer in subsurface.

The 3-D trend of anticline axial planes, fault planes and surfaces has been reconstructed in the offshore area between the Egadi Islands and the Sciacca High from the interpretation of multichannel seismic reflection profiles and well data (available from the VIDEPI project database). In particular, isopach maps generated for the five seismic units of age between Cretaceous and Quaternary allowed highlighting the space-time migration of the tectonic processes. The western portion of the studied area covers the submerged prolongation of the inner sector of the Sicilian-Maghrebian chain, limited in the NW and in the SE by two tectonic lineaments running along the western and eastern margins of the Adventure Bank: the Maghrebian Thrust Front and Adventure Thrust Front, respectively (see Argnani et al., 1986). The eastern portion is characterized by transpressive zones orientated NNE-SSW identifying the Separation Belt that partly corresponds to the foreland area which contains the Gela Nappe Thrust. Age constraints indicate that contraction related to the Sicilian-Maghrebian fold and thrust belt migrated progressively towards the southeast. The emplacement of the western front is attributable to the Middle-Upper Miocene while that of the eastern front is Plio-Pleistocene. Within this tectonic framework, two tectonic basins were identified on the basis of the different trend, age and evolution. The Adventure foredeep exhibits the maximum thickness of 500 m in correspondence of the Adventure Plateau. Here, the younger Gela foredeep displays minor depth showing a thickness increase towards the Gela Nappe and the Pantelleria graben. Positive inversion structures form by the Plio-Pleistocene compressional reactivation of preexisting structures limiting the Saccense and Trapanese domains were recognized the offshore sector between Mazara and Sciacca. Moreover, a correlation between the Campobello di Mazara-Castelvetrano alignment as proposed by Barreca et al., 2013, Ferranti et al., this meeting, and the tectonic units recognized in their offshore prolongation has been recognized. Therefore, we propose that in this area contractional tectonics is still active (see also Pepe et al., this meeting), and occurs on high-angle, NW-dipping crustal ramps (Monaco et al., 1996).

In this study we integrate high-resolution swath bathymetry, single-channel reflection seismic data and gravity core data, to provide new insights into the shallow structure and latest Quaternary to Holocene evolution of the submerged sector of the Neapolitan Yellow Tuff (NYT) caldera (Campi Flegrei) in the Pozzuoli Bay. The new data allow for a reconstruction of the offshore geometry of the NYT caldera collapse – ring fault system, along with the style and timing of deformation of the inner caldera resurgence. Our interpretation shows that the NYT eruption (~15 ka BP) was associated with a caldera collapse bounded by an inward-dipping ring fault system. The ring fault system consists in a 1-2 km wide fault zone that encircles an inner caldera region ~ 5 km in diameter and is often marked by the occurrence of pore fluids ascending through the fault zone, up to the seafloor, particularly in the western sector of the bay. A shallow magmatic intrusion along the ring fault zone was also detected offshore Bagnoli in the eastern part of the Pozzuoli Bay (Sacchi et al., 2014). Following the NYT eruption, the inner caldera region underwent significant deformation and resurgence with a maximum cumulative uplift of the offshore structure in the order of 180 m. The net uplift rate of the caldera resurgent dome was ~ 9 - 12 mm/year during the period 15.0 – 6.6 ka BP. The style of deformation of the resurgent structure can be described in terms of a broad doming, accompanied by subordinate brittle deformation, mostly concentrated in a small apical graben at the summit of the resurgent dome (Cole et al., 2005). Chronostratigraphic calibration of seismic profiles obtained by three tephra layers cored in the Pozzuoli Bay indicates 5 to 25 m of post-Roman differential subsidence and tilting towards ESE of the inner caldera resurgence, as recorded by the drowning of the infralittoral prograding wedge below the present-day storm wave base.

We reconstruct the Plio-Quaternary tectono-stratigraphic evolution in the offshore Capo Vaticano (W Calabria, Italy) by integrating data obtained from single- and multi-channel reflection seismic profiles and a reprocessed version of the CROP M2A/III line. NW-trending, high-angle normal faults, dipping ~70° to the south-west formed along the continental slope connecting the south-west continental shelf of the Capo Vaticano Promontory to the Gioia Tauro Basin (Pepe et al., 2014). Faults generally have small displacements up to 40 m and are sealed by Pleistocene deposits. West of the Capo Vaticano promontory and in the Gioia Basin, a SE-dipping, normal fault system, more than 32 km long, is recognized. Faults affect lower (?) Pleistocene and are sealed by probably post-0.7 Ma deposits. These faults are here tentatively interpreted as the antithetic faults of major, Late Pliocene to Quaternary, NW-dipping, normal faults, which form the currently active tectonic belt along the Calabrian Arc (e.g. Monaco and Tortorici, 2000; Faccenna et al., 2011). In the Santa Eufemia Gulf, reverse faults affecting Plio-Quaternary and older sedimentary successions are observed. Faults also offset the seafloor thus indicating their recent activity. A normal fault system has been also inferred on the basis of the present day depth variations of the edges of submerged depositional terraces and associated abrasion platforms, along which a vertical displacement of ~21 m during the Late Pleistocene-Holocene has been inferred. The information derived in offshore the Capo Vaticano Promontory represents an important step towards an accurate 3-D kinematic description of the tectono-stratigraphic evolution of the western (Tyrrhenian) side of the Calabrian Arc orogenic wedge during the Plio-Quaternary.

High-resolution, seismic profiles were recorded in the offshore of Mazara - Punta Granitola with the purpose of reconstructing the architecture and Pliocene to Recent evolution of the south-west prolongation of the Granitola- Castelvetrano Thrust System, identified as an active structure possibly related to destructive historical earthquakes (Barreca et al., 2014; Ferranti et al., this meeting). A number of seismic units were identified. The oldest one is interpreted as representative of the Lower Pliocene pelagic deposits known in the region as Trubi. Lower-middle Pleistocene calcarenites are widespread along the continental shelf (CS) between Mazara del Vallo while their top rapidly deepens moving southeast-ward Capo Granitola. In this area, lower-middle Pleistocene calcarenites are unconformably overlain by the late Pleistocene- Holocene deposits. These latter are thin or absent NW of Punta Granitola along the CS, at water depth less than ~30 m, suggesting that this sector experienced uplift during the Quaternary. Small scale, NW- and SE-displacing reverse faults are observed along the CS where they cut the lower-middle Pleistocene calcarenites and offset the seafloor. South-eastwards, south-east-verging, reverse faults affect lower-middle Pleistocene calcarenites as well as the late Pleistocene-Holocene layers, suggesting that fault displacement acted during the post-LGM. Growth folding of Upper Pleistocene-Holocene deposits and thrust faults, predominantly dipping to the NW, affecting Pliocene rocks are observed in the immediate offshore Capo Granitola. The integration of the new data with those obtained from multi-channel profiles suggests that the active folds and thrusts are the uppermost expression of steep crustal ramps (Monaco et al., 1996; Lavecchia et al., 2007; Meccariello et al., this meeting) which upthrust the Saccense platform at depth.

I Campi Flegrei rappresentano un distretto vulcanico attivo che si sviluppa al confine tra il settore emerso e sommerso del margine continentale campano. Il distretto vulcanico occupa una superficie di circa 200 km2, è strutturalmente dominato da una caldera di collasso del diametro di circa 8 km formatasi in seguito all’eruzione del Tufo Giallo Napoletano (TGN), un deposito ignimbritico del volume di 30-50 km3 Dense Rock Equivalent, datato a 15 ka B.P. circa, ed è attivo da almeno 78 ka B.P circa. L’obiettivo di questo lavoro è di ricostruire l’architettura stratigrafica e l’evoluzione vulcanotettonica tardo-Quaternaria del sistema caldera di collasso - faglia anulare - risorgenza intra-calderica del settore sommerso della caldera del TGN. A tal fine è stata analizzata una fitta maglia di profili sismici a riflessione monocanale di alta (Sparker) ed altissima (Subbottom Chirp) risoluzione. I dati sismici sono stati successivamente integrati sia con quelli ottenuti dall’analisi di carotaggi a gravità e batimetrici multibeam che con quelli disponibili in letteratura e, nell’insieme, analizzati in ambiente GIS. I nuovi dati indicano che il settore interno dell’area collassata a seguito dell’eruzione del TGN evolve inizialmente in condizioni di mare basso. L’area intra-calderica viene successivamente interessata dalla formazione di una struttura antiforme (risorgenza intra-calderica) il cui tasso di sollevamento è stato comparabile con l’innalzamento eustatico nell’intervallo Pleistocene superiore – Olocene [Lambeck et al., 2011]. A circa 10 ka B.P. il settore centrale della struttura risorgente raggiunge l’esposizione subaerea (terrazzo morfologico de “La Starza”). La calibrazione dei profili sismici Chirp con markers tefro-stratigrafici riconosciuti in un carotaggio e datati al 1538 A.D., 79 A.D. indica l’instaurarsi di un periodo di subsidenza in epoca post-Romana, registrato dall’annegamento di 10-25 m del cuneo di progradazione infralittorale rispetto alle profondità di equilibrio funzionale attualmente segnalate in area Mediterranea. L’interpretazione sismostratigrafica rivela, inoltre, la presenza di fluidi che risalgono attraverso la zona di faglia anulare che delimita la caldera del TGN. Bibliografia Lambeck, K., Antonioli, F., Anzidei, M., Ferranti, L., Leoni, G., Scicchitano, G., Silenzi, S., (2011). Sea level change along the Italian coast during the holocene and projections for the future. Quaternary International, 232, 250-257.

Nuovi dati sismici ad alta (Sparker) ed altissima (Subbottm Chirp) risoluzione, acquisiti durante la Campagna Oceanografica “Teatioca_2010”, integrati da dati sismici multicanale ad alta penetrazione, pubblici disponibili sul sito www.videpi.com, calibrati con pozzi profondi, batimetrici multifascio e carotaggi, rivelano che la dorsale di Amendolara, estensione sottomarina della zona frontale del sistema a thrust dell’Appennino meridionale, è stata controllata nel Quaternario da un sistema di retro-scorrimenti e faglie transpressive (ATFS) che dislocano verso SW la catena mio-pliocenica NE-vergente. Il pacco di sequenze deposizionali attribuito, sulla base della facies sismica e della presenza di discordanze controllate dalle oscillazioni glacio-eustatiche, al Pleistocene medio-superiore risulta piegato in maniera consistente con le strutture desumibili dai profili multicanale. I dati morfometrici e sismici documentano che la dorsale, orientata NW-SE, è formata da 3 banchi lunghi ~10-20 km, cresciuti sopra rampe di sovrascorrimenti ciechi (~2 km) disposti en-echelon a formare un sistema segmentato. Sono stati individuati e modellati i segmenti di Amendolara a NW e Cariati a SE, collegati da una più piccola rampa laterale (segmento di Rossano). La modellazione numerica calibrata sui dati batimetrici e sismici indica che le rampe hanno inclinazione di ~45° e sono radicate a ~10 km di profondità a possibili scollamenti o strutture maggiori. I tassi di scorrimento negli ultimi 4-500 ka, calcolati per i segmenti sulla base degli strati di crescita nei bacini sin tettonici variano da 0.5-0-9 mm/a per il segmento di Amendolara a 0.35-0.5 mm/a per quello di Cariati. L’ATFS coincide con una fascia di moderata sismicità (Mw

The Map Sheet 1:50.000 595 ”Palermo” includes marine and land areas of the topographic map sheet “Palermo”. The map sheet “Palermo” (Palermo Province) covers a part of the Sicily Fold and Thrust Belt (FTB) which has developed along the plate boundary between Africa and Europe in the Central Mediterranean. The Sicily FTB links the African Maghrebide to the Calabrian arc and Southern Apennines. The FTB and its submerged western and northern extensions are part- ly located between the Sardinia block and the Pelagian-Ionian sector, and partly beneath the central southern Tyrrhenian Sea. In this sector of the Mediterranean area, the main compressional move- ments, after the Paleogene Alpine orogeny, began with the latest Oligocene-Early Miocene counterclockwise rotation of Corsica-Sardinia, believed to represent a volcanic arc, and its collision with the African continental margin. Thrusting oc- curred in connection with the westward subduction of the Adriatic and Ionian lithosphere beneath the Corsica-Sardinia block. Today, a westward subduction is indicated by a North-dipping Benioff zone, as deep as 400 km, west of Calabria and the Apennines, and the related calc- alkaline volcanism in the Eolian Islands. Subduction and thrusting are contempo- raneous with a back arc-type extension in the Tyrrhenian Sea.186 LAND AREAS geomorphoLogy Three different sectors can be distinguished in Sheet 595: 1) the Palermo and Bagheria coastal plains, characterized by several poly- cyclic marine terraces organized in different orders; 2) the isolated carbonate reliefs of Monte Pellegrino and Monte Catalfano; 3) the internal Belmonte Mezzagno highlands and the Oreto and Eleuterio river valleys. The geomorphological evolution of the area has been controlled by strong down-cutting and dismantling processes that have produced both the erosion of thick volumes of mainly Tertiary terrigenous deposits and the exhumation of mainly Mesozoic carbonate rocks. Due to tectonic uplifting, these proces- ses are intensely developed on ”soft rocks “(Numidian Flysch clayey deposits), producing large river valleys with slopes affected by water erosion and surficial landslides (valleys of Fiume Oreto, Fiume Eleuterio and Fiume Milicia); they have, however, considerably slowed down along the blocks of more resistant rock (Mesozoic-Tertiary carbonate units), forming the wide Palermo Mountains. At the present-day, relict (planation surfaces and abandoned valleys), structural (fault/fault-line scarps) and karst (sinkholes and polje) forms occur in the highlan- ds. The geomorphological setting of the coastal areas has been influenced more by significant Quaternary extensional tectonics that originated the drowning of the northern sectors of the Sicilian chain in the Tyrrhenian Sea above which the marine deposition was deposited (Marsala synthem). The uplifting, involving also the lowered blocks, has resulted in the progressive retreat of the sea that gave origin to a succession of marine terraces, Ionian-Latest Pleistocene in age, and fi- nally the emersion of the present-day coastal depressions (Palermo and Bagheria plains). During the Upper Pleistocene to Holocene, the uplifting rates reached values generally lower than 0.1 m/ky. stratIgraphy The carbonate and terrigenous rock facies analysis and stratigraphy led to the recognition of large Paleozoic to Miocene sedimentary bodies pertaining to diffe- rent and separate crustal paleogeographic domains; the former, developed along the African passive continental margin and the adjacent Tethyan ocean. The “Tethyan” successions correspond to the deep clayey carbonate and vol- canoclastic rocks known to have been deposited in the Sicilide Domain. The pas- sive margin rock bodies are shallow water carbonates, deep water carbonates and 187 siliceous carbonates that were deposited in domains, locally known as Panormide, Trapanese and, Imerese. Terrigenous, evaporitic and clastic-carbonate rocks, Miocene to Pleistocene in age, formed during the foredeep evolution of the Sicilian FTB. A detailed stratigraphy of the rock-successions is summarized in the paragraph “Legend of the Palermo Sheet”. Quaternary continental deposits have been mapped as unconformity-bounded stratigraphic units limited by lower and upper unconformities, locally marked by palaeosoils, due to erosion/depositional processes, marine/sub-aerial processes or non-depositional events. Locally, the upper boundaries are the present-day topo- graphic surface. The detection of some unconformities of regional extent allowed us to define several synthems. The Marsala synthem is a Lower Pleistocene body of marine/coastal deposits, with abundant fossils; its lower boundary is a mari- ne erosion surface cutting pre-Quaternary rocks. The Buonfornello-Campofelice synthem is composed of middle Pleistocene marine deposits covering abrasion surfaces above the coastal stepped blocks. The Polisano synthem is made up of aeolian sandstones and sands with intercalations of breccias talus, late Middle Pleistocene in age (OIS 6); its lower boundary is a non-depositional surface at the top of older rocks. Eleuterio and Milicia synthems are made up of Middle-Upper Pleistocene, mainly fluvial, deposits deposited on river terrace surfaces; their lo- wer boundary is a stream erosion surface. The Benincasa synthem includes colluvial Middle-Upper Pleistocene deposits of Qz-sandstones interbedded with stone-line, palaeosoils, Fe-rich layers and no- dular concretions. Its lower boundary is an unconformity above the Buonfornello- Campofelice synthem, the upper one is the base of the Capo Plaia synthem of the present soil. The Barcarello synthem encompasses marine/coastal conglomerates and are- nites, with a rich warm-temperate “Senegal fauna” including Strombus bubonius; it is located on two orders of marine terraces (OISs 5e and 5c or 5a) and laterally passes into welded colluvial deposits whose age is correlated with the OIS 5. The lower boundary of the synthem is a marine abrasion surface, laterally extending to a continental erosion surface; the latter is cutting the Polisano synthem or older rocks. The Raffo Rosso synthem consists of aeolian sandstones and sands, collu- vial or gravitational deposits and thick stratified slope deposits of the last glacial climatic event (OISs 4-2); the lower boundary is a non-depositional surface at the top of the Barcarello synthem or older rocks. The Capo Plaia synthem is made up of coastal to continental deposits of the last glacial climatic event of the end - Holocene age (OISs 2-1); its lower boundary is formed by variously origina- ted erosion or non-depositional surfaces; the upper boundary is the topographic surface.188 struCturaL graIn The Paleozoic to Cenozoic, mainly carbonate sedimentary bodies, developed in different sectors of the African passive continental margin and the adjacent Tethyan ocean and were progressively accreted in a pile of tectonic units and are now exposed to form the Sicilian fold and thrust belt. To define the extension and setting of these bodies versus their internal facies pattern, we individuate them as Structural-Stratigraphic Units (U.S.S.), described as large geological bodies per- taining to original paleogeographic domains from where they were removed and later deformed. These bodies are bounded by clearly mappable tectonic features (faults, thrust, etc.) and each of them is characterized by homogeneous lithologies and similar structural behaviours and settings. The outcropping tectonic edifice, in the “Palermo” Sheet, is composed of se- veral U.S.S., which can be locally subdivided into tectonic units of minor order. These subunits have been mapped on the basis of their tectonic relationships. Some U.S.S. have been identified, starting from the geometrically highest and most internal in the FTB. 1) U.S.S. deriving from the deformation of the Sicilide domain succession: - U.S.S. Tusa-Troina outcropping in the south-eastern sector, overlying the Numidian Flysch deposits. 2) U.S.S. deriving from the deformation of the Imerese domain succession and its overlying numidian flysch basin. The units widely outcrop in the cen- tral and southern sector of the geological sheet where Mesozoic deep water carbonates and their oligo-miocene numidian flysch covers are deformed, with the latter often slightly detached from the carbonate substrate. Among them we distinguished: - U.S.S. Sagana - Belmonte Mezzagno, in the western sector, where we indi- viduated the sub-unit Pizzuta-S.Cristina; - U.S.S. Monte Cane-San Calogero, in the eastern sector, subdivided into a) the subunit Monte Cane-S. Onofrio, overlying b) the subunit Bizolelli; 3) U.S.S. deriving from the deformation of the Panormide Domain. The U.S.S. consists of Meso-Cenozoic shelf to pelagic carbonates and the often detached nu- midian flysch cover, pertaining to the U.S.S. M. Gallo-M. Palmeto, forming the margin of the Panormide Platform. It outcrops only at Monte Pellegrino (subunit Pellegrino). 4) U.S.S. deriving from the deformation of the Trapanese domain. It is recognizable only in the seismic profile crossing the eastern sector where it is overlain by the U.S.S. Sagana - Belmonte Mezzagno. Southwards, it oucrops at Monte Balatelle (U.S.S. Kumeta-Balatelle).189 Structural evolution The tectonic edifice outcropping and buried beneath the area of the Palermo Sheet is the result of several deformational events that have taken place since the Triassic, deforming complexly the sedimentary successions deposited during the Mesozoic-Pleistocene. After the detachment from their crystalline basement the original sedimentary bodies were progressively accreted in a pile of tectonic units now exposed in the Sicilian chain. Two main events have occurred during the Miocene and Pleistocene time interval. They are respectively characterized by compression and transpression. Contraction originally involved the Tethyan domains and the internal domains of the continental margin, whose deep water meso-cenozoic carbonates formed the structurally highest tectonic units in the chain. The occurrence of intrastratal decollement originated duplex geometries. Since the Messinian, the deformation moved at depth, progressively involving the carbonate platform rock bodies in large E-W antiforms that were successively (during Late Pliocene) folded by NE- SW structures. The transpressional event is proved by NNW-SSE and NE-SW transcurrent and transpressive structures (dextral); it involves the deep-seated car- bonate platform-forming fold structures and severe uplifting that induces reimbri- cation in the overlying Imerese deep-water units. This transpressive event accom- panies the paleomagnetically evidenced thrust rotations between the Late Miocene and the Early Pleistocene. An abrupt change in the tectonic transport direction of the two compressional structure systems is explained taking into account the 120° clockwise rotations based on the paleomagnetic results of ChanneL et alii (1980, 1990); speranza et alii (2000). As a consequence the present day outcropping structural attitude of the structures (and consequently of the deformation fields) do not coincide with the original trends. The compressional and traspressional structures are down faulted northwards by the extensional tectonics. MARINE AREAS In the marine areas, we distinguished different morphological environments, from beaches through the offshore (inner shelf), to the outer shelf and upper slope where two confined slope basins (Palermo and Termini basins, separated by the Monte Catalfano salient) represent the south-western margin of the large Cefalù basin. The substrate of these basins is represented by the Sicilian FTB tectonic units and their syn- and post-orogenic covers. The area shows a lateral variation from the rocky shores, in front of Monte Pellegrino and Monte Catalfano and in the eastern sector, to the beaches mainly in the central sector.190 Important physiographic changes, as shelf width and gradient and different coast orientations, characterise the continental shelf and slope and influence the hydrodynamic processes (wave activity and shelf current patterns). The continental shelf reaches 250 km2 and shows width values ranging from 1.5 km in the Capo Zafferano offshore to 8,0 km in the gulf of Termini, whereas gradient values range between 1° and 8°. The continental shelf has been subdi- vided into an inner infralittoral domain down to a 30 - 35 m water depth, which is characterized by an abrasion platform at different depths, and the outer shelf domain extends to the shelf edge. The shelf edge, which is both depositional and erosional, located at water depths between 120 m and 140 m, rises to lower depths at the canyon heads. Dominant morphological features along the continental slope are the submari- ne erosive conduits, locally interesting also the continental shelf. The heads of the conduits are characterised by severe episodes of retrogressive failure and incised by small gullies. Some (the Oreto and Eleuterio canyons) are directly linked to rivers and were connected during the last glacial maximum through incised val- leys, now buried by transgressive to highstand deposits. In the central sector of the Gulf of Palermo, we pinpointed almost three pockmarks, depressions tens of meters deep, originating from escaping fluids, while in the western sector of the gulf the same phenomena caused the occurrence of isolated or aligned, outcrop- ping or buried mounds. Finally anthropic features largely characterize the seabottom mainly in the inner shelf. seIsmostratIgraphy and stratIgraphIC settIng The buried sedimentary succession has been investigated by means of a close grid of single and multichannel seismic lines. On the whole, three seismic units (S, C and A) have been distinguished. The S seismic unit represents the offshore prolongation of the Meso-Cenozoic units of the Sicilian FTB and their syn- and post-orogenic cover. They are ge- nerally topped by a pronounced, erosive unconformity, correlated to the exten- sive Messinian horizon, generated during the last phases of the Mediterranean Salinity Crisis (5.5 Ma), and covered by a transparent seismic unit representing the Globigerina - bearing pelagic chalk (Trubi) and the Upper (?) Pliocene slope to shelfal deposits. The C seismic unit is represented by a prograding succession of 4° to 7° dip- ping horizons, which have been correlated with the regressive upper Pliocene- Pleistocene deposits, topped by the regional wide, erosional truncation related to the last glacioeustatic sea level fall, correlated with the δ18 O isotopic stage 2. The A seismic unit corresponds to the Late Pleistocene to Holocene 191 depositional sequence (SDTQ) with sigmoidal to tabular geometry; the deposi- tional sequence consists of a Falling Stage and Lowstand Systems Tracts with a progadational pattern controlling a relevant out-building of the shelf margin and a sedimentary wedge, of variable thickness, made up of the Transgressive (TST) and the Highstand (HST) Systems Tracts. The TST, developed during the Holocene sea level rise, shows a retrograda- tional stacking pattern, while the HST, deposited during the last 6 ka b.P., shows aggradational to faintly progradational geometries, related to the development of a littoral depositional system. Along the upper slope, turbiditic systems, characterized by erosive conduits and scattered mass wasting, developed extensively during the Late Pleistocene to Holocene. Surficial sediments of the continental shelf and slope The continental shelf and slope of the Palermo sheet are veneered with uncon- solidated, late Holocene in age, clastic and biogenic carbonate (Palermo gulf) and in second order, lithoclastic (Termini gulf) sediments. Deposits are composed of sands, relict Pleistocene and older carbonate parti- cles, abundant biogenic carbonate granules and algal-coated grains. In the outer shelf and upper slope, deposits are predominantly fine to very fine grained (silts and silty clays). The inner shelf is veneered by a mixture of gravel (rarely), coarse to fine sands, silts and clays, showing a general trend of decrea- sing size in a general seaward direction. From the sedimentary and the morphological features, four different depo- sitional systems have been distinguished: foreshore depositional systems, inner shelf depositional systems, outer shelf depositional systems and upper slope de- positional systems, mapped as g8 , g19 , g21 , m2 respectively. The systems are laterally gradational and linked by a variety of sedimentary processes. Shallow marine environments (up to a 50 m water depth) are generally characterized by biogenic sediments while terrigenous and carbonate clastic sedi- ments supplied by rivers or coastal erosion locally prevail. The most important facies of the infralittoral domain consists of Posidonia oceanica and Cymodocea nodosa meadows, which extensively cover the rocky substrate or the sandy floors the former and the muddy floors the latter. teCtonIC evoLutIon of the offshore areas The present day structural setting reconstructed in the Palermo sheet marine sectors appears the same as the tectonic edifice depicted on the mainland: it has 192 been interpreted as a consequence of the complex Neogene to Quaternary tectonic evolution. The compressive tectonics, responsible for the wedging of the present day submerged thrust sheets, developed during the Late Miocene span interval. This event was followed by transpressive tectonics that faulted and folded the Late Neogene to Pliocene infill by activation of high-angle, deep faults. During the Pleistocene, extensional tectonics accounted for opening and subsidence of structural lows. Present day active tectonics is still going on, as documented by compressive- transpressive focal mechanisms of shallow to deep, low amplitude earthquakes occurring along the offshore between the Sicilian coast and Ustica Island. A few middle-late Pleistocene marine terraces, outcropping along the coast at different levels, suggest a prolonged, faintly tectonic uplift. On the whole, the Plio-Quaternary geological evolution of the offshore area appears to be constrained by a strong interaction between eustatic sea level chan- ges, sediment supply and tectonics, recorded by strain features and enhanced un- conformities crossing the basin fill.