Fluid escape structures in the Graham Bank region (Sicily Channel, Central Mediterranean) revealing volcanic and neotectonic activity

In the Sicily Channel, (Central Mediterranean), two geodynamic processes overlap each other, the Maghrebides- Apennines accretionary prism and the Sicily Channel rift. Moreover, the northwestern sector (Banks sector) is characterised by an irregular seafloor morphology linked to the recent volcanic and tectonic activity.In order to discriminate the role exerted by both the processes in the morphostructural setting of the area we used a dataset of both high and very high resolution single-channel and multi-channel profiles, acquired in the frame of the RITMARE project respectively with CHIRP and sparker, and airgun sources, and high resolution (5 m cell) morpho-bathymetric data. The data all…

Submarine Slope Failures Along the Northern Sicilian Continental Margin (Southern Tyrrhenian Sea) and Possible Implications for Geo-Hazard

Mass wasting and downslope movements are common processes that have contributed to shape the northern Sicilian continental margin (southern Tyrrhenian Sea) since the Late Quaternary. Nevertheless, processes controlling their evolution are still partially unknown and a variety of geologic factors can be responsible for their formation. In this work we present an overview of the main mass wasting features (submarine canyons, landslides, debris flows) observed and mapped in different sectors of the northern Sicilian margin. The margin is characterized by a narrow, steep continental shelf (1-2°) and a very irregular and steep (6-8°) upper slope. The main aims of this work are: (1) to outline th…

Mantle-derived fluids in Central Mediterranean: Geochemical and geophysical constrains on sources of fluids and migration

The geodynamics of the central Mediterranean is characterized by the interaction between the European plate and the African’s. In this setting Sicily is a sector of the Appenine-Maghrebide accretionary prism, which is located between two areas affected by extensional tectonics (Sicily Channel to the south and the Thyrrenian back arc basin to the north). Significant mantle-derived helium (0.4<R/Ra<2.8; R=3He/4He in the sample, Ra in atmosphere) is found in the CH4 and N2-CO2 rich fluids released in central western Sicily, a region without evidence of recent magmatism. CH4- dominated gases are released from mud volcanoes localized in an area of both low heat flow and seismicity. On the contra…

STRATIGRAPHIC AND STRUCTURAL ANALYSIS OF A HIGH RESOLUTION SEISMIC SURVEY PERFORMED IN THE BAY OF AUGUSTA (SE SICILY)

The Bay of Augusta is located along the NE margin of the Hyblean Plateau (SE Sicily). In this area a mostly bioclastic and terrigenous Quaternary succession outcrops. This area recorded a constant regional uplift rate of 50 kA. Two main groups of faults, referred to as the northwest and the southwest fault zones, are separated by a central zone where no evident fault planes have been imaged by seismic data. The faults in both groups strike from N30W to N52W and are also inferred to be steeply dipping. The faults pertaining to northwestern cluster show a very little offset, 50 kA. As concern the southeastern fault zone, results coming from radiocarbon age dating don’t have sufficient resolut…

The geographic information in the assessment of geohazard in the marine environment

Slope instability and erosion, mass transport, volcanic and tectonic activity, fast sediment accumulation fluid escape are the main processes responsible for the geohazard in marine environment. A major knowledge about the geological setting of the offshore areas and related processes can be crucial to assess and manage the potential geological risks. High resolution morphobathymetric surveys, yielded in the frame of the MaGIC project (Marine Geohazards along the Italian Coasts), integrated with previously acquired data, single-channel seismic reflection profiles, backscatter data and sediments sampling, allow to define the geomorphological, stratigraphic and structural features in the offs…

Towards a new marine structural model of Italy

The exploitation of economic resources in marine environment and the assessment of natural hazards press a greater knowledge of the sea floor geology. Since the Structural Model of Italy was published in the 1991 by the CNR, new data have been collected concerning the marine geology of the sea floor surrounding Italy, also by means of up to date technologies (digital seismics, SBP Chirp, Multibeam). Data collected during the last decades in the frame of research programs as CROP MARE, CARG, morpho-bathymetric survey of the Tyrrhenian Sea, MAGIC, allow investigating the submerged geological structures with different temporal and spatial resolution. As consequence, at present marine geologist…

Mantle-derived helium in sedimentary basins of Central Mediterranean:Geologic and tectonic constrains on fluids accumulation and migration.

The geodynamics of the central Mediterranean is characterized by the interaction between the European plate and the African one. In this setting Sicily is a sector of the Appenine-Maghrebide accretionary prism, which is located between two areas affected by extensional tectonics (Sicily Channel to the south and the Thyrrenian back arc basin to the north). In the present study we present the first dataset of helium isotopic composition measured in fluids released from the central-western Sicily.With the aim to constrain the transfer system of fluids in this area we relate the results of geochemical investigations with the stratigraphy and structural setting, derived from field geology, deep …

Evidences of mud volcanoes in the Palermo and Termini Gulf (N Sicily offshore)

The occurrence of mud volcanoes and mud domes is, for the first time, documented in the continental shelf and upper slope of the Palermo and Termini Gulf (north Sicily offshore region). The study area belongs to the northern Sicily continental margin (southern Tyrrhenian Sea). Along this margin, morphology of the high-gradient continental slope is irregular due to the presence of structural highs, slope failures and canyons, and is interrupted by a flat area at a depth of 1,500 m. Mud volcano activity generally formed in areas characterised by high sedimentation rates and/or as consequences of regional tectonics (often compressional), overpressure in the sediments and gas generated at diffe…

Fluid escape structures in the north Sicily continental margin

Abstract High resolution and multichannel seismic profiles coupled with multibeam echosounder (seafloor relief) data, acquired along the northern Sicily continental margin (southern Tyrrhenian Sea), document the occurrence of mound and pockmark features, revealing fluid escape processes. Along this margin, morphology of the high-gradient continental slope is irregular due to the presence of structural highs, slope failures and canyons, and is interrupted by flat areas at a mean depth of 1500 m. Seismostratigraphic analysis tools and methods were used to identify fluid escape structures and to work out a classification on the basis of their morpho-acoustic characteristics. The detailed 3D ba…

Controlli stratigrafici e tettonici sull'evoluzione morfo-sedimentaria dell'offshore della Sicilia nord-occidentale durante il Quaternario

Submarine canyon of the north-western Sicilian offshore (Southern Tyrrhenian Sea): variability in morphologies, sedimentary processes and tectonic settings

Relationship Between Neotectonics And Fluid Escaping In The Northern Sicilian Continental Margin

New exploration in the marine environments has revealed that the fluid escape structures are often associated with neotectonic elements and are aligned along the same direction. Sometimes is observed the migration of fluid along fault planes to the sea floor as gas venting (Forrest et al., 2005). This paper aims to recognize and to classify the different types of structures associated with fluid seepage, particularly those that develop along alignments coinciding with or parallel to the neotectonic lineaments, in order to assess the interactions between tectonics and fluid circulation. The study area extends, from west to east, from the Gulf of Castellammare to the Gulf of Termini (offshore…

New foundings of contourite deposits in an active continental margin (Southern Tyrrhenian Sea)

Progetto MAGIC: “L’informazione territoriale nella valutazione del rischio geologico in ambiente marino”. . In: Workshop GIS Day: "GIStales: di dati, persone e strumenti”.

MaGIC è un progetto quinquennale (2007-2012) finanziato dal Dipartimento Nazionale della Protezione Civile per l'acquisizione di dati morfobatimetrici ad alta risoluzione. Lo scopo principale del progetto è quello di definire e rappresentare i principali elementi morfologici dei fondali marini, in particolar modo quelli derivanti da dinamiche morfo-sedimentarie che implicano mobilità e/o instabilità dei sedimenti e conseguenti situazioni di pericolosità per le infrastrutture e le aree costiere urbanizzate. I rilievi morfobatimetrici vengono realizzati con un sistema ecoscandaglio radiale multifascio (Multibeam echosounder systems) calibrato ad hoc nell’area di lavoro e corretto in velocità …

Carta geologica d'italia alla scala 1:50.000 e note illustrative del foglio 595_Palermo

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 orog…

A possible evolutionary model of “aligned pockmarks”

PROCESSI ATTIVI NEL MARGINE CONTINENTALE DELLA SICILIA NORD-OCCIDENTALE: NEOTETTONICA, RISALITA DI FLUIDI E FENOMENI GRAVITATIVI

La ricerca riguarda l’analisi degli elementi morfostrutturali, le strutture legate alle emissioni di fluidi ed i fenomeni di trasporto sia gravitativo che selettivo, in ambiente sommerso ed emerso, presenti nel settore del margine continentale nord-siciliano compreso tra i meridiani passanti per le isole Egadi e Cefalù, al fine di ottenere un modello evolutivo durante il Quaternario. In particolare sono stati studiati in dettaglio: a) gli elementi morfostrutturali, al fine di ottenere informazioni sull’evoluzione recente dell’area, concentrando l’attenzione sulle faglie recenti e attive, integrando anche le informazioni concernenti la sismicità dell’area, ricavati dai database online; b) le…