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 strutture legate alle emissioni di fluidi, che rappresentano una conseguenza dei processi superficiali e profondi all’interno del settore crostale indagato, implementate con lo studio geochimico dei fluidi estratti da carote di sedimento prelevate in corrispondenza di queste strutture; c) le forme prodotte dai fenomeni di trasporto gravitativo ed in particolare quelle innescate dalla migrazione dei fluidi, cercando di comprendere le relazioni che intercorrono tra i vari meccanismi e come questi contribuiscono all’evoluzione recente del margine. In questa ricerca, oltre ad un accurato lavoro bibliografico che ha permesso di approfondire le tematiche e di descrivere lo stato dell’arte delle stesse, sono stati utilizzati dati pregressi (acquisiti dal gruppo di Geologia Marina dell’Università di Palermo) e reperiti da database esistenti e fonti bibliografiche e dati di nuova acquisizione. In particolare tra il 2009 e il 2013 sono state effettuate diverse campagne oceanografiche (PUMA 09, MACS_2010, MASVE_2013) svolte nel settore compreso tra le isole Egadi e Cefalù (alle quali la scrivente ha partecipato), nell’ambito del progetto MaGIC (Marine Geohazards along the Italian Coasts), dove sono stati acquisiti dati morfobatimetici e di sismica a riflessione monocanale. Su questi dati sono state effettuate le procedure di editing e/o processing e l’interpretazione. I dati sismici multicanale acquisiti dall’ENI/AGIP e messi a disposizione in formato digitale dal Ministero dello Sviluppo Economico nell’ambito del progetto VIDEPI sono stati inseriti in un database georeferenziato e trasformati in formato seg-y per mezzo di software dedicati, al fine di ricostruire la superficie del riflettore M e verificare l’esistenza di faglie nei settori in cui erano stati individuati nel modello morfobatimetrico le scarpate di faglia, le incisioni, gli allineamenti di pockmark e i mound. I profili monocanale sono stati utilizzati per ricostruire le architetture deposizionali ed i caratteri strutturali della successione plio-quaternaria e per analizzare le strutture riconosciute nel modello morfobatimetrico. Inoltre sono state effettuate l’analisi granulometrica di una carota di sedimento prelevata nel Golfo di Palermo in corrispondenza di una struttura da risalita di fluidi (pockmark) alla profondità di 414 m e l’analisi geochimica dei fluidi estratti dalla stessa; quest’ultima al fine di caratterizzare chimicamente ed isotopicamente la fase fluida che occupa i pori dei sedimenti e di spiegarne l’origine. I dati ricavati da database online (http://www.idromare.it; http://www.ingv.it) e fonti bibliografiche sono in particolare: dati meteomarini (ricavati dalla rete ondametrica nazionale, boa di Capo Gallo), dati meteorologici e sulla circolazione delle correnti, elementi necessari per valutare i parametri relativi alla dinamica esogena in ambiente sottomarino e dati sismologici (localizzazione dei terremoti e soluzione dei meccanismi focali). In questo lavoro le strutture neotettoniche sono state individuate grazie all’interpretazione dei dati morfobatimetrici e dei dati di sismica a riflessione. Le faglie attive, in ambiente sottomarino, si riconoscono in base a dislocazioni del fondo mare o della coltre sedimentaria, causate da faglie che interessano anche strati più profondi; evidenza di faglie che controllano la sequenza tardo-quaternaria; dislocazioni del fondo mare o di sedimenti sub-superficiali, legate alla presenza di scivolamenti o slumping; dislocazioni del fondo mare o di strati più profondi in senso contrario rispetto al gradiente batimetrico; evidenze di morfologie sul fondo marino che testimoniano risalite di fluidi come pockmark, vulcani di fango, mound etc. L’allineamento degli epicentri dei terremoti con le strutture superficiali e sepolte riconosciute, ha permesso inoltre, di riconoscere le faglie sismogenetiche, mentre i meccanismi focali hanno consentito di ricostruire la cinematica delle faglie e il campo regionale degli sforzi. Le strutture da risalita di fluidi sono state riconosciute attraverso l’interpretazione del modello morfobatimetrico, il riconoscimento delle zone di Wipeout (sbiancamento), l’alta riflettività (backscatter), la geometria dei riflettori, le variazioni di velocità e l’inversione di fase nei profili sismici a riflessione. Esse sono state distinte in strutture in rilievo (mound) e strutture depresse (pockmark). I pockmark sono stati parametrizzati in funzione di: diametro, altezza, profondità, distanza dalla linea di costa e dal ciglio della piattaforma, vicinanza dalle faglie e dalle frane e orientazione quando si presentano allineati. Le strutture da trasporto gravitativo che includono canyon e frane sottomarine sono state studiate attraverso l’interpretazione dei dati morfobatimetrici, effettuando analisi morfometriche, come la pendenza dei versanti, l’indice di sinuosità, la lunghezza del thalweg e l’esposizione rispetto alle correnti sottomarine, la stima dei volumi dei sedimenti mobilizzati, fattori chiave per la comprensione della dinamica dei pendii. In particolare queste strutture sono state analizzate per valutare la loro interazione sia con i processi legati alla risalita di fluidi che con quelli legati alla tettonica. Inoltre è stato analizzato l’andamento dei profili longitudinali dei canyon sottomarini e messo a confronto con quelli di canyon (Carlsbad, Oceanside, East Break) presenti in altri contesti geodinamici, per valutare dalla forma del profilo (concava o convessa) e dalle architetture deposizionali il tipo di margine e il modello geologico evolutivo. L’evoluzione del margine continentale nord-siciliano durante il Quaternario, ricostruita attraverso l’analisi e l’interpretazione di dati di diversa tipologia, risulta essere legata: • alla deposizione della successione quaternaria, che è organizzata in sequenze deposizionali legate all’interazione tra tettonica, sedimentazione ed oscillazioni eustatiche. Essa è costituita da depositi clastico-terrigeni pleistocenici immergenti verso mare, troncati nel settore di piattaforma dalla superficie di erosione, formatasi durante l’ultima oscillazione glacio-eustatica, sulla quale poggiano i corpi sedimentari della sequenza deposizionale tardo-quaternaria. • Alla tettonica recente che agisce prevalentemente secondo due sistemi: 1) un sistema distensivo e/o transtensivo orientato NO-SE, che crea una morfologia del fondo mare articolata, nella quale si riconosce un’alternanza di alti e bassi strutturali che individuano nel loro complesso una serie di blocchi tiltati; 2) un sistema compressivo o transpressivo orientato ENE-OSO, evidenziato dalla presenza di faglie inverse ad alto angolo e da sovrascorrimenti come ad esempio nel settore della Barra, in accordo con quelli trovati nel settore emerso. Gli stessi trend sono stati riconosciuti nel settore onshore, dove si osserva la dislocazione dei depositi sin e post tirreniani, e la differente quota a cui sono stati ritrovati i terrazzi recenti. Lo studio integrato dei dati morfo-strutturali e sismologici ha permesso di evidenziare i rapporti tra i meccanismi focali dei terremoti e le principali strutture tettoniche riconosciute nell’area di studio, risultando entrambi coerenti con un modello tettonico compressivo con trend NO-SE. Inoltre i cluster degli epicentri dei terremoti del 2002 (6/9/02 M 5.6), del 2010-2013, localizzati a nord del Golfo di Palermo e allineati con la faglia che borda l’alto morfologico della Barra in direzione ENE- OSO, ed i cluster allineati in direzione NO-SE come quello del terremoto del 1998 e il recente (13/04/2012) localizzato sulla scarpata nella zona antistante Sferracavallo (M 4,2), allineati con le strutture tettoniche, che si riconoscono nell’offshore dei Monti di Palermo, le cui soluzioni focali rivelano meccanismi compressivi, permettono di definire questi due sistemi come sistemi attivi e soprattutto sismogenetici. • Ai fenomeni di risalita di fluidi che si manifestano attraverso strutture sia in rilievo (mound) che depresse (pockmark). I pockmark, che si impostano esclusivamente sulla scarpata continentale sono il risultato della risalita di fluidi che migrano attraverso la successione clastica quaternaria. L’espressione morfologica ancora ben conservata di queste strutture, che non presentano evidenze di erosione (come normalmente riportato in letteratura), permette di ipotizzare una genesi recente. La loro distribuzione areale coincide con gli alti del substrato messiniano. Il segnale chimico ed isotopico delle acque interstiziali, estratte dalla carota di sedimento, prelevata in corrispondenza di una di queste strutture, mostra prevalentemente un arricchimento degli isotopi pesanti rispetto allo standard di riferimento V-SMOW, e piccole variazioni nelle concentrazioni dei cloruri e del sodio, che risultano il 10% inferiori, rispetto a quelle delle acque del Mediterraneo. Questi valori, sono compatibili con la presenza di un fluido a salinità inferiore, rispetto all’acqua di mare, ed arricchito in isotopi pesanti, per cui è possibile ipotizzare la presenza di fluidi, provenienti dalla disidratazione dei gas idrati. I mound, individuati esclusivamente nella piattaforma continentale, si presentano in due tipologie: affioranti e sepolti. Solo su questi ultimi è possibile avanzare un’ipotesi sull’età di formazione. La loro età, compresa tra 20.5 e 5.5 ka, viene indicata, dalla presenza della dislocazione della superficie di erosione, che limita alla base l’ultima sequenza deposizionale (20.5 ka) e dalla superficie di maximum flooding (5.5 ka), che sigilla queste strutture, e che viene datata sulla base della correlazione con la curva di Fairbanks (1989). • Ai fenomeni franosi che vengono evidenziati dalla presenza di nicchie di frana e depositi di accumulo. In quest’area essi si sviluppano in risposta a tre processi: 1) attività tettonica, generando frane di crollo, come quelle che si osservano nell’offshore nord-orientale di Marettimo e Monte Pellegrino, dove si riconoscono gli accumuli costituiti da blocchi di dimensioni decametriche, nel settore nord occidentale del Golfo di Castellammare, dove i fenomeni franosi interessano la piattaforma continentale, e nelle aree dove si riconoscono alte scarpate di faglia, come in corrispondenza dell’Alto di S. Vito, nel settore occidentale di Banco Scuso, nel versante sud-occidentale dell’isola di Marettimo e nel settore orientale del Golfo di Termini; 2) alla risalita di fluidi. Le nicchie di frana sono state trovate a valle dei pockmark nel Golfo di Palermo, nel settore compreso tra i canyon Oreto ed Eleuterio, in corrispondenza di Monte Solunto e nell’Alto di S.Vito; 3) evoluzione retrogressiva dei canyon, come nel caso dei canyon Cofano, Mondello, Addaura, Arenella e in parte Eleuterio. • Ai fenomeni di erosione gravitativa e da incisioni canalizzate che modificano la morfologia della scarpata, sulla quale sono stati riconosciuti due tipologie di canyon: 1) quelli che si sviluppano dal basso verso l’alto, agevolati dalla più alta inclinazione della scarpata, con evoluzione retrogressiva (bottom-up), e cioè che si sviluppano per mezzo di fenomeni franosi, che hanno origine nella parte inferiore, e che avanzano verso la scarpata superiore (Cofano, Mondello, Addaura, Arenella ed Eleuterio in parte); 2) quelli che si sviluppano dall’alto verso il basso (evoluzione top-down), la cui evoluzione è tipicamente legata ai processi torbiditici, innescati dall’attività dei sistemi fluviali presenti a monte (Oreto, Castellammare, Capo Plaia ed Eleuterio in parte). Le incisioni canalizzate, tranne nel settore del Golfo di Castellammare, si dispongono lungo una direzione, che generalmente coincide con quella dei lineamenti tettonici. All’interno di alcune di queste incisioni, sono stati osservati i pockmark, che presentano orli erosi. Disposti parallelamente, e in direzione dei trend tettonici riconosciuti, si ritrovano sia allineamenti di pockmark, che incisioni più profonde. Questa evidenza permette di ipotizzare il loro meccanismo genetico. Le strutture circolari allineate, formatesi in corrispondenza di lineamenti tettonici, coalescono creando i solchi, questi sia per effetto di risalite continue, che per effetto della dinamica esogena, possono svilupparsi, evolvendo prima in canali e poi forse in canyon. Sulla base dei risultati ottenuti è possibile considerare il margine continentale nord siciliano come un margine immaturo, nel quale l’instabilità è fortemente legata all’attività tettonica. Le faglie, oltre a modificare l’articolazione del margine, facilitano la risalita dei fluidi, evidenziata dalla formazione dei pockmark. Questi ultimi agevolano a luoghi l’innesco dei fenomeni franosi, che a loro volta possono determinare l’evoluzione retrogressiva dei canyon.In obtaining an evolutionary model of the northern Sicilian continental margin during the Quaternary, this research is concerned with the analysis of morphostructural elements, fluid escape structures, and selective and mass movement transport mechanisms, both in offshore and onshore settings, in the sector spanning between the Egadi Islands and Cefalù meridians. In particular the following have been studied in detail: a) morphostructural elements, in order to gather information pertaining to the recent evolution of the area, focusing on the recent and active faults, also integrating seismicity data of the region, taken from online databases; b) structures linked to the fluid escape, subsequent to shallow and deep processes within the investigated crustal sector, integrated with data from geochemical analysis of pore water derived from core sediment samples; c) structures produced by mass movement mechanisms and in particular those triggered by fluid migration, seeking to highlight the relationships between different mechanisms and their contribution to the recent evolution of the margin. In addition to a meticulous bibliographic search which allowed for an in-depth analysis and an up-to-date account on the subjects, pre-existing data has been used (provided by the Marine Geology group of the University of Palermo), as well as those derived from established databases and bibliographic sources, and overall newly acquired. Regarding the latter, morpho-bathymetric and single-channel seismic reflection data was collected during several oceanographic cruises between 2009 and 2013 (PUMA 09, MACS_2010, MASVE_2013) carried out in the area between the Egadi islands and Cefalù (in which the writer participated), in the context of the MaGIC project (Marine Geohazards along the Italian Coasts). The data collected was edited and/or processed accordingly before being interpreted. The multi-channel seismic reflection data acquired by ENI/AGIP and provided in digital format by the Italian Ministry of Economic Development in the context of the VIDEPI project has been inserted into a georeferred database and converted into seg-y format via a dedicated software, so as to reconstruct the surface of the M-reflector and verify the actual existence of faults in the sectors where fault escarpments, incisions, pockmark alignments and mounds have been identified through the morpho-bathymetric model. The single-channel profiles have been utilized to reconstruct the depositional architecture and the structural characteristics of the Plio-Quaternary succession, also allowing for an analysis of the structures of the morpho-bathymetric model. In addition, on a sediment core sample collected in proximity to a fluid escape structure (pockmark) in the Gulf of Palermo, at 414 m b.s.l., granulometric analysis as well as pore-water analysis have been performed; the latter aimed to chemical and isotopic characterization of the fluid phase occupying pores so as to determine its origin. The specific data obtained from online databases (http://www.idromare.it; http://www.ingv.it) and from literature sources is: meteo-marine, meteorological and sea surface current data; elements necessary to evaluate the parameters relative to submarine dynamics and seismological data (location and focal mechanisms of earthquakes). In this study neotectonic elements have been identified through interpretation of morpho-bathymetric and seismic data. Active faults, in a submarine environment, are recognized as displacements of the seafloor or shallow sedimentary layers by faults that clearly displace deeper geological strata at the same localities; evidence of fault control on late Quaternary sedimentation; displacement of the seabed or near-surface sediments where evidence of large-scale land-sliding or slumping occurs; displacement of the seafloor and deeper strata in the opposite sense to the local bathymetric gradient; evidence of morphologies on the seabed as pockmark and mound. The alignment of the earthquake epicenters with recognized seabottom and buried structures, allowed to recognize seismogenic faults, whilst focal mechanisms have permitted the reconstruction of the fault kinematics and the regional stress field. The fluid escape structures have been recognized thanks to interpretation of the morpho-bathymetric model, presence of wipeout zones, backscatter, reflector geometry, change of velocity and phase inversion in seismic reflection profiles. They have been distinguished as mounds or pockmarks. The latter have been characterized according to the following parameters: diameter, height, depth, distance from coastline and shelf edge, proximity to faults and landslides. Mass wasting structures including canyons and submarine slope failures have been studied through morpho-bathymetric analysis, conducting morphometric analyses, such as slope steepness and aspect, sinuosity index and thalweg length, estimation of volume of sediments mobilized, all key factors for understanding slope dynamics. In particular, these structures have been analyzed for their interaction with the processes related both to the ascent of fluids as well as to those related to tectonics. In addition, the longitudinal profiles of submarine canyons were compared to those present in other geodynamical settings (Carlsbad, Oceanside, East Break), so as to make inferences about the margin type and evolutionary geological model from the physical features (concave or convex) and depositional architecture. The evolution of the north-Sicilian continental margin during the Quaternary, reconstructed through analysis and interpretation of different types of data, appears linked to: • the deposition of the Quaternary succession, which is organized in depositional sequences associated with the interaction between tectonic, sedimentation and eustatic oscillations. It is made up of seaward dipping clastic and terrigenous Pleistocene deposits, truncated by an erosional surface formed during the last glacio-eustatic oscillation, on which lie the late Quaternary depositional sequence. • the recent tectonic that operates mainly by two fault systems: 1) a NW-SE trending extensional and/or transtensional system, which produces the recent articulation of the seabed, and 2) an ENE-WSW trending compressive system, highlighted by high-angle reverse faults and thrusts in accordance to those found onshore. The integrated study of the morpho-structural and seismological data has highlighted the relationship between the focal mechanisms of earthquakes and major tectonic structures recognized in the study area, both being consistent with a compressional tectonic model with NW-SE trend. Moreover, the earthquake clusters of 2002 (M 5.6 06/09/02), 2010 to 2013, located in the northern Gulf of Palermo and aligned with the ENE -WSW trending fault recognized in “La Barra High”, and the clusters aligning in NW-SE direction such as that of the earthquake of 1998 and the recent one (13/04/2012) located in the offshore Sferracavallo upper continental slope (M 4.2), aligned with the tectonic structures, which are recognized in the offshore Palermo Salient, whose focal solutions reveal mechanisms compression, which allow to define these two systems as active and especially seismogenic systems. • The fluid escaspe processes that form both positive structures (mound) and negative structure (pockmark). Pockmarks that are found exclusively on the continental slope are the result of the ascent fluids that migrate through the Quaternary clastic succession. The morphology of these structures, still well-preserved, allow to suggest a recent formation. The chemical and isotopic signal of pore water extracted from sediment core, taken at one of these structures, mainly proved that pore water is slightly enriched in heavy isotopes with respect to Mediterranean seawater V-SMOW, while the distribution profiles of EC, ion concentration (Cl, SO4, Na, K, Mg, Ca), ion/Chloride ratios (Na/Cl, K/Cl, Ca/Cl, Mg/Cl and Alk/Cl) seem to indicate the existence of an external source of fluids and the occurrence of sediment-fluids interaction processes. A possible mechanism causing pore water freshening could be to be the destabiliza

"La Selezione del Personale, dall'economia dei contratti all'organizzazione delle Risorse Umane"

Un’analisi approfondita sull’ importanza della gestione strategica delle risorse umane, il cosiddetto “Strategic Human Resource Management”, le sue implicazioni sul sistema di gestione del personale e sulle performance dell’azienda. Inoltre viene analizzata la selezione in un’ottica economica di tipo contrattuale, per poi affrontare lo svolgimento del processo di ricerca e di selezione, con particolare riferimento alle tipologie di mercato del lavoro in cui poter reclutare personale e alle modalità di selezione dei candidati. Infine, vengono analizzate le implicazioni sulle risorse umane, alla luce dei cambiamenti che la recente riforma del lavoro, il cosiddetto Jobs Act, ha introdotto su alcune tipologie di contratti

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 <1 mm/yr during the Late Pleistocene and recurrent, strong (up to 7.0 Md) historical earthquakes. Data for this study come from a recent nearshore geophysical survey performed by URS Corporation Ltd with the aim to evaluate the potential for seismic hazard. The collected data consist of: 1) a high resolution seismic survey (sparker source and sub-bottom profiling); 2) five soil borings to characterize and obtain age dates for shallow subsea sediments. Four main seismic units have been recognized inside the sedimentary infill: • Unit D is the oldest, seawards dipping, unit overlying the acoustic basement. Upwards this unit is bounded by a rough, erosional truncation (horizon H4). • Unit C shows sub-horizontal reflectors with variable seismic attributes, forming a prominent angular unconformity above H4; in the proximal sector of the Augusta Bay they lie seaward dipping. This unit shows valuable thickness change across the Bay and is bounded upwards by a very rough erosional truncation (horizon H3). • Unit B shows planar parallel reflectors with good lateral continuity. Its thickness change and it is very thin along the slope of the morphostructural highs formed by uplift of units D and C. Upwards it is bounded by a very prominent erosional truncation (H2 horizon). • Unit A is imaged by sub-horizontal, continuous reflectors, alternating with intervals of transparent seismic facies. The reflectors onlap the H2 horizon and, in a few places, display prograding geometry. On the collected samples biochronological and radiometric age-dating has been performed. The cores drilled the unit A and the uppermost part of the unit B, where the sediments have revealed absolute age > 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, < 15 m. These faults have displaced mostly seismic unit C and have controlled two, NW-SE trending little structural lows in the central and in the northernmost sectors of the investigated area. These restricted basins have been filled by B and A seismic units deposits that don’t appear displaced by the fault cluster. The southeastern fault zone is long less than 700 m and show an offset of 1 to 5 m. These faults displaced the horizons of seismic Unit C in a sector where this unit outcrops at the sea bottom or it is draped by a very thin veneer of Unit A sediments. The faults pertaining to the northwestern zone post-date Unit C but they appear older than Units B and A.Radiocarbon age-dating have demonstrated that the most recent horizons involved in the northwestern fault zone displacement is > 50 kA. As concern the southeastern fault zone, results coming from radiocarbon age dating don’t have sufficient resolution to correlate deposits to seismic horizons involved in tectonic deformation. Nevertheless, there the seismic unit A also appears slightly involved by the latest faults activity. The analysis of the Bay of Augusta seismic grid has shown that very recent tectonic features have displaced the Late Quaternary sedimentary infill; interpretation of our results could better constrain the neotectonic setting of an area characterized by high seismic hazard

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 allowed us to identify and characterise two areas where different geological features (sedimentary and volcanic) are prevailing. They present fluid escaping evidence, which often appears to be active and generating different types of morphologies (both positive and negative). In the western sector we recognised pockmarks at water depths of 195 to 317 m, with diameters from 25 to 580 m, depths from 1.3 to 15 m, and slope up to 23◦ . They show sub-circular shape in plan-view and reflectors with upward concavity in cross section, and are oriented along a NW-SE trend.The CHIRP and multichannel profiles highlight fluids that affect the Plio-Quaternary succession, especially in areas where the top surface of the Messinian succession is shallower. Conversely, wipe-out acoustic facies were recognised in proximity of: i) extensional faults of Mesozoic age with NW-SE trend; ii) dip/strike slip faults of Cenozoic age with NW-SE, N-S and about NNE-SSW trends, and iii) extensional neo-tectonic faults with NW-SE and NNW-SSE trends. We cannot exclude that they could feed the shallower reservoir producing a mixing between the two. In the eastern sector we recognised a cluster of volcanoes composed of seven cone-shaped structures (SCV1-7), pertaining to a wide area known as Graham Bank. A detailed morphometric analysis of these volcanoes has been conducted: they are up to about 115-160 m high and 500-1500 m wide. Most of them show very strongly inclined flanks with 30◦ of average slope. The SCV2 and SCV3 form the Graham Bank, 3.5X2.8 km wide, elongated in the NW-SE direction. At the top of SCV2 focused seepage plumes were observed in the entire water column, through the CHIRP data, where we calculated that they release, a volume of about 10950 m3 and 43960 m3of gases, respectively. In this work, we present the first results of a data collection that have got as main result the identification and mapping of the fluid escape structures revealing the relationship between the active tectonic with migration of fluids, to be used to assess the Submarine Geo-Hazard in the Sicily Channel. We identified two fluid escape fields whose genesis and evolution appear linked to the neotectonic and volcanic activities respectively, that represent the main controlling factors for the migration of fluid; considering the good correlation between pockmarks and the main identified fault systems. In conclusion, our results suggest that the degassing of fluids in this region is rooted at depth, and is mainly aligned with the NW-SE dip/strike slip fault systems, repeatedly reactivated, and linked to the volcanic activity.peer-reviewe

VARIABILITY OF DEPOSITIONAL SETTING ALONG THE NORTH-WESTERN SICILY CONTINENTAL SHELF (ITALY) DURING LATE QUATERNARY: EFFECTS OF SEA LEVEL CHANGES AND TECTONIC EVOLUTION

The geological, geomorphological and sedimentological features of the north-western Sicily continental shelf are here illustrated with the aim to propose a geological model able to explain the Neogene-Quaternary evolution of the Sicilian continental margin in the context of the central Mediterranean region. Above the continental shelf and upper slope the sedimentary succession, showing along the different sectors of the margin considerably variable internal geometry and stratigraphic relationships with the underlying units, is interpreted as a IV order depositional sequence (Late Quaternary Depositional Sequence, LQDS) deposited during the last eustatic change (last 125 ky). The lower boundary of the LQDS is represented by a subaerial erosional surface formed during the last eustatic sea level fall ended in the LGM (20-18 ka). This unconformity lies above a seaward dipping Pleistocene succession whose depositional architecture is in turn controlled by Quaternary eustatic sea-level fluctuations. A dense dataset of morphobathymetric and high resolution seismic data allowed to recognize along the continental shelf to bathyal plain system different types of continental shelf with different stratigraphic and morphostructural settings, associated to both large-scale processes and specific factors related to more local control: a) predominantly rocky shelves, both accompanied by a moderate frontal sedimentary prism and with a structural edge, in the structural highs of the Monti di Palermo offshore and around the main rocky headlands (Capo San Vito, Monte Catalfano); b), depositional shelves, in the Castellammare, Palermo and Termini Imerese gulfs, both with a regular seaward deepening of the substrate and with a substrate uplift at the shelf break. We confirm that depositional sequences in this margin are the result of the interaction between sea level changes and sedimentation, but demonstrate that the tectonic activity has played a key role, not only in the creation of different types of continental shelves, but also to determine the different characters of each sequence in different areas. The general tectonic uplift during the Pleistocene, together with the episodic alternation of extensional and compressional events, often with strike-slip component, is responsible for the thickness and facies variation both onland, where residual Pleistocene marine deposits today outcrops, and in the continental shelf, where most of the depositional sequences developed and are now recognized. As well tectonic activity exerted a control on the geomorphological features (e.g. pockmarks and mounds) of the present day coastal areas and shelf-slope system, as well as for the submarine canyons and the mass failure processes

Addressing the magnetic properties of sub-monolayers of single-molecule magnets by X-ray magnetic circular dichroism

We report on a comparative study of electronic and magnetic properties of Mn6 single-molecule magnets (SMMs) grafted on gold surface. Two derivatives with spin-ground states S ¼ 4 andhave been functionalized with 3-tp-CO2 (3-thiophene carboxylate, tpc) ligands and characterized thick films (TFs) as well as sub-monolayers (sMLs) by synchrotron based techniques. X-ray absorption spectroscopy at the Mn L2,3 edges shows the modification of the spectral lineshape in the sMLs respect to the TFs suggesting that the local symmetry at the Mn sites changes once the molecules deposited on gold surface. In spite of this, the expected MnIII oxidation state is preserved. X-ray magnetic circular dichroism (XMCD) spectra show that the total magnetic moment is only spin part because of the quenched orbital moment. Moreover, variable temperature and variable XMCD spectra reveal an effective decrease of the Mn spin moment for both derivatives

Antiferromagnetic coupling of TbPc2 molecules to ultrathin Ni and Co films

The magnetic and electronic properties of single-molecule magnets are studied by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. We study the magnetic coupling of ultrathin Co and Ni films that are epitaxially grown onto a Cu(100) substrate, to an in situ deposited submonolayer of TbPc2 molecules. Because of the element specificity of the X-ray absorption spectroscopy we are able to individually determine the field dependence of the magnetization of the Tb ions and the Ni or Co film. On both substrates the TbPc2 moleculescouple antiferromagnetically to the ferromagnetic films, which is possibly due to a superexchange interaction via the phthalocyanine ligand that contacts the magnetic surface

Spin-communication channels between Ln(III) bis-phthalocyanines molecular nanomagnets and a magnetic substrate

Learning the art of exploiting the interplay between different units at the atomic scale is a fundamental step in the realization of functional nano-architectures and interfaces. In this context, understanding and controlling the magnetic coupling between molecular centers and their environment is still a challenging task. Here we present a combined experimental-theoretical work on the prototypical case of the bis(phthalocyaninato)-lanthanide(III) (LnPc 2) molecular nanomagnets magnetically coupled to a Ni substrate. By means of X-ray magnetic circular dichroism we show how the coupling strength can be tuned by changing the Ln ion. The microscopic parameters of the system are determined by ab-initio calculations and then used in a spin Hamiltonian approach to interpret the experimental data. By this combined approach we identify the features of the spin communication channel: the spin path is first realized by the mediation of the external (5d) electrons of the Ln ion, keeping the characteristic features of the inner 4 f orbitals unaffected, then through the organic ligand, acting as a bridge to the external world

Fluid escape structures revealing volcanic and tectonic activity in the Graham Bank (Sicily Channel)

The Graham Bank (NW Sicily Channel, Central Mediterranean) is characterised by a complex seafloor morphology, where morphostructural highs, submarine plain, escarpments, and negative and positive relieves indicate a complex structural setting and the occurrence of seepage fluids. New high-resolution acoustic data (multibeam, Chirp profiles) and multi-channel profiles, allowed us to differentiate two main morphological sectors, and to identify several pockmarks and mounds linked to fluid escape phenomena. The eastern sector, corresponding to the volcanic edifices of the Graham Bank, is characterised by volcanic context with rough morphology, several mounds, focused seepage plumes and magmatic acoustic substrate, all related to the activity forming both the Graham Bank and the new volcanic cones here identified. The western sector displays a generally flat morphology dominated by Late Pleistocene-Holocene outer shelf deposits, where mounds and pockmarks with sub-circular and ellipsoidal shapes, V- to U-shaped in cross-section, are the prevailing features indicating the migration of fluids to the seafloor. These two areas are separated by a vertical deep fault forming a deeply incised channel with NW-SE direction. The latter is bordered by steep walls forming fault escarpments, which shed the eroded materials to the adjacent lower slope and deep-water zones. The overall morphostructural setting suggests a tectonic control in the morphological conformation of the seabed and in the distribution of both pockmarks and mounds. The aligned mounds have both NW-SE and NNW-SSE orientation, sometimes extending several hundred metres and forming hummocky surfaces. The aligned pockmarks are strictly comparable to the orientation of the faults related to the most recent tectonic activity. The good correlation between fluid escape structures and the main fault systems involving the kilometric sedimentary cover suggests that the degassing of fluids is rooted in depth revealing that extensional tectonics acts with very deep subvertical recent faults developing along and reactivating the Cenozoic (both Plio-Quaternary and Messinian) and Mesozoic tectonic systems.peer-reviewe

Volcano- and neoectonic-related slope failures in the north-western Sicily Channel (Central Mediterranean Sea) : implications for understanding and assessing geohazard risk

The southern Sicily coasts represent an important contribution to Italian tourism and marine geological processes in the Sicily Channel could pose a significant risk to neighbouring populations and goods. In this work, we are presenting the first results of the data collection that allowed us to identify and map several geological elements that can be used to assess submarine geohazards in the Sicily Channel. By using multibeam data and high-resolution seismic reflection profiles acquired during the ACUSCAL 2015 Cruise, we defined the characteristics of the morphostructural highs, and the morphology of slope failures and the stratigraphy of the mass transport deposits (MTD).peer-reviewe