Palaeo-Shoreline Configuration of the Adventure Plateau (Sicilian Channel) at the Last Glacial Maximum

The Adventure Plateau, located in the NW sector of the Sicilian Channel, experienced several episodes of exposure/erosion and subsequent drowning, with the most recent occurring after the Last Glacial Maximum (LGM). Unlike other parts of the Sicilian Channel, the Adventure Plateau is relatively tectonically stable and is therefore best suitable for reconstructing its coastal configuration before the post-LGM marine transgression. Here, we use high-resolution seismic data to identify and map the palaeo-coastline at the LGM on the basis of the internal architecture of the prograding wedges (i.e., the location of the subaqueous clinoform rollover point) and the erosional markers such as the subaerial unconformities and the wave ravinement surfaces. These data, which show an extreme variability in the palaeo-morphology of the coastal margins of the Adventure Plateau, have been complemented with vintage seismic profiles in order to entirely cover its perimeter. The mapped LGM coastline has then been compared to predictions from glacial isostatic adjustment (GIA) modeling, which considers the horizontal migration of the shorelines in response to sea level rise and to Earth's rotational and deformational effects associated with deglaciation. The two shorelines (i.e., the coastline derived from the marine data interpretation and the one derived from the GIA model) are in good agreement at 21 kyears BP, although some discrepancies occur in the southern part of the plateau, where the seabed slope is extremely gentle, which makes the clinoform rollover points and the buried erosional unconformities difficult to detect. After 20 kyears BP, an acceleration in the rate of the sea level rise occurred. The results of this study indicate the importance of comparing experimental data with model predictions in order to refine and calibrate boundary parameters and to gain a better picture of the evolution of sea level rise over various time scales

From shallow to very shallow image of the highly active Kefalonia - Zakynthos fault system

4 pages, 2 figuresIn May 2022 and June 2023 two oceanographic cruises were carried out around the Ionian Islands with the aim of defining the real geometry of the strike-slip fault system of Kefalonia and of the reverse faults present south of Zakynthos. The acquired multidisciplinary and multiresolution data will also allow to understand the dynamics of the area offshore the Peoloponnese peninsula, the deformation of the surface sediments at the transition of the two systems, i.e. from reverse fault system to strike-slip fault system, and the relationship between the recorded seismicity and mapped fault activity. To date, the analysis of the processed data has allowed us to define the tectonic and morphological complexity of the fault system affecting the investigated area. [...]Thanks to the CNR for supporting the cruise with time ship, IONIANS 2022 project. Interpretation of seismic profile has been done using the Kindgom IHS Markit. Poseidon project has been supported by Eurofleet+ SEA02_13_POSEIDONPeer reviewe

Editorial of Special Issue “Tectonics and Morphology of Back-Arc Basins”

Back-arc basins are tectonic domains within subduction systems shaped mainly by extensional and transtensional tectonics or in some cases by compression, volcanism and intense hydrothermalism [...

Evidence for fluid circulation, overpressure and tectonic style along the southern Chilean margin

The southern Chilean convergent margin, between 50° and 57° S, is shaped by the interaction of the three main plates: Antarctic, South America and Scotia. North of 53° S, the convergence between Antarctic and South America plates is close to orthogonal to the continental margin strike. Here, the deformational style of the accretionary prism is mainly characterized by seaward-verging thrusts and locally by normal faults and fractures, a very limited lateral extension of prism, a very shallow dip (∼ 6°) décollement, and subduction of a thick and relatively undeformed trench sedimentary sequence. South of 53° S, convergence is oblique to the margin, locally, the trench sediments are proto-deformed by double vergence thrusting and the front of the prism grows through landward-verging thrusting. The décollement is sub-horizontal and deep, involving most of the sediment over the oceanic crust in the accretionary process, building a comparatively wide and thicker prism. A Bottom Simulating Reflector is present across the whole prism to the abyssal plan, suggesting the presence of gas in the sediments. The analysis of P- and S-wave velocity reflectivity sections, derived by amplitude versus offset technique (AVO), detailed velocity information and the velocity-derived sediment porosity have been integrated with the structural analysis of the accretionary prism of two selected pre-stack depth migrated seismic lines, aiming to explain the relation between fluid circulation and tectonics. Accretion along double vergence thrust faults may be associated with the presence of overpressured fluid, which decreases the effective shear stress coefficient along the main décollement and within the sediments, and modify the rheolgical properties of rocks. The presence of an adequate drainage network, represented by interconnected faults and fractures affecting the entire sedimentary sequence, can favour the escape of pore fluid toward the sea bottom, while, less permeable and not faulted sediments can favour fluid accumulations. Gravitational and tectonic dewatering, and stratigraphy could control the consolidation and the pore overpressure of sediments involved in subduction along the trench. The results of our analysis suggest the existence of a feedback between tectonic style and fluid circulation

Offshore Antarctic Peninsula Gas Hydrate Reservoir Characterization by Geophysical Data Analysis

energie

Geological and structural evolution of tectonically active areas of the central Calabria Arc

Scuola di Dottorato "Archimede" in Scienze, Comunicazione e Tecnololgie, indirizzo Scienze della Terra, Ciclo XXVII, a.a. 2015-2016The Catanzaro Trough is a Neogene-Quaternary basin developed between the Serre and the Sila Massif, filled by up to 2000 m of Upper Miocene to Quaternary sedimentary succession, belonging to the central Calabrian Arc and extended from offshore, Sant’Eufemia Basin (SE Tyrrhenian Sea), to the onshore, Catanzaro Basin. By joining on land geo-structural with marine geophysical data, we performed a detailed analysis of processes that during last 5 My have controlled the evolution of western portion of the Catanzaro Trough. The fieldwork study, focused on the onshore area, has allowed to acquire more than 700 fault planes, classified on the base of kinematics and fault directions, whereas the geophysical data (sub-bottom, multi- and mono-channel seismic profiles), coming from some scientific cruises within the Sant’Eufemia Gulf (SE Tyrrhenian Sea), gave us the opportunity to reconstruct the tectono-stratigraphic evolution of the offshore area. The combination amongst abrupt sea level changes, transpressional and trans/extensional tectonics and back-arc Tyrrhenian subsidence during SE-drifting of Calabrian Arc controlled sedimentary basin hosted by the Catanzaro Trough, as the result we have recognized three tectonic events formed in the Upper Miocene- Zanclean, Piacezian-Lower Pleistocene, and Middle-Upper Pleistocene. The data analysis provide information about stratigraphy and tectonics in the strata and also give some indication of the tectono-stratigraphic architecture. Sedimentary basin, in fact, looks to be mainly controlled by the activity of NW–SE and NE–SW oriented fault systems. The NW-SE oriented faults showing strike slip and oblique kinematics can be considered responsible for the opening of a WNW–ESE paleo-strait connecting the Tyrrhenian Sea with the Ionian Sea during multi-phases tectonics that have acted in the study area since Miocene. The integrated geo-structural and geophysical data show a change from left-lateral to right-lateral kinematics during Piacezian-Lower Pleistocene, as the result of a change of the stress field. Since Middle Pleistocene, the study area experienced an extensional phase, WNWESE oriented, controlled mainly by NE-SW and subordinately N-S oriented normal faults, which split obliquely the western Catanzaro Trough, producing up-faulted and downfaulted blocks, arranged as graben-type systems, extending from onshore to offshore area. In agreement with and Jacques et al., (2001) and Presti et al., (2013), the NE-SW and NS trend normal faults play a relevant role as part of recent seismotectonic processes controlling the Late Quaternary geodynamic of the central Calabrian Arc, representing the source of the main destructive earthquakes occurred in the area. Thanks to these multidisciplinary approach we are able to provide a more reliable and detailed structural frame of the central Calabria segment, providing new elements about recent activity of faults, and giving a further contribution for the seismogenetic potential assessment of an area historically considered with the highest earthquake and tsunami risk throughout Italy.Università della Calabri

Back-Arc Spreading Centers and Superfast Subduction: The Case of the Northern Lau Basin (SW Pacific Ocean)

The Lau Basin is a back-arc region formed by the subduction of the Pacific plate below the Australian plate. We studied the regional morphology of the back-arc spreading centers of the Northern Lau basin, and we compared it to their relative spreading rates. We obtained a value of 60.2 mm/year along the Northwest Lau Spreading Centers based on magnetic data, improving on the spreading rate literature data. Furthermore, we carried out numerical models including visco-plastic rheologies and prescribed surface velocities, in an upper plate-fixed reference frame. Although our thermal model points to a high temperature only near the Tonga trench, the model of the second invariant of the strain rate shows active deformation in the mantle from the Tonga trench to ~800 km along the overriding plate. This explains the anomalous magmatic production along all the volcanic centers in the Northern Lau Back-Arc Basin

Extensional tectonics during the Tyrrhenian back-arc basin formation and a new morpho-tectonic map

21 pages.-- The data that support the findings of this study are available from Banca Dati Crop. Restrictions apply to the availability of these data, which were used under license for this study. Data are available at http://www.crop.cnr.it/ with the permission of the CROP DATABASE Project ManagerWe present a new tectonic map focused upon the extensional style accompanying the formation of the Tyrrhenian back-arc basin. Our basin-wide analysis synthetizes the interpretation of vintage multichannel and single-channel seismic profiles, integrated with modern seismic images, P-wave velocity models, and high-resolution morpho-bathymetric data. Four distinct evolutionary phases of the Tyrrhenian back-arc basin opening are further constrained, redefining the initial opening to Langhian/Serravallian time. Listric and planar normal faults and their conjugates bound a series of horst and graben, half-graben and triangular basins. Distribution of extensional faults, active throughout the basin since Middle Miocene, allows us to define an arrangement of faults in the northern/central Tyrrhenian mainly related to a pure shear which evolved to a simple shear opening. At depth, faults accommodate over a Ductile-Brittle Transitional zone cut by a low-angle detachment fault. In the southern Tyrrhenian, normal, inverse and transcurrent faults appear to be related to a large shear zone located along the continental margin of the northern Sicily. Extensional style variation throughout the back-arc basin combined with wide-angle seismic velocity models allows to explore the relationships between shallow deformation, faults distribution throughout the basin, and crustal-scale processes as thinning and exhumationWith the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI

Extensional tectonics during the Tyrrhenian back-arc basin formation synthetized in a new morpho-tectonic map

European Geosciences Union (EGU) General Assembly 2020, 4-8 May 2020A new tectonic map is presented focused upon the extensional style accompanying the formation of the Tyrrhenian back-arc basin. Our basin-wide analysis synthetizes the interpretation of vintage multichannel and single channel seismic profiles integrated with modern seismic images and P-wave velocity models, and with a new morpho-tectonic map of the Tyrrhenian (Palmiotto & Loreto, 2019). Four distinct evolutionary opening stages have been constrained: 1) the initial Langhian(?)/Serravallian opening phase actives offshore central/southern Sardinia and offshore western Calabria; 2) the Tortonian/Messinian phase dominated by extension offshore North Sardinia-Corsica, and by oceanic accretion in the Cornaglia and Campania Terraces; 3) the Pliocene phase, dominated by mantle exhumation which was active mainly in the central Tyrrhenian and led to the full opening of Vavilov Basin; and 4) the Quaternary phase characterized by the opening of the Marsili back-arc basin. Listric and planar normal faults and their conjugates bound a series of horst and graben, half-graben and triangular basins. Distribution of extensional faults, active since Middle Miocene, throughout the basin allowed us to define a faults arrangement in the northern / central Tyrrhenian mainly related to in a pure shear which evolved a simple shear opening of continental margins. At depth, faults accommodate over a Ductile-Brittle Transitional zone cut by a low-angle detachment fault possibly responsible for mantle exhumation in the Vavilov and Magnaghi abyssal plains. In the southern Tyrrhenian, normal, inverse and transcurrent faults appear to be related to a large shear zone located along the continental margin of the northern Sicily. Extensional style variationthroughout the back-arc basin combined with wide-angle seismic velocity models, from Prada et al. (2014; 2015), allow to explore the relationship between shallow deformation, represented by faults distribution throughout the basin, and crustal-scale processes, subduction of Ionian slab and exhumation. References: Palmiotto, C., & Loreto, M. F., (2019). Regional scale morphological pattern of the Tyrrhenian Sea: New insights from EMODnet bathymetry. Geomorphology, 332, 88-99. Prada, M., Sallarès, V., Ranero, C.R., Vendrell, M.G., Grevemeyer, I., Zitellini, N. & De Franco, R., 2014. Seismic structure of the Central Tyrrhenian basin: Geophysical constraints on the nature of the main crustal domains. J. Geophys. Res.: Solid Earth, 119(1), 52-70. Prada, M., Sallarès, V., Ranero, C.R., Vendrell, M.G., Grevemeyer, I., Zitellini, N. & De Franco, R., 2015. The complex 3-D transition from continental crust to backarc magmatism and exhumed mantle in the Central Tyrrhenian basin. Geophys. J. Int., 203(1), 63-78Peer reviewe

Evidence of extensional and strike-slip deformation in the offshore Gokova-Kos area affected by the July 2017 Mw6.6 Bodrum-Kos earthquake, eastern Aegean Sea

The interpretation of new multichannel seismic profiles and previously published high-resolution swath and seismic reflection data from the Gokova Gulf and southeast of Kos Island in the eastern Aegean Sea revealed new morphotectonic features related to the July 20, 2017 Mw6.6 Bodrum-Kos earthquake offshore between Kos Island and the Bodrum Peninsula. The seafloor morphology in the northern part of the gulf is characterized by south-dipping E-W-oriented listric normal faults. These faults bend to a ENE-WSW direction towards Kos Island, and then extend parallel to the southern coastline. A left-lateral SW-NE strike-slip fault zone is mapped with segments crossing the Gokova Gulf from its northern part to south of Kos Island. This fault zone intersects and displaces the deep basins in the gulf. The basins are thus interpreted as the youngest deformed features in the study area. The strike-slip faults also produce E-W-oriented ridges between the basin segments, and the ridge-related vertical faults are interpreted as reverse faults. This offshore study reveals that the normal and strike-slip faults are well correlated with the focal mechanism solutions of the recent earthquake and general seismicity of the Gokova Gulf. Although the complex morphotectonic features could suggest that the area is under a transtensional regime, kinematic elements normally associated with a transtensional system are missing. At present, the Gokova Gulf is experiencing strike-slip motion with dominant extensional deformation, rather than transtensional deformation