Holocene sedimentary archives from Antarctic coastal embayments provide exceptional records of past ice-ocean interactions and marine biological productivity. Here we present a multiproxy study of sediment core BAY05-18c from Edisto Inlet (northern Victoria Land, Ross Sea), a fjord basin that preserves a high-resolution postglacial sedimentary sequence. Diatom assemblages reveal major changes in paleoceanographic conditions since similar to 11 ka. An early Holocene well-laminated facies is characterized by high productivity, dominated by Chaetoceros resting spores and Corethron pennatum, indicating strong stratification, prolonged open-water seasons, and enhanced nutrient supply from glacial and sea-ice melt. This laminated interval reflects deglacial calving-bay conditions and parallels similar facies across Antarctic fjords and troughs. From similar to 9.7 kyr BP, a massive and bioturbated diatomaceous mud marks reduced meltwater input, longer seasonal sea-ice cover, and weaker stratification. Mid-to late Holocene assemblages indicate persistently cool conditions with extended sea-ice duration, contrasting with warmer intervals recorded at other Antarctic coastal sites. Comparison with regional records suggests that Edisto Inlet oceanography was strongly influenced by the retreat history of the Ross Ice Shelf and local fjord geometry, which governed the formation and preservation of laminated diatom ooze. These results highlight the role of fjord morphology and freshwater fluxes in modulating Antarctic primary productivity and carbon export, providing analogs for ecosystem responses to ongoing ice retreat.

The new detailed geological mapping at 1:10.000 scale of >1800 km2 collected in the frame of the Italian Geological Survey Project (CARG project), resulted in a large amount of structural data throughout the Ligurian Alps and the adjacent Ligurian Sea, representing the connection area between the Alpine and Apennine orogenic arches. Field- and remote-sensing-based data highlight the presence of a dense fault-fracture network developed throughout the entire orogenic sector. Detailed structural analysis has been performed in selected sites, through the building of Digital Outcrop Models (DOM) derived from digital photogrammetry and the use of Unmanned Aircraft Vehicles (UAV). The onshore survey is based on the integration of a new set of seismic reflection lines and high-resolution bathymetric data (MBES) with pre-existing available geological and geophysical datasets. The integrated geological mapping and structural analysis can be summarized as follows: i) the entire orogenic sector encompasses a very dense network of relatively small fractures and faults showing complex intersection relationships; ii) from this network, several, previously unreported, km-scale transtensive fault zones emerge; iii) these faults postdate the metamorphic foliation associated with the main thrust-and-fold architecture of the Ligurian Alps; iv) the recognition of earthquake-related soft-sediments deformation structures in Miocene-Pliocene deposits highlights continuous seismicity related to the fault development. The offshore area consists of a continental shelf and the upper slope both intersected by well carved submarine canyons and characterized by a complex fault network. The fault network is characterized by dominant E-W left-lateral and NE-SW right-lateral faults. The entire fault network is interpreted as a complex network of subsidiary, en-échelon Riedel fractures encompassed within a regional sinistral transtensional/transpressional shear zone. The fault network primarily developed in the Oligo-Miocene times, thus during the pre-to-syn Corsica drifting phase. Moreover, both the Ligurian orogen and Ligurian Basin fault systems experienced Miocene to present-day seismicity marked by i) the cyclic occurrence of earthquake-induced soft sediment deformation structures found in the Miocene to Pleistocene sediments and ii) the present-day instrumental recording. In light of the new dataset, we reconsider the role of the local-scale fault network as a direct surface expression of the ongoing bending of the Ligurian Alps, driven by the combination of Adria rotation and the pull of the Apennine subduction.

Recent sub-ice topography investigations have imaged-with greatly improved detail-a set of low-elevation V-shaped basins hidden beneath a very large sector of the East Antarctic Ice Sheet. Here we jointly interpret sub-ice topography and geophysical data and show that these basins form a semi-continental-sized, fan-shaped physiographic unit that radiates from a focal point near the South Pole. We name this the East Antarctic Fan-Shaped Basin Province. We propose that the fan-like landscape is the product of distributed intraplate rotational extension before the breakup of Gondwana, with three continental-scale consequences. Laterally, to the west, it caused compression and the consequent uplift of the Gamburtsev Mountains. To the east, the northernmost Transantarctic Mountains segment was rotated clockwise by similar to 20 degrees, overriding the West Antarctic Rift System's hot lithosphere and causing segmentation of the mountain chain into three blocks and their differential uplift due to thermal buoyancy. To the north, the transcurrent edge of the fan formed the lithospheric weakness that controlled the breakup of Gondwana by driving the propagation of Antarctica-Australia separation and shaping the resulting semi-circular passive continental margins. These processes have influenced the present-day East Antarctica sub-ice landscape and the evolution of the overlying ice sheet, including the development of glacial troughs and outlet glaciers.

Recent sub-ice topography compilations of East Antarctica have imaged a wide sector, spanning from 100° E to 160° E in longitude and from the Oates, George V and Adelie coastlines to 85° S in latitude, which contains numerous low-lying basins of variable size and uncertain origin. The sector shows a Basin and Range style tectonics comprising two major basins of continental proportions, the Wilkes Basin and the Aurora Basin complex, and many smaller basins such as the Adventure, Concordia, Aurora and Vostok trenches. The main longitudinal axes of the basins consistently point towards the South Pole and many exhibit intriguing distinct triangular shapes, sitting within an approximately 2000 x 2000 km fan-shaped physiographic region limited by a semi-circular coast line. We name this region as the East Antarctic Fan shaped Basin Province (EAFBP). To the West, this sector is limited by the intraplate Gamburtsev Mountains (GM) and to the East by the Transantarctic Mountains (TAM) constituting the uplifted shoulder of the Cenozoic West Antarctic Rift System (WARS). Origins and inter-relationships between these four fundamental Antarctic tectonic units (WARS, TAM, EAFBP, GM) are still poorly understood and strongly debated. Very little is known about the mechanism generating the basins in the EAFBP, their formation time, whether they are all coeval and if and how they relate to Australia basins before Antarctica-Australia rifting. Present genetic hypotheses for some of the basins span from continental rifting to a purely flexural origin or a combination of the two. Also, post-tectonic erosional and depositional processes may have had a significant impact on the present-day topographic configuration. Here we interpret the EAFBP as the result of a single genetic mechanism: a wide fan-shaped intra-continental extension around a near pivot point at about 135° E, 85° S that likely occurred at the Mesozoic-Cenozoic transition. We discuss evidence from the sub-ice topography and potential field airborne and satellite data. We have applied image segmentation techniques to the rebounded sub-ice topography to semi-automatically trace the first order shape of the sub-ice basins, that we assume to be fault controlled. Then we have fitted the edges of the basins by maximum circles and estimated the best Euler pole identified by their intersection. Potential field anomalies have been taken into account in order to enlighten major discontinuities not revealed by the sub-ice topography. The reconnaissance of this large sector of East Antarctica as the result of rotational extension may have major implications on global and regional tectonics plate reconstructions, plate deformation assumptions and new tectonic evolutionary models of WARS, TAM, and GM.

Understanding the source processes and wave propagation in heterogeneous rock media is one of the most challenging frontiers to improve the seismic risk assessments in densely populated areas. In this framework, the sector of the Voltri Massif (NW Italian Alps) forming the hinterland of the city of Genoa is a natural laboratory to investigate (i) the interaction between rock faulting and fluid circulation during (potential) paleo-seismic activity and (ii) the detection, location, and source characterization of micro-earthquakes along tectonic lineaments developed inland and offshore the city area (i.e., in the Ligurian Sea). Our multi-scale and multidisciplinary study is part of the PNRR research program RETURN (“Multi-risk science for resilient communities under a changing climate”): it will include the structural and petrographic characterization of fault rocks (i.e., serpentinite breccias), the quantification of serpentinite carbonatization and its impact on the fault strength, and the analysis of the network of inland-offshore tectonic lineaments. This work, coupled with the analysis of historical seismic clusters, is crucial to identify suitable areas for the deployment of high-resolution seismometers and for tracing the spatial-temporal evolution of micro-earthquakes and their static and dynamic source parameters. The detailed structural mapping of selected fault zones has revealed a complex, multi-stage deformation history, with older ductile structures (paragenesis: antigorite + ilmenite ± chlorite ± pyrite ± chalcopyrite, likely ascribed to the alpine-subduction and collision stages) cut by steeply dipping fault planes NNE-SSW striking. These latter are subparallel with the (low magnitude) seismic clusters detected in the area and develop multiple, anastomosed fault cores consisting of serpentinite-rich ultracataclasites, locally bound by chrysotile-rich shear bands. The faults damage zones textures (e.g., breccias and microbreccias), the paragenesis of newly formed shear bands and associated veins (chrysotile + chlorite) and the orientation of these faults (NNE-SSW striking, subparallel to the Miocene-age lineaments detected in the Gulf of Genoa) suggest recent tectonic reactivation at the regional scale. Future developments of the research project will include more detailed, high-magnification microscopy of selected samples (e.g., raman, field emission SEM, EBSD and microprobe), regional scale morphotectonic characterization by satellite image analysis, and integration of field and seismic data. This will clarify the link between inland-offshore tectonic lineaments and the (low magnitude) seismicity of the area.

Recent sub-ice topography investigations have imaged with greatly improved detail a set of enigmatic low-elevation V-shaped basins hidden beneath a very large sector of the East Antarctic Ice Sheet. Here we show that these basins form a semi-continental sized fan shaped physiographic unit which radiates from a pin point near the South Pole and name it the East Antarctic Fan-shaped Basin Province. By jointly interpreting sub-ice topography and geophysical data, we demonstrate that the fan-like landscape originated from a distributed intraplate rotational extension before Gondwana breakup which had three continental-scale consequences. i) Laterally, to the west, it caused compression and the consequent uplift of the Gamburtsev Mountains. ii) To the east, the northernmost Transantarctic Mountains segment was rotated clockwise of ~20° overriding the West Antarctic Rift System’s hot lithosphere, causing segmentation of the mountain chain into three blocks and their differential uplift due to thermal buoyancy. iii) To the North, the transcurrent edge of the fan formed the lithospheric weakness that controlled the break-up of Gondwana by driving the propagation of Antarctica/Australia separation and shaping the resulting semi-circular passive continental margins. These processes have substantially influenced the present-day East Antarctica sub-ice landscape and the evolution of the overlying ice-sheet.

The continental shelf remains underexplored in terms of large-scale seafloor morphologies, despite their importance for reconstructing past sea-level changes and coastal dynamics. In this study, a sector of the LiguroProvençal shelf was investigated to test the hypothesis that most of the currently detectable submerged morphologies were formed during past sea-level lowstands prior to the Last Glacial Maximum (LGM). To this end, newly acquired high-resolution single-channel seismic reflection and multibeam bathymetry data were integrated, enabling a detailed reconstruction of the seabed morphologies in the study area. The systematic mapping, description, and genetic interpretation of geomorphological features confirm that landforms shaped during periods of subaerial exposure before the LGM are still preserved and influence the postLGM sedimentary record. Some of these landforms record shoreline positions during phases of relative sea-level stability from Marine Isotope Stages (MIS) 4 to 2. The investigated portion of the continental shelf is bordered landward by a cliff hosting caves that preserve globally significant evidence of Palaeolithic cultures. Reconstructing the submerged palaeo-landscape in this area is essential for understanding early human interactions with the coastal environment during key phases of human evolution.

The integration of existing seismic data with new ultra-high-resolution Sparker lines and processed multibeam bathymetric data, collected within the framework of the Italian CARG Project, enabled a detailed reconstruction of the geological setting and the Late Quaternary evolution of coastal environments on the continental shelf of the Gulf of Genoa. This study allowed a reconstrucion and mapping of the stratigraphic characters of Late Quaternary deposits (facies, thickness, distribution), the shelf’s paleo-morphology (barriers, terraces, channels, pockmarks, cliffs) and recent or active morphodynamic processes (erosion, mass wasting, fluid escape) and related structural conditioning (inherited faults and recent tectonics). The data show active erosion and landslide scars affecting several sectors of the shelf edge delimiting the heads of the Polcevera and Bisagno canyons, while in others cases, a thin layer of Holocene mud (HST) covers a paleoshelf break, mainly formed during the Last Glacial Maximum.Along the shelf edge bordering the canyon heads, small subcircular bedrock highs and small depressions interrupt the flat shelf morphology. Based on seismic line interpretation, these features are interpreted as mud volcanoes and pockmarks linked to deep-seated fluid escape, which often coincide with the main Mio-Pliocene blind faults. The identified fluid escape phenomena influence the seabed instability, favouring in some sectors the retreat of canyon heads.The new structural setting reconstruction of this sector of the Ligurian margin, marking the Alpine–Apennine margin transition, is characterised by NW–SE and NNE–SSW fault systems that delimit several Upper Miocene–Pliocene grabens within the shelf.The results, including high-resolution mapping and stratigraphic analysis, provide valuable information for paleogeographic reconstructions, archaeological studies of the Late Quaternary and are invaluable tools for geohazards analysis and forecasting, as well as engineering planning and coastal infrastructure projects.

North Victoria Land (NVL), Antarctica is one of the most remote and inaccessible outposts of our planet where few outcrops are available for direct geological investigation. The long-lasting tectonic evolution of this region results in a complex architecture characterized by the presence of regionally sized, crustal scale faults whose structural characteristics (e.g. geometry, thickness, location of transfer zones and off-shore prosecution) are still debated.In this work we present a map of the intensity of brittle deformation measured in 113 field outcrops along the Rennick-Aviator km-scale fault corridor, and quantified through the non-dimensional and scale invariant H/S parameter (H = fracture dimension and S = spacing among fractures belonging to the same azimuthal family; see Cianfarra et al. 2022). The sparse fracture measurements where then interpolated with Surfer® (Golden Software, LLC) v. 23.2.17 to analyse the spatial variability of deformation with the aim of clarifying the tectonic link between the Rennick and Aviator faults.The thematic map is prepared by a polymodal regression by full cubic surface that was applied to the field measurements (between 70.5°-71 °S and 160-165.5°E) collected during scientific expeditions funded and logistically supported by the Italian National Antarctic Program (e.g.; PNRA16-00056_G-IDEA and PNRA18-00338_LARK projects). Measurements were normalized by a weighting factor to take into account the brittle strength variability of the analysed lithotypes (e.g., basalts-dolerites, well cemented sandstone-conglomerates, granites-migmatites, gneiss)The comparison of our georeferenced thematic map with existing maps of satellite-derived potential fields, bed subglacial topography and off-shore bathymetry, and Antarctic geology which are available as free dataset in the web (e.g. ADMAP, BEDMAP, Quantarctica, GeoMAP dataset, among the others) allows to supply constraints for modelling ice covered tectonic structures, to better highlight the active role of the main tectonic lineaments of NVL, as well as to clarify the relationship, connection and link between onshore and offshore tectonic structures (this last topic is being investigated in the frame of the ongoing PNRA19-00051_BOOST project).Cianfarra et al. 2022, Tectonics 41, e2021TC007124, https://doi.org/10.1029/2021TC007124

As part of the PNRA_BOOST project (Bridging Onshore-Offshore STructures at the Pacific Coast of North Victoria Land, Antarctica: an integrated approach), new offshore geophysical data (multichannel high-resolution seismic lines, bathymetric and magnetic data) were acquired on board of OGS R/V Laura Bassi (Feb 2023, XXXVIII Italian Antarctic Expedition), along the Pacific side of North Victoria Land, an underexplored key area at the boundary between East and West Antarctica. A preliminary analysis of the seismic and bathymetric data allows the identification and interpretation of morphological and tectonic features representing key hints for the study of the influence of lithosphere dynamics on ice-sheet evolution.In the study area, the northern sector of the shelf has an outer concave shape of its break and slope and is incised by several gullies; on the contrary the southern sector shows a stepped geometry with a WNW-ESE straight linear trend abruptly turning to a NW-SE trend. The continental shelf consists of a thin, horizontally layered succession lying on a crystalline basement dissected by two U-shaped glacial troughs several kilometers wide. The slope consists of seaward-prograding sedimentary strata that are truncated on the shelf by a regional unconformity (RSU 1). In the upper part of the slope of the NW sector, three distinct seaward prograding wedges were recognized, whereas they were not identified in the southern sector.NW-trending basement highs, bounded by faults, are visible both on the shelf and on the continental rise (towards the abyssal plain). Growth strata associated with these faults allow a tentative dating of activation to Oligocene times. The unconformity at the top of the growth strata may be related to the U3 surface (36 Ma) of Sauermilch et al. (2019). In addition, a ca. 20 km-long ridge of basement, covered by drift deposits, revealed at a depth of about 2500 m, is bounded by faults with indications of recent tectonic activity. The observed faults could have reactivated inherited zones of weakness that bound rift blocks formed during the breakup between Australia and Antarctica. In particular, the U3 surface is associated with the beginning of the phase of fast seafloor-spreading between Australia and Antarctica.In the SW part of the study area, two broad “linear” volcanic zones occur along a roughly NNW-SSE direction; i.e. the orientation of the main tectonic lineaments inland. These zones consist of individual volcanic edifices and small volcanic ridges composed of coalescing bodies. Several volcanoes are clearly active and fluid-related features are visible cutting through the surrounding sedimentary successions. This volcanism correlates well with airborne magnetic observations and may represent the NNW continuation of the Mid-Miocene to Quaternary Hallett Volcanic Province forming the Adare Peninsula, or may be related to the post-spreading Pliocene-Recent volcanism of the Adare Basin.Sauermilch et al., 2019. JGR: Solid Earth, 124, 7699–7724 (doi.org/10.1029/2018JB016683).

The remote Pacific side of northern Victoria Land (NVL) lies at the boundary between East and West Antarctica and represents the area where the final continental breakup between the Antarctic and Australian conjugate margins occurred, leading to the opening of the Tasman Gateway since the Eocene-Oligocene boundary. Understanding the tectonic evolution of this area is crucial for the geodynamics of the Australian-Antarctic separation and the formation of the independent Antarctic plate in the Late Mesozoic-Cenozoic. This study, based on new multibeam data and multichannel seismic profiles combined with aeromagnetic data, presents an updated picture of the structural architecture of the NVL offshore area. The main novelties of this picture include the discovery of two large active submarine magmatic ridges in the southern sector and an isolated rifted crustal block in the north. The tectonic interpretation supports a NW-oriented, intraplate right-lateral megashear zone with associated magmatism that was active in the Pliocene-Quaternary and was accompanied by thinning of the continental crust. This deformation zone likely represents the intraplate continuation of the Balleny Fracture Zone off NVL and developed along the previous transform plate boundary between the Antarctic and Australian margins, characterized by left-lateral kinematics in the late Eocene-early Oligocene.

Here we present a detailed description of different geomorphic features to complement the Maps of Geohazard Features of the Ionian Calabrian Margin produced by the Magic project (Marine Geohazard along Italian Coasts). Some of the most striking features we imaged are sources of widespread and recurrent geohazards. These include multiple coastal landslides, failure scars along open slopes, shelf-indenting retrogressive canyon headwalls and active fluid venting structures, that we investigated by integrating regional high-resolution multibeam sonar and sub-bottom profiling data. The main triggers and predisposing factors for the marine geohazards that we identify in our study area include frequent seismic activity, the rapid uplift of the margin since 1 Ma and the presence of Messinian evaporites at depth. Large-scale gravity-driven movements and the incipient retrogressive canyon headwalls are of particular concern, as they are located just a few hundred meters from the coast, where critical infrastructures and densely populated urban centers are situated, and also where high-resolution geophysical data are often lacking. Overall, our study provides a key reference for more detailed follow-up studies to foster a better understanding of marine geohazard occurrences. The insights provided are critical for planning monitoring programs and for the protection of coastal settlements and marine infrastructures along the Calabrian Ionian margin.

Regional-scale swarms of subparallel linear topographic features, known as lineament domains, are a common feature of planetary surfaces. Lineament domains are superficial manifestations of the crustal stress field trajectory. Notably, one of the effects of active tectonics is seismicity. Italy is one of the most seismically active regions in the Mediterranean, with many destructive earthquakes that have occurred in past centuries. Here, we assess the seismic meaning of the main lineament domain in the tectonically active region of Central Italy. We describe the use of an automated analysis of satellite imagery coupled with spatial grid analysis to identify three lineament domains of the Central Apennines. Spatial and azimuthal comparisons of the main lineament domain (i.e., the Apennine Domain), with the known locations of earthquakes (moment magnitude of Mw > 5.5) that occurred during the past century, revealed the most seismically active tectonic areas and their spatial distributions. Further, we present a conceptual seismo-geodynamic model for the Central Apennines, which is characterized by regional arching and explains the presence of an extensional tectonic regime in the upper crustal layer of the active Apennines fold-and-thrust belt.

We present the characterization of geohazard-related features of the Ligurian Sea with the map of its physiographic domains (1:250,000 scale) and five maps (1:100,000 scale) of the morphological and morpho-bathymetric elements. These were realized in the framework of the MaGIC (Marine Geohazard along Italian Coasts) project, promoted by the Italian Civil Protection Department. The characterization of submarine geohazards along continental margins, together with mapping of marine geological features are critical for the management of coastal risks. Multibeam bathymetric data combined with high-resolution 2D reflection seismic data, allowed to identify and map the main tectono-sedimentary features related to mass movements along the Ligurian continental margin. A dense grid of seismic profiles allowed to improve the comprehension of the margin structure as well as its recent tectonic activity providing new insights concerning mass wasting processes and active tectonics relationships to plan further, focalized investigations in areas of maximum risk.

The response of the Antarctic ice sheet to climate warming is the main source of uncertainty regarding future global sea level rise, since little is known about its present and past dynamics. The last deglaciation is the most recent interval of large-scale climate warming, during which the Northern and Southern Hemisphere ice sheets retreated, and sea level rose globally, although at a non-uniform rate. Geologic records from the polar regions are fundamental in determining the factors that caused the major changes in ice sheets during the last deglacial under different boundary conditions. Here, we combine morpho-bathymetric and seismic data with sediment cores and oceanographic measurements to reconstruct the processes that influenced the deposition of the southernmost, most extensive, ultrahigh-resolution record of the Holocene in Edisto Inlet fjord (Ross Sea, Antarctica). We find that post-glacial sedimentation resulted in a layered diatom mud up to 110 m thick that was locally redistributed by bottom currents over confined drifts-moats in the central part of the fjord. After the Holocene climatic optimum, the fjord was not carved by ground ice, and there continued to be internal fjord water circulation associated with Ross Sea circulation. These results support a retreat of coastal glaciers by about 11 kiloyears ago (ka) from the continental shelf of North Victoria Land.

Antarctic fjords and coastal bays are excellent traps for sediment and represent key areas for high-resolution investigation of past environmental conditions. Robertson Bay is an understudied coastal area located at the confluence of the Ross Sea and the Southern Ocean. Recently obtained seafloor morphology data indicate the presence of a cross-shelf elongated valley, composed of three minor basins separated by sills and seabed ridges with an arcuate shape. Several cores were collected within the basins, and investigated using a multiproxy approach including sedimentological, chemical, geochemical, and micropaleontological characterization to reconstruct the paleoenvironmental evolution from the last glacial period to present. The ages of two of these cores are constrained using ramped pyrolysis oxidation radiocarbon dating. Four sedimentary facies were recognised from which we developed a sedimentary model covering the last 21,000 years (21 ka BP). Our record provide evidence for a covering ice shelf cover from 21 to 16.5 ka BP, which gradually receded between 16,5 and 11 ka BP due to the progressive intrusion of modified Circumpolar Deep Water, thereby promoting the formation of Ice Shelf Water and High Salinity Shelf Water. From 11 to 5,8 ka BP, the ice shelf continued shrinking and nutrient-rich of modified Circumpolar Deep Water penetration onto the continental shelf progressively favoured diatom blooms and a general increase in primary productivity until 5.8 ka BP. The Late Holocene is characterised by an alternation of prolonged sea ice cover with stratified water column and strong bottom current with prolonged sea-ice free season with the intrusion of modified Circumpolar Deep Water and very slow energy bottom current.

<p>Mélanges are abundant in both accretionary and collisional orogenic belts. Their chaotic, block-in-matrix structure can have different origins: sedimentary mélanges can be overprinted by later metamorphic and deformative events or, conversely, tectonic mélanges can form directly at the plate interface, at different tectonic levels and either in prograde (i.e. during underplating) or retrograde (i.e. during exhumation) conditions.</p> <p>The HP-metaophiolitic Voltri Massif (W Alps, Italy), considered as an exhumed piece of the plate interface of the Alpine orogen, includes various, well-preserved examples of tectonic mélanges at different scales (from m- to km-scale). Here, we investigate a 100 meters-thick tectonic mélange, where blocks of various metamorphic lithologies (e.g. metagabbro, eclogite, serpentinite, calchschist and qtz-micaschist) and sizes (0,1-m- to 10-m scale) are dispersed within an intensely foliated, lithologically heterogeneous matrix made of a mixture among serpentinite-schist, chlorite-actinolite schist and graphitic schist, predominantly equilibrated at grenschist facies conditions.</p> <p>Preliminary field investigations reveal a pronounced strain and metamorphic partitioning between the matrix and the blocks. These latter show internal metamorphic layering, shear zones and extensional veins discordant to the pervasive s-c-fabric and folding that characterize the enclosing matrix. Locally, eclogitic blocks show progressive internal fragmentation (e.g., fracturing/veining) up to pervasive brecciation. Petrographic/microanalytical investigations on the most preserved (Fe-Ti-bearing) metagabbro and metabasalt blocks indicate prograde peak metamorphism either in eclogite (grt + omp + rt ± Na-amp ± ph assemblage) or blueschist-facies (Na-amp + ttn + chl ± ep ± ph assemblage); some eclogites show either a retrograde syn-tectonic stage in blueschist facies or a static greenschist overprint. PT estimates on eclogitic blocks indicate a peak stage at P = 18,6 ± 1,0 Kbar (gnt-ph-cpx geobarometer) and T = 530 ± 10°C. The block-matrix transition is characterized by dm- to cm-thick metasomatic rinds rich in hydrous minerals, such as tremolitic amphiboles, biotite, chlorite and minor titanite, tourmaline, adularia and sulphides. Locally, tensile fractures filled by a polymineralic gouge material with the same mineral composition (±biotite) and syntectonic extensional veins with fibrous amphibole depart from the rinds and intrude the prisitne blocks. Abundant hydrothermal fluid circulation is suggested, among other, by peculiar microstructures, i.e. the growth of chlorite in vermicular form.</p> <p>The block-in-matrix structures and microstructures (shear zones and extensional cracks repeatedly crosscuting eachother) point to the occurrence of a cyclic deformation characterised by episodic switch between brittle and ductile regimes and changes in the rehological properties of blocks and matrix. The occurrence of (i) abundant mélange matrix, (ii) metasomatic rinds digesting blocks with (iii) sets of veins/cracks irradiating inside the intact rocks suggest the key-role played by fluids in the evolution of the Piota River mélange.</p> <p>The evidence recorded in the studied lithologies, such as episodic switch between deformation regimes assisted by transient exceed of the rock tensile strenght by pore fluids overpressure, would permit to better understand the mechanisms controlling slow earthquake generation at shallow plate interface. Morover, this study, combined with studies of other melange occurrences of the Voltri Massif, will help to better understand the complex geodynamic phenomena acting on collisional orogens.</p>

The Calabrian Arc represents one of the most active sectors of the upper plate of the Tyrrhenian-Ionian subduction system. This research aims to reconstruct the evolution of the Squillace Basin (Ionian offshore of the Calabrian Arc) from the Late Miocene to Recent times and recognise active shallow and deep structures using a multiscale approach. The latter is based on interpreting high-penetration and high-resolution seismic reflection profiles, calibrated with well-log data coupled with bathymetric data and the distribution of instrumental earthquakes. Data highlight three steps in the evolution of the Squillace Basin. A Late Miocene extensional event led to the formation of WNW-ESE oriented horst and half-graben structures. During the Pliocene, deformation was localised in the central and northern sectors of the basin and expressed by a WNW-ESE oriented strike-slip fault and NW-SE normal to trastensional faults, respectively. A transpressional event started in the Early Pleistocene, causing the positive inversion of deep (> 3 km) extensional faults and the formation of NW-SE to WNW-ESE oriented transpressional/reverse faults and related anticlines. The kinematics of these faults agree with the NW-SE oriented left-lateral Albi-Cosenza, Lamezia-Catanzaro and Petilia-Sosti crustal fault zones developed in north Calabria. The results of this work suggest that the transpressional structures in the northwestern sector of the basin likely represent the offshore prolongation of the Albi-Cosenza fault zone. NW-SE to WNW-ESE trending, shallow (<2 km) high-angle normal faults offset the younger deposits. Their depth and direction indicate that these faults are secondary structures formed in the extrados of the anticlines associated with the transpressional faults. The distribution of earthquakes shows events with M > 3 and depth <15 km located in the hanging wall of transpressional faults. The integrated data suggest that these structures are active and probably responsible for the major earthquakes that affected the Ionian offshore.

ABSTRACTSeismic lines and sediment cores collected along the shelf between Albenga and Loano (Liguria, NW Italy) allowed an unprecedented reconstruction of the characters and distribution of late Quaternary transgressive littoral deposits. Multiple seismic lines datasets and stratigraphic logs were managed within a single, GIS-based software. This approach allowed the merging, analysis, and interpretation of multimethodological datasets, greatly increasing the understanding of the study area. On seismic reflection lines, the identification of high-amplitude acoustic facies (i.e. coarse-grained deposits), coupled with the analyses of the identified paleo-morphologies, allowed the mapping of (at least) five paleo shorelines along the continental shelf at 30–40 40–60, 60–80, 80–90 and 90–100 m below sea level. Their retrogradiational geometry and terraced distribution likely indicate episodic, stepwise retreats of Late Quaternary coastal system (last 18–11 Ky), compatible with phases of fast sea level rise interspersed by long periods of sea level stillstand.

The review of recent bathymetric and geophysical data collected in the framework of several research and cartographic projects have allowed a detailed reconstruction of the morpho-structural setting and the (neo)tectonic evolution for both the Alpine and Apennine margins of the Ligurian Sea (Italy). The widespread occurrence of erosional processes and sediment mass movements along the steep continental slope and within the system of submarine canyons reflect the close correlation between the active tectonics and the recent morpho-dynamic evolution of the Ligurian Margin. This relation is better constrained in the western sector (Alpine) of the Ligurian Sea, where the recent uplift of the continental margin is associated to a well-developed system of inherited structures reactivated under a compressive/transpressive regime and widespread seismicity. In the eastern sector, where the seismicity is lower or absent, the mass movements are limited to few areas (e.g., the Portofino slope) coinciding with seismic clusters. Additionally, this sector is characterized by moderate and episodic fault reactivations under a compressive regime. The evidence of compressive deformation along the inherited fault systems has been revealed in some areas of the Ligurian Sea where the post-drifting extensional tectonics is interrupted by episodic tectonic inversion (at least) during the Middle–Upper Miocene and the Plio–Pleistocene until present.