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The recent release of a large number of subsurface geological data by the Italian Minister of Economic Development, including boreholes and seismic profiles, provided the occasion for a new assessment of the deposits associated with the Messinian salinity crisis (MSC) in the Adriatic foreland basin system and a new integration with the outcropping successions of the Apennines. In particular, the study of the Messinian evaporites allowed to reconstruct a new detailed palaeogeographic and palaeobathymetric framework for all the stages of the crisis. We identified the largest evaporitic marginal basin ever described for the Mediterranean hosting the precipitation of the primary shallow-water gypsum deposits (PLG, Primary Lower Gypsum) during the first stage of the crisis. During the second and third stages of the crisis, the PLG basin underwent uplift and erosion and the evaporite accumulation moved to the deeper part of the basin and was characterized by the deposition of the Resedimented Lower Gypsum unit including clastic evaporites, recycling the PLG ones, primary halite and terrigenous deposits. The distribution of the different evaporitic facies, was the basis for an improved reconstruction of the upper Miocene tectonic evolution of the Apennines thrust belt. Our results show a clear separation between shallower depocenters, located in the wedge-top and in the Adriatic foreland basins and characterized by MSC stage 1 PLG deposition, and deeper-water ones, located in the Adriatic foredeep and close to the Calabrian Arc, where MSC stage 2 terrigenous and gypsum-bearing clastic deposits and primary halite accumulated.

This study presents new geological and seismological data that are used to assess the seismic hazard of a sector of the Po Plain (northern Italy), a large alluvial basin hit by two strong earthquakes on May 20 (M-W 6.1) and May 29 (M-W 6.0), 2012. The proposed interpretation is based on high-quality relocation of 5369 earthquakes ('Emilia sequence') and a dense grid of seismic profiles and exploration wells. The analyzed seismicity was recorded by 44 seismic stations, and initially used to calibrate new one-dimensional and three-dimensional local Vp and Vs velocity models for the area. Considering these new models, the initial sparse hypocenters were then relocated in absolute mode and adjusted using the double-difference relative location algorithm. These data define a seismicity that is elongated in the W-NW to E-SE directions. The aftershocks of the May 20 mainshock appear to be distributed on a rupture surface that dips similar to 45 degrees SSW, and the surface projection indicates an area similar to 10 km wide and 23 km long. The aftershocks of the May 29 mainshock followed a steep rupture surface that is well constrained within the investigated volume, whereby the surface projection of the blind source indicates an area similar to 6 km wide and 33 km long. Multichannel seismic profiles highlight the presence of relevant lateral variations in the structural style of the Ferrara folds that developed during the Pliocene and Pleistocene. There is also evidence of a Mesozoic extensional fault system in the Ferrara arc, with faults that in places have been seismically reactivated. These geological and seismological observations suggest that the 2012 Emilia earthquakes were related to ruptures along blind fault surfaces that are not part of the Pliocene-Pleistocene structural system, but are instead related to a deeper system that is itself closely related to re-activation of a Mesozoic extensional fault system. (C) 2015 Elsevier B.V. All rights reserved.

Palynological studies are considered as an excellent tool for palaeoaltitude estimates as sedimentary basins receive abundant pollen grains from surrounding uplands, especially through riverine detritic inputs. Here, we provide new evidence for estimating the palaeoaltitude of the Northern and Central Apennines (Italy) during the late Neogene (from the late Tortonian to the early Zandean), based on vegetation data derived from pollen analysis of five sections (Trave, Legnagnone, Cava Li Monti, Maccarone and Stirone). The past vegetation changes reflect shifts in the vegetation belts on the nearby massifs. The climate reconstruction realised on these sites, at sea-level, suggests that mean annual temperatures were higher than today at the end of the Neogene. Therefore, the different vegetation belts occurred at higher elevation than at present to compensate for the higher temperatures. The results obtained in our study suggest that the Northern and Central Apennines were uplifted as early as the Tortonian attaining significant minimum altitudes around 1350 m up to 1500 m at the end of the Miocene in the Central part, a minimum altitude around 1900 m during the Messinian and around 2150 m during the early Zandean in the Northern part. (C) 2014 Elsevier B.V. All rights reserved.

Geophysical studies point to a complex tectonic and geodynamic evolution of the Alboran Basin and Gulf of Cadiz. Tomographic images show strong seismic waves velocity contrasts in the upper mantle. The high velocity anomaly beneath the Alboran Sea recovered by a number of studies is now a well established feature. Several geodynamic reconstructions have been proposed also on the base of these images. We present and elaborate on results coming from a recent tomography study which concentrates on both the Alboran and the adjacent Atlantic region. These new results, while they confirm the existence of the fast anomaly below the Alboran region, also show interesting features of the lithosphere-asthenosphere system below the Atlantic. A high velocity body is imaged roughly below the Horseshoe Abyssal plain down to sub-lithospheric depths. This feature suggests either a possible initiation or relic subduction. Pronounced low velocity anomalies pervade the upper mantle below the Atlantic region and separate the lithospheres of the two regions. We also notice a strong change of the upper mantle velocity structure going from south to north across the Gorringe Bank. This variation in structure could be related to the different evolution in the opening of the central and northern Atlantic oceans.

Along the similar to 500 km long Sicily-Calabria segment of the Nubia-Eurasia plate boundary GPS data highlight a complex, and debated, kinematic pattern. We focus on eastern Sicily, where the style of crustal deformation rapidly changes in the space of few tens of kilometers. In southeastern Sicily, struck by the 1693 M-W similar to 7.4 earthquake, GPS measurements highlight a steep velocity gradient, with similar to 2.4 mm/yr of similar to N-S shortening in similar to 10 km, changing to broader extension (similar to 3 mm/yr in similar to 60 km) in northern Sicily and shortening in the southern Tyrrhenian Sea. GPS data and kinematic elastic block models highlight a complex fragmentation of the Sicilian domain into three tectonic blocks, which move independently from Nubia, describing an overall clockwise rotation of this crustal domain with respect to Eurasia. Shortening in southeastern Sicily is associated with a system of high-angle reverse faults resulting from tectonic inversion of extensional faults at the northern tip of the Hyblean plateau. Extension in northern Sicily occurs on a broader deformation belt, developed on the former Kumeta-Alcantara line, extending west of Mount Etna toward the southwestern Tyrrhenian Sea, accommodating the faster rotation of the northeastern Sicily block with respect to central Sicily. Although the seismic potential of inland faults is not negligible, our results strengthen the hypothesis that the Malta escarpment is the likely source of the large 1693 earthquake and tsunami. The observed kinematics appears only subordinately driven by the Nubia-Eurasia convergence and the dynamics of the Mediterranean subduction system is likely playing a major role in governing block motions and active tectonics in Sicily. (C) 2014 Elsevier B.V. All rights reserved.

Despite the clear evidence of active flank dynamics that is affecting the eastern side of Mount Etna, the contribution of tectonic processes has not been yet understood. So far, the various models proposed to explain the observed flank deformation have been based on onshore structural data, coming from the volcanic edifice. The Ionian offshore of Mount Etna has been only recently investigated using multichannel seismic profiles, and offers the opportunity to image the structural features of the substrate of the unstable flank of the volcano. This contribution aims at describing the deformation located offshore Mount Etna using multichannel seismic profiles recently acquired during three seismic surveys. The onshore flank deformation of Mount Etna appears to be laterally confined by two tectonic guidelines, trending roughly E–W, located to the north and south of the deforming flank; the northern guideline, in particular, takes the surface expression of a sharp fault (Pernicana Fault). Though often assumed that these boundary structures continue offshore as linear features, connected to a frontal thrust ramp, the occurrence of this simple offshore structural system has not been imaged. In fact, seismic data show a remarkable degree of structural complexity offshore Mount Etna. The Pernicana Fault, for instance, is not continuing offshore as a sharp feature; rather, the deformation is expressed as ENE–WSW folds located very close to the coastline. It is possible that these tectonic structures might have affected the offshore of Mount Etna before the Pernicana Fault system was developed, less than 15 ka ago. The southern guideline of the collapsing eastern flank of the volcano is poorly expressed onshore, and does not show up offshore; in fact, seismic data indicate that the Catania canyon, a remarkable E–W-trending feature, does not reflect a tectonic control. Seismic interpretation also shows the occurrence of a structural high located just offshore the edifice of Mount Etna. Whereas a complex deformation affects the boundary of this offshore bulge, it shows only limited internal deformation. Part of the topography of the offshore bulge pre-existed the constructional phase of Mount Etna, being an extension of the Hyblean Plateau. Only in the northern part, the bulge is a recent tectonic feature, being composed by Plio-Quaternary strata that were folded before and during the building of Mount Etna. The offshore bulge is bounded by a thrust fault that can be related to the intrusion of the large-scale magmatic body below Mount Etna.

The polarity of subduction in the Corsica–Northern Apennine system is a long-debated issue. Models adopting an original W-dipping subduction and models preferring a flip in the polarity of subduction, from E-dipping to W-dipping present inconsistencies that are mainly due to the 2D approach. A new proposal is presented, using Late Cretaceous to Present-Day kinematic reconstructions of the Central Mediterranean. A wide oceanic embayment is required to the west of the Adriatic Promontory, to account for the Oligocene-Present calcalkaline volcanism and back‐arc extension. This implies that the continental collision that originated the Alps s.s. could not continue SW-ward of Adria. The change in subduction polarity, going from the Alps, to the Apennines, is taken as on original feature since the beginning of convergence. Kinematic reconstructions show that the point where subduction polarity changes moved N-ward along the plate boundary, from Late Cretaceous to Eocene. As a result, areas that previously experienced the continental collision of the Adriatic Promontory were subsequently affected by the oceanic subduction of the Tethyan embayment. This sequence of events caused the collapse of Alpine Corsica and led to the opening of the Balearic back‐arc basin. A similar kinematic evolution is ongoing in Taiwan, where the N-ward subduction of the Philippine Sea plate is progressively substituting the E-ward subduction of the Eurasian plate, causing the collapse of the orogen in northern Taiwan. The slivers of continental basement rocks that are encased within the uppermost nappe in Corsica have been interpreted as remnants of a microplate that collided with Corsica. Plate kinematics offers an alternative explanation, with these basement rocks being derived from the colliding Adriatic promontory during Paleocene–Eocene; the promontory then passed away laterally, allowing the juxtaposition of the Alpine belt of Corsica with the early Apennines.

The Straits of Messina and its surroundings are considered as one of the most tectonically active area of the Mediterranean, but in spite of their hazard potential, modern geophysical data aimed at investigating their hidden structures are lacking. In order to bridge this gap, we carried out a marine multichannel seismic survey primarily aimed at: i) studying the regional fault pattern in the area of the Messina 1908 earthquake; and ii) checking the existence of a potentially seismogenic fault, the Taormina Fault, which many authors locate offshore, along the coast between Taormina and Messina. Our seismic profiles show a great structural complexity within the Messina Straits, with the best imaged faults occurring on the Calabrian side. In particular, a more than 30 km long NW-trending fault located at the SW tip of Calabria is cutting the sea floor. Moreover, our data did not image any extensional fault plane attributable to the Taormina Fault; rather, the whole slope has been tilted east-ward. The geodynamic implication is that extension in south-eastern Sicily, on the Ionian side of the Hyblean Plateau, and extension in southern Calabria and Messina Straits belong to two different tectonic systems and cannot be mechanically linked.

The neotectonics of the Northern Apennines is illustrated using a crustal-scale geoseismic cross-section, based on seismic profiles and field mapping. The geological profile crosses a variety of tectonic settings, from the Val di Vara and Val Magra (VV–VM) grabens in the inner side of the Apennines, to the pede-Apennine thrust fronts (PTF), and finally to the external fronts of the Apennines. Both the VV–VM extensional system and the PTF show evidence of Early Pleistocene tectonic activity, whereas thrusting in the external Apennine ended by Late Pliocene. The sole decollement of the external thrusts cuts down westwards into the basement to a depth of about 15 km, whereas the PTF joins a shallower detachment surface that follows the top of the basement. This basal surface also represents the basal detachment of the VV–VM extensional system, with the VV–VM and PTF defining a large-scale gravitational spreading system. We hypothesise that the regional Quaternary uplift that affected the internal sector of the Apennines promoted a gravitational spreading in the upper part of the orogenic wedge, accounting for the coeval extension in the VV–VM and shortening at the PTF, and applicable to a 100 km long sector of the Northern Apennines.

Paleomagnetic analysis was carried out in the northern Apennines on Eocene to Pliocene Epiligurian units. Five Early Miocene and two Middle Miocene sites yielded dual polarity site-mean directions which show signs of clustering after correction for bedding tilt. These likely primary magnetizations, in conjunction with data from the literature, give an overall mean Late Oligocene–Middle Miocene paleomagnetic pole which shows a large and significant counterclockwise rotation of 52° (±≈8°) with respect to the Africa reference paleopoles (or a similar amount of rotation with respect to the coeval Europe reference paleopole). However, this paleopole falls close to the roughly coeval paleopole for Corsica–Sardinia, which is here calculated by averaging data from the literature. Three additional Early Miocene sites from an area west of Parma affected by Pliocene tectonics yielded site-mean directions which pass the fold test and are rotated counterclockwise by a lesser amount than the rest of the Miocene sites. Most of the remaining sites bear paleomagnetic directions acquired after tilting during a recent phase of remagnetization. We suggest that the large-scale rotation observed in the northern Apennines was associated with the motion of the Corsica–Sardinia block within the general context of the Africa–Europe relative motions. A compilation of published data from the central Apennines also shows a differential rotation of the northern relative to the southern Umbria belt which occurred after the motion of Corsica–Sardinia and may have been due to pivoting of the northern Umbria belt against a deep-seated lineament during the non-rotational opening of the Tyrrhenian Sea.

Extensional basins are known to occur on top of the Apennine Maghrebian fold-and-thrust belt that runs along Sicily and peninsular Italy. They formed mainly during the Plio-Quaternary, presumably in relation to the opening of the Tyrrhenian back-arc basin, while contraction was active at the thrust front. Contractional structures are often present within their sedimentary infill. One of these basins, INVO-2 located southwest of the Egadi islands, has been investigated using a closely spaced grid of multichannel seismic reflection profiles in order to define its structural style. Basin INVO-2 was formed along a system of NW-SE-trending extensional faults and is subdivided into two subbasins separated by a morphologic high. Flipping of half-graben polarity is often encountered along the axis of the two subbasins. Contractional structures, trending both perpendicular and parallel to the basin axis, occur within the basin infill, and in some instances these structures can be related to reactivation of previous extensional faults. Although the lack of well control does not allow a precise dating of the contractional episodes, they appear to occur intermittently, from the onset of the basin until recent times, intercalated to a dominant extensional regime. The origin of compressional pulses in this extensional setting can be looked for in the dynamics of the adjacent Maghrebian collision zone.

Geophysical and geological marine data recently collected allow to outline the structure of the basement-involved fold-thrust belt, developed during the Late Cenozoic between Sardinia and Tunisia, along the Africa-Europe plate boundary. By integrating these with inland data, it is possible to document, step by step, the progression of crustal thickening from north to south, and the collapse of the first uplifted northern units, while collision was still going on. The geodynamic setting suggests that coupled extensional collapse and fold-thrust propagation were driven by island arc drifting above a southward-retreating subduction zone.

A reappraisal of the seismic profiles available over the Strait of Sicily rift zone has been undertaken in order to unravel its tectonic evolution. Although the area presents great structural complexity, the motion along the basin-boundary faults appears to have been mostly dip-slip with extension directed roughly NE-SW. A wide N-S trending belt characterized by localized uplifts and depocentres, alkaline volcanics and structural inversions, separates the Pantelleria Trough to the west from the Malta and Linosa troughs to the east. This belt presents evidence of strike-slip tectonics and acted as a transfer fault zone between two segments of the rift system. The rifting occurred mostly during the Pliocene and was followed by a post-rift phase, with no sign of extension within the troughs, that probably spanned the whole Quaternary. Only within the Pantelleria Trough has a recent contractional episode been observed. The origin of the rift system is hypothetically related to the opening of the Tyrrhenian back-arc basin which occurred at the same time. Roll-back of the subducted slab and lithospheric mantle delamination have been proposed as feasible mechanisms originating the Tyrrhenian back-arc basin and the coeval contraction in the Apennine-Maghrebian fold-thrust belt. Both these mechanisms can also produce a limited amount of extension in the Strait of Sicily due to slab-pull and secondary mantle convection, respectively.