CORAL (Catamaran fOr UndeRwAter expLoration) is a compact, unmanned catamaran-type vehicle designed and developed to assist the scientific community in exploring marine areas such as inshore regions ...that are not easily accessible by traditional vessels. This vehicle can operate in different modalities: completely autonomous, semi-autonomous, or remotely assisted by the operator, thus accommodating various investigative scenarios. CORAL is characterized by compact dimensions, a very low draft and a total electric propulsion system. The vehicle is equipped with a single echo-sounder, a 450 kHz Side Scan Sonar, an Inertial Navigation System assisted by a GPS receiver and a pair of high-definition cameras for recording both above and below the water surface. Here, we present results from two investigations: the first conducted in the tourist harbour in Pozzuoli Gulf and the second in the Riomaggiore-Manarola marine area within the Cinque Terre territory (Italy). Both surveys yielded promising results regarding the potentiality of CORAL to collect fine-scale submarine elements such as anthropic objects, sedimentary features, and seagrass meadow spots. These capabilities characterize the CORAL system as a highly efficient investigation tool for depicting shallow bedforms, reconstructing coastal dynamics and erosion processes and monitoring the evolution of biological habitats.
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.
The southern part of Tyrrhenian back-arc basin (NW Sicily), formed due to the rifting and spreading processes in back-arc setting, is currently undergoing contractional tectonics. The analysis of ...seismic reflection profiles integrated with bathymetry, magnetic data and seismicity allowed us to map a widespread contractional tectonics structures, such as positive flower structures, anticlines and inverted normal faults, which deform the sedimentary sequence of the intra-slope basins. Two main tectonic phases have been recognised: (i) a Pliocene extensional phase, active during the opening of the Vavilov Basin, which was responsible for the formation of elongated basins bounded by faulted continental blocks and controlled by the tear of subducting lithosphere; (ii) a contractional phase related to the Africa-Eurasia convergence coeval with the opening of the Marsili Basin during the Quaternary time. The lithospheric tear occurred along the Drepano paleo-STEP (Subduction-Transform-Edge-Propagator) fault, where the upwelling of mantle, intruding the continental crust, formed a ridge. Since Pliocene, most of the contractional deformation has been focused along this ridge, becoming a good candidate for a future subduction initiation zone.
Since the Tortonian, the geodynamic evolution of the Tyrrhenian Sea has been driven by an eastward roll-back of the entire Apennine subduction system, triggering distinct episodes of back-arc basin ...formation with spots of oceanic crust. Major structural differences are observed between northern and southern portions of the Tyrrhenian Sea, reflecting two distinct evolution stages of the Ionian slab retreat. In the central portion of the Tyrrhenian Sea, the seafloor morphology is characterized by a set of magmatic intrusions and structural highs associated to an Ee W magnetic lineament along the 41 st geographical parallel. The Vercelli seamount represents one example of structural highs correlated to Miocene magmatic episodes along the 41 st parallel zone. In this study, we discuss the results of new high resolution magnetic data and morphological mapping of the Vercelli seamount acquired during the VER2010 cruise. The seamount represents the relict part of a granitic intrusion emplaced during the Tortonian phase of Tyrrhenian rifting. Tectonic and deep-sea erosive processes have jointly modified the seamount structure that can be observed nowadays. Cumulative gradient analysis highlights an asymmetric morphology of the flanks as a result of erosive action of opposite water mass gyres which modelled the southern portion of the seamount. The joint interpretation of magnetic and bathymetric datasets identifies a high magnetized source laying close to the base of the seamount and located in correspondence to a small basin. This structure has been modelled as a post-Tortonian lava sequence emplaced between structural highs in correspondence of Ne S elongated flat sedimentary basin.Modelling of new geophysical data highlights the relationship between crustal setting and magnetic evidences of the central Tyrrhenian Sea, providing a new interpretation of the 41 st magnetic lineament.
Very high resolution bathymetric map obtained through multibeam echo-sounders data are crucial to generate accurate Digital Terrain Models from which the morphological setting of active volcanic ...areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the island of Lipari, the largest and the most densely populated of the Aeolian Islands (southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultra-high resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters.
Volcanism is the most widespread expression of cyclic processes of formation and/or destruction that shape the Earth’s surface. Calderas are morphological depressions resulting from the collapse of a ...magma chamber following large eruptions and are commonly found in subduction-related tectono-magmatic regimes, such as arc and back-arc settings. Some of the most impressive examples of seafloor hydrothermal venting occur within submarine calderas. Here, we show the results of magnetic investigations at two hydrothermally active submarine calderas, i.e., Palinuro Seamount in the Southern Tyrrhenian Sea, Italy, and Brothers volcano of the Kermadec arc, New Zealand. These volcanoes occur in different geodynamic settings but show similarities in the development of their hydrothermal systems, both of which are hosted within calderas. We present a new integrated model based on morphological, geological and magnetic data for the Palinuro caldera, and we compare this with the well-established model of Brothers caldera, highlighting the differences and common features in the geophysical expressions of both hydrothermal systems. For consistency with the results at Brothers volcano, we build a model of demagnetised areas associated with hydrothermal alteration derived from 3D inversion of magnetic data. Both these models for Brothers and Palinuro show that hydrothermal up-flow zones are strongly controlled by caldera structures which provide large-scale permeability pathways, favouring circulation of the hydrothermal fluids at depth.
The TOMO-ETNA experiment was devised for the investigation of the continental and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the Aeolian Islands, through an active source ...study. In this experiment, a large amount of geophysical data was collected both inland and in the Ionian and Tyrrhenian Seas for identifying the major geological and structural features offshore Mt. Etna and NE Sicily. One of the oceanographic cruises organized within the TOMO-ETNA experiment was carried out on the hydrographic vessel “Galatea” by Italian Navy. During the cruise a detailed magnetic survey and a set of ROV (remotely operated vehicle) dives were performed offshore Mt. Etna. The magnetic survey allowed the compilation of a preliminary magnetic map revealing a clear direct relationship between volcanic structures and high frequency magnetic anomalies. Significant positive magnetic anomalies were identified offshore the Timpa area and along the easternmost portion of the Riposto Ridge and correlated to a primitive volcanic edifice and to shallow volcanic bodies, respectively. On the whole, the magnetic anomaly map highlights a clear SW-NE decreasing trend, where high amplitude positive magnetic anomaly pattern of the SW sector passes, northeastwardly, to a main negative one. ROV dives permitted to directly explore the shallowest sectors of the Riposto Ridge and to collect several videos and seafloor samples, allowing us to identify some locally developed volcanic manifestations.
The TOMO-ETNA experiment was planned in order to obtain a detailed geological and structural model of the continental and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the ...Aeolian Islands (southern Italy), by integrating data from active and passive refraction and reflection seismic methodologies, magnetic and gravity surveys. This paper focuses on the marine activities performed within the experiment, which have been carried out in the Ionian and Tyrrhenian Seas, during three multidisciplinary oceanographic cruises, involving three research vessels (“Sarmiento de Gamboa”, “Galatea” and “Aegaeo”) belonging to different countries and institutions. During the offshore surveys about 9700 air-gun shots were produced to achieve a high-resolution seismic tomography through the wide-angle seismic refraction method, covering a total of nearly 2650 km of shooting tracks. To register ground motion, 27 ocean bottom seismometers were deployed, extending the inland seismic permanent network of the Istituto Nazionale di Geofisica e Vulcanologia and a temporary network installed for the experiment. A total of 1410 km of multi-channel seismic reflection profiles were acquired to image the subsurface of the area and to achieve a 2D velocity model for each profile. Multibeam sonar and sub bottom profiler data were also collected. Moreover, a total of 2020 km of magnetic and 680 km of gravity track lines were acquired to compile magnetic and gravity anomaly maps offshore Mt. Etna volcano. Here, high-resolution images of the seafloor, as well as sediment and rock samples, were also collected using a remotely operated vehicle.
Geology, geophysics and geodynamics of the Tyrrhenian Back-Arc Basin (BAB; central Mediterranean Sea) have been studied extensively during the last 50 years. However, some topics are still open: for ...example, the possible migration of the volcanic arc during the Ionian subduction of the past few Ma. We improved our knowledge of the geodynamics of the Tyrrhenian BAB in the area South of the Vavilov Volcano by analyzing multibeam bathymetry and unpublished single-channel reflection seismic and magnetic data. Furthermore, we studied the petrology of igneous rocks as well as facies and microfaunas of carbonates dredged from the Aurelia and Augusto seamounts. The Aurelia basement is made of basalts with calc-alkaline affinity. Carbonates from the Aurelia and Augusto seamounts consist of cemented Mg-calcite biomicrite crusts rich in planktonic foraminifera not older than Early Pleistocene. Based on our results, we interpret the Augusto and Aurelia seamounts as part of the active volcanic arc seaward of the Tyrrhenian BAB in Late Pliocene–Early Pleistocene.
•We studied the Augusto and Aurelia seamounts in order to improve the geodynamics of the Tyrrhenian Sea.•A morpho-structural study has been done creating bathymetric maps and interpreting unpublished sparker profiles.•Facies, microfauna and petrography of samples of rocks dredged from the Aurelia and Augusto seamounts have been analyzed.•A new map of the reduced to pole magnetic anomalies of the Southern Tyrrhenian was created using unpublished magnetic data.•Results reveal that the Augusto and Aurelia seamounts were part of the fossil volcanic arc of the Tyrrhenian Back-Arc Basin.
Half a century ago, our view of the Earth shifted from that of a Planet with fixed continents and ancient stable ocean basins to one with wandering continents and young, active ocean basins, reviving ...Wegener’s Continental Drift that had rested dormant for years. The lithosphere is the external, mostly solid and relatively rigid layer of the Earth, with thickness and composition different below the oceans and within the continents. We will review the processes leading to the generation and evolution of the Earth’s lithosphere that lies beneath the oceans. We will discuss how the oceanic lithosphere is generated along mid-ocean ridges due to upwelling of convecting hot mantle. We will consider in particular lithosphere generation occurring along the northern Mid Atlantic Ridge (MAR) from Iceland to the equator, including the formation of transform offsets. We will then focus on the Vema fracture zone at 10°–11° N, where a ~ 300 km long uplifted and exposed sliver of lithosphere allows to reconstruct the evolution of lithosphere generation at a segment of the MAR from 25 million years ago to the Present. This axial ridge segment formed 50 million years ago, and reaches today 80 km in length. The degree of melting of the subridge mantle increased from 16 million years ago to today, although with some oscillations. The mantle presently upwelling beneath the MAR becomes colder and/or less fertile going from Iceland to the Equator, with “waves” of hot/fertile mantle migrating southwards from the Azores plume. Scientific revolutions seem to occur periodically in the history of Science; we wonder when the next revolution will take place in the Earth Science, and to what extent our present views will have to be modified.
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