7 new submerged volcanoes discovered in the Tyrrhenian Sea which, together with the already known ones, form a chain 90 km long. These conclusions are reached by a study by Ingv, Institute for the coastal marine environment of the Cnr and Geological and Nuclear Sciences (New Zealand), published in Nature Communications.
The southern Tyrrhenian Sea reveals a new chain of 15 submerged volcanoes, of which 7 hitherto unknown, a linear structure, in East-West direction, measuring approximately 90 km in length and 20 km in width. According to a study, the result of numerous oceanographic campaigns conducted in recent years by an international team of volcanologists, geophysicists and marine geologists from the National Institute of Geophysics and Volcanology (INGV and IAMC), the Institute for the Marine Coastal of the National Research Council (IAMC-CNR) and del Geological and Nuclear Sciences (GNS), New Zealand. the job'Volcanism in slab tear faults is larger than that in island-arcs and back-arcs', Published on Nature Communications., impacts on the knowledge of the Tyrrhenian Sea and opens up new avenues for the interpretation of volcanism in subduction zones in the world (https://www.nature.com/articles/s41467-017-01626-w).
"The Southern Tyrrhenian Sea is characterized by the presence of numerous volcanoes, some emerged, such as the Aeolian Islands, others submerged, such as Marsili", explains Guido Ventura, INGV and IAMC volcanologist and coordinator of the research group. “This chain of volcanoes recently identified and described in the study, extends from about 90 km south of the coast of Salerno to 30 km east of the coast of Sangineto, Calabria. The chain, defined as Palinuro, extends in depth from about 3200m to 80m below sea level. Taken together, these volcanoes represent a fissure in the earth's crust from which magmas rise from the Aeolian Islands, from the central-southern Tyrrhenian Sea, and from the area between Puglia and Calabria”.
The data collected show that the size of the entire volcanic chain is greater not only than that of the Aeolian Islands but also of the other submarine volcanoes of the southern Tyrrhenian Sea, including Marsili.
"Furthermore, many of these volcanic structures have characteristics compatible with the opening of oceanic micro-basins where new earth's crust is created following the rising of magmas along fractures", adds Salvatore Passaro, marine geologist of the Iamc-Cnr. “These volcanoes were certainly active between 300.000 and 800.000 years ago, but it cannot be excluded that they may have been active more recently. Today they are characterized by submarine hydrothermal activity and are located in a thermal anomaly zone (about 500°C at 1 km under the seabed)."
During the oceanographic campaigns, bathymetric, magnetic, and gravimetric data were collected; core drilling and direct observations of the seabed were also carried out with the ROV (Remote Operating Vehicle), an underwater vehicle piloted from a remote location.
"The research began with the analysis of each individual volcanic edifice, and then concluded with the modeling of the geophysical and morpho-structural data on the entire crustal structure", adds the INGV researcher Luca Cocchi, who edited together with Fabio Caratori Tontini geophysical modeling of the GNS.
“The study is still in its infancy. The knowledge of the eruptive history of these volcanoes is still partial and requires further data and oceanographic research”, concludes Ventura. “Despite this, the results achieved so far partially revolutionize the geodynamics of the Tyrrhenian Sea and of the subduction zones in the world, and open new paths not only for the reconstruction of the evolution of the earth's crust, but also for the interpretation and geodynamic significance of the submarine volcanic chains active and island arcs”.
Extended
Volcanism in slab tear faults is larger than that in island-arcs and back-arcs
Luca Cocchi, Salvatore Passaro, Fabio Caratori Tontini, Guido Ventura
Subduction-transform edge propagators are lithospheric tears bounding slabs and back-arc basins. The volcanism at these edges is enigmatic because it is lacking comprehensive geological and geophysical data. Here we present bathymetric, potential-field data, and direct observations of the seafloor on the 90 km long Palinuro volcanic chain overlapping the EW striking tear of the roll-backing Ionian slab in Southern Tyrrhenian Sea. The volcanic chain includes arc-type central volcanoes and fissural, spreading-type centers emplaced along second-order shears. The volume of the volcanic chain is larger than that of the neighbor island-arc edifices and back-arc spreading center. Such large volume of magma is associated to an upwelling of the isotherms due to mantle melts upraising from the rear of the slab along the tear fault. The subduction-transform edge volcanism focuses localized spreading processes and its magnitude is underestimated. This volcanism characterizes the subduction settings associated to volcanic arcs and back-arc spreading centers.
Location of the Palinuro volcanic chain
3D reconstruction of the Palinuro volcanic chain
Underwater lavas of the central building of the Palinuro volcanic chain