Volcanism at Slab Tear Faults: the Diamante-Enotrio-Ovidio volcanic complex (offshore north-west Calabria)

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Abstract

Several arc-shape sectors form the central and southern part of the Italian peninsula, representing the emergedportion of the continental crust disjoined by slab tear faults (e.g., Olevano-Antrodoco, Ortona-RoccamonfinaTindari-Letojanni faults). These sectors are characterized by different drift velocities and tectonic patterns,while above to them important volcanic phases developed, such as the Vulture volcano (onshore) and theVulcano-Lipari-Salina alignment (offshore). In the Tyrrhenian basin such kind of volcanism is still poorlyinvestigated and understood though it could be revealed by low-resolution geophysical anomalies and volcanicseafloor morphologies. This is probably due to the fact that this volcanism is characterized by multifariousevolutionary steps, developed and overlapped during its formation since Miocene time. In this work, wepresent new geophysical data about an unknown intrusive-effusive volcanism affecting a 40 × 52 km largearea of the northern part of the Western Calabrian Offshore, about 20 km far the shoreline. The integrationof high-resolution multibeam bathymetric data, seismic reflection data, regional magnetic anomalies andlocal earthquake tomography highlights the volcanic nature of this area, where the Diamante, Enotrio andOvidio seamounts structure (DEOS) is present. Seismic profiles show that the DEOS developed in an areastrongly intruded by volcanics that locally reach the seafloor forming the volcanic edifices. Magmatic moundsand associated structures, which include chimneys and lava flows, are observed within different upper PQsedimentary levels. Three fault systems associated with positive flower structures are identified. They offsetboth volcanics and sedimentary cover of the Diamante volcano reaching the sea floor, giving place to a set ofsteep and 1-6 km long scarps oriented between N10°E and N34°E. Moreover, significative magnetic signaturesplaced in correspondence of northern side of the Ovidio as well as above the Diamante seamounts highlight thepresence of deep rooted magnetized volcanic feeding system remnant. The local earthquake tomography furthersupport these findings, revealing beneath the DEOS evidence of gas-filled porosity probably related to magmacooling. The DEOS area lies at the northern boundary of the subducting Ionian slab, at the termination of thePalinuro-Glabro seamounts alignment. We suggest that DEOS represents the easternmost Pleistocene volcanicactivity developed along the TF bordering the northern side of the Ionian subducting slab, in proximity of itshinge. We also discuss the overall flat-topped morphology of Ovidio Seamount as the result of the interplaybetween sea-level fluctuations and subsidence.
Lingua originaleEnglish
Numero di pagine1
Stato di pubblicazionePublished - 2018

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