Active Tectonics along the South East Offshore Margin of Mt. Etna: New Insights from High-Resolution Seismic Profiles

Abstract

The offshore margin of Mt. Etna has been shaped by Middle Pleistocene to Holocene shortening and extension and, more recently, by gravity-related sliding of the volcanic edifice. These processes have acted contemporaneously although the gravitational component largely prevails over the tectonic one. In order to investigate this issue, we focused on the main role of active tectonics along the south-eastern offshore of Mt. Etna by means of marine high-resolution seismic data. Seismic profiles revealed post-220 ka sedimentary deposits unconformably overlaying the Lower-Middle Pleistocene Etnean clayey substratum and volcanics of the Basal Tholeiitic phase and the Timpe phase. Offshore Aci Trezza-Catania, the architecture of the sedimentary deposits reflects syn-tectonic deposition occurred into “piggy-back” basin setting. Shortening rate was estimated at ~0.5 mm/a since ~220 ka. Asymmetric folding also involves post Last Glacial Maximum deposits, evidencing that compressional deformation is still active. In the continental slope, a belt of normal faults offset the Lower-Middle Pleistocene Etnean clayey substratum and younger deposits, also producing seafloor ruptures. Thrust and fold structures can be related to the recent migration of the Sicilian chain front, while extensional faults are interpreted as part of a major tectonic boundary located in the Ionian offshore of Sicily.