GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.2 139 TIME AND SPACE SCATTERED VOLCANISM OF MT. ETNA DRIVEN BY STRIKE-SLIP TECTONICS M. Firetto Carlino 1 , D. Cavallaro 1 , M. Coltelli 1 , L. Cocchi 2 , F. Zgur 3 , D. Patanè 1 1 Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Roma2, Roma, Italy 3 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Trieste, Italy Although Mt. Etna (eastern Sicily, Italy) is one of the most intricate and studied examples of volcanism, its origin and evolution are still the object of debate. Several geodynamic models were proposed to explain the origin of Etna’s magma in the mantle and its pathways in the crust, as well as the relatively fast shifting of the eruptive centres (Branca et al. , 2011). Mt. Etna basaltic volcanism takes place along the Ionian coast of Sicily in a complex geodynamic setting, where the front of the African vs European plates’ collisional belt overlaps the continental foreland crustal block of the Hyblean domain. During 2014, high-resolution multi-channel seismic reflection profiles were acquired, together with magnetic and gravity data, offshore of Mt. Etna by the “Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Etneo” within the marine activities of the TOMO- ETNA experiment (Coltelli, et al. , 2016). This dataset was used, together with high-resolution bathymetric data and others seismic profiles acquired in the same area in 2005 (Mazzarini et al. , 2017), to provide new insights in understanding the relationship between tectonics and spatial- temporal evolution of volcanism in the Mt. Etna area and the significant neo-tectonic activity affecting the instable eastern flank of the volcano. Some of the main insights of the present study are reported in Firetto Carlino et al. (2019). The study area is dominated by the Timpe Plateau (TP), a rhombohedral morpho-structural high, extending for nearly 10 km off the coast between Aci Trezza and S. Tecla and deepening down to about 1000 m bsl. TP is bounded by NNW-SSE and NE-SW lineaments, related to the Malta Escarpment and the foreland flexure beneath the thrust belt, respectively. TP displays a step arrangement, with few N-S to NW-SE oriented and tens of meters high scarps and is affected by small and large-scale gravitational instability. The seismic reflection profiles revealed that the whole continental margin offshore of southeastern Mt. Etna, is entirely rooted by a well-defined succession of highly reflective, laterally continuous and locally deformed seismic horizons, pertaining to the carbonate succession of the Hyblean foreland domain. Its top is ascribable to the base of the Pliocene sedimentary succession, mostly corresponding to the Messinian evaporites. TP and its continental slope are strongly affected by strike-slip tectonics (Fig. 1), highlighted, in the southern sector, by a large, wedge-shaped, roughly symmetric transpressive push-up, developing along the WNW-ESE trending Aci Trezza Lineament (ATL). The strike- slip kinematics of ATL is also highlighted by the dextral displacement of the volcanic bodies offshore of Aci Trezza (Chiocci et al. , 2011) and by submarine geodetic data (Urlaub et al. , 2018). Dextral strike-slip tectonics along WNW-ESE fault planes is also consistent with the main NW oriented maximum horizontal stress axis characterizing the region (Mattia et al. , 2012). The push-up is made up of several splay-faults of the ATL and produces an overall remarkable shortening. The strike-slip kinematics of this fault system is also highlighted by out-of-plane reflections, due to the lateral superimposition of the faulted blocks. The push- up is bounded to the north by the NW-SE oriented Acireale Lineament (AL), which displays evidence of positive reactivation (i. e. fault-bend anticlines). North of the wedge, TP is only slightly deformed. The push-up seems to continue offshore of Catania, where it likely controls the sinuous path of Catania Canyon. The deformation on TP also involves the shallow seismic horizons up to the seafloor, suggesting a still active tectonics, although the faulting style affecting the Plio-Quaternary succession differs locally from that of the underlying substratum. In fact, some of the small- scale NNW-SSE trending scarps on the seafloor, sharply confined within the deformed wedge,