A multidisciplinary study of the volcanoclastic deposit named "Chiancone", inland and offshore, in the frame of the evolution of volcanism in the Etna area

Santo La Delfa (1) , Maria Giovanna Camuti (1) , Giuseppe Patanè (1)

1 Dipartimento di Scienze Geologiche

► In the CH's pyroclasts there are various lithological facies which were generated 50-40 Ky B.P., in particular violent geodynamic manifestations of the volcano (various opening episodes of the Valle del Bove, strong hydromagmatic, strombolian explosions, etc.). ► In various phases, the CH's volcaniclasts have occupied some Grabens of the pyroclastic body C, which is in southern zone of the area studied (La Delfa et al., 2007). In the northern zone, a tectonic depression as deep as 400 m and oriented WNW-ESE (Fig. 9:3), accommodated most of the pyroclastic flows. The North face of this ditch, towards Giarre-Riposto seems to be made up of non-volcanic sedimentary rocks, while the South face is formed by the pyroclasts from the geological body C, as the offshore multibeam surveys show (Fig. 11). ► The CH's pyroclasts poured into the sea reaching a maximum depth of 100 m b.s.l. (surveys by the "Istituto Idrografico della Marina", 1993), near Torre Archirafi, overcoming two morpho-tectonic steps: the sedimentary one North of Torre Archirafi (Fig. 9:3; Fig. 10,E) and the pyroclastic one (body C), South of Torre Archirafi, near Praiola Piccola (Fig. 4). In accordance with our results, Loddo et al. (1989) using deep dipole measurements found a rise in the non-eruptive substratum in the same area along the coast. ► Considering the presence of morpho-structural steps near the coast and the different depth of the base of the CH to the west (about 300 m, below the sea level) and to the east, off the coast line (at about 100 m below the sea level) of these steps, the possibility that the impact of the mass of the detritus, although quite modest, falling into the Ionian Sea may have caused a tsunami wave (Pareschi et al., 2006) big enough to affect the central-eastern Mediterranean about 8 000 years B.P. is excluded, in our opinion. Indeed, as is known, the CH's pyroclasts were deposited in various successive episodes, over quite a long time frame (40-50 ky) and considering the particular morphology of the conductive substratum in the area under study, they mostly filled the various existing depressions to the west of these steps, interacting only a bit with the waters of the Ionian Sea.

Mots clés: Mt. Etna; Chiancone; Morphology; Vertical Electrical Soundings

Domaines: Sciences de la Terre

Santo La Delfa, Maria Giovanna Camuti, Giuseppe Patanè. A multidisciplinary study of the volcanoclastic deposit named "Chiancone", inland and offshore, in the frame of the evolution of volcanism in the Etna area. Physics of the Earth and Planetary Interiors, 2011, ⟨10.1016/j.pepi.2011.04.004⟩. ⟨hal-00759564⟩