GNGTS 2014 - Atti del 33° Convegno Nazionale

16 GNGTS 2014 S essione 3.1 great explosions, leaving at its place a caldera having an elliptical shape. The caldera depression was then infilled by the growth of a new volcano, reaching the height of 700 m (Paleostromboli II). The life of this volcano concluded about 35 ky ago with the downthrowing of a new caldera, having a circular shape. About 34 ky B.P. a new volcano, called Vancori underwent a giant sliding in its upper part and in the western flank. To testify this collapse a large amphitheater remains, which nowadays surrounds the present top of the Stromboli volcano, including the active crater. The structure of the Stromboli volcanic island has been related to that one of the Campania volcanoes: in both ones a well-developed low velocity layer, having a thickness of 10-15 km occurs under a thin lid, overlain by a thin continental crust (Panza et al. , 2003). The structural difference among the Stromboli volcano and the proximal volcanoes of Volcano and Lipari is confirmed by the different geochemical characters (Finizola et al. , 2003; Revil et al. , 2004). The geological data here discussed well fit with some previous results obtained on the geology of the Aeolian islands and of the Stromboli canyon (Kidd et al. , 1998). The basin margins are characterized by slump scars, channels and large debrites on the continental slope off Campania region, not imaged by the data discussed in the present paper. Blocky hummocky avalanche deposits have been recognized on the flanks of the Stromboli volcano (Kidd et al. , 1998). This hint is in agreement with seismo-stratigraphic data shown by Chirp interpretation. In the Stromboli canyon and in minor deep sea channels sediment transport by turbidity currents generates sediment waves. Between the basin margins and the abyssal plain, the outcropping volcanic basement traps part of the sediment coming from the marginal area (Kidd et al. , 1998). The volcanic acoustic basement genetically related to the Stromboli lavas has been widely recognized also in the seismic lines study in the present paper. Moreover, the abyssal plain surrounding the volcanic edifice is characterized by low relief lobes and ponded sediments (Kidd et al. , 1998). Circular high backscatter patches have been recognized through the interpretation of Sidescan Sonar photomosaics (Kidd et al. , 1998), indicating that volcanic blocks have been transported downslope in the Stromboli canyon. Blocky hummocky facies have been widely recognized in the Chirp lines analyzed in the present paper. The streaked high backscatter patterns at the scarp base are interpreted as coarse-grained sediments transported downslope along the Stromboli canyon (Kidd et al. , 1998). Coarse-grained units have also been often recovered. References Aiello G., Budillon F., Conforti A., D’Argenio B., Putignano M.L., Toccaceli R.M.; 2010: Note illustrative alla cartografia geologica marina. Foglio geologico n. 464 Isola d’Ischia. Regione Campania, Settore Difesa Suolo, III SAL, Geologia Marina, Preprints. Aiello G., Marsella E., Passaro S.; 2012: Stratigraphic and structural setting of the Ischia volcanic complex (Naples Bay, southern Italy) revealed by submarine seismic reflection data. Rend. Lincei, 23 (4) , 387-408. Aiello G., Di Fiore V., Marsella E., Passaro S.; 2014: High resolution seismic data coupled to Multibeam bathymetry of Stromboli Island collected in the frame of the Stromboli geophysical experiment: implications with the marine geophysics and volcanology of the Aeolian Arc volcanic complex (Sicily, Southern Tyrrhenian sea, Italy). Springerplus, 3 (232) , doi:10.1186/2193-1801-3-232. Aiello G., Marsella E.; 2014: The Southern Ischia canyon system: examples of deep sea depositional systems on the continental slope off Campania (Italy). Rendiconti online della Società Geologica Italiana, in press. Castellano M., Augusti V., De Cesare W., Favali P., Frugoni F., Montuori C., Sgroi T., De Gori P., Govoni A., Moretti M., Patanè D., Cocina O., Zuccarello L., Marsella E., Aiello G., Di Fiore V., Ligi M., Bortoluzzi G., Ferrante V., Marchetti E., La Canna G., Ulivieri G.; 2008: Seismic Tomography Experiment at Italy’s Stromboli volcano. EOS Transactions AGU, 89 (30) , 26, 259-276. Chiocci F.L., Marani M., Tommasi P., Romagnoli C., de Alteriis G., De Vita S., Senatore M.R., Vezzoli L.; 2003: The submarine portions of Italian Volcanoes: their survey and assessment of the potential volcanic hazards. Final Report on the GNV Project, available on the website, 23 pp. Finizola A., Sortino F., Lenat J.F., Aubert M., Ripepe M., Valenza M.; 2003: The summit hydrothermal system of Stromboli: self-potential, temperature, CO2 and fumarolic fluid measurements with structural and monitoring implications. Bulletin of Volcanology, 65 , 486-504.