GNGTS 2017 - 36° Convegno Nazionale

600 GNGTS 2017 S essione 3.1 The back-arc Tyrrhenian basin opening history, new insights from a recent geophysical data acquisition N. Zitellini 1 , C.R. Ranero 2 , V. Sallares 3 , I. Grevemeyer 4 , M.F. Loreto 1 , M. Prada 5 , M. Ligi 1 , P. Diviacco 6 , G. Brancatelli 6 , R. de Franco 7 1 Istituto di Scienze Marine, Consiglio Nazionale della Ricerche, Bologna, Italy 2 Barcelona Center for Subsurface Imaging ICREA at CSIC, Barcelona, Spain 3 Barcelona Center for Subsurface Imaging at CSIC, Barcelona, Spain 4 GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany 5 Dublin Institute for Advanced Studies, Dublin, Ireland 6 Istituto nazionale di Oceanografia e di Geofisica Sperimentale - OGS, Trieste, Italy 7 Istituto per la Dinamica dei Processi Ambientali, CNR, Milano, Italy On 2010 and 2015 two geophysical surveys were carried out in the Tyrrhenian basin within the framework of a Spanish-German-Italian projects MEDOC and the CHIANTI, respectively. During the MEDOC survey a total of 17 Multichannel Seismic (MCS) lines for a total length of 2.808 km and 5 longWide-Angle Seismic (WAS) profiles were collected, crossing the Tyrrhenian basin from side to side. The data were acquired with the Spanish R/V Sarmiento de Gamboa in coordination with the Italian R/V Urania. The WAS data were also recorded by several land stations installed in Corsica and Sardinia (Fig. 1). The CHIANTI survey was carried out by the R/V Sarmiento de Gamboa and two long Wide-Angle Seismic profiles, CHIANTI-WAS 2 and CHIANTI WAS 4 (Fig. 1), were collected. CHIANTI-WAS 2 is WNW-ESE trending and crosses the deepest part of the Tyrrhenian basin, from the Vavilov basin to the Marsili basin. The CHIANTI - WAS 4 is oriented almost N-S and crosses the whole Vavilov Basin, from the Campanian margin till the Sicilian margin. The Tyrrhenian basin has been studied with numerous geophysical investigations that have provided tens of thousands of kilometers of seismic reflection lines, gravity and magnetic field measurements, heat flowmeasurements, and considerable seafloor sampling and drilling (DSDP leg 13, site 132, DSPD leg 42, site 373, and ODP leg 107, sites 650-656, Fig. 1). During the nineties, the collection of the deep penetration MCS Italian CROP (Crosta Profonda) program, MS and CS89 datasets were followed with high-resolution multibeam bathymetry of the basin. The availability of this data set, including information on age, lithology and structural trends of major tectonically-formed seamounts; age and distribution of major volcanic edifices; maps of thickness of Messinian deposits; provided a good understanding of regional stratigraphy (Fabbri and Curzi, 1979; Colantoni et al. , 1981; Funiciello et al. , 1981; Sartori, 2005). From a morpho-tectonic standpoint, the Tyrrhenian has three different domains; 1) the region north of ~40º 45’N displaying shallow and rough seafloor; 2) the central region from ~40º 45’N to ~39º 30’N with deeper seafloor and extended abyssal plains spotted with prominent volcanic like the Magnaghi and Vavilov Smts (Fig. 1) and non-volcanic seamounts like the Secchi, Farfalle, Flavio Gioia and De Marchi Smts (Fig. 1); and 3) the southern Tyrrhenian from 39º 30’N to 38ºN including the Marsili volcano and its basin, the Aeolian volcanic arc and Sicilian-Calabrian margin. The northern Tyrrhenian margins are formed by a N-S-trending system of normal faults on a 20-25 km-thick continental crust affected by limited magmatism (Mauffret and Contrucci, 1999, Moeller et al. , 2013, 2014). These structures developed with an E-W directed extension (Faccena et al. , 2001) related to the eastward migration of the Apennines-Calabrian subduction system. Rifting started in Tortonian and ended in Early-Middle Pliocene. In central and southern Tyrrhenian, higher extension factors created sub-basins that were originally interpreted to be underlain by either continental crust (Cornaglia Terrace) or oceanic crust (Magnaghi, Vavilov and Marsili basins; Duschenes et al. , 1986; Kastens and Mascle, 1990; Sartori, 1990; Faccena et al. , 2001; Sartori et al. , 2003, 2004; Fig. 1). Both regions contain several-km-tall volcanic edifices of Magnaghi, Vavilov and Marsili (Fig. 1), attributed to an upper Pliocene to present day extension-related volcanism (Savelli, 1988, 2002; Lustrino et al. , 2011).