GNGTS 2014 - Atti del 33° Convegno Nazionale

Discussion-dataset comparison. In Fig. 2 the seismic facies of the Messinian UU of the Algero-Balearic (A1-A2-A3) and east Sardo-Provençal (B1-B2-B3) basins have been compared. The time depth of the top of UU in the Algero-Balearic basin is generally shallower than in the east Sardo-Provençal basin (respectively 4.10 sec TWT and 4.65 s TWT). In A1 a detail of the seismic profile SF12-03 shows a well reflecting package of about 10 reflectors that depict the UU, here partially deformed by salt tectonic. Also Geletti et al. (2014), interpreted an UU depicted by a package of stratified reflectors with a thickness ranging between 250 and 500 ms TWT along the seismic profiles of the west Sardinia Margin (B1). An average velocity of 3500 m/s, deduced by the velocity spectra analysis, suggests an UU thickness of about 440-880 m. In A1 the UU reaches a thickness of about 300-400 ms TWT, that is 500-700 m assuming the same velocity. A thin transparent layer has been observed in the shallower part of the UU; this level rarely exceeds a time thickness of 15-20 ms TWT and it could be recognized along most of the SF 2012 seismic profiles. Locally it produces little salt domes (Fig. 2A2, part of SF12-07). Due to its seismic facies and depth position below the UU top, it can be associated to the autochtonous salt layer “s” inner the UU interpreted by Geletti et al. (2014), and evidenced in Fig. 2B2. The stratified UU overlies a sequence with a transparent seismic facies which is typical of the salt litology (MU); it exhibits a transparent layer on the foot of the slope, where a negative reflector, related to the high interval velocity of salt, marks its base (blue dotted line in Fig. 2A3). The scattered seismic signal of the upper UU (detail in frame z1) and the gas chimneys Fig. 1 – Location map of the two seismic dataset used for this study and location of seismic profiles displayed in figures; in inset A position map of WS 10 seismic profiles and in inset B position map of SF 12 SATFLU seismic profiles. GNGTS 2014 S essione 1.2 159