GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 3.1 541 Sardinia10 project (WS10) acquired and processed in 2010 by the R/V OGS Explora in the western Sardinian offshore; one profile of MS survey, sponsored by National Council of Research (CNR) and acquired and processed by OGS in 1972; SARDINIA experiment project; Campagne Océanographique LISA, IFREMER; Campagne Océanographique SESAME, CNRS. The re-processing of the profile WS10_02 has been carried out at OGS in Trieste, using Echos software (Paradigm Inc.) . Discussion. The Messinian Trilogy can be recognised in the deep basin; LU unit is present only in the basin, until the foot of the slope. On the lower continental slope are present gradually thinning MU and UU units. The MU disappears more quickly, due to its detachment and sliding toward the deep basin, often producing rollover tectonics. In the central part of the slope has been interpreted the only presence of Upper Unit, which turns into the Messinian Erosional Surface. Halokinesis is characterized by several differences in the shape of dome: from the deep basin to the coast are observable frequent and narrow salt domes, “terraced” salt and tabular salt with isolated domes. From the Sardinian coast toward the basin, the MU deforms in a “terraced salt”; in this case, the domes are very close and deform the Pliocene reflectors. Sometimes, the salt can be recognized above the UU, where it intruded producing some little dome. The base of MU is interpreted at 4.5/4.8 TWT seconds. Further, the area of “terraced salt”, toward the basin, the domes are narrow and frequent and they often deform the sea level. In this case the MU base is at 5.2/5.4 s TWT. In Fig. 2 are highlighted the differences between the Gulf of Lion and the Sardinian margins. The main differences are due to the different size of the salt domes, which are bigger and more isolated in the Gulf of Lion, where also the sea bottom deformation testifies to be often still active. The total volume of salt seems to be similar on the two opposite margins. Furthermore, the PQ sequence is thicker on the French side, due to the rivers entry. The gravimetric map presents a low gravity anomaly in the basin and a high anomaly close to the margin. At the same time, the magnetic anomaly presents very similar pattern to that one of the gravity anomalies. Conclusion. The work analysed the Messinian to recent geological evolution of the eastern sector of the Sardo-Provençal basin. The main feature involving the sedimentary sequences of the studied area is the presence of the evaporite units deposited during the Messinian event. The salt tectonic forms domes, diapirs and sliding on deepening basement. This deformation Fig. 2 - Lines SARDINIA 102-101 (on the left) and line WS10_05 recorded by OGS (on the right) in the Sardo- Provençal basin. The Messinian Trilogy is clearly imaged: LU (Lower Unit), MU (Mobile Unit), UU (Upper Unit). Halokinesis of MU deform the overburden composed of UU and Plio-Quaternary sequence. On the E-W line is highlighted the pull-up event, above the Oligo-Miocene deposits. Seismic images have the same horizontal and vertical scales.