GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 3.1 537 on the MS29 profile, mainly about the bright spot and the erosive surfaces: two interpretation problem directly linked each other’s. Data interpretation. The interpretation was carried out using Petrel - Schlumberger dedicated software. The dataset was composed by multi-channel seismic lines: the OCSS_15 seismic lines, the MS29 seismic line, the ViDEPI lines (zones D and F), CHIRP profiles of the OCSS_15 survey and boreholes information. The data show that, in the study area, the thick Apulia carbonate platform is present, surrounded by pelagic basins (Ionian, South Adriatic and South Apulia Basins) and capped by a hemipelagic sedimentary cover developed by Pliocene, that is coherent with what we know about this sector of the Adriatic Sea. From the Late Liassic to the Early Cretaceous, indeed, the Adria plate was affected by tensional tectonics that caused the break-up of the Triassic carbonate platform; this event generated horsts (carbonate platform relative higher structures) and grabens (surrounding basins) superimposed respectively by carbonate sequences and by pelagic basin sedimentation (Verschuur et al. , 1991). We focused on the main seismostratigraphic sequences recognized in the East Salento offshore, trying to give a regional scale interpretation at: the top of the carbonate platform, two major erosive surfaces and a huge bright spot previously discussed in literature (Del Ben et al. , 2011) near the Merlo-1 borehole. The main seismic features recognized in our sections could be grouped into five different features: carbonate platform, basinal sediments, carbonate platform margins and reef structures, erosive surfaces, Plio-Quaternary sedimentary cover. We focused on a huge gas accumulation (e.g. bright spot as seismic evidence) visible in numerous lines. Gas accumulation is figured by a high amplitude reflector evidenced by a polarity inversion at its termination and by antiformal shape. A major evidence of gas accumulation was in the MS29: above the carbonate platform top there is a wide bright spot. However, the higher resolution of the OCSS3 seismic profile - which lies at the same location of the MS29 – highlighted that the reflector termination seems not to be marked by a polarity inversion as previously seen on the MS29 seismic section. Likely, an erosional surface (Fig. 2) or, maybe, a platform Fig. 2 - Bright spot and erosive surfaces interpretation problems.