Modern inner-shelf sedimentation: a comparison between Bonifacio Straits and Gulf of Cagliari (Sardinia - IT)

This abstract presents a comparison results on inner shelf sedimentation between Bonifacio Straits (between Sardinia and Corsica) and Cagliari Gulf (South Sardinia). The studies were carried out in the context of the following projects: Interreg IIIA – G.E.R.E.R., “Environmental control system and management of the coastal and marine area of the Gulf of Cagliari - M.I.U.R., CAR.G. Project – “Geological Map of Italy, 1:50,000 scale” and continue thanks to the RIAS project and two fellowship grants funded by the Sardinia Regional government. Seismic and echographic data were recorded and used to identify different acoustic facies (sediment deposits, posidonia meadows and rock outcrops) and bedforms (sandwaves, comet marks, ripples etc.). A total of 230 samples were collected and analyzed. The mineralogical composition of samples was classified by distinguishing bioclasts, lithoclasts, quartz, feldspars, micas and other minerals. The taxonomical classification was performed categorizing sediments in the following groups: Red Algae, Bryozoans, Mollusks, Cnidarians, Arthropods, Echinoderms, Foraminifers, Polychaeta–Serpulida and indeterminate grains. The sedimentological maps were drawn using the classification into sedimentary facies, realized by multivariate statistical techniques, which distinguish sample groups on the basis of different sediment characteristics (texture, mineralogy, taxonomical groups). Different sedimentary facies were recognized: shoreface sediments, coastal detritic sands, reworked detritic sands, mixed gravelly sands, maërl beds, coralligenous and three different types of muddy sandy sediments. Modern inner shelves sedimentation is controlled by eustatic, hydrodynamical and morphological features of the basins and by in situ production of marine ecosystems as Posidonia oceanica (L.) Delile meadows, coralligenous and maërl beds. Both shelves were classified as mixed carbonate-terrigenous shelves