SEDIMENTOLOGICAL MAP OF THE GULF OF CAGLIARI – SOUTH SARDINIA, ITALY

Abstract

The SEDIMENTOLOGICAL MAP OF THE GULF OF CAGLIARI IS PRESENTED. The reseach is based on 323 sediment samples, collected during 7 oceanographic cruises carried on in the context of the following project: - "Environmental control system and management of the coastal and marine area of the Gulf of Cagliari" - Italian University and Research Office (M.I.U.R.); - CAR.G. Project - "Geological Map of Italy, 1:50,000 scale" - Sheet 557 "Cagliari" and sheet 566 "Pula". The purpose of this research is to finally contribute to reaching a thorough understanding of the sea bed in the area between Capo Spartivento and Capo Carbonara, improving the knowledge of the present accumulation, transport and sedimentation processes on the inner shelf. The preliminary phase consisted in the examination of previous data: sonar data, seismic data, sedimentary data derived from surveying carried out by the Marine and Coastal Geology researchers of Cagliari University - Earth Science Department over the last 15 years; followed by the digital cartographic base drawing, geo-referred in 1:50,000 scale. These objectives were reached by revising acoustic data (Side Scan Sonar, Multi-Beam and Single-Beam) and seismic data (Sub Bottom Profiler e Sparker). As cartographic bases we used the Regional Technical Maps (CTR, Regione Autonoma della Sardegna, 1998), in 1:10,000 scale, revised with the Ortophotos, in 1:10,000 scale (Regione Autonoma della Sardegna, 2006) and compared with previous Ortophotos from 77, '98, '02. In the sea area we used the Italian navy nautical maps (I.I.M.I.) and new acoustic data obtained during the last two years surveying (2005 and 2006 Gulf of Cagliari Campaign; 2006 and 2007 "Santa Margherita" and "Solanas" Campaign and 2006/07 "Cagliari Sub" Campaign). New sedimentary samples were collected with a Van Veen sampler (5 litres), 163 samples in the gulf area and further 54 samples were collected onshore and on the shoreline in detailed areas. Afterwards underwater and direct dip (ARA) samples were collected. In addition, 106 precedent samples were examined. Every sample was analysed (grain size and composition) and classified (Udden-Wentworth scale) and facies association were recognised. All cartographic, acoustic and sedimentary data collected, was revised, processed and digitized. The data was added in a single G.I.S. file used to create the "SEDIMENTOLOGICAL MAP OF GULF OF CAGLIARI - South Sardinia, Italy" (1:50,000 scale), that represents the sea bed facies association

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