GNGTS 2013 - Atti del 32° Convegno Nazionale

Marine geological mapping of the Campania Region at the 1:10,000 scale: the example of the geological map n. 465 “Isola di Procida” (Naples Bay, Southern Tyrrhenian sea, Italy) G. Aiello Institute of Marine Environmental and Coastal Area (IAMC), National Research Council of Italy (CNR), Naples, Italy Introduction. Marine geological mapping of the Campania Region at the 1:10.000 scale is herein presented, focussing, in particular, on the geological map n. 465 “Isola di Procida” (Ispra, 2011). The geological map n. 465 “Isola di Procida” covers the Naples Bay from the Sorrento Peninsula up to the Procida island. In this geological map a total amount of 622 km 2 of surface about 10 km 2 are represented by emerged areas and 612 km 2 by marine areas. The bathymetric belt 0/200 extends for 378 km 2 and represents about the 60.8% of the total surface of the map. Sidescan sonar data have been calibrated by numerous sea bottom samples. The geological structures overlying the outcrop of acoustic basement, both carbonate (in correspondence to the Sorrento Peninsula) and volcanic (in correspondence to the Phlegrean Fields) have been investigated using Subbottom Chirp, Sparker and Watergun profiles. The interpretation of seismic data lends support for the reconstruction of the stratigraphic and structural setting of Quaternary continental shelf and slope successions and correlation to outcrops of acoustic basement, Mesozoic carbonate in the Sorrento Peninsula structural high and Quaternary volcanic in the Phlegrean Fields and Procida island. These areas result from the seaward prolongation of the stratigraphic and structural units widely cropping out in the surrounding emerged sector of the Sorrento Peninsula (Cinque et al. , 1997), Naples town, Phlegrean Fields and Procida island (Scarpati et al. , 1993; Perrotta et al. , 2010; Ispra, 2011). Source data and methods of cartographic representation. Several geological and geophysical surveys on the continental shelf and slope of the Naples Bay have been carried out, particularly referring on the geological map n. 465 “Isola di Procida”. In particular, a high resolution Multibeam bathymetry of the Naples Bay allowed for the construction of a marine DEM (Digital Elevation Model) of the area, giving a detailed image of the morpho-structures at the sea bottom (D’Argenio et al. , 2004). Moreover, Sidescan Sonar acoustic profiles covering the whole Naples Bay have been acquired for the construction of photomosaics of the sea bottom. The Sidescan Sonar photomosaics and the Multibeam bathymetry represented the base for the marine geological mapping. The integrated geological interpretation of seismic, bathymetric and Sidescan Sonar data has been tied by sea bottom samples and piston cores. The geological structures and the seismic sequences, both volcanic and sedimentary in nature, which characterize the Naples Bay at a regional scale have been the object of detailed studies carried out using multichannel and single channel seismics of various resolution and penetration, including the Sub-bottom Chirp profiles, often integrated with marine magnetics (Aiello et al. , 2001; Secomandi et al. , 2003; Aiello et al. , 2004, 2005; D’Argenio et al. , 2004; Ruggieri et al. , 2007). The interpretation of high resolution seismic reflection profiles (Sub-bottom Chirp, Sparker and Watergun) has supported the reconstruction of stratigraphic and structural framework of the continental shelf and slope successions. The seismo-stratigraphic analysis allowed distinguishing the main volcanic and sedimentary seismic units, separated by regional unconformities, tectonically and eustatically controlled. The Dohrn and Magnaghi canyons, eroding the slope up to 1000 m of water depth, represent in the Naples Bay important morpho- structural lineaments, at the boundary between the sedimentary units of the eastern shelf of the Naples Bay and the volcanic units of the western shelf, in correspondence to the Ischia and Procida islands. The complex stratigraphic architecture of the Naples Bay has revealed, during the Late Quaternary, a strong control of the volcano-tectonic processes in triggering submarine gravity instabilities. This regional geological framework did not allow a simple application of principles 175 GNGTS 2013 S essione 3.3