The contribution of marine geology to the knowledge of marine coastal areas off the Campania region: the geological map n. 502 "Agropoli" (Southern Campania)

In the last ten years the Institute of Marine Coastal Environment of the National Research Council (CNR) of Naples, Italy has carried out an extended marine geological survey for the redaction of experimental geologic maps committed by the National Geological Survey of Italy (APAT, now ISPRA). Starting from the 2003 the CNR-IAMC Institute of Naples has further increased its activities through a Convention with the Regional Geological Survey of the Campania for a geological survey of the Campania Region at the scale 1:10.000 of the whole coastal belt comprised into the - 200 m isobath. In this framework, the necessary geophysical and geological data on the continental shelf and slope have been collected in the Salerno and Policastro Gulfs (geological maps n. 486 "Foce Sele"; ISPRA, 2009; n. 502 "Agropoli", n. 519 "Capo Palinuro", n. 520 "Sapri"); between them, it is worth mentioning a high resolution Multibeam bathymetry, allowing for the construction of a marine DEM (Digital Elevation Model). Moreover, Sidescan Sonar acoustic data have been acquired for a total coverage of the study area, in order to construct photomosaics of acoustic images of the sea bottom. The latter ones, merged to the bathymetry, have represented the base for the marine geologic cartography. The geological map n. 502 "Agropoli" (scale 1:50.000) includes the coastal sector offshore the Cilento Promontory between the Agropoli and Agnone towns (southern Campania) and the surrounding marine areas. On this geological map on a total amount of 635 km2 of surface about 74 km2 are represented by emerged areas and 562 km2 are represented by marine areas. The bathymetric belt 0/200 m extends for 507 km2 and represents the 79,8% of the total surface of the map. The integrated geologic interpretation of seismic, bathymetric and Sidescan Sonar data have been suitably calibrated by sea bottom samples. The sub-bottom geological structures, and, as a general rule, the morpho-structures and the seismic sequences, overlying the outcrops of acoustic basement mapped in the marine area of the geological map n. 502 "Agropoli" have been studied in detail using multichannel and single-channel seismics of different resolution and penetration, including the Subbottom Chirp. The interpretation of high resolution reflection profiles (mostly Subbottom Chirp) has been a valid support for the reconstruction of the stratigraphic and structural setting of the Quaternary continental shelf successions and the outcrops of rocky acoustic basement in correspondence to the Punta Licosa morpho-structural high. These areas result from the seaward prolongation of the stratigraphic and structural units, widely cropping out in the surrounding emerged sector of the Cilento Promontory ("Flysch del Cilento" Auct.). The Cilento Promontory constitutes a morpho-structural high, interposed between the coastal depressions of the Salerno Gulf-Sele Plain and of the Policastro Gulf, whose reliefs are high up to 1700 m. These mounts are constituted by thick successions of turbidite carbonatic and siliciclastic sequences ("Flysch del Cilento" Auct.; Fig. 1), dipping landwards in the main carbonatic reliefs of the southern Apennines ("Alburno-Cervati Unit" Auct.). Normal faults, Quaternary in age, identify the rims of the structure of the Cilento Promontory. Apart the carbonatic structures of the Palinuro Cape and Bulgheria Mt and other few isolated outcrops, the reliefs of the Cilento Promontory are composed of terrigenous rocks, accumulated into deep basins in a time interval ranging from the Late Mesozoic and the Late Miocene. The oldest of these formations pertains to the North-Calabride Unit, composed of dark shales, marls and marly limestones, reaching a thickness of 1300 m. The North-Calabride Unit is overlai