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We adopted a combined geophysical-stratigraphic approach to identify grain size anomalies in sediment distribution of the Bagnoli coastal brownfield site. A large industrial plant occupied this area during most of the 20th Century. We used 18 core logs to identify macroscopic variation in sediment stratigraphy, and 72 supplemental cores to mark changes between sandy- and silt-dominated intervals. The stratigraphy evidenced the presence of anomalous lens of silt within a sandy coastal sector inside the Bagnoli industrial harbour. Cores description helped us to calibrate the interpretation of 4 subbottom profiles, that we used to obtain information on geometries of silty deposits. The spatial layout of sediments revealed that silt intervals are present in the area bounded by the old industrial wharfs. We suggest that these silty sediments are likely the result of uncontrolled discharge occurred during the last century. Once calibrated, high-resolution mono-channel seismic profiles helped us to define the shape as well as the real extent and thicknesses of silty deposits, resulted to be ca. 515.000 m2, with an overall volume of 480.000 m3. These results are a first attempt to define the amount of polluted sediments in the area facing the Bagnoli industrial harbour. [ABSTRACT FROM AUTHOR]

Bagnoli-Coroglio is a Site of National Interest (SNI) facing the Pozzuoli Bay that has been the place of an industrial activity for more than a century (1854-1985). The modern coastal geology of this area results from the recent evolution of an antecedent volcanic landscape that originated after a caldera collapse following the eruption of Neapolitan Yellow Tuff (NYT) of Campi Flegrei (15 ka). After the NYT eruption, a shallow marine depression formed within the caldera collapse area that underwent progressive filling-up, due to volcaniclastic sediment input from the caldera borders, within a semi-enclosed source-to-sink system. The integrated interpretation of the Digital Terrain Model (DTM) of the Bagnoli-Coroglio area and the high resolution reflection seismic profiles acquired off the Pozzuoli Bay suggests that the present-day coastal plain of Bagnoli-Fuorigrotta and conterminous continental shelf represent the latest infilling phase of the annular depression (caldera 'collar') between the structural border of the NYT caldera and the inner caldera resurgent dome. The stratigraphic architecture and morpho-bathymetry of the Bagnoli inner shelf provide a record of the complex interplay between eustatic sea level changes, volcano-tectonic (ground/seafloor) deformation, and supply of volcaniclastic sediments, with associated coastline shifts over the last millennia. [ABSTRACT FROM AUTHOR]