Multiproxy approach to urban geology of the historical center of Naples, Italy

The complex urban geology of the historic center of Naples is characterized by the emplacement of products from two adjoining volcanic areas that were reworked by alluvial and coastal processes. To expand the geologic knowledge of this densely populated area, multidisciplinary research was carried out on the recently drilled San Marcellino borehole, as part of a larger borehole collection project. Critical revision of 290 previously drilled sequences, and a complete set of tephrostratigraphic, sedimentologic, and paleoecologic data obtained on the San Marcellino stratigraphy, informed a hydrogeological conceptual model of water circulation and paleoenvironmental reconstruction of the city historic center. Both before and after the Neapolitan Yellow Tuff eruption, ca. 15 ka, the landscape was characterized by a marine to transitional paleoenvironment. This signifies a good balance between sea-level rise and volcaniclastic inputs, consisting of both primary and remobilized deposits in an area that is also subject to bradyseismic oscillations. Amongst the primary pyroclastic deposits, the products of an explosive event from Campi Flegrei about 16 ka, with an eastward-directed sustained-column phase, were recognized. Collectively, the multidisciplinary data obtained in this study favor the presence of a double-aquifer conceptual model, characterized by a volcanic and a marine-sedimentary aquifer.