Coastal paleogeography of the western periphery of Campi Flegrei volcanic area during the Late-Republican age

Abstract

<p>Campi Flegrei, located within the Gulf of Pozzuoli (SW Italy), is one of the most active volcanic districts of the Mediterranean basin and is characterized by sudden vertical ground movements that have locally exacerbated the glacial-hydro-isostatic sea-level rise since the late Pleistocene.<br>In this research, a geoarchaeological study of the coastal sector between Torregaveta Promontory and the western margin of Miseno Cape, located in the peripherical area of Campi Flegrei caldera, was carried out through a multi-technique approach.<br>Along this coastal sector, several archaeological remains, witnessing the past Roman occupation, were deeply studied to investigate the ancient sea levels. In particular, at the foot of Torregaveta Promontory, the ruins of an ancient Roman maritime villa, belonged to the Roman consul Publio Servilio Vatia Isaurico and dated back to the second half of the first century BC, are still visible. Among these, the fish tank and the nymphaeum were surveyed by specialized scuba divers in order to interpret them as archaeological sea-level markers. The submersion of the lowest level of crepido was measured at -2.94 m MSL and interpreted as sea-level index point (SLIP) and, on the other hand, the tuffaceous platform found at the base of the apsidal area of the nymphaeum (located at -1.35 m MSL) of the villa was interpreted as a Terrestrial Limiting Point (TLP). Indirect investigations were also carried out by using a prototype of a marine drone (ARGO engineered in the Parthenope University laboratories) equipped with acoustic and optical sensors in order to obtain a multi-scale high-resolution mapping of both the underwater landscape and archaeological structures. This data was crucial to interpret the main coastal changes mainly related to Late-Holocene relative sea-level changes.<br>Along the NW side of Miseno Cape, a direct survey was carried out in the surrounding area of Dragonara cave, where the remains of several fish tanks are located. The submersion of the lowest level of crepido of the best-preserved fish tank was measured at -2.8 m MSL.<br>The RSL at -3.2 ±0.29 m MSL archaeologically dated at I century BC was compared with the glacial- and hydro-isostatic adjustment (GIA) models available for the study area, assessing a subsidence of about 2 meters and probable volcano-tectonic origin occurred in the last 2100 years.<br>Finally, all the data were crossed with bibliographic studies on low coast sectors in order to reconstruct the paleo-geographic scenario of this complex coastal sector during the Roman Age. The consolidation of the dune cordon at Fusaro (ancient <em>Acherusia</em>) that allowed the construction of a coastal road during the I century BC (in accordance with historical sources) coupled with the building of the studied <em>otium villas</em> led to suppose a period of RSL stability or slow rate in sea-level rise. After that moment, the subsiding trend induced a progressive coastal retreat of the high coast sectors (Monte di Procida and Miseno Cape). While the sandy areas underwent a progradation of a maximum of ~250 meters thanks to the sedimentary inputs coming from the nearby Volturno river.</p>