Late-Holocene to recent evolution of Lake Patria, South Italy: An example of a coastal lagoon within a Mediterranean delta system

摘要

Lake Patria is a mesoaline coastal lagoon that develops along the coastal zone of the Volturno River plain (Campania, South Italy). The lagoon is a saline to brackish water body, ca. 2.0 long, and 1.5 km wide, with an average water depth of 1.5 m, reaching a maximum of ca. 3.0 m. The freshwater input into the lagoon is provided by a series of fresh to brackish water channels and small springs, landwards, while a permanent connection with the Tyrrhenian Sea is provided by a channel, 1.5 km long and a few meters wide. Drilling data from 12 boreholes acquired in the study area indicate that Lake Patria is a man-modified remnant of a larger lagoonal area that developed during the last millennia along the Campania coastal zone within an alluvial delta system at the mouth of the paleo-Volturno River. Sedimentological and stratigraphic analyses of drill cores suggest that the lower Volturno delta plain developed in the last 6000 years. Depositional conditions during this period were dominated by flood-plain and alluvial plain settings, with transition to coastal bars and associated back-barrier coastal lagoons. Lake Patria started evolving at an early stage of the Volturno delta plain formation as a consequence of foreshore deposits damming-up by littoral drift The first marine layers display a radiocarbon age of ca. 4.8 ka BP and overlie a substrate represented by volcaniclastic deposits, originated by the Campi Flegrei, and associated paleosols. The lagoonal succession cored at Lake Patria may be interpreted as the result of a dynamic equilibrium between marine influence and riverine input into the lagoonal system through time, and has been tentatively correlated with the major climatic changes that occurred during Mid-Late Holocene. Insights into the recentmost evolution of the coastal lagoon of Lake Patria are provided by the GIS-based analysis of the physiographic changes of the region conducted on a series of historical topographic maps dating back to the early ⅩⅦ century. Particularly, the superposition of historical cartography reveals the secular trends in the change of coastal environments and the role of human modification of natural habitats over the last 400 years.