Morphological and palaeoenvironmental evolution of the Lagoon of Papas, southwestern Greece, during the Holocene (*)

Geomorphological, stratigraphic and palaeoecological surveys have been carried out along the coastland of the Lagoon of Papas (Kalogria) since 1994, with the aim of depicting its morphodynamic and palaeoenvironmental evolution during the Holocene, until the present. The coast was previously affected by tectonic activity which exerted a morphologic control, interacting with the Quaternary sea-level changes. These processes resulted in subsidence during the MIS 7, followed by the MIS 5 transgression with marine and lagoon sediment deposition. The subsequent regression caused the deposition of alluvial covers and fans, later dislocated by the differential uplift which formed a terrace and a coastal plain at its base, tilted towards the northwest. This plain was dissected and uplifted by recent tectonics which has developed a new terrace, separated from the former by a post-Tyrrhenian fault scarp. Particularly, during the Holocene the coastal plain was characterized by the deposition of alluvial sediments eroded from the southwestern hills, increase of fluvial meanders, westward deviation of watercourses, development of ponds, swamps and finally of a lagoon. Multidisciplinary studies, including examination of historical cartography, bathymetric map, microfossil analysis and geomorphological surveys, have shed light on the gradual genesis of the lagoon. The lagoon developed during the Holocene in a pre-existing wide bay, starting from a sequence of a few littoral spits elongated from southeast to northwest. Palaeoecological analysis confirmed the alternation of brackish to marine environments, through the recognition of different groups of microfossil assemblages. Morphological and sedimentological study of the lagoon bottom showed some hummocks and facies related to buried relict spit and overwash structures. This morphodynamic evolution is analogous to that described for some Tyrrhenian and Adriatic lagoons from Italy, as well as for other Mediterranean lagoons.