Palaeo-shorelines of the historic period, Sant’Antioco Island, south-western Sardinia (Italy)

Abstract

This article illustrates the results of the recent multidisciplinary studies carried out in the southern part of Sardinia (Western Mediterranean Sea) on the last 2.5 ka palaeo-sea level. The survey has specifically investigated some geo-archaeological sea level markers related to two submerged structures. The first represents a near port building of Punic-Roman age (2300 ± 100 BP) and is located in the Sant’Antioco Lagoon. The second structure is a road of Roman age (1030 ± 20 BP). In the near coastal area of Palmas Gulf, a bone and ceramics fragment-rich pericoastal beach rock, chronologically referable to the Imperial Roman age between Tiberius and Claudius (1940 ± 20 BP), has been studied. The results of this study fit the new predicted glacio-hydro-isostatic model of Lambeck et al., and agree with similar data from other Sardinian sites that show almost no vertical tectonic mobility during the Late Holocene. The study of a new stratigraphic section along the western coast of Sant’Antioco Island has identified the inner margin of a wave cut platform with fossils, referred to MIS 5.5 at + 7.5 m, highlighting a relative tectonic stability since the upper Pleistocene for this area. The geomorphological context of Palmas Gulf continental shelf shows a buried palaeo-riverbed referred to MIS 2, and a coastal palaeo-system related to the Holocene sea level change between −15 and −25 m. These features are typical of the conservative style of low tectonic mobility areas.