Late Holocene geomorphic evolution of the Livadi coastal plain, Gulf of Argostoli, Cephalonia Island, western Greece

Abstract

This study deals with the late Holocene evolution of the coastal swampy Livadi plain, which is located on the northern part of the Gulf of Argostoli (Cephalonia Island). Cephalonia Island is located at the north-west edge of the Hellenic Arc in a tectonically and seismically highly active area. For the purposes of the study, a detailed DEM, produced by topographic sheets (at the scale of 1:5000), was utilized for geomorphological mapping together with extensive fieldwork. In addition, four shallow boreholes, varying in depth from 3 to 5 m, were drilled using a portable vibratory corer. The stratigraphy has been described in detail and four samples (peat – plant material, foraminifera assemblages and shell material) were collected for radiocarbon dating. Additionally, sedimentological and micro/macrofaunal identifications of forty-five sediment samples from the various stratigraphic units were performed to reconstruct the palaeoenvironments of deposition. The results suggest that cores L1 and L2, which are located close to the present day shoreline, are marine/coastal dominated while cores L3 and L4 have a shallowing-upward sedimentary sequence since the lower units correspond to a marine environment of shore-face conditions, which progressively becomes a backshore brackish environment that gradually changes upwards to a terrestrial environment. The dated sea-level indicators (samples of peats, foraminifera and shells) from 5000-4000 BP are too high compared to local relative sea-level curves, indicating local coseismic uplift(s) of around 1 m before 1200 BP and after 4800 BP. This uplift idea is supported by recent (ca. 0.2 m) uplift observed clearly along the beach face at Livadi caused by the recent Cephalonia earthquake in 2014.