Palaeoceanographic evolution of the Gulf of Corinth (Greece) during Quaternary glacial-interglacial cycles

The Gulf of Corinth (GoC), derived from a geologically young active rift, offers a unique opportunity to study changes in environmental conditions during the Quaternary period in a region where long sequences are few. Due to periods of isolation during Quaternary lowstands, the water conditions were not favorable for the occurrence of conventional palaeoceanographical proxies such as planktonic foraminifera. We present here the first almost continuous record of phytoplankton proxies (dinoflagellate cysts) and freshwater palynomorphs (green algae) for the past 1.1 Myr aiming to provide a comprehensive insight into palaeoceanographic variability between glacial and interglacials cycles. Core M0078A retrieved during the IODP expedition 381 contains a rich and diverse dinoflagellate cyst assemblage, sorted into two major ecogroups, representing alternations between marine and brackish conditions. Our results allow for the first time the reconstruction of the Gulf environmental history of connection and disconnection from marine conditions from late Pleistocene to Holocene (1.1Ma – present). Dinocysts and other palynomorphs (NPPs) suggest that the GoC was repeatedly isolated and reconnected to the Mediterranean Sea during global sea-level lowstands associated with glacial intervals. These combined proxies suggest that marine water flowed into the GoC during the eustatic highstands associated with interglacial intervals. The dinocyst assemblages show a close affinity to modern assemblages from the Black, Caspian, and Marmara Seas. • Record of phytoplankton proxies and freshwater palynomorphs for past 1.1 Ma from Gulf of Corinth. • Alternation of marine-brackish dinocyst assemblages as response to eustatic sea-level. • Sea-level fluctuations during the Quaternary glacial/interglacial cycles. • Dinocyst assemblages similar to modern assemblages from Black, Caspian, and Marmara Seas. • Multiproxies offer an integrated perspective on the evolution of the basin and its surroundings.