Paleoecology and paleoceanography of the Gulf of Corinth revealed by ostracod assemblages

Abstract

The evolution of the Corinth Basin during the last 450,000 years (450 ka) has been investigated using ostracod analyses of two IODP expedition 381 sites M0078 and M0080. M0078 was drilled in the center of the Gulf of Corinth, and M0080 is from the Gulf of Alkyonides. Ostracods were abundant and well preserved in both cores and allowed the correlation of M0078 to M0080 using ostracod assemblages. The ostracods documented brackish lake to marine transitions in both cores during three glacial Terminations (Terminations I, II and V) signifying Marine Isotope Stages (MIS) 2-1, MIS 6-5, and MIS 12-11-10. Radiocarbon dates provided age constraints for the uppermost unit in both cores. For core intervals beyond the range of radiocarbon dating, ages were estimated using the midpoint of depth intervals corresponding to transitions in ostracod assemblages, from brackish Ponto-Caspian to marine-brackish and fully marine biofacies, identified in both cores. These age estimates align well with previous findings from IODP exp. 381, as well as with orbital-scale chronostratigraphic frameworks developed for the Corinth region based on biostratigraphy, tephrochronology, and geophysical data. We interpret the succession of ostracod assemblages during Terminations as evidence for rapid flooding of Corinth and Alkyonides by Mediterranean water during deglacial global sea level rise breaching the shallow (50–60 mwd) Rion and Acheloos sills.