Radiocarbon dating of the end of the latest Caspian Sea overflow through the Manych Depression (southeastern European Plain)

Abstract The Manych Depression is a relatively narrow elongated depression of tectonic origin, connecting the Caspian and Azov-Black Sea basins. The Caspian Sea repeatedly discharged its waters through this depression into the Black Sea and further into the Mediterranean Sea during the Quaternary period. The last discharge occurred in MIS 2 when the Khvalynian transgression waters exceeded the drainage divide between those two basins. The geochronology of the last flow of Caspian waters into the Black Sea was established recently based on 14 C dating of Khvalynian shells, carried out mainly by liquid scintillation counting, and the end of this event was dated to 12.5–12.8 ka cal BP. Recently obtained OSL dates for one of the most complete sections of the Khvalynian deposits of the Manych Depression indicate an older time for the end of the flow. This study aimed to clarify the timing of the Khvalynian transgression discharge by examining two sections containing the Khvalynian mollusk fauna in layers that, according to their stratigraphic and geomorphological position, belong to the final phase of the flow of the Caspian waters. Four 14 C AMS dates were obtained from single shells of Didacna ebersini and Hypanis plicata , which agree with the OSL dating results. The results indicate that the last overflow of Caspian waters through the Manych Depression had ceased at around 14.5 ka cal BP.