ИСТИНА

The Manych Depression is a narrow and elongated depression connecting the Caspian and Azov-Black Sea basins. During the Quaternary period, the Caspian Sea repeatedly discharged its waters through this depression into the Black Sea and the Mediterranean Sea. The most recent discharge happened at the end of MIS 2 when the Khvalynian transgression waters surpassed the watershed's height between those two basins. Dating of the Khvalynian deposits is challenging. They are represented in the Manych Depression in fragments and described mainly in coastal outcrops as thin loams, sandy loams, and sands. They rarely include the characteristic Khvalynian mollusc fauna, which complicates their identification. The geochronology of the last flow of Caspian waters into the Black Sea was established based on the 14C dating of Khvalynian shells, mainly carried out through liquid scintillation counting. This event's end was dated to 12.5–12.8 ka years before present (BP). Until now, the section of Levy Island (the central part of the Manych Depression) was considered the most complete section of deposits of the Khvalynian discharge. However, during fieldwork in 2022, in the area of the Ponto-Caspian watershed, an outcrop was discovered in the valley of the East Manych River (Zunda Tolga section) with a relatively thick layer of fluvial sands, including shells of molluscs of the Khvalynian species (Monodacna caspia and Hypanis plicata). Using the shells of these molluscs, we obtained AMS dating in the range 14–15 ka years ago, which showed good agreement with OSL dating of deposits of the Levy Island section, obtained earlier in the laboratory of the Technical University of Denmark. Here, we demonstrate the first results of OSL dating of the Zunda Tolga section, which was carried out at the OSL laboratory of the University of the Witwatersrand (Johannesburg, South Africa). We have compared the results of OSL dating with those of AMS dating to evaluate the efficacy of the OSL method in dating different facies of Khvalynian deposits.