Ice-free interval corresponding to Marine Isotope Stages 4 and 3 at the Last Glacial Maximum position at Kileshino, Valdaj Upland, Russia

Abstract

Radiocarbon and optically stimulated luminescence dates, together with bio- and lithostratigraphical data, revealed an interval of ice-free conditions between 72.2 OSL and 33.8 cal 14C ka BP at the Kileshino site (Valdaj Upland, Russia), corresponding to Marine Isotope Stages (MIS) 4 and 3. Limnic sedimentation conditions occurred at the Kileshino site between 57.5 OSL and 33.8 cal 14C ka BP, corresponding to MIS 3 ‘megainterstadial’ in European Russia (Oerel to Hengelo interstadials in Central Europe). During the last glaciation, a sedimentary unit of laminated silt and sand of fluvial origin was redeposited at that site due to expansion of the Scandinavian Ice Sheet (SIS). This unit expresses fluvial sedimentation conditions NW of Kileshino between 72.2 and 40.8 OSL ka. All dates together suggest that the Kileshino site was ice-free between 72.2 OSL and 33.8 cal 14C ka BP. The sedimentary unit of laminated silt and sand was redeposited at the Kileshino site during the last SIS not before 33.8 cal 14C ka BP, according to previous studies, possibly at its maximum extent between 19.1 cal 14C BP and 18 OSL ka. Only one till, younger than 72.2 ka, was found from the Kileshino outcrop. It can be concluded that the SIS reached this area only once during the last 72.2 ka – in the late Valdaj (Weichselian), after 33.8 cal 14C ka BP. The expansion of the SIS to the study area between 115 and 58 ka could be neither proved nor disproved as there is no chronological information about the time between 115 and 72.2 ka.

Keywords

• Scandinavian Ice Sheet
• Last Glacial Maximum
• Marine Isotope Stage
• MIS
• late Valdaj
• Weichselian.