Short-term soil formation events in last glacial east European loess, evidence from multi-method luminescence dating

The pIR-IRSL290 dating of the loams immediately underneath Pryluky unit in the range of ∼120 ka to ∼168 ka and of the Pryluky mollisol from ∼90 ka to 126 ka confirm the broad correspondence of this unit with MIS 5, although poor dose recovery results open the possibility for further testing on the degree these ages provide overestimated results. Quartz data severely underestimate the pIR-IRSL290 ages for these samples. The application of pIR-IRSL290 dating for the underlying Dnieper till previously linked to the Saalian glaciation resulted in natural signals at the level of laboratory saturation, yielding minimum ages of c. 700 ka. For the same sample, the natural SAR-OSL signals for 4-11 μm quartz were found significantly below laboratory saturation level, resulting in finite ages of ∼250-270 ka interpreted here as underestimates, while coarse quartz (63-90 μm) signals reached about 85% of the laboratory saturation level. These data suggest extreme caution must be taken when dating such old samples using quartz OSL. Results from our high-resolution luminescence dating raises important implications for the chronological representativeness of Stayky as a key loess site in Eastern Europe beyond MIS 2.