Testing feldspar and quartz luminescence dating of sandy loess sediments from the Doroshivtsy site (Ukraine) against radiocarbon dating

Post-infrared infrared stimulated luminescence (pIRIR) dating has reactivated the use of feldspar minerals to date Pleistocene deposits. We compared pIRIR stimulation measured at 290 °C (pIRIR290) of coarse grain feldspar (100-200 μm) and optically stimulated luminescence (OSL) of coarse grain quartz (100-150 μm) with radiocarbon dating. The samples were taken from the lower part of the Doroshivtsy sandy loess sequence, which contains Gravettian artefact layers. The site is one of the very few sections in Europe that provides a high-resolution sedimentary record including prehistoric finds of the last glacial cycle's cooling maximum. Field observation indicated that the deposits in the lower part of the loess section were redeposited. We applied early background subtraction for equivalent dose estimation of the quartz samples. The comparison of late background and early background subtraction revealed late background subtraction to be less suitable for estimating the net OSL signal of the quartz samples. Although the pIRIR290 signal resets slowly, we chose this stimulation for feldspar dating because the pIRIR290 signal is the most stable infrared simulated luminescence (IRSL) signal. The section was convenient for testing two different luminescence techniques because a potential influence of partial bleaching can be uncovered by independent age control. The OSL signal of quartz and the pIRIR290 signal of potassium feldspar bleach at different rates, but this had little influence because the coincident dating results confirmed complete resetting of both luminescence signals prior to deposition. Moreover, the quartz, feldspar and radiocarbon ages were within the time range of the Gravettian period in Ukraine (22-28 ka).