Conventional IRSL dating of Romanian loess using single aliquots of polymineral fine grains

Investigations of the luminescence characteristics of polymineral fine grains extracted from the loess-palaeosol sequence near Mircea Vodă (SE Romania) were performed using IR stimulation at 50 °C in a single-aliquot regenerative-dose (SAR) protocol. Initial sensitivity changes were observed to influence the ability to measure a given dose. They are shown to depend on preheat temperature, bleaching procedure and size of the given dose. An apparent influence of the preheat temperature on equivalent dose and fading corrected ages is documented through thermal stability experiments. These suggest that, in the absence of a sufficiently high preheat treatment, thermally unstable components contribute to the IRSL signal leading to significant age underestimation. When a high preheat temperature is used (250 °C for 60 s), the age results are in good agreement with previously obtained quartz-OSL ages for material deposited during the last glacial period. However, this agreement may be caused by initial sensitivity changes and limitations of the fading correction.

► SAR-IRSL investigations of polymineral fine grains.
► Dose recovery dependence on preheat temperature, given dose and bleaching procedure.
► Thermally unstable contributions in the absence of high preheats.
► Fading corrected ages obtained using a 250 °C preheat agree with quartz-OSL ages.
► Agreement is questionable due to poor dose recovery & fading correction limitations.