Combined IRSL and post-IR OSL dating of Romanian loess using single aliquots of polymineral fine grains

Abstract

The paper reports on continuing luminescence investigations of Romanian loess using samples collected from the loess-palaeosol sequence near Mircea Vodă (SE Romania). Previous optically stimulated luminescence (OSL) studies using different grain-sizes of quartz (4–11μm and 63–90μm) yielded discrepant chronologies for the last interglacial–glacial cycle. In this study, a double-SAR protocol is used to determine the age of polymineral fine (4–11μm) grains through their infrared stimulated luminescence (IRSL) and post-IR optically stimulated luminescence (post-IR OSL) emissions in the UV. Laboratory tests confirm the suitability of the protocol for both signals. Fading measurements indicate a significant feldspathic contribution to the post-IR OSL signal. In general, the fading-corrected IRSL and post-IR OSL age results are mutually consistent, and they agree with previously reported OSL ages for fine-grained (4–11μm) quartz. This agreement enhances the reliability of the ages obtained using luminescence signals from fine-grains, and allows more confident correlation of the weakly-developed palaeosol in the uppermost loess unit (L1) with marine isotope stage 3 (MIS3). The fading-corrected ages underestimate the depositional age of older material (units L2–L4), probably owing to limitations of the correction model.