A luminescence dating study of the upper part of the loess-palaeosol sequence at kuldara, Khovaling Loess Plateau, Tajikistan

Abstract

The aim of this study was to develop an independent luminescence chronology for the upper part of the important Loess Palaeolithic site at Kuldara (Khovaling Loess Plateau, Tajikistan). We applied high sampling-depth resolution (n = 85) luminescence dating to the upper ∼26 m of the sequence from loess L4 to pedocomplex PC0. Luminescence characteristics of the post-IR₂₀₀ IRSL₂₉₀ signal from coarse-silt polymineral grains are satisfactory (reproducible growth and good dose recovery). Comparison with quartz OSL for samples <50 ka and results from modern analogues (Challier et al. these proceedings) shows that the pIRIR_200,290 signal is, as expected, sufficiently bleached at deposition. The luminescence chronology extends back to ∼250 ka and shows distinct erosional hiatuses ranging in duration from ∼15 ka to a full glacial-interglacial cycle (∼100 ka); some of these breaks were not identifiable in the field. We suggest an upper dating limit of 2.5xD_c; this yields minimum ages of ∼300 ka for this material. Dust Accumulation Rates (DAR) are reconstructed for the Late Pleistocene (from ∼100 to ∼40 ka) and reveal, next to several minor dust accumulation peaks, two major peaks at the end of MIS5 (∼75 ka) and at MIS3b (∼40 ka). We conclude that detailed post-IR₂₀₀ IRSL₂₉₀ dating of loess-palaeosol sequences in Tajikistan is necessary to exploit fully the potential of this important terrestrial (dust) record.