LOESS CHRONOLOGY OF THE MIDDLE AND UPPER PLEISTOCENE IN TAJIKISTAN

The loess/paleosol sequences of Central Asia are continuous terrestria l records of the Quaternary period and enable detailed comparison with paleoclimatic archives such as marine and ice core records in order t o reconstruct regional and global paleoclimatic and paleoecological de velopment during the past 130 000 years. Thermoluminescence (TL) and i nfrared stimulated luminescence (IRSL) dating methods are applied to t he extensively studied loess/paleosol sequence of the section at Darai Kalon/Chashmanigar, Tadjikistan, in order to determine a more accurat e chronological framework and climatostratigraphic reconstruction for the last interglacial/glacial cycle. Luminescence dating suggests that the loess above the first pedocomplex from the top, PC1, accumulated during the last glacial period. A high accumulation rate of up to 1.20 m per 1000 years was determined for the last glacial loess, especiall y for the uppermost 5-8 m. PC1 formed during the last interglacial per iod (oxygen-isotope stage 5). The loess between PC1 and PC2 is designa ted to be of penultimate glacial deposition age. Infrared stimulated l uminescence and TL age estimates are in agreement to 80 000 years befo re present (BP), indicating a long-distance transport of the aeolian d ust prior to deposition. The upper numerical age-limit range is betwee n 300 000 and 450 000 years. However, reliable dating of the loess old er than 130 000 years is not possible due to age scatter between sampl es and an inadequate increase of paleodose with depth. This high-resol ution dating study underlines the importance of the section at Darai K alon and indicates that it is one of the most continuous loess/paleoso l records of the Northern Hemisphere. The chronological results are pa rticularly important for the reconstruction of the human evolution in Central Asia, suggesting much older age estimates than previously obta ined for most of the archeological key sites associated with PC5 and P C4 in Tadjikistan.