Loess chronology of the Caspian Lowland in Northern Iran

The loess/palaeosol sequences of the Caspian Lowland in Northern Iran provide detailed archives of climate and environmental change showing a close relationship to global cooling and warming trends for the Quaternary period. The magnitude of these changes is under discussion owing to uncertainties in the chronologies for individual sites. A chronological frame was set up for the last glacial loess record for three Upper Pleistocene key sections by infrared optically stimulated luminescence (IRSL). In the Caspian Lowland, IRSL dating gives reliable ages for sediments covering at least the past 60 ka. However, for sediments older than 60 ka, a significant age underestimation is likely. The first strongly developed buried Bt/Bwt horizons or pedocomplexes at the three sections under study correlate most likely with the last interglacial (MIS 5). At least four periods of increased sediment accumulation were determined for the last glacial period intercalated by periods of weak soil formation. The loess/palaeosol sequences in Northern Iran recorded coeval and similar major climatic changes as in South-Eastern Central Europe and Central Asia.