Correlation of Upper Pleistocene sediments in northern West Siberia

Abstract

A geochronometric database, comprising 121 optically stimulated luminescence and 59 radiocarbon dates plus U/Th date on peat from 24 key sections in northern West Siberia is presented and discussed. These data have been obtained during Russian–Norwegian joint research for the past 15 years and are augmented by reports on radiocarbon dated mammoth carcasses in West Siberia. Together they provide the basis for revising the regional stratigraphic scheme and for correlation to the European Quaternary chronostratigraphy and marine oxygen isotope record. The geochronologic correlation of sedimentary formations across West Siberia involves classical stratotypes of fluvial, shallow limnic and temperate marine sediments of the Karginsky Horizon, ca 130 ka, which was previously attributed to MIS 3. The older Kazantsevo marine formation is thus assigned a Middle Pleistocene age. The uppermost glacial sedimentary complex containing glacial ice was deposited by shelf-based ice sheets between ca 100 and 60 ka BP. The postglacial Pleistocene sediments are mostly ice-bound loess-like deposits and sink-hole silts containing numerous mammoth carcasses that are radiocarbon dated to between ca 42 and 25 ka BP. There are no traces of glacial activity on the Siberian plains during MIS 2, a period for which palaeoclimatic proxies suggest a cold and dry environment. This synthesis indicates that the prior usage of the Siberian correlation horizons of Kazantsevo and Karginsky as equivalents of the Eemian and Middle Pleniglacial is stratigraphically invalid.