The loess record from the section at Kurtak in Middle Siberia

Abstract

Loess, loess-like sediments and the intercalated palaeosols along the bluffs of the river Yenisei provide a detailed Upper Pleistocene climate archive for the southern part of Middle Siberia. The section at Kurtak is one of the most detailed loess/palaeosol sequences in Middle Siberia. Two major periods of sediment accumulation were recorded in the sequence: the stratigraphically oldest one post-dating the last interglacial palaeosol and pre-dating the Kurtak Pedocomplex (oxygen isotope stage (OIS) 3); the younger one post-dating the Kurtak Pedocomplex and predating the Holocene soil. Three major phases of soil formation occurred during the Upper Pleistocene. The Kameny Log Pedocomplex (OIS 5e) consists of at least two pedogenetic episodes, a lower clayey chernozem forming during a more humid and warmer climate than today, and an upper chernozem representing a drier climate than today, the latter one including a well-pronounced carbonate-rich horizon. The Sukhoy Log Pedocomplex consists of a chernozem-like palaeosol and two kastanozjems (OIS 5c-a) and the Kurtak pedocomplex (OIS 3) with two chernozem-like palaeosols and up to three humic-rich layers. Additionally, weakly developed gleyed horizons are considered to represent palaeohydrological groundwater high levels. The results indicate a synchronous evolution of climate and environment change in both the more oceanic driven climate of West and Central Europe and Middle Siberia, as evidenced by luminescence dating results.