Stratigraphy and paleogeography of the Sartan glaciation in West Siberia

The Paleogeography of the last glaciation in West Siberia is outlined on the basis of detailed chronostratigraphy. Evidence indicates an ice sheet with a centre on the Kara Sea shelf, the existence of ice-dammed lakes that drained through Turgai Pass to the Aral Sea and onward to the Caspian and Black seas, and traces of Lateglacial transgression. Discussion involves problems connected with the hypothesis of 'retarded deglaciation' (Astakhov, 1992) which disputes the existence of a Sartan ice sheet, ice-dammed basins, and traces of Lateglacial transgression. The terraced plains of silt and clay, previously considered to have been deposited in proglacial lakes, are re-interpreted to have formed by loess deposition modified by thermokarsting. Topography which resembled glaciated terrain appears to have developed during the Holocene through glaciokarsting, rather than by glaciation. It is suggested that the new model of Sartan glaciation renders unjustifiable contentions of its universal significance. (C) 1997 INQUA/Elsevier Science Ltd.