Paleopedogenesis during the Mikulino interglacial (MIS 5е) in the East-European plain: buried toposequence of the key-section 'Alexandrov quarry'

The Alexandrovsky quarry exposure (near Kursk, central European Russia) represents one of the most complete and detailed records of paleosols, colluvial sediments and loess for the last glacial-interglacial cycle in Eastern Europe. The buried toposequence of Mikulino (Eemian) paleosols, developed on a gully slope cut in the Dnepr (Riss) loess and overlain by Early Valdai (Wurmian) colluvium, was subjected to detailed morphological study. The paleosol on the upper slope is an Albeluvisol that contrasts from the Holocene Chernozem. Analysis of thin sections of the Albeluvisol demonstrated that elluvial features – concentrations of bleached silt in the pores and in the groundmass – dominate not only in E and EB but also in the Bt 1 horizon. They also penetrate into lower Bt 2 and Bt 3 horizons where they combine with illuvial clay pedofeatures. The paleosol profile at the bottom of the gully shows synsedimentary development with several A, AE and E horizons reflecting several phases of geomorphic activity as a response to a complex environmental history during the last interglacial. The shift from dark humus accumulation under grasslands towards forest pedogenesis dominated by clay illuviation and stagnic processes comprised the major trend of the Mikulino (Eemian) soil evolution.