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

Resumen

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 (Würmian) 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 Bt1 horizon. They
also penetrate into lower Bt2 and Bt3 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.