Detailing the Stratigraphic Scheme of the Upper Neopleistocene of the Central East European Plain and Correlation with Other Loess Regions of Eastern Europe. Presentation of the Aleksandrov Quarry Section as a Stratotype

Abstract

Abstract This paper proposes a substantial refinement of the regional stratigraphic scheme of Upper Neopleistocene loess deposits in the central East European Plain. The Aleksandrov quarry is considered as the main stratotype section of the late Neopleistocene. A variety of modern paleogeographic methods, including paleosol, biostratigraphic, radiocarbon (14C) and optically stimulated luminescence (OSL) dating, were used in this study. During the Mikulino Interglacial, the Ryshkovo paleosol MIS 5e (marine isotope stage) or Ryshkovo pedolithic complex formed under accumulative mesorelief conditions. During the first Early Valdai cooling, permafrost episodes appeared in the Seim loess (MIS 5d), the eponymous cryogenic horizon (CH). The Valdai Early Glacial (MIS 5c-5a) is recorded not by one, as previously believed, but by two interstadial paleosols in the Chermeninsk horizon: Kukuevo (MIS 5c) and Streletsk (MIS 5a), separated by the Mlodat loess and CH (MIS 5b). At the beginning of the Valdai Pleniglacial, a significant increase in cryogenesis was noted, which was accompanied by the formation of the Selikhovodvor CH (MIS 4). In the Middle Pleniglacial (MIS 3), not one but two paleosols formed and were better preserved in the Leningrad horizon: Aleksandrov and Bryansk. Under accumulative conditions, the structure of the deposits becomes more complex, with the addition of the Gidrouzel and Monastyrshchino paleosols, which reflect more fractional climatic rhythms. In the Late Pleniglacial (Ostashkov horizon, MIS 2), several paleosols were identified that do not yet have a stratigraphic significance, with the exception of the Divnogorsk pedolithic complex, which records repeated pulses of pre-Holocene warming. The proposed scheme has been shown to be more detailed than Velichko’s scheme. The structures of the Upper Neopleistocene deposits in glacial and non-glacial regions of the central East European Plain have been correlated. Similarities in the structures of loess-soil sections from the first half of the late Neopleistocene in the Central Russian Upland, the Azov region, the Lower Volga region, and the Ciscaucasus have been demonstrated. Correlating the structures of the sections of the Central Russian Upland, the Donetsk Ridge, and the Volyn Upland demonstrated interregional similarities in the reflection of climatic signals by paleosols. This confirms the global (astronomical) causes of the major climatic rhythms in the Neopleistocene.