The stratigraphic transition and suggested boundary between the Early and Middle Pleistocene in the loess record of northern Eurasia

Abstract

Abstract This review focuses on the loess-palaeosol record across the Early-Middle Pleistocene transition to show the main structural features in key sections from the Loess Plateau of China via central Asia to Europe. Loess-palaeosol sequences in general demonstrate an impressive coherence with oxygen isotope osillations, providing a high-resolution terrestrial record for stratigraphic subdivision. Accordingly, they are considered useful for detailed climatostratigraphy and correlation. Nonetheless, there are many uncertainties in loess-palaeosol stratigraphic correlation across the Early-Middle Pleistocene transition from region to region within northern Eurasia. The interval between the top of the Jaramillo Subchron and the Matuyama-Brunhes (M-B) Chron boundary is discussed in detail because it embraces suitable horizons for placing the Early-Middle Pleistocene boundary. This interval contains a variable number of loess and palaeosol horizons in sections along the different loess provinces from east to west. A distinctive palaeosol unit just below the M-B reversal can serve as a marker horizon for establishing the Early-Middle Pleistocene boundary. In south Tajikistan, it corresponds to the pedocomplex 10 (PC10) and to palaeosol S8 in the Loess Plateau of China. The base of this soil horizon correlated with the base of Marine Isotope Stage 21 can be considered as a distinctive geological level for recognizing the Early-Middle Pleistocene boundary on the continent.