Matuyama–Brunhes boundary in key sections of the loess–paleosol–glacial formations on the East European Plain

Multidisciplinary studies of two key sections (parastratotypes) of the loess–soil–glacial formation (Strelitsa and Sebryakovo-Mikhailovka sections) located in the central part of the East European Plain placed the Matuyama–Brunhes reversal well below the Lower Pleistocene till. The till attributed to the Don glaciation (maximum glaciation on the East European Plain) is separated from the M/B reversal by several units, as follows: (1) a horizon of humified loam of still uncertain stratigraphic position; (2) a loess horizon, and (3) a paleosol complex (Rzhaksa). The polarity reversal is within a “transitional zone” which includes the base of the lower (Bobrov) loess and the upper portion of the underlying soil complex (Balashov). The primary constituent of remanent magnetization has been identified using two methods—demagnetization by heating and by alternating magnetic field; such a technique ensures a high degree of reliability.