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PALEOCLIMATIC CHANGES AND SHORT-PERIOD EVENTS OF THE LATE PLEISTOCENE IN THE RECORD OF LOESSIAL SEDIMENTS OF THE LOZHOK SECTION, SOUTH-EASTERN WEST SIBERIA

A. O. Volvakh, N. E. Volvakh, L. G. Smolyaninova

V.S.Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, Russia

Data on the detailed distribution of the Ba/Sr, Mg/Ca, Sr/Ca, Mg/Sr ratios, magnetic susceptibility, and U-ratio, which are paleoclimatic indicators, are presented. Records of geochemical proxies and magnetic susceptibility show good convergence. It is shown that the climatic conditions of the cold stadials of the last ice age (70,000–11,700 years old) gradually became drier. Within each stadial, there is also a decrease in precipitation from its beginning to completion. In the same direction, the force of the wind flow expressed by the U-ratio coefficient increased. It is established that the climate of loess accumulation periods was not consistently dry and cold: fast short-period climatic fluctuations have been revealed in each loess horizon; they are expressed in a sharp increase in the amount of precipitation with its gradual decrease. An attempt is made to compare the identified millennium-old climatic oscillations with the Dansgaard-Oeshger events recorded in the ice record of the NGRIP core climate and reflected in many deposits of the Northern Hemisphere.

Keywords: Pleistocene, loess, loess-paleosoil sequence, West Siberia, short-period climatic fluctuations, magnetic susceptibility, weathering proxies.

DOI 10.20403/2078-0575-2019-4-17-27