PAST GLOBAL CLIMATE CHANGE: A HIGH RESOLUTION EVIDENCE FROM SW SIBERIA

Abstract

The southern Siberian loess, being a continuation of the Eurasian loess-belt, has provided one of the most complete terrestrial proxy records on the global past climate development. New high-resolution loess-paleosol sections from the Priobie Loess Plateau (Iskitim) and the Altay Plains (Biysk, Bystrianka and Krasnogorskoe), SW Siberia, recently studied as a part of the 2000 km W-E Siberian paleoclimatic transect, provide new detailed information on the Late Pleistocene climate evolution and landscape development in the parkland-steppe zone of southern Siberia. The complete stratigraphic records documented by magnetic susceptibility, grain-size, % CaCO3 and % organic carbon as proxy climatic data, and supplemented by thin-section studies, show cyclic climatic variations within the last interglacialglacial cycle. A strongly continental warm climate culminated around the peak of the last interglacial (sensu stricto OIS 5e) and cooler conditions occurred during the following interstadial stages (OIS 5c and 5a), corresponding to shifts in palaeolandscape development with gradual replacement of parklandsteppe and mixed southern taiga by boreal forest, transformed into a cold arid periglacial tundra-steppe during the stadial stages (OIS 5d and 5b). A similar trend with short warm and very cold intervals can be observed in the mid-last glacial interglacial interval (OIS 3) in accordance with the evidence from other Siberian key high-resolution loess sections from the Yenisei and Angara region, separated by the early and late last glacial loess beds (OIS 4 and 2, respectively). The pedosedimentary record, reflecting the effects of syndepositional pedogenic processes, attests to a dynamic global climate pulsation during the Late Quaternary in north-central Asia.