The dynamics of the Late Pleistocene loess formation, Lozhok section, Ob loess Plateau, SW Siberia

摘要

There are unique loess-paleosol sections that fully reflect paleoclimate changes during the Late Pleistocene in southern West Siberia. This record of climate shows a good correlation with the marine oxygen isotope curve and other global climate records, and consequently the loess-paleosol sequence of West Siberia is a detailed reference scale. Lozhok is a key section for the Late Pleistocene loess-paleosol sequence of the Novosibirsk Ob' Region. Average loess accumulation rates of each studied loess layer were calculated on the basis of previous C-14 and TL dating results and on correlation of the loess-paleosol sequence of southern West Siberia with MIS and the Middle Siberia loess-paleosol sequence. The grain-size distribution data indicates intensification of environmental dynamics until the Last Glacial. Bulk chemical composition reveals the intensification of aridization from the Tulino to the Bagan loess, and that this trend was not constant. Greater accumulation loess activity during Bagan time (MIS-2) is also confirmed by loess accumulation rate calculations. Results of sand quartz grain morphoscopy show that loess layers were formed by aeolian processes in periods of deep cooling and aridization. The Late Pleistocene loess layers were formed in periglacial environments, in arid cold deserts. (C) 2014 Elsevier Ltd and INQUA. All rights reserved.