Paleoclimatic Change During Late Stadial Of The Last Glaciation Based On Loess From Xining Basin

During the late stadial of the Last Glaciation in late Pleistocene, several loess sections with paleosol have been found in the northeastern fringe of Qinghai-Tibet plateau. The loess and paleosol emerged alternately in these sections, which revealed the environmental and/or climatic changes. Research has indicated that the paleoclimate in late stadial of the Last Glaciation is unstable.Xining Basin of Qinghai province is situated in the alternated zone of east monsoon area, north-west arid area and Qinghai-Tibet plateau. There deposited a lot of deep loess in this basin. The section in Xining Basin is studied in this paper.Field investigation and analysis of grain size, total ferric oxide (TFe),total organic carbon (TOC) and high-temperature loss on ignition (HLI) in the studied section detailed the characteristics of paleoclimatic change during late stadial of the Last Glaciation. The thesis draws the following conclusion:Two weakly soil-forming layers contained in the strata of late stadial of the Last Glaciation. They reflected climatic events in one stadial period,2 interglacial intervals and 3 glacial stages recorded in the loess.Before 26 kaB.P., paleoclimate was cold and dry in Xining Basin. Winter monsoon was stronger and summer monsoon was weaker. It was a glacial stage in late stadial of the Last Glaciation.During 26 kaB.P.～22 kaB.P., paleoclimate was relatively warm and humid. It was an iterglacial interval and the climate was mild in the late stadial of the Last Glaciation.During 22 kaB.P.～16 kaB.P., it was another glacial stage in late stadial of the Last Glaciation and paleoclimate was cold and dry.After 16 kaB.P., there was an alternation of glacial stage and interglacial interval.