Paleoclimate Changes Recorded In The Loess Profile From Xishan Mountain Of Beijing Since The Last Glaciation

Since the last glaciation,the frequent climatic fluctuations have initiated great impacts on the surface ecoenvironment.A lot of aeolian and secondary loess profiles thus developed in western mountain of Beijing due to the East Asian monsoon,providing a good material basis for the study of climate change in this region.This article selected the Hedong loess profile in western mountain of Beijing as the research object,in combination with the chronology data,particle size,magnetic susceptibility,and chroma analyses to reconstruct the paleoclimatic evolution since the last glaciation.The regional comparison analyses with the previous studies were also implemented to preliminarily discuss the possible causes of climate change.Several conclusions can be summarized.(1)Analysis of the study profile indicated that the lithology of sediments has changed from clayey silt to silty clay,and then to silt since the last glaciation,showing a coarser-finer-coarser characteristics and indicating the obvious variations since the last glaciation.(2)Analyses of multiple climate proxies illustrated that climate of study area has changed from cold-dry to warm-humid to more colder and drier process since the last glaciation,suggesting the obvious fluctuation since MIS 4 stage.(3)The regional comparative analyses demonstrated that the climate change in the study area since the last glaciation was very similar to that of global background,but some differences still existed.The climate of the study area entered the last glaciation much earlier and lasted longer when compared with the southern Beijing.We speculated that these differences should be attributed to the local topography,altitude and more inland location of the study area.