Climate change since the late Middle Pleistocene indicated by geochemical characteristics of major elements of Jing'erwa section in Yangyuan Basin, Hebei Province
Filled up by a succession of Quaternary fluvial and lacustrine sediments, and containing a large number of remains of ancient human beings, Yangyuan Basin is one of the ideal regions to study the living environmental background of ancient human beings. Based on the contents and their ratios of major element oxides, geochemistry elements characteristics of Jing'erwa section as well as the climate change process of Yangyuan Basin since 220 ka were studied. The results showed that: (1) The sediment of Jing'erwa section was mainly composed of SiO_2, Al_2O_3 and CaO, with the contents of 27.85% ~ 53.23%, 3.38% ?12.97% and 5.43% ?28.36% respectively. Contents of Fe_2O_3 and MgO, with the range of 2.65% ?7.67% and 1.93% ~ 14.42% respectively, are also considerable. Those reflected the environmental change from semi-humid to semi-arid.(2) The climate in this area since the late Middle Pleistocene varied from warm-wet, slightly warm-slightly wet, warm-slightly wet, cold-slightly wet to warm-dry. Features of hydrothermal combination and evident secondary climatic fluctuations of each period reflected the complexity of environmental evolution.(3) Comparison with the oxygen isotope phases of deep sea shows that the changing process of climate for the Yangyuan Basin not only responds to the trend of the global climate change but also bears obvious regional features.