The Geochemistry and Paleoclimate Significance of Magnesium arid.Aluminum in Loess of Late Quaternary in Northwestern China

Presented in this paper are the changing characteristics and its paleoclimatic and environmental.aignificanoe of magnessium and aluminium content ration (m value) of loessic sections of Quaternary in arid and relatively arid regions of China. The changes of the m values in loess一paleosol show the changes of the paleoclimatic aridity and wet.during loess deposition and paleosol development. During loess deposition. the m valurea are higher. the variation curves of the m values appear the peaks showing the arid climate and environ- ment. During paleosol development .the m values are lower. the variation curves of the m valures appear valley showing the relative wet climate and environment. The result of study of magneatum and aluminium content rations of loess sections in arid and relatively aric rgeions of China shows alternatives of four times of arid and wet climate since late Pleistocene at least.