关键词: 微量元素, 化学风化, 晚更新世, 东亚季风, 巴丹吉林沙漠

Abstract: This paper deals with the variations of the chemical weathering and climatic change in Badain Jaran desert area that induced by the repeated advances and retreats of the East Asian monsoon since Late Pleistocene period. The Chagelebulu section, which located at the southeastern fringe of the Badain Jaran desert, is composed of seven sedimentary facies, i.e., three types of aeolian sands, loess, paleosol, lacustrine and peb-sends layers. The total mass fraction of 15 trace elements increased in the direction from aeolian sands to lacustrine layers, and to loess, and then to paleosol. The total mass fraction of most of those trace elements changed inversely in the section with the middle size and the silica-alumna ratio of the sediments. According to the variations in time of the trace elements in the Chagelebulu section it can be seen that the humidity in this area had been fluctuating from dry environment to relative humid one. A comparison of the chemical weathering degree was made between the Late Pleistocene stratum in the Chagelebulu section with the Malan loess stratum of the Loess Plateau in Luochuan section. The chemical weathering degree is relatively lower in Chagelebulu section than that in Malan loess of Luochuan section, Loess Plateau. The variations of the humidity in Badain Jaran desert area were depended upon the rise and fall of East Asian summer monsoon in the Late Pleistocene period, when the precipitation brought by the west wind could not arrived Badain Jaran desert area.

Key words: trace elements, chemical weathering, Late Pleistocene period, East Asian monsoon, Badain Jaran Desert