Abstract: Yili basin is located at the northwest of China where the climate is influenced by westerlies year in year out and loess is widespread. According to the dating of TL, most of the loess accumulated during the last glaciation. 48 samples of loess and paleosols collected from Yili area of China were analyzed. The major element composition were measured by a VA-320 A X-ray fluorescence spectrometer. Analytical uncertainties are less than ±2% for all major element and the loss ignition was obtained by weighting after one hour of caldination at 950℃. The result shows that the loss ignition of loess and paleosol are positively related to the concentration of CaCO 3 and the percentage of SiO 2 as well as. The relative coefficient (R 2) are 0.9548 and 0.7029 respectively. The paleosol can be distinguished by a relatively high content of Al, Fe, Mn and K from the loess, even though the percentages of SiO 2 are not different significantly. This implies that the pedogenisis was stronger during the paleosol developing and the soil was formed under an oxidation and alkaline condition. The paleosol developed during last glaciation in Yili basin is rich in Ti, Fe, Mn, Mg and Ca, while S 1 at the Loess Plateau is poor at Ca, Na and K contrasting to that of the Loess Plateau, the Yili loess (L 1) is characterized by a high content of Ca, Mg and Mn All of these suggest that the Yili loess and paleosol developed under more arid climate.

Key words: Westerly area, loess, paleoenvironment, Yili, Xinjiang