关键词: 西风区, 黄土, 黄土状土, 新疆伊犁地区

Abstract: Yili area is located in the west of Xinjiang and is an intermountane basin of Tianshan, in which the loess iswidespread. Only a few studies were carried out during past decades. For this reason, there are different opin-ions on the origin of loess. The results of grain size analysis of loess and reworked loess show that the texturalfeatures of both are same on one side and different on the other side.
Firstly, the composition of grain size of loess is similar to that of the reworked loess, but the sand particles of loess is higher and the clay particles is lower than that of reworked loess.
Secondly, the frequency curve of loess and reworked loess occures to be positive normal distribution. Themode of both locates in the range of 15～30 um, but the percentages are different. The amount of loess is lessthan 20%, while the maxmum percentage of reworked loess reaches 50%.
Thirdly, the sorting of loess is better than that of the reworked loess, even though both are poor sorting de-posits. The skewness of loess ranges from 0.13 to 0.43 and most of them is lower than 0.3.Comparied withthe loess, the skewness of reworked loess is higher and the mediun size moves toward coarse side. The kurtosisof loess is medium, while peak of reworked loess is steep.
In surnmary, the loess and the reworked loess were transported and sorted by different dynamics before thedust deposited. In addition, the depositing environments were also different. The evidences from the grain sizeshow the loess in Yili area is a typical eolian deposit.

Key words: Yili area, Loess, Reworked loess