Distribution,Age and Dust Sources of Loess in the Ili Basin

Abstract

On the basis of previous studies and new data,the authors investigated the distribution,age and origin of the Ili loess.The conclusions are drawn as follows: the Ili loess is mainly distributed at the piedmont and high terraces.The loess sediments in the study area have been mainly deposited since the last glaciation,which is consistent with the time of loess deposition in other parts of Xinjiang Uygur Autonomous Region.However,there maybe have older loess than Middle Pleistocene.The particle size distribution and surface morphology of minerals indicate that the Ili loess may be the result of superposition of the close source material and far dust deposition,and the dynamic conditions in the process of deposition of loess in different regions in the Ili Basin may have significant differences.The grain size analysis shows that the clay components in loess in the Ili Basin may be transported from the Central Asia desert and the middle and lower reaches of the Ili River,but the dust brought by the westerlies have different contributions to the loess in the different regions of the Ili Basin.