晚更新世中期以来克里雅河流域黄土沉积特征与环境演化

昆仓山中段克里雅河流域不同海拔黄土样品的物质组成，地球化学成分、孢粉组合表明塔里木盆地的继粒物质是其物源。黄土分布于２３００ｍ的前山地带至４９００ｍ高山带，自低而高，黄土厚度变薄，颗粒由粗变细。＾１４Ｃ年龄测定显示本区黄土物质由晚更新世中期（５００００－６００００ａＢ．Ｐ．）－全新世风力搬运的粉尘堆积而成。

DEPOSITIONAL CHARACTERISTICS AND ENVIRONMENTAL EVOLUTION OF LOESS IN KERIYA RIVER BASIN SINCE LATE PLEISTOCENE

The loess distribution in Keriya River basin at the middle part of Kunlun mountain is not restricted by geomorphological conditions. The loess covers in a belt from hills over 2 300 m a. s. l. denuded by aridity to high mountains of 4 900m a. s. l. Its thickness becomes thin and the content of fine materials increases gradually from the hills to high mountains. Ac cording to the study on the depositional characteristics, material composition, formation age and environmental evolution of the loess, it is considered that the loess is formed by the ac cumulation of silt-dust materials blown and transported by strong wind under an environ ment of arid desert since the middle period of Late Pleistocene (50-60ka B. P. ) including Holocene and modern times. The mineral composition and characteristics of geochemistry and granularity of the loess are similar to that of the desert material composition in Tarim Basin and that of the dust composition in modern atmosphere, which shows that the fine materials in Tarim Basin are the sources of the loess accumulation. The depositional characteristics of the loess represent that the climate changed violently and friquently, and especially represent sensitively about the dry-cold events. The depositional environment of loess has experienced the dry grassland, desert grassland, semi-desert grassland and arid-desert gassland since the middle period of Late Pleistocene.