新疆塔城黄土的形成

中亚黄土是研究区域古气候和古环境变化的重要载体。但是对于受到广泛研究的黄土高原黄土来说，对中亚东部塔城黄土的报道较少。基于对塔城黄土粒度的系统分析，与伊犁盆地黄土、典型黄土高原的黄土对比，我们发现无论是粒度频率曲线、粒度结构散点图、还是三角图，塔城黄土与伊犁盆地清水河黄土较相似，而与黄土高原黄土不同，塔城黄土粒度频率分布曲线为三峰分布，粒度组成比较分散，分选较差，细、中颗粒含量较少，主要以粗颗粒物质为主，属近源风成黄土。结合当地地形和现代环流分析，我们认为中亚萨雷耶西克阿特劳沙漠为塔城黄土提供主要的物源，盛行西风为粉尘的搬运提供足够的动力，向西开口的山间盆地地形为粉尘的沉积提供有利的沉积中心，这三个条件的共同作用导致了塔城盆地厚层黄土的沉积。

Formation of the Tacheng Loess, Xinjiang

Loess deposits in Central Asia provide an important record of regional climate and environmentchange. However, in contrast to the intensively investigated loess deposits on the Chinese Loess Plateau(CLP), loess sediments in the Tacheng Basin of eastern Central Asia are poorly understood. In this study,the grain-size features of the Tacheng loess are compared with the Ili loess (Qingshuihe section and Zeketaisection) in the west of China and Chaona loess in the Chinese Loess Plateau. The results indicate that thegrain-size characteristic of the Tacheng loess is similar to the Qingshuihe loess in the west of the Ili Basin,and displays a trimodal distribution, and undergoes poor differentiation, the grain-size content of the fineand middle competent is small, while the coarse competent is large, so we conclude that the Tacheng loessis of near-source aeolian origin. Combined with regional topographic and climatic characteristics, wesuggest that Sary-Ishikotrau Desert provides a sustained source of dust, westerly provides adequate windenergy to transport the dust and an intermontane basin resembling a trumpet shaped terrain facing the westgives a suitable accumulation site for dust, these three fundamental requirements lead to the formation ofthe loess in Tacheng.