慕士塔格新冰期以来冰碛物风化成土特征

Grain-size Features and Magnetic Susceptibility Characteristic of the SurfaceLayer of the Moraines in the Muztag Ata

对慕士塔格西坡冰碛物粒度及磁化率分析表明：＜1 mm的冰碛物以4～6φ（0．063～0．016 mm）含量为主，平均粒径（Mean）在2～6φ之间，分选系数（δ）在1～3之间，峰态系数（Kg）为1．5～3．5，偏度（SK）系数在-2～2之间；磁化率分别与时代较老的冰碛土的粘土，和时代较新的冰碛土的粗砂成正相关。土壤发育过程和风力作用是影响冰碛物演化的重要因素，原生冰碛物保留的平均深度在30 cm以下。

Grain size and magnetic susceptibility of 116 samples from moraine soil on the west of the Mustag Ata over 4 000 meters were analyzed. It is found that a main peak occurs at 4～6 φ in the grain size distribution curves, the mean grain-size ranges between 2 φ and 6 φ, the sort coefficient changes from 1 to 3, and the kurtosis coefficient changes from 1.5 to 3. 5. Furthermore, the grain size properties are strongly correlated with the magnetic susceptibility.The grain size characteristics are different with altitude, location and depth of the moraine soil. It is concluded that the grainsize and the magnetic susceptibility of moraine soil on the Mustag Ata are mainly controlled by the soil development, wind and the dry and cold climate under the westerlies. The original moraines lie at 30~55 cm deep below the surface.