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江仑地区是祁连山南麓的一个山间盆地,它的自然条件与祁连山具有同一属性。祁连山是由一系列褶皱断块山及其相间的陷落盆地所构成,地势高亢,海拨4000m以上,最高峰达6300m,气候严寒,多年平均气温为-3°～-56℃,江仑多年冻土就是在这样的环境中形成的。多年冻土带的下限大致与年平均气温-2.5℃的等温线相吻合。在江仑地区,冻土厚度为60m左右,季节冻融层厚度阳坡1.6～1.8m,阴坡1.2～1.7m。江仑多年冻土的岩性比较复杂,主要可分为细粒土、粗粒土和冻结岩石三类,自丘垅顶部至斜坡带再下至河谷平原带,岩相变化由粗到细。(如图1所示)
Jianglun area is an intermountain basin in the south of Qilian Mountain. Its natural conditions are the same as Qilian Mountain. The Qilian Mountains are composed of a series of fold-faulted faulty mountains and their subducted basins. The terrain is high-pitched, over 4000m above sea level, and the highest peak is 6300m. The climate is cold. The average temperature for many years is -3° to -56°C. Jianglun is frozen for many years. Soil is formed in such an environment. The lower limit of the permafrost is roughly in line with the isotherm of the annual mean temperature of -2.5°C. In Jianglun area, the frozen soil thickness is about 60m, the seasonal freeze-thaw layer thickness is 1.6-1.8m on the sunny slope, and the shady slope is 1.2-1.7m. The lithology of permafrost in Jianglun is complex and can be divided into fine-grained soil, coarse-grained soil, and frozen rock. From the top of the hillock to the slope belt and down to the valley plain, the lithofacies changes from coarse to fine. (As shown in Figure 1)