中文摘要：

黄河上游贵德盆地滑坡泥石流灾害制约着该地区河谷城镇化建设。文章在野外调查和室内研究的基础上,首次划分了尕让河阶地序列,分析了阿什贡滑坡群的发育期次及与河道演变的宏观地质作用过程和机制,主要取得以下认识：（1）尕让河至少发育了7级阶地,根据阶地与滑坡堆积体的披覆关系,厘定了滑坡发育的时间先后顺序;（2）阿什贡滑坡演化过程分为二期,Ⅰ期滑坡为巨型滑坡并触发了前缘革匝滑坡,发生时间为16 ka BP以来,阿什贡Ⅱ期滑坡为Ⅰ期的解体滑坡;（3）阿什贡滑坡群发育时间先后顺序为：尕让滑坡→尕让河Ⅲ级阶地形成→阿什贡滑坡Ⅰ期→革匝滑坡→堰塞湖及湖相层发育→尕让河Ⅱ级阶地形成→阿什贡滑坡Ⅱ期→现代河道;（4）阿什贡滑坡群目前总体处于稳定状态,但Ⅱ期滑体发生局部解体的可能性较大,须加强滑坡灾害防治。

英文摘要：

The landslide and debris flow disasters are the key constrained problems to the valley urbanization construction in the upper reaches of the Yellow River. On the basis of field investigation and laboratory studies, the terraces sequences of the Garang River （GR） are divided and the forming stages of the Ashigong landslide cluster, the macro-geological processes and mechanisms by evolution of landslides and river courses are also analyzed. Some main conclusions are as follows ： （ 1 ） there are at least 7 river terraces developed in the GR, of which chronological sequences are determined according to the mutual overlap relationships between the landslides mass and the river terraces; （2） there are two stages of the Ashigong landslide and the first stage triggered the Geza landslide, which is located in the front edge of the Ashigong landslide, so they occurred in the same time of Holocene period; （3） the chronological forming Sequences of the Ashigong landslide cluster are in following order： occurrence of the Garang landslide →formation of the Ⅲ terraces of GR →the first stage of the Ashigong landslide→occurrence of the Geza landslide→formation of the dammed lake and the lacustrine layers →fromation of the Ⅱ terraces of GR→the second stage of the Ashigong landslide→fromation of the modern river course; （4） the Ashigong landslide cluster are stable in a general view, but has the occurrence possibility of the second stage of the landslide. Thus the landslide disaster prevention must be strengthened in this area.