一、前言长石梯沟—西流水河断层(以下简称长—西断层)位于甘肃省张掖盆地西南80余公里,榆树山活动断层之南,同属祁连山北缘断裂的组成部分。长—西断层北西起黄羊大沟,向南东经长石梯沟、黑河、西流水河、黑石头沟、大野口水库到柳谷城南消失,在黑石头沟附近断层呈右阶错列,航、卫片上线性影像清晰。断层走向N40°～45°W,倾向NE,倾角65°；在大野口水库断裂走向N40°W,倾向SW,倾角50°,全长56km I. INTRODUCTION The Changshitou-Xiluishuihe fault (hereinafter referred to as Chang-Xishan fault) is located in the southwest of the Yushu Mountain active fault more than 80 kilometers southwest of the Zhangye Basin in Gansu Province and belongs to the fault of the Qilian Mountains. The Chang-Wester fault fades from the Huangyang Gully to the north and disappears to the south along the Changshitou, Heihe, Xiluishui, Heishitou and Dayongkou reservoirs in the south of Liuguoguang. The faults in the vicinity of Heishitougou are staggered right-angled , The linear image of the film clear. The fault strike is N40 ° ~45 ° W with a tendency of NE and a dip angle of 65 °. In the case of the Da Nokou Reservoir, the strike of the fault is N40 ° W with a dip of SW and an inclination of 50 ° with a total length of 56 km