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黑河口断层位于张掖西南约３０ｋｍ，是一条走向北西，倾向南西的逆断层。黑河沿岸的一个天然剖面上见断层面向南西陡倾，奥陶系向北东逆冲于晚更新世河流砾石层之上，垂直断距１７ｍ。断层活动在黑河阶地上形成了一个断层陡坎。年龄约为５ｋａＢ．Ｐ．的阶地被垂直错断２ｍ，年龄约为１０ｋａＢ．Ｐ．的阶地被垂直错断４ｍ，年龄约为１３ｋａＢ．Ｐ．的阶地被垂直错断９ｍ。这些错距及断层附近的沉积物反映断层至少有３次活动，每次活动的垂直位移为２～５ｍ，活动时间间隔为３～５ｋａ，平均活动速率为１．６７～０．４ｍｍ／ａ。
The Heihekou fault is located about 30 km southwest of Zhangye, a reverse fault that runs northwest and runs southwest. On a natural profile along the Heihe River, faults are observed to steeply face the southwestern and west-trending faults. The Ordovician thrusts northerly over the late Pleistocene river gravel with a vertical offset of 17 m. Fault activity formed a fault scarp on the Heihe terrace. The age is about 5kaB. P. The terraces are vertically offset by 2m and are about 10kaB in age. P. The terraces are vertically offset by 4m and are about 13kaB in age. P. The terrace is vertically off 9m. These faults and the sediments near faults show that the fault has at least three activities, with a vertical displacement of 2 ~ 5m per activity and an activity interval of 3 ~ 5ka with an average activity rate of 1.67 ~ 0.4mm / a.