关键词: 黑河口断层, 阶地位错, 活动周期, 活动速率

Abstract: The Heihekou fault, being apart 30 km from Zhangye in the southwest, is a reversed fault which trends to the northwest and dips to the southwest. It is found that the fault on a natural section along the bank of the Heihe River dips steeply to the southwest, and that the Ordovician system thrusts to the northe-ast on the Late Pleistocene alluviam with a throw of 17m. A fault scarp was formed in the fault movement on terraces of the Heihe River. The terrace withan estimated age of 5 ka B.P. is vertically dislocated by 2m, age of 10 ka B.P. by 4m, and age of 13 ka B.P. by 9m. These dislocations and the sediments near the fault indicate there had been 3 movement enents at least. The vertical dislocationis 2～5 m each, the average recurrence interval is 3～5 ka, and the average slip rate is 1.67～0.4 mm/a.

Key words: Heihekou fault, terrace dislocation, recurrence interval, slip rate