甘肃迭部—白龙江南支断裂中东段晚第四纪构造活动特征

通过卫星影像解译、野外实地调查与地质填图，对甘肃东南部迭部—白龙江南支断裂中东段晚第四纪构造活动特征进行了研究。结果表明:迭部—白龙江南支断裂中段活动性明显强于东段；中段线性特征明显，可见清晰的断崖，不同期次的阶地之上都有断层陡坎发育，晚第四纪以来有过明显活动，最新活动的离逝时间为1 300年左右，属于全新世活动断裂；东段活动性明显减弱，没有发现断错全新世地层的证据，在地貌上多表现为线性沟谷，属于晚更新世断裂。根据对断错阶地的测量和年代测试，迭部—白龙江南支断裂中段左旋滑动速率为每年(1.3±0.1)mm，垂直滑动速率为每年(0.39±0.04)mm。

Characteristics of Late Quaternary Tectonic Activity in the Middle Eastern Segment of the Southern Branch of Diebu Bailongjiang Fault,Gansu

Based on satellite image interpretation, field survey and geological mapping, the characteristics of Late Quaternary tectonic activity in the middle-eastern segment of the southern branch of Diebu-Bailongjiang fault, Gansu, were discussed. The results show that the activity of the middle segment of the southern branch of Diebu-Bailongjiang fault is stronger than that of the eastern segment; the characteristic along the middle segment is significantly linear, and the scar and fault scarp cutting through several terraces can be easily distinguished; the middle segment is active since Late Quaternary, and the elapsed time of the last event should be less than about 1 300 years; the middle segment is Holocene active fault; the activity of the eastern segment is obviously weakened, and there is no evidence of Holocene fault; the landform in the eastern segment is a linear valley, and the eastern segment is Late Pleistocene fault. According to the measurement of fault terrace and dating, the left-lateral and vertical slip rates are (1.3±0.1) mm and (0.39±0.04) mm per year in the middle segment of the southern branch of Diebu-Bailongjiang fault.