武都—康县断裂带活动性初步研究

Preliminary Study on Activity of the Wudu-Kangxian Fault Zone

武都—康县断裂是位于甘东南地区区域大断裂中的一条左旋走滑并兼有逆冲分量的活动断裂。通过卫片解译和野外地质调查,对活动断裂几何分段、地貌和地质特征进行了研究。结果表明:武都-康县断裂可分为西(F1)和东(F2)两段,分别为上板桥-长坝镇断裂段和沈家园-窑坪断裂段;晚更新世以来断裂的活动形成了丰富的断错地貌现象,例如水系和山脊左旋位错、断层三角面、断层崖、垭口、鞍部、跌水和地裂缝。断裂西段为全新世断层,年代距今(1.730±0.111)ka至(1.670±0.141)ka之间,活动性比较强烈,并在甘泉一带发现全新世活动特征明显,主要以左旋走滑为主,同时伴有逆冲分量;而东段可能是晚更新世断层,以逆冲作用为主,并伴有左旋水平运动。

Wudu-Kangxian fault is one of the regional faults with left-lateral strike slip and thrusting active in southeastern part of Gansu province. Through satellite image interpretation and field investigation, the geometric segmentation and geomorphological and geological characteristics of the fault are studied. The result shows that the fault zone can be divided into the west（F1 ） and east（F2） segments, named Shangbanqiao-Changba fault and Shenjiayuan-Yaoping fault. Since the late Pleistocene, fault activity has formed rich dislocation landform phenomena, such as the left lateral of streams and ridges, terminal facet, fault cliff, saddle, waterfall and ground fissures. The new active of west segment（F1） was in Holocene, occurred from （1. 730 ±0. 111） ka to （1. 670 ± 0. 141） ka ago. Its strong and obvious Holocene active characteristics are found in Ganquan town, mainly shows left-lateral strike slip accompanied by reverse component. The east segment（F2 ） may be a late Pleistocene active fault, mainly shows reverse component accompanied by the left-lateral strike slip.