黄河黑山峡大柳树坝址区F201和F7(8)断层的活动性

Activity of faults F7(8)and F201 in the Daliushu dam region,Heishan Gorge of the Yellow River

摘要: 黄河黑山峡大柳树坝址区位于青藏高原中卫-同心活动断裂带内F7(8)和F3断层所夹持的寒武系变质砂岩夹千枚岩推覆岩片中。对F201、F7(8)断层活动性的认识是坝址稳定性评价的关键,也是争议的焦点。通过对大柳树坝址区F201、F7(8)断层带特征的追索观测、工程揭露和断层泥测年,获得F201、F7(8)断层活动特征的新资料,证实了F201断层是一条晚更新世晚期和全新世以来强烈活动的区域发震断层,同时确定了F7(8)断层水平左旋走滑作用的存在;发现断层通过之处二级阶地堆积物的震陷槽;获得了小于20ka断层泥测年数据,尤其是确定了F7(8)断层与F201断层的交会地点。因此熏按水电规范,F201和F7(8)断层被定为活动断层。

Abstract: The Daliushu dam region in the Heishan gorge of the Yellow River is located in the Zhongwei-Tongxin active fault belt on the northeast margin of the Qinghai-Tibet Plateau, in a Cambrian phyllite-bearing metasandstone thrust slice sandwiched between fault