【摘要】 本文主要根据《西宁市活断层探测与地震危险性评价》项目中跨断层钻探工作的初步结果,对西宁盆地河谷区两条主要的目标断层——北川河西岸断层、湟水断层的活动性予以阐述。通过对断层两侧钻孔岩芯的地层对比及年代学研究结果,建立跨断层柱状剖面,获得各地层层序主要界面的形成时代,并取得如下认识:北川河西岸断层在畜牧研究所场地并未断错到第四系覆盖层,晚更新世以来断层没有活动;湟水断层在彭家寨镇场地未断开第四系覆盖层,晚更新世晚期(约2万年)以来断层没有活动。更多还原

【Abstract】 Based on the preliminary drill results across the fault system for the project of"Active fault detection and seismic risk evaluation in Xining city",this paper discusses the activities of two key target faults,Huangshuihe fault and Beichuanhe West fault,developed in the Xining Basin.The column sections at two sides of the target faults are established through the stratigraphic correlation,and the formation ages for the main boundary strata are obtained from chronological data analysis.The major conclusions of our study are as follows:(1)Beichuanhe West fault at the Fanning Institute has no effect on the overlying Quaternary deposits,which indicates that this fault is not active since Late Pleistocene;(2)Huangshuihe fault at Pengjiazhai and Sujiahe towns does not offset the overlying Quaternary deposits,which implies that this fault is not active since Late Pleistocene(～20ka).更多还原