渭河断裂东段中更新世晚期以来活动速率

摘要

综合地形、断裂遥感解译以及钻孔联合剖面，考虑到渭河断裂东段在金家庄、东耳村一带存在一个左阶斜裂区，阶区宽约1 km，将断裂分为杨家村-金家庄段和东耳村-张家湾段，均为同生正断层，全新世有活动。使用研究区的十一条钻孔联合剖面，结合典型断错地层光释光年龄，建立了渭河断裂东段中更新世晚期以来的断裂活动速率曲线。结果显示杨家村-金家庄段全新世活动速率为0.04 mm/a，晚更新世活动速率在0.16～0.40 mm/a之间，中更新世平均活动速率在0.24～0.30 mm/a之间；东耳村-张家湾段全新世平均活动速率为0.12 mm/a，晚更新世活动速率在0.11～0.23 mm/a之间，中更新世平均活动速率在0.19～0.24 mm/a之间。通过与渭河断裂东部地区晚更新世以来的沉积速率曲线对比，在较长时间段里，地层沉积速率大于断裂活动速率，反映了渭河断裂垂向差异运动较弱，以至于隐伏于渭河阶地之下。%Integrated with the landform remote sensing interpretation and composite drilling section,consider-ing there is a left-stepped,oblique-arranged zone in Jinjia village and Donger village near the Weihe fault with width about 1 km.We divided the east section of Weihe fault into Yangjia village-Jinjia village section and Donger village-Yaodian section.They are both contemporaneous normal faults and Holocene active.Eleven composite drill-ing sections are used in the study area and the typical fault OSL age strata.Fault activity rate curve of late middle Pleistocene of the east section of the Weihe fault is build,which shows that the activity rate of Yangjia village-Jinjia village section in Holocene is 0.04 mm/a,Late Pleistocene is 0.16 to 0.40 mm/a,Middle Peistocene is 0.24 to 0.30 mm/a.The activity rate of Donger village-Zhangjiawan section in Holocene is 0.12 mm/a,Late Pleistocene is 0.1 1 to 0.23 mm/a,Middle Peistocene is 0.19 to 0.24 mm/a.Contrast with the deposition rate curve of late middle Pleistocene of the east section of the Weihe fault.Stratum deposition rate is greater than fault activity rate in a long time.And it is shown that the Vertical differential movement is weaker of Weihe fault.So it blind in the Weihe terrace.