柯坪塔格山前层状地貌面与晚第四纪逆断层变形--以三岔口北西山前断错地貌为例  

DEFORMATION OF REVERSE FAULT AND LAYERED LANDFORM IN PIEDMONT OF KALPINTAG MOUNTAINS DURING THE LATE QUATERNARY:EXAMPLE FROM THE FAULTED LANDFORM OF NORTHWESTERN SANCHAKOU

作　　者：徐良鑫[1] 冉勇康[1] 刘华国[1,2] 李安[1] 

机构地区：[1]中国地震局地质研究所,国家地震活断层研究中心,北京100029 [2]中国地震灾害防御中心,北京100029

出　　处：《地震地质》2011年第4期777-788,共12页Seismology and Geology

基　　金：国家自然科学基金(40872130);财政部重大专项“我国地震重点监测防御区活动断层地震危险性评价”共同资助

摘　　要：柯坪塔格山前三岔口北西发育了5级不同期次的冲洪积扇面,其中较年轻的3期完整地保留了断裂最新活动形成的陡坎。依据断错地貌面上砾石混合样品的10Be暴露年龄及差分GPS地形实测结果,计算出(20.2±1.91)ka以来T1、T2、T3级冲洪积扇上记录的断裂垂直滑动速率分别为(0.16±0.02)、(0.17±0.02)和(0.15±0.02)mm/a。T4、T5级地貌面的抬升速率为(0.51±0.05)、(0.58±0.05)mm/a,稍大于T1、T2、T3冲洪积扇面的结果。柯坪塔格断裂在三岔口处出露的断层倾角为20°～40°,据此计算得到(20.2±1.91)ka以来柯坪塔格的水平缩短速率为0.18～0.44mm/a。There are five different levels of alluvial fans developed at Sanchakou in the south edge of the Kalpintag Mountains.Kalpintag Fault has faulted three younger alluvial fans on which fault scarps caused by the latest fault activities are perfectly retained.To estimate the vertical slip magnitude and rates of the Kalpintag Fault during the late Quaternary,we investigated the latest evidences from the topographic and geomorphic survey of the fault scarps on the fans using differential GPS and the exposure10Be age of amalgamated samples on the surface of abandoned fans.We estimated the cosmogenic nuclide contents accumulated during the post-depositional processes in the amalgamated samples on the fans collected from nearby active gullies.The vertical displacements of fault scarps we measured on the T1,T2 and T3 alluvial fans are 0.6±0.05,1.3±0.05 and 3.0±0.05m,respectively.Based on the10Be exposure age of each alluvial fan,we calculated the vertical slip rate on T1,T2,T3 alluvial fans to be 0.15±0.02,0.16±0.02 and 0.15±0.02mm/a since（20.2±1.91）kaBP,with a corresponding crustal shortening rate of the Kalpintag Fault to be 0.18～0.44mm /a.The uplift rate since the formation of the T4 and T5 alluvial fans is 0.51±0.05 and 0.58±0.05mm/a,respectively,which is slightly bigger than that of T1,T2 and T3 alluvial fans.

关 键 词：柯坪塔格断裂 断错地貌 10Be 暴露年代 滑动速率 

分 类 号：P315.2[天文地球—地震学]