Paleoseismic ruptures and evolution of a small triangular pull-apart basin on the Zemuhe fault  

作　　者：WANG Hu RAN YongKang LI YanBao CHEN LiChun 

机构地区：[1]Key Laboratory of Active Tectonics and Volcano,Institute of Geology,China Earthquake Administration

出　　处：《Science China Earth Sciences》2013年第3期504-512,共9页中国科学（地球科学英文版）

基　　金：supported by Special Foundation of China Earthquake Administration(Grant No.200808016);National Basic Research Program of China(Grant No.2004CB418401)

摘　　要：Trenching is a primary technique on paleoseismology to reveal evidence of surface deformation produced by large earthquakes.A good trenching site requires completeness of geologic recording on paleoseismic events and corresponding reliable dating from radiocarbon samples.Based on three-dimension trenching,we show a structure of a small triangular pull-apart basin at the Daqingliangzi section on the Zemuhe fault,then explore interrelation between paleoseismic surface rupturing and evolution of the pull-apart basin,and give a corresponding identification model.Sedimentary boundary of the pull-apart basin is tightly bounded by two branch faults,which produced multiple paleoseismic events with deformation of some large fissures in sequence.Strata are thinner at north of the pull-apart basin,however thicker at south.These above characteristics show that evolution of the pull-apart basin is a continuous sedimentation process accompanying extensional deformation produced by multiple paleoseismic events.Small pull-apart basins are favorable sites for trenching and paleoseismic study on active strike-slip faults.Trenching is a primary technique on paleoseismology to reveal evidence of surface deformation produced by large earthquakes A good trenching site requires completeness of geologic recording on paleoseismic events and corresponding reliable dating from radiocarbon samples. Based on three-dimension trenching, we show a structure of a small triangular pull-apart basin at the Daqingliangzi section on the Zemuhe fault, then explore interrelation between paleoseismic surface rupturing and evolution of the pull-apart basin, and give a corresponding identification model. Sedimentary boundary of the pull-apart basin is tightly bounded by two branch faults, which produced multiple paleoseismic events with deformation of some large fissures in se- quence. Strata are thinner at north of the pull-apart basin, however thicker at south. These above characteristics show that evo- lution of the pull-apart basin is a continuous sedimentation process accompanying extensional deformation produced by multi- ple paleoseismic events. Small pull-apart basins are favorable sites for trenching and paleoseismic study on active strike-slip faults.

关 键 词：active strike-slip faults Zemuhe fault a triangular pull-apart basin PALEOSEISMOLOGY TRENCHING 

分 类 号：P542[天文地球—构造地质学]