摘要
骊山北缘山前断层是渭河盆地东部一条具重要地震地质意义的活断层,第四纪以来活动标志明显。断层一带的断错地貌显示,该断层以引张倾滑兼反扭活动为特征;断层泥中石英碎屑的SEM形貌特征显示,断层粘滑活动标志显著;断面擦痕电算结果显示,断裂带引张构造应力场格局为:σ~1—NE64°∠12°,σ_2—NE20°∠74°,σ_3—SE154°∠2°;冲沟裂点的实测分析结果显示,全新世以来该断层可能有过七次以上的快速活动;陡坎扩散方程计算和热释光测年确定出了该断层距今12万年左右的一次强烈活动的年代。
The movement of the active fault at the Northern piedmont of the Lishan mountains has repeatedly occured since the Cenozoic Era.In recent years the activities of the fault seem to gradually intensify and some geological hazards,such as landsides ground fissures along the fault, are constantly occuring,seriously threatening the scenic spots and the historic sites, such as the Huaqing pool, the hall for the warrior figures and so on.The offset landform along the fault suggests that it is characterized by the tensile and dip slip with the reversal activities.The features of the SEM observation of the cataclastic quartz in the fault gouge indicate that its movement is mainly sticky slip.The calculation results of the scratching slip data show that its structural stress field is σ1-NE64°/12°, σ2-NE20°/74°, σ1-SEl54°/2°, corresponding to the modern tectonic stress field of the weihe Basin. The measurement of gullis and knick points shows that there were at least seven activities during 5000years.Through calculating with the diffusion equation of the fault scarps and determinating age of the thermoluminesence, the absolute chronology of a strong activity occured about 0.12 Ma ago was ascertained
基金
陕西省科委的资助
中科院西安黄土与第四纪地质开放室的资助
关键词
断层
活动性
应力场
冲沟裂点
active fault, quartz grains, stress field, gully and knick point, diffusion equation
