利用水系方位角和GPS数据研究龙门山后山断裂运动模式

Study on the Fault Movement Model of the Backmountain of Longmen Mountain Based on the Azimuth Angle and GPS data

构造地貌能够记录构造运动长期积累的地表变形,能通过相关地貌参数定量表达。水系是对构造作用反映最敏感的地貌之一,可以用来研究构造。通过分析断层附近的水系类型及特征来研究断层的运动模式,反映断层的空间展布和活动性,已得到广泛的应用。本研究利用Arcgis软件空间统计工具提取了龙门山后山断裂两侧的水系方位角,结合GPS运动学数据,探讨了构造运动对水系类型的控制作用。结果表明:龙门山后山断裂两侧的水系方位角呈现出系统性偏转,断裂北西侧水系方位角分布在88°~165°,由南向北呈现逐渐增大的趋势,断裂南东侧水系方位角分布在262°~344°,由南向北呈现逐渐变小的趋势,表明断裂两侧块体的相对运动存在差异。水系方位角和偏转角作为研究走滑断裂运动学特征和性质的有力工具,未来在活动构造定量化及数值模拟中将发挥巨大作用。

Tectonic geomorphology can record the long-term accumulation of crustal deformation and can be quantitatively expressed through relevant geomorphological parameters.The river drainage pattern is one of the most sensitive landforms to reflect tectonic effects.It can be used to study structure.By analyzing the types and characteristics of river drainage pattern near the fault,we study the motion mode of the fault to reflect the spatial distribution and activity of the fault.In this study,the spatial analysis tool in arcgis software is used to automatically extract the river drainage azimuths on both sides of the Longmenshan Back Fault,and combined with GPS kinematics data,the control effect of tectonics on river drainage pattern is discussed.The azimuth angles of the river drainage pattern on both sides of the Back fault show a systematic deflection,the azimuth angles of the rivers on the northwest side of the fault is between 88°~165°,and it shows a gradually increasing trend from south to north,while the azimuth angles of the rivers on the southeast side of the fault is between 262°~344°,and it also shows a southward decrease,the relative movement of blocks on both sides is different.The azimuth angle and deflection angle of the river drainage pattern are powerful tools for studying the kinematic characteristics and properties of strike-slip faults,and will play a huge role in the quantification and numerical simulation of active structures in the future.