用大地测量方法分析三江地区运动态势

Preliminary Study of Crustal Movement of San Jiang Region by Using Geodetic Method

本文利用绝对重力测量、重力场、形变和 GPS测量资料浅析该地区水平和垂直形变态势。用 5′× 5′实测资料编绘了布格异常图 ,编绘了 1975～ 1997年川西垂直形变速率图及多年绝对重力变化图等。经分析研究有以下初步结果 :1.重力异常等值线展布形态与构造格局一致 ,由北向南倾。此外 ,还发现了一条东西向异常梯级带 ,估计是一条未被证实的东西向断层 ,且是一条与构造活动密切相关的断层 ,应予以关注 ;2 .布格异常等值线的舌状态势反映了川滇菱形断块南南东向楔入的运动状态。另外断层若是水平错断 ,则在布格异常图上没有梯级带表现 ;3.研究结果表明 ,川西地区的垂直形变是以隆升为主的继承性运动 ,北部山区的隆升速率大 ,由北向南 ,垂直形变速率绝对值减小。滇西的垂直形变速率与绝对重力的时间变化率基本呈逆相关。洱源、丽江位于隆升速率大的地区 ,也是绝对重力变化负值大的点 ,下关则位于垂直形变速率平缓的零值附近 。

The paper analyses the vertical and horizontal deformations in San-Jiang region by means of absolute gravity,deformation and GPS data.5′×5′resolution practice grid data is used to compiled Bougure gravity anomalies map.Also,we compiled vertical deformation velocity and gravity changes maps from 1975 to 1997 in this area.Study results as: 1.The shape of gravity anomaly contour line is similar to the tectonic shape.2.Bougure anomaly contour shows the situation of Sichuan-Yunnan block thrust into this area in SSE direction.The vertical deformation of Western Sichuan region is mainly rising.Eryuan and Lijiang regions are high velocities rising regions and gravity quick descend regions.