Abstract：Indirect terrain correction method was used to remove the terrain effect on 1:100000 gravity survey on complex two-layer structure terrain of loess plateau in Eerduosi sedimentary basin,It is a comprehensive method and includes the following steps: •Lonvert raw gravity anomaly into free-air gravity anomaly. •Use triangle series to convert the gravity anomaly on an undulatory terrain into the gravity anomaly on a plane that is above the unaulatory terrain,This procedure is called"reduced to datum". •Calculate and remove the gravity effect of layered undulatory terrain mass by using frequency-domain forward formula •Use regression analysis to remove residual terrain effect. Besides traditional terrain eorrection,this method can make easy gravity correction in the case of multilayered terrain,and remove the residual terrain effect which is caused because mid layer density is inaccurate and variable laterally. Theoretical model test shows that this method is fairly accurate.The processing of gravity rata of 4974 nravity stations on 7000 km2 resulted in clear gravity anomaly map,thus creating a fine geological result.
