Abstract: When we invert gravity gradient data to recover 3D density distributions by cokriging, the dip angle impacts the recovered results seriously. Where there is a lack of the prior information about dip angle, to obtain reasonable results we present a method to determine the angle. Keeping the parameters same in cokriging, we introduce some different angles, then according to the prior information, only zero or positive density contrast is chosen. The standard deviation of the residuals between the observed and predicted data changes with the angle changing. The evaluated angle of this method is the corresponding angle to the minimum standard. In this paper, we choose four typical dipping dike models with the dip angle of 0°, 45°, 90°, 135° respectively. The vertical component T_zz of the gravity gradient data is inverted to test the valid of the method, and it shows the correct dip angles of the dipping dike. This result makes cokriging can be applied in more conditions that the dip angle is unavailable.

Key words: cokriging, 3D inversion, gravity gradient data, dipping dike