Analysis of combined gravity and magnetic fields in wave number domain

Potential field data has been analyzed in the two-dimensional wave number domain to obtain the ratio of intensity of magnetization to the density (J/ρ). A two-dimensional fast Fourier transform is used to obtain convolution, upward continuation, vertical and horizontal derivatives, and reduction of the total field to the pole. A coherency test is used on the two sets of data to evaluate the validity of the calculated J/ρ ratio for each wavelength. A high-coherency value is assumed to arise if the gravity and magnetic anomalies are caused by the same body. A theoretical prismatic model and a field example from northern Saskatchewan illustrate the techniques.