Estimating magnetic dike parameters using a non-linear constrained inversion technique : an example from the Sarna area, west central Sweden

摘要: In this paper, we describe a non-linear constrained inversion technique for 2D interpretation of high resolution magnetic field data along flight lines using simple dike model. We first estimate the strike direction quasi structure based on eigenvector corresponding to minimum eigenvalue pseudogravity gradient tensor derived from gridded, low-pass filtered anomalies, assuming that magnetization is known. Then measured can be transformed into coordinate system and all parameters – horizontal position, depth top, dip angle, width susceptibility contrast estimated by least squares lines. We use Levenberg-Marquardt algorithm together with trust-region-reflective method enabling users define inequality constraints model such are always in trust region. Assuming maximum calculated gzz (vertical field) approximately located above causative body, points enclosed window, profile, centred at of gzz are used scheme estimating parameters. The size window increased until it exceeds predefined limit. solution fit error chosen as most reliable one. Using synthetic study effect random noise interfering sources models apply our new aeromagnetic set Sarna area, west central Sweden including laboratory measurements rock samples area.