Equivalent layer technique for estimating magnetization direction

We propose a new method for estimating the total magnetization direction of magnetic sources based on the inversion of total-field anomaly via equivalent-layer technique. This technique is commonly used for processing magnetic data by estimating a magnetic-moment distribution over a planar layer of dipoles having an uniform magnetization direction. It can be shown that this distribution is all-positive if the magnetization direction of the dipoles is equal to that of the arbitrary magnetic sources producing the observed data. Based on this theoretical property, we propose an iterative algorithm to estimate the magnetization direction of 3D magnetic sources by imposing a positivity constraint on the magnetic-moment distribution of the dipoles forming the equivalent layer. Our approach imposes neither information on the shape nor on the depth of magnetic sources. Tests with synthetic data and field data, from an alkaline intrusion in southern Brazil, show that our method is able to correctly estimate the magnetization direction of the sources.