Potential field geophysical data fast imaging versus inverse modeling

Imaging and inversion of potential field geophysics data permit the estimation of the source-property distribution in 2D/3D space. In this work, the advantages and performances of a fast gradient-based imaging technique, known as the normalized full gradient (NFG), are examined to depict the source distribution in 2D space. In addition, a conventional Tikhonov norm-based inversion technique is used to estimate physical properties in 3D space. The functionality of these approaches are evaluated first for synthetic data sets, which involve three scenarios of a single source, a sloping source and a combination of them. Where the constructed sources and property distributions (i.e. density contrast and magnetic susceptibility) were compared. Then, algorithms were employed to the potential field data pertaining to the Shavaz iron-bearing deposit in Iran. Both methods have shown accurately the centroid depth of all sources, but the boundary is better preserved by the inversion method for simulated sources and the real data set. Iron ore occurrence is in the forms of hematite and magnetite lens which mainly has an elongation along a NW-SE strike, indicating the impact of the Dehshir-Baft fault on trapping the iron. It is worth pointing out that the inversion method led to more accurate information on geometry of the sought source by estimating density contrast and magnetic susceptibility values, but with higher execution time. In addition, the NFG algorithm took less time to run, more sensitive to noisy data, and severely smeared-out the border of the source responsible for potential field anomaly.