A focused and constrained 2D inversion of potential field geophysical data through Delaunay triangulation, a case study for iron-bearing targeting at the Shavaz deposit in Iran

Abstract

This work illustrates the performance of a focused algorithm for 2D inversion of potential field geophysics (gravity and magnetic) in regions with rugged topography. A non-structured model discretization mesh is performed through Delaunay triangular cells to accurately represent the rugged observation surface and recover complex-shaped sources. Several synthetic single and multi-source targets are simulated to evaluate the applicability of the focused algorithm for simultaneously preserving the edges, correct depth estimation and body distribution of the inverted models. The algorithm is written in such a way that it is able to improve the modeling result per iteration by imposing physical properties constraining (magnetic susceptibility or density contrast), depth weighting and focused term in the central system of linear equation. Whereby a preconditioned conjugate gradient scheme is used iteratively to solve efficiently the L2-norm cost function comprising of a data misfit norm and a model stabilizer. Potential field data pertaining to a real case study for iron-bearing targeting are also inverted along two profiles to investigate the geometry of the sought targets at the Shavaz deposit in Iran. Iron-oxide ore occurrence was approved by exploratory drilling indicating a shallow hematite target with minor compounds of magnetite. Of note is that the significant point of this study lies in accurate recovering of causative sources responsible for potential field anomaly when a severe undulating topography occurs.