Determination of Anomaly Source Border Using Reweighting Focusing Inversion of Two-Dimensional Gravity Horizontal Gradient Data and Conventional Edge Detection Methods (Case Study: A Chromite Mass in Sabzevar, Iran)

There are numerous methods to detect the edge of gravity and magnetic field anomaly source, most of which are based on the combination of first and second-order horizontal and vertical gradients of the potential field. Gradient-based and other edge detection methods determine the anomaly source borders on the ground surface. In the present study, a linear reweighting focusing inversion method has been used to detect the vertical edges of a subsurface mass using gravity horizontal gradient data. With simultaneous evaluation the results of the proposed method and the conventional edge detection methods, we can accurately detect the subsurface anomaly sources boundary. The efficiency of the linear reweighting focusing inversion method is applied for two sets of gravity horizontal gradient data, with and without noise, related to two synthetic models. The subsurface density contrasts distribution obtained from the analysis of the synthetic models by this inversion method has well determined the underground location of the farther edges of the anomaly source. This method is used to detect the underground edges of a chromite mass in Sabzevar. Also, to compare and validate the results, three conventional local phase filters namely the analytical signal, tilt angle, and total horizontal differential have been used to detect the anomaly source border. The results obtained from various methods show an acceptable conformity in chromite mass border detection. Based on the analysis conducted over real gravity data, the depth of the farthest subsurface vertical.