Inversion of Source Parameters from Magnetic Anomalies for Mineral/Ore Deposits Exploration Using Global Optimization Technique and Analysis of Uncertainty

Abstract

Global optimization algorithm using very fast simulated annealing has been used for modeling of magnetic anomaly over various idealized geobodies for mineral/ore deposit investigation. The present technique shows that it can match the observed data very well assuming some simple geometrical bodies such as sphere, horizontal cylinder and thin dyke or sheet. Uncertainty associated with the modeling was also studied. It has been found that the obtained source parameters are strongly identical when all the parameters are optimized. The present study shows that amplitude coefficient depends on the shape factor. The relation between them shows a multimodel-type uncertainty. The shape factor modeled from several VFSA runs shows the different kind of subsurface structure. Constraining the shape factor gives reliable results and analysis of histograms and cross-plots also gives the utmost reliable results, which show a unimodel character. Inversion of synthetic noise-free and noisy data shows the worth of the present work. The present algorithm was also tested in five field case studies for mineral/ore exploration. Computation time for this present work is very minimal.

Inversion of Amplitude from the 2-D Analytic Signal of Self-Potential Anomalies

“…VFSA takes any value in a model space, whereas SA does it in a predefined model space and hence the resolution increases for VFSA. Moreover, in VFSA optimization process, it does not recall all models and hence needs very small memory [35,87,88]. In every geophysical inversion, the main objective is to minimize the error function or the misfit.…”

Spectral analysis and source parameter imaging of aeromagnetic anomaly over Ogoja and Bansara areas of lower Benue trough, Nigeria

“…Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License of the orientation, geometry, size, depth, and magnetic susceptibility of the body as well as the intensity and inclination of the earth's magnetic field in the survey area (Biswas, 2016(Biswas, , 2017Biswas and Acharya, 2016). For the exploration purposes, both ground and aero-magnetic data have been used to investigate the presence of mineral deposits in combination with gravity.…”

Estimation of sedimentary thickness using spectral analysis of aeromagnetic data over Abakaliki and Ugep areas of the Lower Benue Trough, Nigeria

“…This method of investigating the subsurface geology is based on the magnetic anomalies in the earth's magnetic field resulting from the magnetic properties of the underlying rocks. Measurements of the horizontal or vertical component or horizontal gradient of the magnetic field may also be made (Biswas et al, 2017). The shape, dimensions, and amplitude of an induced magnetic anomaly is a function of the orientation, geometry, size, depth, and magnetic susceptibility of the body, as well as the intensity and inclination of the earth's magnetic field in the survey area (Biswas, 2016(Biswas, , 2017Biswas and Acharya, 2016).…”

“…Measurements of the horizontal or vertical component or horizontal gradient of the magnetic field may also be made (Biswas et al, 2017). The shape, dimensions, and amplitude of an induced magnetic anomaly is a function of the orientation, geometry, size, depth, and magnetic susceptibility of the body, as well as the intensity and inclination of the earth's magnetic field in the survey area (Biswas, 2016(Biswas, , 2017Biswas and Acharya, 2016). For exploration purposes, both ground and aero-magnetic data have been used to investigate the presence of mineral deposits in *Corresponding author.…”

“…Interpretation of aeromagnetic data can be carried out both quantitatively and qualitatively. Quantitative interpretation involves making numerical estimates of the depth and dimensions of the sources of anomalies and this often takes the form of modeling of sources which could, in theory, replicate the anomalies recorded in the survey (Biswas, 2015;Biswas, 2016;Singh and Biswas, 2016;Biswas et al, 2017). Spectral analysis has successfully been applied in interpretation of aeromagnetic data (Bhattacharyya, 1966;Spector, 1968;Mishra and Naidu, 1974;Hahn and Mishra 1976).…”