Geophysics
mohammad rasool nikbakhsh; Mir Sattar Meshinchi Asl; Hamidreza Siyahkohi; Mohsen Oveisy Moakhar
Abstract
An important goal in mining exploration is the estimation of the depth and the thickness of the causative source. According to this simplification, several methods have been developed for interpreting magnetic field anomalies. In this article, the Hilbert transform has been used to calculate the ...
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An important goal in mining exploration is the estimation of the depth and the thickness of the causative source. According to this simplification, several methods have been developed for interpreting magnetic field anomalies. In this article, the Hilbert transform has been used to calculate the depth and thickness of 3-D thin plate anomalies. The Hilbert-Fourier transform performs an important role in analytic signals. Since the total magnetic fields anomalies function has the characteristics necessary for an analytic function, i.e. its real and imaginary parts form a Hilbert transform pair, the function can be used to interpret networked data in terms of three-dimensional origins. The Hilbert transform does not change the amplitude of a function but shifts the phase by and for positive and negative phase values, respectively. This paper uses a two-dimensional Hilbert transform and a 3-D analytic function to calculate the depth of a thin three-dimensional plate modeled based on the method of Talwani for noisy data and without noise data. The results show that the estimated depth values derived from the Hilbert transform method are associated with an error of less that 3% for data without noise, and an error of 8% for data of 15% noise. . This method was also tested on the real magnetic anomaly data from the Kheirabad iron mine located at 5 km NE of Golgohar, Sirjan, Iran. The results were compatible with the Euler method and with drilling information of the mine. The obtained depth is in good agreement with the actual depth, which confirms the application of the Hilbert transform for the interpretation of field data and estimation of magnetic anomalies depths.
Geophysics
Ali Ramzani; Mir Sattar Meshinchi Asl; Mohsen Oveisy Moakhar
Abstract
Geophysical surveys have been carried out to characterize the structure and to better understand the karstic water reservoirs in the Quchan area. Deep 2-D resistivity tomography and magnetic method have been used to detect the most promising zones for new water-well siting. Magnetic method has a common ...
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Geophysical surveys have been carried out to characterize the structure and to better understand the karstic water reservoirs in the Quchan area. Deep 2-D resistivity tomography and magnetic method have been used to detect the most promising zones for new water-well siting. Magnetic method has a common usage in the interpretation of the tectonic framework, faults and fractures that are triggering parameters of karstification phenomena. Therefore a high resolution magnetic survey was carried out as the first detection approach at selected sites in the studied region with the aim of probable buried fault exploration for karstic zone detection. The geomagnetic results detect magnetic anomalies in NW-SE direction agreed with the known faults system in the area. As the second approach, a Deep Electrical Resistivity Tomography (DERT) process has been designed according to magnetic results. Tree sections of 2-D electrical tomography using the Wenner-Schlumberger array has been carried out along a survey line of 100 m and an investigation depth of about 250 m with resolution of 5 m. The 2-D inversion modeling provides suitable information about the exploration targets and essential geological formations. The studies illustrate that low resistivity areas on the sections related to karstic zones. We used this combination of geophysical methods in this study to prove that these geological phenomena can be detected by such quick, economic and confident sequence of geophysical methods.