Environment
Ali Bahrami; Abolghasem Kamkar-Rouhani; Alireza Arab-Amiri; Farzaneh Jamali
Abstract
One of the main goals of geophysical methods is to image subsurface structures. Among these, electrical resistivity and electromagnetic (EM) methods are the most effective for detecting water qanats, as their responses depend on water and ion content. In this study, the electrical resistivity method ...
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One of the main goals of geophysical methods is to image subsurface structures. Among these, electrical resistivity and electromagnetic (EM) methods are the most effective for detecting water qanats, as their responses depend on water and ion content. In this study, the electrical resistivity method was used to reveal groundwater and locate qanats through profiling surveys with the Wenner array and three electrode spacings. Two-dimensional inverse models of resistivity data clearly indicated the qanat position by low resistivity, while three-dimensional modeling further defined the qanat and its conduit. The EM34 system, a reliable frequency-domain instrument for mapping subsurface conductivity, was also applied. EM profiling perpendicular to the qanat used both vertical and horizontal dipole modes. The obtained EM models identified the qanat location through high conductivity values. In the quasi-3D EM conductivity model, only traces of the qanat appeared due to contrasts between the conductivity of soil and the qanat conduit at various depths. Results show that the EM method requires less time and personnel than resistivity surveys. However, resistivity provides higher resolution and clearer details due to shorter electrode spacing and shallower data acquisition, whereas the EM34 system collects limited information from depths shallower than one or two meters. Overall, both methods successfully detected the qanat by contrasting electrical responses—high conductivity or low resistivity—demonstrating their complementary roles in subsurface water exploration.
F. Jamali; A.R. Arab Amiri; A. Kamkar Rouhani; A. Bahrami
Abstract
In any geophysical exploration, the final goal is to achieve an accurate image of the relevant underground property. In order to achieve this, the geophysical operation using the electrical resistivity and induced polarization (IP) methods is conducted to explore the sub-surface sulfide mineralization. ...
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In any geophysical exploration, the final goal is to achieve an accurate image of the relevant underground property. In order to achieve this, the geophysical operation using the electrical resistivity and induced polarization (IP) methods is conducted to explore the sub-surface sulfide mineralization. Considering the mineralization evidence in the Kaboudan area near the Bardeskan city, first, geophysical surveying of the polymetallic deposit is carried out using the electrical resistivity and IP methods by employing the rectangle array in order to detect the electrical anomalies in the area. Then for delineation of the identified anomalies and investigation of the mineralization in the area, the 2D resistivity and chargeability cross-sections are prepared and interpreted with the help of the geological information. This geophysical survey in the area has led to the identification of several potential areas for mineralization. Then in order to obtain a detailed picture of the sub-surface mineralization and an overview of the in-depth mineralization distribution, a 3D modeling of the acquired data is made, and the results of this modeling are shown in 3D forms. The mineralization zones are identified in the studied area from their high chargeability values as well as the low to medium electrical resistivity amounts. This can be attributed to the metal mineralization and the presence of sulfide minerals in the mineralization zones. Mineralization in many places of the studied area is determined with an approximate east-west trend as well as somewhat varying the intensities of the electrical resistivity and chargeability amounts. The geological and drilling information obtained from the area confirm the interpretations.
