This study is based on the analysis and interpretation of aeromagnetic data using version 8.4 of the Geosoft Oasis Montaj Software, to map the subsurface or deep geological structures that affected the geological form...This study is based on the analysis and interpretation of aeromagnetic data using version 8.4 of the Geosoft Oasis Montaj Software, to map the subsurface or deep geological structures that affected the geological formations of the Ngaoundere area. The use of the standard aeromagnetic methods made it possible to draw up the maps of the residual magnetic field reduced to the equator (RTE), the horizontal gradient (HG), the analytical signal (AS) and that of the Euler solutions (ED) to find the main magnetic facies corresponding to these structures. The geological formations of the studied area thus appear to be intensely fractured by a NE-SW (N45°E) and ENE-WSW (N70°E) main orientation fault system, the depth of which has been estimated by combining the three-analytical methods HG, AS and ED. Advanced magmatic map analysis revealed dikes associated with vertical faults in the studied area. The development of an interpretative geological map taking into account the basic geology, the deep faults, the identified dikes and the mineralization index made it possible to extract a correlation between geological structures and mineralization of the studied area. The 2.5D modelling of two magnetic profiles plotted on the reduced residual map at the equator was performed to approximate the geometry and depth of the dikes sector, which are potential sources of mineralization here.展开更多
The aim of this study is to carry out hydrothermal alteration mapping and structural mapping using ASTER images in order to identify indices that could guide mining exploration work in the Poli area and its surroundin...The aim of this study is to carry out hydrothermal alteration mapping and structural mapping using ASTER images in order to identify indices that could guide mining exploration work in the Poli area and its surroundings. To achieve this, the ASTER images were first preprocessed to correct atmospheric effects and remove vegetation influence. Secondly, a lineament mapping was conducted by applying Discrete Wavelet Transform (DWT) algorithms to the First Principal Component Analysis (PCA1) of Visible Near-Infrared (VNIR) and Shortwave Infrared (SWIR) bands. Lastly, band ratio methods were applied to the VNIR, SWIR, and Thermal Infrared (TIR) bands to determine indices of iron oxides/hydroxides (hematite and limonite), hydroxyl-bearing minerals (chlorite, epidote, and muscovite), and the quartz index. The results obtained showed that the lineaments were mainly oriented NE-SW, ENE-WSW, and E-W, with NE-SW being the most predominant direction. Concerning hydrothermal alteration, the identified indices covered almost the entire study area and showed a strong correlation with lithological data. Overlaying the obtained lineaments with the hydrothermal alteration indices revealed a significant correlation between existing mining indices and those observed in the field. Mineralized zones generally coincided with areas of high lineament density exhibiting significant hydrothermal alteration. Based on the correlation between existing mining indices and the results of hydrothermal and structural mapping, the results obtained can then be used as a reference document for any mining exploration in the study area.展开更多
The aim of this study is to estimate the variations in curie point depth, geothermal gradient and heat flux from the frequency analysis of magnetic data in order to evaluate the geothermal potential of the Kaladi loca...The aim of this study is to estimate the variations in curie point depth, geothermal gradient and heat flux from the frequency analysis of magnetic data in order to evaluate the geothermal potential of the Kaladi locality and its surroundings. For this purpose, the magnetic field map was first reduced to equator (RTE). The centroid method was used to divide the RTE grid into a set of 40 blocks. The spectral analysis applied to each block allowed determining the depth to top (Z<sub>t</sub>), center (Z<sub>0</sub>) and bottom (Z<sub>b</sub><sub> </sub>also called curie point depth or CPD) of the magnetic sources. Knowing the different CPD, the geothermal gradient associated with each block was calculated. The heat flow was then calculated from the geothermal gradient associated with the anomaly block considered. From the set of values obtained for each block, maps of geothermal gradient and heat flow variations were established. Analysis of these maps shows that the sectors that could be favourable for geothermal exploration are the north of Kaladi and the Goro-Bembara corridor, because they show variations in the geothermal gradient and heat flow between 0.4 and 0.8℃/m and between 1.2 and 2 mW/m<sup>2</sup> respectively. In addition, the superposition of the different hot springs highlighted in previous studies with areas of high geothermal gradient and heat flow values supports this analysis. The proposed models can be used as background documents for any geothermal exploration project in the study area.展开更多
文摘This study is based on the analysis and interpretation of aeromagnetic data using version 8.4 of the Geosoft Oasis Montaj Software, to map the subsurface or deep geological structures that affected the geological formations of the Ngaoundere area. The use of the standard aeromagnetic methods made it possible to draw up the maps of the residual magnetic field reduced to the equator (RTE), the horizontal gradient (HG), the analytical signal (AS) and that of the Euler solutions (ED) to find the main magnetic facies corresponding to these structures. The geological formations of the studied area thus appear to be intensely fractured by a NE-SW (N45°E) and ENE-WSW (N70°E) main orientation fault system, the depth of which has been estimated by combining the three-analytical methods HG, AS and ED. Advanced magmatic map analysis revealed dikes associated with vertical faults in the studied area. The development of an interpretative geological map taking into account the basic geology, the deep faults, the identified dikes and the mineralization index made it possible to extract a correlation between geological structures and mineralization of the studied area. The 2.5D modelling of two magnetic profiles plotted on the reduced residual map at the equator was performed to approximate the geometry and depth of the dikes sector, which are potential sources of mineralization here.
文摘The aim of this study is to carry out hydrothermal alteration mapping and structural mapping using ASTER images in order to identify indices that could guide mining exploration work in the Poli area and its surroundings. To achieve this, the ASTER images were first preprocessed to correct atmospheric effects and remove vegetation influence. Secondly, a lineament mapping was conducted by applying Discrete Wavelet Transform (DWT) algorithms to the First Principal Component Analysis (PCA1) of Visible Near-Infrared (VNIR) and Shortwave Infrared (SWIR) bands. Lastly, band ratio methods were applied to the VNIR, SWIR, and Thermal Infrared (TIR) bands to determine indices of iron oxides/hydroxides (hematite and limonite), hydroxyl-bearing minerals (chlorite, epidote, and muscovite), and the quartz index. The results obtained showed that the lineaments were mainly oriented NE-SW, ENE-WSW, and E-W, with NE-SW being the most predominant direction. Concerning hydrothermal alteration, the identified indices covered almost the entire study area and showed a strong correlation with lithological data. Overlaying the obtained lineaments with the hydrothermal alteration indices revealed a significant correlation between existing mining indices and those observed in the field. Mineralized zones generally coincided with areas of high lineament density exhibiting significant hydrothermal alteration. Based on the correlation between existing mining indices and the results of hydrothermal and structural mapping, the results obtained can then be used as a reference document for any mining exploration in the study area.
文摘The aim of this study is to estimate the variations in curie point depth, geothermal gradient and heat flux from the frequency analysis of magnetic data in order to evaluate the geothermal potential of the Kaladi locality and its surroundings. For this purpose, the magnetic field map was first reduced to equator (RTE). The centroid method was used to divide the RTE grid into a set of 40 blocks. The spectral analysis applied to each block allowed determining the depth to top (Z<sub>t</sub>), center (Z<sub>0</sub>) and bottom (Z<sub>b</sub><sub> </sub>also called curie point depth or CPD) of the magnetic sources. Knowing the different CPD, the geothermal gradient associated with each block was calculated. The heat flow was then calculated from the geothermal gradient associated with the anomaly block considered. From the set of values obtained for each block, maps of geothermal gradient and heat flow variations were established. Analysis of these maps shows that the sectors that could be favourable for geothermal exploration are the north of Kaladi and the Goro-Bembara corridor, because they show variations in the geothermal gradient and heat flow between 0.4 and 0.8℃/m and between 1.2 and 2 mW/m<sup>2</sup> respectively. In addition, the superposition of the different hot springs highlighted in previous studies with areas of high geothermal gradient and heat flow values supports this analysis. The proposed models can be used as background documents for any geothermal exploration project in the study area.
