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ASTER Data Processing by Discrete Wavelets Transform and Band Ratio Techniques for the Identification of Lineaments and Hydrothermal Alteration Zones in Poli, North Cameroon

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Journal of Geoscience and Environment Protection 2023年第9期11卷 216-232页

作者： Mohamadou Ahamadou May Nome Stella meying arsène School of Geology and Mining Engineering University of Ngaoundéré Ngaoundéré Cameroon Centre for Geological and Mining Research Garoua Cameroon

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.

关键词： Discrete Wavelets Transform Band Ratio Lineaments Hydrothermal Alteration

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Study of the Geothermal Potential of the Locality of Kaladi and Its Surroundings (Adamawa-Cameroon) from the Frequency Processing of Magnetic Data

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International Journal of Geosciences 2022年第11期13卷 1024-1039页

作者： Ndam Njikam Mohamed Moustapha meying arsène Zanga Amougou Alain Abdou Raouf Nkemndem Agendia Demianus School of Geology and Mining Engineering University of Ngaoundere Ngaoundere Cameroon Department of Physics Faculty of Sciences University of Douala Douala Cameroon Research Center for Deep Ocean Science and Underwater Engineering School of Resources and Geosciences China University of Mining and Technology (CUMT) Xuzhou China Department of Geography University of Buea Buea Cameroon

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 (Zt), center (Z0) and bottom (Zb 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/m2 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.

关键词： Spectral Analysis Curie Point Depth Heat Flow Geothermal Gradient

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2.5D Modelling of Aeromagnetic Data and their Mining Implications over the Ngaoundere Area (Adamawa Province, Cameroon)

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International Journal of Geosciences 2019年第2期10卷 173-192页

作者： meying arsène Gouet Daniel Hervé Ndougsa Mbarga Theophile Ndam Njikam Mouhamed Owono Amougou Olivier Ulrich Igor School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Department of Petroleum Mining & Groundwater Resources Exploration Faculty of Mines and Petroleum Industries University of Maroua Maroua Cameroun Department of Physics Advanced Teacher’s Training College University of Yaoundé I Yaoundé Cameroon Postgraduate School of Science Technologies & Geosciences University of Yaoundé I Yaoundé Cameroon

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.

关键词： Aeromagnetic Data Analytical Methods Faults Mineralization 2.5D Modelling

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Evidences by Multiscale Analysis and 2D3/4 Models from the Magnetic Anomalies and Iron Mineralization (BIF) over the DJADOM-ETA Area, Southeastern Cameroon

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Open Journal of Earthquake Research 2020年第1期9卷 19-32页

作者： Justine Yandjimain Théophile Ndougsa-Mbarga arsène meying Paul Claude Ngoumou Postgraduate School of Sciences Technologies & Geosciences University of Yaoundé I Yaoundé Cameroon Department of Physics Advanced Teacher’s Training College University of Yaoundé I Yaoundé Cameroon Department of Applied Geophysics Geology and Mining Exploitation College University of Ngaoundéré Ngaoundéré Cameroon

The Magnetic method is one of the best geophysical techniques used to delineate subsurface structures. This study was conducted to investigate the basement faulting and ore mineralization into the overlying geological cover. The GEOSOFT v8.4 software was used to process the data. Upward continuation of the residual magnetic intensity map at various altitudes and the maxima of their horizontal gradient magnetic were used to highlight faults from shallow to deep, as well as, their dips and mineralization zones. The faults with the directions E-W, ESE-WNW and Ene-WSW are identified confirming the result of [1]. This study also reveals that, the layer is affected by faults propagating from the basement upwards into the cover. Our results added additional information to the knowledge of the geological structure and the mineral resources potential in the study area. Based on the 2D3/4 modeling, the Dja Fault (DF) is revealed and highlighted sub-area marked by a magnetite/or hematite dolerite, schist and sandstone blocks, which show strong magnetization. Specifically, in this area, models are made of BIF (bounded iron formation) and BIQ (bounded iron quartzite) as dominant minerals.

关键词： Aeromagnetic Anomalies Multiscale Mineralization (BIF (Bounded Iron Formation) BIQ (Bounded Iron Quartzite)) HMG (Horizontal Gradient Magnetic) Faults

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Aeromagnetic Data Modeling for Geological and Structural Mappings over the DJADOM-ETA Area, in the Southeastern Cameroon

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International Journal of Geosciences 2018年第6期9卷 354-370页

作者： Justine Yandjimain Théophile Ndougsa-Mbarga Marcelin Bikoro Bi-Alou arsène meying Postgraduate School of Sciences Technologies & Geosciences University of Yaoundé I Yaoundé Cameroon Department of Physics Advanced Teacher’s Training College University of Yaoundé I Yaoundé Cameroon Department of Earth Sciences Faculty of University of Maroua Maroua Cameroon Department of Applied Geophysics Geology and Mining Exploitation College University of Ngaoundéré Ngaoundéré Cameroon

The DJADOM-ETA area is in south-eastern of Cameroon, within the Congo Craton (CC) formations and composed of gneiss and amphibolite, migmatites and intrusive rocks. Few geophysical studies have been carried out over surrounding areas, but no investigation on the study area. The existence of aeromagnetic data covering the study area has motivated the application of a multiscale approach for tectonic features identification. The aim of this work is to interpret Aeromagnetic Data for Geological and Structural Mappings in the southeastern Cameroon. The GIS and GEOSOFT v8.4 softwares are used to treat data of Compagnie Minière du Cameroun getting in February 2012. The Tilt Angle method is used to delineate geological structures and to estimate the depth. The Euler’s Deconvolution method is used to estimate the specific depth of structural contacts. The presence of bifurcations, accompanied by virgations, leading to the occurrence of several faults. Principal lineaments are determined with the main direction being ESE-WNW and E-W for the minor lineaments. The study highlights two major faults: ESE-WNW and Ene-WSW, where the former dominates, what could be called the geological accident of ETA. The Euler’s Correlation and Tilt derivative contact map shows that most of the faults are vertical contacts. The geometrical description of this structure suggests an open synclinal transposed on vertical foliations: the major fault at the DJADOM axis is quasi-parallel to the Northern limit of the CC and parallel to the Sanaga Fault (SF) and the Central Cameroon Shear Zone (CCSZ). The features show a base strongly affected by tectonic which characterizes the transition between the zone from the CC and the belt from folds of the Pan-African. Also, the presence of the network characterizes the subsurface undulation in this study area: the intrusion of sandstone ochre quartz and schist of the Bek complex, the dolerite of the doleritic complex, and the silver micaschiste and ore quartzi

关键词： Tilt-Angle Euler Deconvolution Lineaments Djadom Fault

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near Surface Fractures Evidence from Audio-Magnetotelluric (AMT) Investigation in Ayos-Nguelemendouka Area (Eastern Cameroon)

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International Journal of Geosciences 2013年第2期4卷 480-493页

作者： arsène meying Théophile Ndougsa Mbarga Daniel Gouet Patrick Assembe Stéphane Department of Physics Advanced Teacher’s Training College University of Yaoundé Yaoundé Cameroun Department of Physics Faculty of Science University of Yaoundé Yaoundé Cameroun School of Geology Mining and Mineral Processing University of Ngaoundéré Ngaoundéré Cameroun

The current study deals with an interpretation of audio-magnetotelluric (AMT) data collected in the Ayos/Nguelemendouka area, using a Stratagem EH4 unit. The study’s objective is to provide a better understanding of the area’s subsurface structure. Thus, AMT soundings were realised through seven profiles ne30° oriented, each profile made up of four stations. Data modelling highlights a SW-ne tectonic unevenness which seems to correlate with the Centre Cameroon Shear Zone. Moreover, this interpretation put into evidence an uplift of the basement at Lamba 2, a tabular structure at depth and an absence of discontinuities beneath 300 mdepth.

关键词： AMT Sounding Tectonic Unevenness Stratification Uplift Discontinuities

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Clay Minerals Channels Identification in the Tindikala-Boutou Area (Eastern-Cameroon) along the Kadey River Using Direct Current (DC) Method

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Journal of Geoscience and Environment Protection 2015年第6期3卷 123-133页

作者： Daniel Hervé Gouet arsène meying Stéphane Patrick Assembe Théophile Ndougsa-Mbarga Department of Petroleum and Gas Explorations Institute of Mines and Petroleum Industries University of Maroua Maroua Cameroun Department of Applied Geophysics Geology and Mining Exploitation College University of Ngaoundéré Ngaoundéré Cameroun Department of Physics Faculty of Science University of Yaounde I Yaoundé Cameroon Department of Physics Advanced Teacher’s Training College University of Yaounde I Yaoundé Cameroon

To achieve the current study, geoelectrical surveys along six (06) profiles of 4 km long in a 100 m × 200 m grid defined according to the triangulation principle in the Tindikala-Boutou (Eastern-Cameroon) area along the Kadey River have been made through electrical sounding and profiling following Schlumberger array. The instrument is the resistive meter Syscal Junior 48 (IRIS Instrument). The data have been processed and modelled with Res2Dinv and Winsev softwares, and then interpolated with Surfer software. Investigation method used is the Direct Current (DC) method. Interpretations and analyses of results from the investigation method highlight weak zones or conductive discontinuities. The latter has been identified as shear zones within granitic structures of the Precambrian basement, according to the geologic and tectonic background of the area. The structural trend of these shear zones is E-W approximately. The mineralization characterized by conductive zones proves the presence of clay minerals disseminated in weathered quartz vein, which cross the shear zones. The intense activities of gold washers encountered in the studied area are able to attest the presence of clay minerals concentrations.

关键词： Geoelectrical Surveys Direct Current Method Resistivity Shear Zones Clay Minerals

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Geoelectrical Inversion Study of Limestone Attributes at Mayo Boki Area (Northern Cameroon)

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International Journal of Geosciences 2014年第8期5卷 816-825页

作者： Theophile Ndougsa-Mbarga Quentin Yene-Atangana Joseph William Teikeu Assatsé arsène meying Pactrick Assembe Stéphane Department of Earth Sciences Faculty of Science University of Yaoundé I Yaoundé Cameroon Department of Physics Advanced Teachers’ Training College University of Yaoundé I Yaoundé Cameroon Department of Physics Faculty of Science University of Yaoundé I Yaoundé Cameroon School of Geology and Mining Exploitation College University of Ngaounderé Ngaounderé Cameroon

A geoelectrical survey using the electrical resistivity method was carried out in the Mayo Boki (Northern Cameroon), to investigate the subsurface layering and evaluation of the limestone characteristics. In addition to geological data collection, three vertical electrical soundings and one electrical resistivity profile were measured. Joint interpretation of the DC data allows us to obtain reliable 1D models of the resistivity distribution. The interpretation of the field data was carried out using the RES2DINV software, which converts the apparent resistivity as a function of electrode spacing to the true resistivity as a function of depth in two dimensions. The results obtained from the electrical resistivity survey showed that: 1) A limestone layer was put in evidence at a depth of 4 m and the thickness varies from 13 m to 44 m;2) The limestone layer resistivity is ranged from 125 to 2410 ohm.m;3) An area of probable limestone deposit with interesting thicknesses have been identified. These facts are useful for future mining exploration as drilling map definition and operations. The geologic section of a nearby location termed resistivity profile was delineated and its total depth was found to be 57 m, which corroborates the lithologs of the boreholes from the area. The correlation of geological data and the geoelectric section has led to envisage pursuing exploration activities. Based on the limestone layer characteristics extracted from this DC investigation, the exploration drilling operations have to be initiated in order to define the limestone resource over the area of study, which will certainly enables to built the exploitation project prefeasibility document.

关键词： Geoelectrical Method 1D Model Resistivity Limestone Mayo Boki Cameroon

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Combined Geoelectrical Approach DC and IP Methods in the Identification of the Mineralized Bodies Parallel to the ne-SW Tectonic Line of Kadei River: Case of Quartz or Pegmatite Gold Bearing Veins of Ngoura Subdivision (East Cameroon)

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International Journal of Geosciences 2016年第7期7卷 891-903页

作者： Daniel Hervé Gouet Stéphane Patrick Assembe arsène meying Marcelin Bikoro Bialou Josué Kalaza Haskandi Théophile Ndougsa-Mbarga Department of Petroleum and Gas Explorations Institute of Mines and Petroleum Industries University of Maroua Maroua Cameroun Department of Physics Faculty of Science University of Bamenda Bambili Cameroon Department of Applied Geophysics Geology and Mining Exploitation College University of Ngaoundéré Ngaoundéré Cameroon Department of Earth Sciences Faculty of Science University of Maroua Maroua Cameroun Department of Earth Sciences Faculty of Science University of Ngaoundere Ngaoundere Cameroon Department of Physics Advanced Teacher’s Training College University of Yaounde I Yaounde Cameroon

A geophysical investigation of subsurface structures using the Syscal Junior 48 resistivity-meter was conducted in Ngoura subdivision (East Cameroon) following a combined geoelectrical direct current (DC) approach involving Resistivity and IP methods. This investigation was allowed to collect data on forty-five (45) profiling lines at three acquisition levels (AB = 100 m, MN = 10 m;AB = 200 m, MN = 20 m and AB = 500 m, MN = 50 m) and two electric panels L1 and L4, using the Schlumberger array. Processing, modeling and interpretation of data collected using the Winsev, Res2Dinv and Surfer software helped in highlighting a conductive and strongly mineralized discontinuity in granite formations, which lined up with the ne-SW Kadei tectonic line. It extends beyond 100 m depth over an average width of 600 m. The mineralization associated with this discontinuity is identified by a high concentration of disseminated metalliferous minerals in quartz or pegmatite veins. The mining reconnaissance works in the study area and those of several authors have characterized this anomaly to a lode gold quartz or large pegmatite. The results of this study correlate with geological and tectonic data for the region marked by ne-SW Kadei tectonic line. Therefore, they confirm the reliability of a geoelectrical DC investigation method combining Resistivity and IP to the identification of ore bodies.

关键词： Geoelectrical Investigation Direct Current IP Method Resistivity ne-SW Tectonic Line Mineralized Body Conductive Area

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Gold Mineralization Channels Identification in the Tindikala-Boutou Area (Eastern-Cameroon) Using Geoelectrical (DC &IP) Methods: A Case Study

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International Journal of Geosciences 2013年第3期4卷 643-655页

作者： Daniel Hervé Gouet Theophile Ndougsa-Mbarga arsène meying Stéphane P. Assembe Alphonse D. Man-Mvele Pepogo Department of Applied Geophysics Geology and Mining Exploitation College University of Ngaoundéré Ngaoundéré Cameroun Department of Earth Sciences Faculty of Science University of Yaoundé I Yaoundé Cameroon Department of Physics Advanced Teacher’s Training College University of Yaoundé I Yaoundé Cameroun Department of Physics Faculty of Science University of Yaoundé I Yaoundé Cameroun

To achieve the current study, geoelectrical surveys along six (06) profiles of 4 km long in a 100 m × 200 m grid defined according to the triangulation principle in the Ngoura area (Tindikala-Boutou villages) have been made through electrical sounding and profiling following Schlumberger array. The instrument is the resistivimeter Syscal Junior 48 (IRIS Instrument) which uses the electrical current. The data have been processed and modelled with Res2Dinv and Winsev softwares then interpolated with Surfer software. Electrical methods used are the Direct current (DC) and the Induced Polarization (IP). Interpretation and analyses of results from each investigation method highlight weak zones or conductive discontinuities and mineralized zones. Conductive zones have been identified as shear zones within granitic structures of the Precambrian basement, according to the geologic and tectonic background of the area. The structural trend of these shear zones is E-W. The mineralization within it is N-S and characterized by high values of chargeability, essentially in the eastern part of the area under study. This mineralization proves the presence of metalliferous or sulphide heaps disseminated in weathered quartz veins which cross shear zones. Also, the poor mineralization and conductive structures in shear zones characterize the groundwater zones. The intense activities of gold washers encountered in the area enable to link that mineralization to gold within quartz veins. The near surface gold mineralization is eluvial or alluvial, and in depth this mineralization is primary.

关键词： Geoelectrical Surveys Direct Current IP Method Resistivity Chargeability Shear Zones Gold Mineralization

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