A geological based remote sensing study was carried out over the Poli group in Garoua (northern Cameroon), renowned for its hydrothermally occurring mineralizations (Gold and Uranium). In this study, Landsat 8 OLI/TIRS coupled with magnetic data were used in order to realize a regional litho-structural mapping of hydrothermal alteration targets, required for mineral exploration. Hence, the enhancement of both Landsat 8 and magnetic data was achieved via digital image processing (DIP) techniques notably Band rationing (BR), Principal Component Analysis (PCA), Horizontal gradient (HG), and lineament extraction algorithms. Based on reference band ratio combinations (Sultan's and Kaufmann's) and Crosta Technique (PCA analysis), hydrothermally altered minerals such as hydroxyl-bearing minerals and iron oxides were identified. The PCA map was shown to better illustrate hydrothermally altered areas than Band ratios. Thus, a classification map emphasizing on mineral targets was obtained from the PCA map. Besides, the CET grid analysis tool (horizontal gradient) from Geosoft software 8.4 and the line algorithm (pan band 8) from Geomatica 2013 allowed the extraction of subsurface and surface lineaments respectively. The resulting lineaments showed a predominant E-W trending direction, which suggests a major tectonic event having prevailed within the area. Other directions include NE-SW/ENE-WSW, and N-S. The generation of a target exploration map, via ArcGIS 10.4.1, was performed by the overlay of hydrothermal alteration mapping and structural mapping. New regional maps, providing a useful insight for further mining exploration, were obtained.

In mineral exploration, detailed hydrothermally altered minerals mapping is an important approach prior to the field campaign. The study area contains several gold‐bearing quartz veins associated with hydrothermally altered zones rich in sulphides, muscovite/sericite, iron oxides, and hydrous silica. In this study, Aster 07XT, Landsat 8, and aeromagnetic data were integrated to detect potential zones associated with gold mineralization in Northern Cameroon. For this purpose, the relative band absorption depth, band ratioing, and analytic signal techniques were applied to enhance, identify and map hydrothermal alteration minerals, that is, hydroxyl‐bearing, iron oxide/hydroxide. In addition, a semi‐automatic approach was applied to extract remotely sensed and aeromagnetic lineaments from PCI Geomatica and Centre for Exploration Targeting Grid Analysis respectively. Hence, several potential mining targets were delineated from the processing of both remote sensing and aeromagnetic data. The major directions of the lineaments affecting the area include NE–SW/ENE–WSW, E–W, and N–S. Detailed field campaigns, petrographic analyses, and spectral measurements of rock samples were carried out in Tchollire and environs to verify the results from remotely sensed data. The analytical observations indicated the presence of quartz, epidote, chlorite, magnetite, haematite, sericite, galena, sulphide, telluride minerals, etc. Moreover, the target hydrothermal alteration zones were proved to be spatially associated with known mining areas and gold occurrences in the study area. Consequently, new prospective mining areas have been designated. This study confirmed the reliability and applicability of the processing of satellite imagery in mineral exploration in Northern Cameroon. It is suggested that the dataset used in this study provides a suitable tool for mapping hydrothermal alteration minerals linked to gold deposits and can be applied in other provinces with similar geological settings.

Shales in the reservoir causes complications for the petrophysicist because they generally are conductive and mask the high resistance characteristic of hydrocarbons. Data from a suite of well logs were used to estimate the effect of reservoir shaliness on petrophysical parameters of some reservoir rocks of the eastern Niger Delta Basin. The log section was digitized using Neuralog software. Delineation of the productive clean and dirty formations, as well as mapping of the fluid contents of the possible reservoir zones was carried out using Interactive Petrophysics software. Fifteen shaly sand bodies were identified. It was observed that, shale correction leads to a significant change in petrophysical parameters. The results obtained indicate that, the Simandoux and Indonesian models used for the study are both suitable for water saturation, and hydrocarbon saturation analysis in shaly sands of this part of the Basin. The porosity results for the Indonesian and Simandoux models gave, respectively 0.14-0.23 and 0.22-0.28, while the hydrocarbon saturation results are 0.650-0.908 and 0.650-0.911 with permeabilities values of 1487.442-8881.697 mD and 1568.532-7451.592 mD for uncorrected and corrected permeability, respectively. Thomas-Stieber model shows that shale distribution in sands of the eastern Niger Delta Basin is mainly structural with few of disperse and laminar ones.

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Groundwater is the major water reserve in the present context of global warming-related droughts that appear to be more intense in hard rock terrains. The use of Geographical Information Systems (GIS) and Remote Sensing (RS) technologies are increasingly beneficial to groundwater research, by allowing for low cost and larger-scale high-resolution mapping compared to conventional hydrogeological exploration methods. This study aimed at developing a high-resolution map of potential groundwater recharge (GWRpot) zones for the drought-stricken Banka hard rock terrain, straddling the Cameroon Volcanic Line (CVL). Shuttle Radar Tomography Mission (SRTM)-30m and Landsat 8 satellite images constituted the main data source that was ground-truthed through field mapping and used to produce various thematic GIS layers: geology slope, aspect, land use & land cover, drainage density and lineament density of spatial resolution 16m x 16m. The layers were each attributed a fixed score and weight to groundwater recharge, computed using Multi-Influencing Factor (MIF) and Analytical Hierarchy Process of Multi-Criteria Decision Analysis (AHP-MCDA) techniques. Lastly, a Weighted Overlay Analysis was done using the layers to produce the GWRpot zones for the study area. The resulting map shows that 60% of the study area, covering the south, west-northwest and the north-northeast portions of the map have moderate to very high recharge potentials. This result is particularly useful for groundwater targeting in the area and demonstrates the effectiveness of the method in hard rock terrains where traditional methods have been less efficient in properly delineating groundwater recharge zones. Article highlights Groundwater is generally the safest and most reliable source of water in water scarce environments, and forms when surface water goes into the ground. More areas where water can enter the ground means more chances of getting enough groundwater. Conventional ways of knowing these areas are time consuming and costly, whereas RS and GIS-based methods are less costly and use lesser time. We used the RS, GIS, high-resolution field mapping and statistical methods of blending several factors to produce the potential groundwater recharge zones on a part of the hardrocks of the CVL, that shows 60% of the study area, covering the south, west-northwest and the north-northeast portions of the area have moderate to very high recharge potentials.

Vertical electrical sounding was done at 47 points using an ABEM 1000 Terrameter and a set of cables that could probe up to a depth of 500m. Resistivity was determined in two sites located in the district of Douala III (Bomkoul and Ngoma) 6 km west of the main town on the left bank of the Wouri River. The choice of these neighbourhood is as a result on the one hand, the presence of clay deposits from which sections have helped to configure resistivity data with those of geoelectric sections, and on the other hand, by the ability to extend the measuring device over great distances without being hindered by urbanization. The depths of investigation range from a minimum of 30 m and a maximum of 120 m. The results show a wide variability in resistivity values throughout the study area; it may be related to the high variability of facies described on sections by diggers. This variability may be due to the complexity of deposits recorded in the Douala sedimentary basin and also because of the presence of water in both sandy and clay sediments due to climate. The suggested resistivity is between 20 and 600ohm.m for clays and greater than 1000 ohm.m for sand. Given the weak thickness of some layers, the cancellation phenomena that affect very thin layers between two layers of different geoelectric properties of the latter have been observed, thus assigning to clay layers, sand resistivity.