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The renewed interest in the reactivation of the defunct National Konongo Gold Mine located in the Ashanti Greenstone Belt, calls for a further probe into its geology and the associated mineral hosting structures to discover its mineralization potential. In order to achieve this, airborne magnetic, radiometric and electromagnetic datasets were interpreted to determine the potential gold hosting features in the studied area. The results show the area to consist of the metasediment, the metavolcanic, Tartwaian Formation and their associated granitoids. Results also show that the Tarkwaian sediments, observed largely in the north-eastern side of the site; widen out substantially and truncate in the south. The analysis of the structure lineaments using a rose diagram reveals three main tectonic structures trending in N-S, NNW-SSE, and third the structure trending in the NNE-SSW to NE-SW directions in the area. The dominant structures in the area, form 90% of all the delineated structures and trend in the NE-SW and NNE-SSW direction with the remaining 10% trending in the N-S and NNW-SSE. These structures are associated with the major shear and fracture zones located mainly at the contact between the basin sediments and volcanic belt and also associated with the Tarkwaian Formation. The mapped potential gold mineralization zones located mainly at the contact between the metasediment and the metavolcanic units of the Birimian Supergroup, as well as the Tarkwaian Formation, were mapped by integrating the structures, alteration zones as well as the complex dyke systems. This paper delineates the prominent geological structures with the potential of hosting economic gold mineralization in and around the Konongo Gold Mine.

The discovery of oil in commercial quantity in Ghana has led to increase in infrastructural development to provide the needed services to the oil industry. The siting of these industries requires the characterization of the subsurface to determine its suitability to host these facilities. It is in this line that seismic refraction and geo-electrical surveys were conducted on a site near Takoradi, Ghana that has been planned to host a generator and its appurtenances for the oil industry. The objective of the survey was to provide subsurface information critical for the design of earthing system for the proposed generator plant and its appurtenances. The ABEM SAS4000 Terrameter with the Lund imaging system and a 24-channel ABEM Terraloc MK6 were respectively used for the electrical and seismic refraction data collection. The seismic refraction and resistivity results identify three lithological units namely, dry gravel, sand and silty clay layer, water saturated sand and silty clay layer and granodiorites basement rocks. The first layer has a thickness of 10 m and the second layer with thickness in the range of 5 to 10 m. The lithological classifications as obtained from these results correlate with the drill logs. Electrical grounding will be suitable at a depth of 10 m beneath resistivity profile two at a distance between 32 to 52 m.

Non-invasive geophysical investigation using magnetic gradiometry, magnetic susceptibility survey and electrical resistivity tomography (ERT) was carried out on the Sunyani Municipal Assembly (SMA) solid waste disposal (SWD) site. The study was aimed at delineating the physical boundaries and the area extent of the waste deposit, mapping the distribution of the waste at the site, detecting and delineating zones of leachate contamination and its preferential migration pathways beneath the waste deposit and its surroundings. The results of both magnetic susceptibility and gradiometric methods displayed in anomaly maps clearly delineated the physical boundaries of the waste deposit with an approximate area extent of 82,650 m2 that are characterised by high magnetic susceptibilities between 426 × 10−5 SI and 9890 × 10−5 SI. They also revealed high magnetic anomalies erratically distributed within the waste deposit attributable to its heterogeneous and uncontrolled nature. The high magnetic anomalies outside the designated waste boundaries were also attributed to indiscriminate deposition of the waste. Similarly, the ERT sections delineated and characterised zones of leachate contamination beneath the waste body and its close surroundings as well as pathways for leachate migration with low resistivity signatures up to 43.9 Ωm. In spite of the successes reported herein using the ERT, this research also revealed that the ERT is less effective in estimating the thickness of the waste deposit in unlined SWD sites due to leachate infiltration into the ground beneath it that masks the resistivities of the top level ground and makes it indistinguishable from the waste body.

Geophysical datasets namely electrical resistivity, induced polarization, magnetic susceptibility were measured and aeromagnetic interpreted on the Subika concession of Newmont Ghana Gold Limited in order to delineate and model the zone of gold mineralization. The electrical resistivity and induced polarization results delineated the gold mineralized zone as a narrow discrete resistor (>4900 Ωm) and high chargeability (>7.2 ms) zone with a strike length of about 2 km. A strip log plots of twelve diamond drilled core samples showed the zone of mineralization with high alteration and low magnetic susceptibility. Analysis of laboratory magnetic susceptibility measured on selected samples from the pit and selected core samples from the mineralized zones showed a negative correlation between the magnetic susceptibility and gold grades with a correlation coefficient of -0.2 and -0.74 respectively. Similarly, magnetic depthslice produced from 3D model of the aeromagnetic data depicts the zone of gold mineralization with low magnetic signature. The zone mineralization was also observed to be striking in the north-east direction. Mineralogical analyses of rock samples revealed alteration processes such as carbonitization, sericitization, silicification, chloritization and sulphidation resulting from hydrothermal alteration which accounted for the low magnetic and the magnetic susceptibility signatures of the mineralization zones. The strong resistivity and chargeability response of the mineralized zones are therefore attributed to the silicification and sulphidation alteration respectively. The results show the effectiveness of applying integrated geophysical, petrophysical as well as minerological study in revealing gold mineralization potential of the Subika deposit and the Sefwi belt as a whole.

In this paper, the southern Kibi-Winneba belt, which shares geological resemblance with the renowned Ashanti belt in Ghana has been investigated to delineate prospective zones of gold mineralization occurrences. The generation of a mineral prospectivity map (MPM) for the study area comprised the integration of nine (9) exploration layers obtained from geological, remote sensing and geophysical datasets based on the Fuzzy analytical hierarchy process (FAHP) approach and geographical information systems (GIS). The employability of the FAHP in the assignment of weight to the nine (9) evidential layers based on their comparative importance with respect to the mineral being sought (which is gold in this study) was carried out by experts in remote sensing and geophysical techniques for mineral exploration. The weights of the evidential layers were subsequently normalized and integrated to produce an MPM of gold deposits within the study area based on a fuzzy operator of γ = 0.9 in GIS. For an elaborate evaluation of the MPM, the concentration-area (C-A) fractal model was employed to classify the generated MPM to obtain 6 thresholds for the generation of a final MPM for the study area. Further evaluation of the MPM was carried out by the prediction-area (P-A) plot based on 15 locations of known gold occurrences, with results obtained predicting that 25% of the study area as prospective regions of gold deposits, within which 75% of the known gold occurrences have been delineated.

Airborne magnetic and radiometric datasets are used to interpret the geology and geological structural patterns which serve as potential gold mineralization zones in the Kyerano area located at south-western boundary of the prospective Sefwi Gold Belt and the Kumasi Basin in south-western Ghana. The geophysical data processing approach adopted concentrated on mapping geological boundaries, geological structures and possible gold mineralization zones is link to hydrothermally altered zones. The application of the enhancement filtering algorithms such as the reduction to the pole and analytic signal to the magnetic data, as well as the ternary radiometric image aided in the mapping of the mafic metavolcanics, basin metasediments and the belt-type granitoid complexes. The first vertical derivative and tilt angle derivative filters helped to delineate fractures, folds, and the contact zones of the formations such as that of the metavolcanics-metasediments that host the main Bibiani Shear Zone. Lineament analysis of the structures using rose diagram, reveals two main tectonic episodes in the area. These are NE-SW and NNW-SSE trending regional structures which account for about 90% of the extracted structures and are associated with the D1 and D2 deformational episodes of the Birimian Formation respectively. These structures are major fracture systems and play a pivotal role in the localization of gold mineralization in the study area.

Time-domain induced polarisation and magnetic data were acquired to map and characterise the decommissioned and un-engineered municipal solid waste disposal site of the Kwame Nkrumah University of Science and Technology, located in the Kumasi Metropolis of Ghana. In this survey, 13 induced polarisation profiles 500–800 m long and 26 magnetic profiles 400–800 m long were acquired. In addition, two boreholes were drilled to help in the interpretation of the geophysical data. The study was carried out with the aim of determining the risk posed by the waste deposit to the quality of the soil and the ground water system, which is the main potable water supply for the Secondary School, the University Teaching Hospital and the Veterinary School, situated within the catchment area of the site. Full-decay 2-D time-domain induced polarisation inversions in terms of Cole–Cole parameters were used for interpreting the induced polarisation data. The chargeability, resistivity and normalised chargeability distributions, together with the magnetic results, aided in a full characterisation of the site geology, the waste and the associated pollution plume. In particular, clear contrasts in resistivity and the polarisation parameters were found between the saprolite layer and the granitic bedrock, which are the main lithological units of the area. Furthermore, it was found that the Kwame Nkrumah University of Science and Technology waste deposit is characterised by a low-chargeability and low-resistivity signature and that the low-resistivity area spreads out from the waste deposit into the permeable saprolite layer, indicating the presence of a leachate plume. A fracture zone in the granitic bedrock beneath the waste deposit, which is a potential conduit for leachate contamination of the ground water system, was also identified. The study thus provides the information needed for assessing the future impact of the waste on the water quality in the area and for designing risk-mitigation actions.

Environmental pollution from solid waste landfilling is a serious risk for groundwater and downstream surface water, especially when landfilling is carried out unengineered, with no protective layer underneath the waste deposits. Most research in Ghana and in other developing countries on unengineered landfills depend almost exclusively on hydrochemical and geochemical analysis, which is not necessarily representative of the entire dumpsite catchment area. For this reason, integrated and cost effective geophysical methods, namely DC electrical resistivity, full waveform time-domain induced polarization and ground based magnetic measurements were employed to map and characterize four dumpsites in the Kumasi Metropolis, the seconds most populated city in Ghana. The results of one site, namely the decommissioned Ohwim waste dumpsite, are presented. The magnetic surveys helped in the mapping of the lateral extent of the waste deposit. The DC /full wave induced polarization tomography on the other hand mapped the vertical extent of the dumpsite and characterized the hosting geology. Furthermore, some regions were identified, where a pollution plume is likely to be present.