Research Articles (Geology)

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A collection containing some of the full text peer-reviewed/ refereed articles published by researchers from the Department of Geology

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Protracted emplacement and multi-stage evolution of the Kunene Complex (Angola and Namibia) revealed by multi-mineral U-Pb geochronology
Milani, Lorenzo; Ngomane, Glenance; Lekoetje, Thoriso; Bybee, Grant M.; Bolhar, Robert; O'Sullivan, Gary J.; Lehmann, Jeremie; Hayes, Ben; Owen-Smith, Trishya M. (Elsevier, 2026-09-15)
The Mesoproterozoic Kunene Complex of Angola and Namibia is the world’s largest massif-type anorthosite complex, and represents an exceptional area for studying the large-scale magmatic and thermal record of long-lived Proterozoic anorthosites. We examined evolved pegmatoidal enclaves and their host anorthosites from the central part of the complex to clarify their crystallisation sequence and investigate the magma emplacement dynamics and post-crystallisation thermal and metasomatic history. In combination with detailed petrography and mineral mapping, zircon, apatite and titanite were analysed for U-Pb isotope and trace element concentrations. Zircon dates for both the enclaves and the host anorthosites are ca. 1500 Ma, indicating contemporaneous crystallisation, but some zircon grains underwent coupled dissolution-reprecipitation, likely driven by high-temperature fluids related to protracted regional Kunene magmatism. The oldest age for one Kunene anorthosite, at 1510 ± 4 Ma, attests to a total duration for the magmatism reaching 150 Myr. Apatite also crystallised at ca. 1500 Ma as it mostly preserves magmatic textures and igneous trace element compositions, but records resetting ages of ca. 1400 Ma, corresponding with a subset of zircon dates and the crystallisation ages of secondary titanite, which may reflect a major Kunene magmatic pulse at this time. Overall, zircon age variability in single samples, combined with trace element decoupling, suggest localised post-crystallisation disturbance of the magmatic system. This study shows the contribution that multiple geochronological datasets from large igneous bodies can provide to explain prolonged histories of magma recharge, thermal rejuvenation and fluid-rock interaction. HIGHLIGHTS • Combined multi-mineral geochronology testifies to prolonged magmatic activity in the Kunene Complex, extending up to 150 Myr. • Anorthosite and pegmatoidal enclaves crystallised simultaneously, at ca. 1.5 Ga. • Protracted magmatism produced age decoupling and heterogeneous trace elements in zircon and apatite.
Topical collection : progress in groundwater investigation, monitoring and management in South Africa
Dippenaar, Matthys Alois (Springer, 2025-12)
Groundwater monitoring and management is becoming increasingly important in South Africa. This essay critically reviews the regulations of the South African National Water Act in the context of groundwater investigation, monitoring and management. The complexity of South African aquifers and groundwater management challenges are presented together with advances in policy development. The articles contained in this topical collection contribute to the verification of new techniques and ways forward to assist South Africa’s progress in groundwater investigation, monitoring and management.
Review and characterization of the 2014 Orkney damage datasets for damage pattern mapping and fragility curve construction
Nqasha, Thando; Akombelwa, Mulemwa; Singh, Mayshree; Kijko, Andrzej (Frontiers Media, 2025-01-07)
The 2014 Orkney earthquake caused significant damage to unreinforced masonry buildings in the surrounding townships. After the earthquake, field surveys were conducted to assess the extent of damage in the affected areas. This study reviews data collected from the 2014 Orkney earthquake to investigate damage patterns, evaluate building safety for occupancy, and support fragility curve construction. Damage was quantified based on the European Macroseismic Scale (EMS-98) to assess building safety and conduct regression analysis. The results indicate that the collected data is suitable for investigating damage patterns and determining building safety for occupancy. However, it is not suitable for constructing fragility curves. Empirical fragility curves are typically developed using logistic regression, but this study found the data unsuitable for regression analysis due to sampling errors and limited data quantity. This study recommends the use of first-order approximation methods to supplement the dataset, reducing sampling errors and increasing data quantity.
Petrogenesis of syenites at Phalaborwa, Kaapvaal Craton: (isotope) geochemical, modelling and age constraints
Bolhar, Robert; Maghdour-Mashhour, Reza; Milani, Lorenzo; Mondal, Suman; O'Sullivan, Gary J.; Klemd, Reiner; Chang, Qing (Elsevier, 2026-04)
Whole rock major and trace element data and apatite compositions (including Nd isotopes) for fifteen syenites from intrusions surrounding the Phalaborwa carbonatite-phoscorite Complex are presented to evaluate magmatic sources, processes, and also petrogenetic relationships across alkaline provinces in the Kaapvaal Craton. Thermodynamic modelling (alphaMELTS) of fractional crystallization assuming a gabbroic parental melt reproduces syenite compositions, involving early clinopyroxene and apatite removal, dominant K-feldspar crystallization with minor ilmenite and magnetite, and late biotite and quartz fractionation. Discrepancies between observed and modelled major element compositions (higher K₂O, Al₂O₃; lower CaO, Na₂O, P₂O₅) are explained by accumulation of K-feldspar (minor biotite and clinopyroxene) and dilution by apatite, plagioclase and Ti-oxides. Apatite displays zoning and high REE–Sr contents indicative of a magmatic origin. Minor and compositionally distinct apatite and unradiogenic εNd (2.06 Ga) (−1.4 to −12.0) imply assimilation of granitic/gneissic basement in some syenites. For most syenites, however, mixing models using suitable endmembers do not reproduce whole rock compositions. LA-SF-ICP-MS U-Pb ages of zircon, titanite, rutile and monazite range from 2.03 to 1.86 Ga. Titanite and rutile ages (1936 ± 24 Ma, 1860 ± 65 Ma, 2 SE) record post-emplacement hydrothermal alteration. Only one monazite age of 2032 ± 9 (2 SE) Ma likely dates magmatic emplacement, slightly post-dating emplacement of the 2060 Ma carbonatite-phoscorite complex, but coeval with mafic dyke intrusions. Imprecise zircon upper-intercept ages (2.5–1.9 Ga) and petrographic features in zircon, titanite and rutile are ascribed to hydrothermal alteration by fenitizing fluids or thermal overprinting related to dyke emplacement. We propose a model whereby alkaline melts at Phalaborwa were (partly) derived from metasomatically-enriched subcontinental lithospheric mantle (SCLM). Mantle (re)fertilization likely began during a 2.9–2.8 Ga subduction event and continued with a major ∼2.0 Ga hydrous metasomatic episode. A shared SCLM signature among several Kaapvaal alkaline complexes therefore registers (plume-induced?) melting of a subduction-metasomatized lithospheric mantle as an important crust formation process at 2 Ga.
Facies architecture, depositional environments, and organic matter enrichment of the Mamu Formation on the western flank of the Anambra Basin, Nigeria
Oluwajana, Oladotun; Adebambo, Bamidele; Opatola, Abraham; Ehinola, Olugbenga; Johnson, Temitayo; Omietimi, Erepamo Job; Olawuyi, Gabriel; Afolabi, Akinwande; Olowa, Folakemi (Elsevier, 2026-07)
Coal-bearing strata of the Maastrichtian Mamu Formation on the western flank of the Anambra Basin are widely recognised. Yet, the controls on facies variability, organic matter enrichment, and reservoir distribution remain poorly resolved. This study integrates detailed sedimentological logging, agglutinated foraminiferal assemblages, and inorganic geochemical proxies from representative outcrops to reconstruct depositional environments and sequence stratigraphic architecture. Eight lithofacies are grouped into swamp, tidally influenced estuarine, estuarine mudflat, bay-fill delta, and braided fluvial facies associations. Vertical stacking patterns and key stratigraphic surfaces define a complete LST-TST-HST succession comprising lowstand peat-forming coastal mires, retrogradational estuarine deposits capped by an Ammobaculites-rich maximum transgressive interval, and highstand bay-fill delta to braided fluvial progradation. Geochemical proxies indicate brackish estuarine conditions with strong terrigenous influx, predominantly oxygenated bottom waters, and reducing pore-water conditions favourable for organic matter preservation. Organic enrichment reflects estuarine restriction, sediment dilution, and early diagenetic recycling rather than persistent anoxia. By integrating facies architecture, micropalaeontology, and redox-salinity proxies, this study establishes the high-resolution sequence stratigraphic model for the western flank of the basin and clarifies the paleoenvironmental controls on organic matter enrichment. Coal seams and Ammobaculites-bearing shales constitute potential gas-prone source rocks, whereas braided-channel sandstones represent the most prospective reservoirs. The proposed model provides a predictive framework for reservoir and source-rock distribution and reduces exploration uncertainty in this underexplored sector of the Anambra Basin. HIGHLIGHTS • Integrated facies, geochemistry, and foraminifera refine basin evolution. • LST-TST-HST succession defined for western Anambra Basin. • Coal mires formed during lowstand under freshwater–brackish conditions. • Maximum transgression marked by Ammobaculites-rich estuarine muds. • Coal and shale are gas-prone sources; braided sands are key reservoirs.
Baseline data on selenium micronutrient concentration in parts of Southern Nigeria show provenance and paleodepositional controls
Edegbai, Aitalokhai J.; Owonaro, Jennifer B.; Pajiah, Jubemi A.; Omietimi, Erepamo Job; Lenhardt, Nils; Ukpebor, Justina E. (Springer, 2026-03)
This study evaluates the Se concentration and examines the geologic controls on Se concentration in Upper Cretaceous and Palaeogene mudrocks in parts of Southern Nigeria. Geochemical analysis [(major and trace elements, total organic and inorganic carbon (TOC and TIC)] and pH measurements were conducted on seventy-three mudrock outcrop samples from the estuarine Late Campanian to Mid-Maastrichtian Mamu Formation and ditch cuttings from water wells that penetrated the marine Palaeogene Imo Formation from the Anambra basin and Niger Delta basin in the Southern Benue Trough. Selenium concentration in the Palaeogene calcareous marine mudrock samples reaches up to 21 ppm, significantly exceeding data observed in the Upper Cretaceous estuarine mudrock samples. Covariation charts suggest that Se adsorption onto clay, Fe-minerals, and limited sorption by organic matter in the estuarine mudrock samples are compared to adsorption onto clays, calcite, and very limited sequestration by Fe-minerals observed in the calcareous marine mudrocks. Principal component analysis and redundancy analysis reveal a dominant influence of carbonate minerals on selenium sequestration. Additionally, the Palaeogene calcareous marine mudrock samples are less acidic (mean pH 5.92) than the Upper Cretaceous estuarine mudrocks with a mean pH of 5.02. Therefore, it is hypothesized that higher pH may slightly promote the bioavailability of Se, resulting in higher Se intake by plants in areas underlain by the Palaeogene calcareous mudrocks.
Quantifying baseflow with radon, H and O isotopes and field parameters in the urbanized catchment of the little Jukskei River, Johannesburg
Diphofe, Khutjo; Diamond, Roger; Kotze, Francois (MDPI, 2025-08-02)
Understanding groundwater and surface water interaction is critical for managing water resources, particularly in water-stressed and rapidly urbanizing areas, such as many parts of Africa. A survey was conducted of borehole, spring, seep and river water radon, δ2H, δ18O and field parameters in the Jukskei River catchment, Johannesburg. Average values of electrical conductivity (EC) were 274 and 411 μS·cm−1 for groundwater and surface water, and similarly for radon, 37,000 and 1100 Bq·m−3, with a groundwater high of 196,000 Bq·m−3 associated with a structural lineament. High radon was a good indicator of baseflow, highest at the end of the rainy season (March) and lowest at the end of the dry season (September), with the FINIFLUX model computing groundwater inflow as 2.5–4.7 L·m−1s−1. High EC was a poorer indicator of baseflow, also considering the possibility of wastewater with high EC, typical in urban areas. Groundwater δ2H and δ18O values are spread widely, suggesting recharge from both normal and unusual rainfall periods. A slight shift from the local meteoric water line indicates light evaporation during recharge. Surface water δ2H and δ18O is clustered, pointing to regular groundwater input along the stream, supporting the findings from radon. Given the importance of groundwater, further study using the same parameters or additional analytes is advisable in the urban area of Johannesburg or other cities.
Hydrochemistry, stable isotopes, and radon in waters of the Greater Timbavati catchment, South Africa
Raible, Kirsten; Diamond, Roger; Dippenaar, Matthys Alois (Springer, 2025-12)
A baseline study was conducted to better understand the relationship between groundwater, geology, and geography in the Greater Timbavati area, South Africa. Samples of rainwater, surface water, and groundwater were collected across nature reserves and rural communities. Basic water chemistry parameters, nitrates, and ammonium were measured in the field using an Aquaread AP-5000 probe, and water samples were collected for radon determination and stable isotope analysis. Significant differences in chemistry and isotopic signatures between surface water and groundwater were observed. Groundwater exhibited a mean total dissolved solids (TDS) of 1217 mg/l and pH of 7.5, whereas surface water had mean TDS of 332 mg/l and pH of 8.3. Groundwater δ2H and δ18O means were – 20.5 and – 3.8‰, respectively, contrasting with + 12.2 and + 2.3‰ in surface water. Hydrochemistry correlated with bedrock type and a close correlation between land use and nitrate concentrations was evident, particularly in groundwater, exceeding 500 mg/l in areas with dense human and livestock presence, suggesting urban and agricultural contamination. Radon concentrations in groundwater ranged from 188 to 51,400 Bq/m3, showing no clear correlation with underlying geology, suggesting groundwater flow paths across bedrock types. Overall, a strong distinction between groundwater and surface water characteristics suggests limited interaction, caused by deep water tables, especially at the end of the dry season when streams stop flowing, warranting further research in quantifying sustainable levels of groundwater abstraction.
Occurrence, concentration, and risk assessment of selected pharmaceuticals in representative cropland soils and their underlying groundwater in Gauteng province, South Africa
Ngoetjana, Matome Peter; Tesfamariam, Eyob Habte; Brown, Sally; Wooding, Madelien; Dippenaar, Matthys Alois (Springer, 2025-08)
Traceable levels of pharmaceuticals are frequently detected in various environmental matrices. However, studies investigating the occurrence of pharmaceuticals in cropland soils and underlying groundwaters are relatively limited, hindering risk assessments. This study aims the following: (1) determine the occurrence of selected pharmaceuticals in cropland soils and underlying groundwater, (2) investigate the correlations between pharmaceutical’s occurrence in cropland soils and underlying groundwater, (3) evaluate the correlations between soil and water parameters and pharmaceutical’s concentration, and (4) estimate human health risk from pharmaceuticals present in groundwater. A single soil and groundwater sampling campaign was conducted across eighteen farmers’ fields, characterized by varying farm management practices. Caffeine, carbamazepine-10,11-epoxide, carbamazepine diol, and N4-acetylsulfamethoxazole were detected in groundwater, with concentrations reaching 67.1, 106.7, 506.7, and 113.8 ng L−1, respectively. Three of these compounds, carbamazepine-10,11-epoxide, carbamazepine diol, and N4-acetylsulfamethoxazole, were also present in soils with concentrations reaching 10.0, 353.5, and 59.1 ng g−1 dry weight, respectively, indicating potential soil-to-groundwater transfer. Principal component analysis revealed a strong correlation between the application of commercial inorganic fertilizers and carbamazepine-10,11-epoxide levels and the irrigation practices and the levels of caffeine, carbamazepine diol, and N4-acetylsulfamethoxazole in the soil and groundwater. Risk quotients showed that caffeine poses negligible risk to human health through drinking water exposure. Overall, the findings suggest that pharmaceuticals are present in South African croplands and underlying groundwater, though current levels do not pose a significant risk to human health. However, future studies should focus on other metabolites of pharmaceuticals due to their higher concentrations in the soil and groundwater.
Seismically induced soft-sediment deformation in alluvial fans : mechanisms and implications for geological evolution of the Ordos Basin (China)
Bilal, Ahmer; Yang, Renchao; Chen, Shaojie; Lenhardt, Nils; Mughal, Muhammad Saleem; Kontakiotis, George (Elsevier, 2025-12)
Well-exposed soft-sediment deformation structures (SSDS) outcrops are rare and often mistaken for tectonic folds, leading to limited research and underutilisation in sedimentary geology. The Taitongshan section of the Middle-Permian Shihezi Formation in the Ordos Basin, China, provides insights into SSDS, whose spatial distribution and sedimentation reveal information about paleoenvironments, tectonic movements, and seismic events crucial for understanding basin development. This study uses fieldwork and sedimentology to investigate SSDS formation and triggers. Fieldwork identified six siliciclastic facies with SSDS and associated syndepositional structures. Sedimentological interpretations highlighted the connection between seismic activity and the genesis of SSDS, reinforcing their value as proxies for tectonic events in basin evolution studies. SSDS formation is triggered by seismic shaking, initiating liquefaction, erosion, slurry-clump formation, hydroplastic deformation, mass consolidation, and lithification. Rayleigh waves-induced liquefaction in partially-lithified subsurface sediments forms water escape structures. Provenance analysis reveals seismically active, orogenic source areas southwest and southeast of the NCC, with significant uplift and erosion during the Middle-Permian. Key findings indicate that the Middle-Permian braided river facies of the Taitongshan section originated from the Qilian Orogenic Belt, followed by a subsequent provenance shift towards the eastern-North Qinling Orogeny (NQLO), highlighting the dynamic tectonic forces driving rapid provenance shifts, further shaping sediment deposition and advancing basin evolution. Furthermore, the southeastern NCC experienced a more rapid uplift than the southwestern part during that time. These facies were deposited on the distal fan region of a prograding alluvial fan, where seismites likely formed due to active seismicity in the NQLO. The study identifies inter-facies shifts during seismite formation, introducing an innovative concept beyond traditional in-situ genesis models and broadening the understanding of sedimentary dynamics. This critical role of SSDS in sedimentation architecture enhances the understanding of basin evolution in sedimentary geology and provides a framework for interpreting similar structures globally. HIGHLIGHTS • SSDS formation driven by seismic activity reveals complex basin evolution processes. • Taitongshan section shows braided stream and sheet flood deposits on alluvial fan. • Seismic shocks induce SSDS via liquefaction in partially lithified sediments. • New SSDS inter-facies shift concept challenges traditional in-situ models. • Provenance analysis links Qilian and North Qinling Orogenies to tectonic uplift patterns.
Data from high temperature and high-pressure carbon dioxide sequestration experiments limited to 24 hours, performed on Platinum Group Metals mine tailings from the South African Bushveld Igneous Complex
Nkosi, Zakhele H.; Altermann, Wladyslaw; Doucet, Frédéric J.; Mohamed, Sameera; Phala, Karabo; Gauert, Christoph (Elsevier, 2025-12)
Please read abstract in the article.
Crystallisation and petrogenesis of cenozoic alkaline basaltic lavas on the Kapsiki Plateau (Moukoulvi, Far-North Cameroon) : unveiling the mantle's heterogeneity and HIMU signature
Djamilatou, Diddi Hamadjoda; Dedzo, Merlin Gountie; Lenhardt, Nils; Tsozue, Desire; Nkengmatia, Elvis Asaah Asobo; Ngarena, Moussa Klamadji (Elsevier, 2025-06)
The Kapsiki Plateau represents the northernmost extension of the Cameroon Volcanic Line (CVL) in West Africa. Unlike other regions of the CVL, this area is characterised by a higher prevalence of felsic and intermediate rocks compared to basaltic ones. Detailed investigations into the petrogenetic evolution of these rocks are currently limited. For this reason, Cenozoic alkaline basaltic lavas from the Kapsiki Plateau (Moukoulvi) were studied to enhance comprehension of their crystallisation process, genetic evolution of the magma, and insights into its petrogenesis and source mineralogy. The examined lavas are comparable to the mafic lavas that span the whole range of the CVL and demonstrate major and trace element characteristics similar to those seen in ocean island basalts (OIB). The major and trace element compositions suggest fractional crystallisation mainly including olivine, clinopyroxene, and Fe–Ti oxide with evidence of crustal contamination. The multi-element diagrams reveal consistency with those reported from other CVL volcanoes, displaying depletion of heavy rare earth elements (HREE) and enrichment of light rare elements (LREE), indicating an enriched source and the existence of garnet. The studied lavas have high large ion lithophile element (LILE) contents (Sr = 812–1065 ppm, Ba = 394–467 ppm) relative to high field strength elements (HFSE) (Sr/Zr = 3.97–4.94; average OIB = ∼1 Ba/La = 9.42–11.72; average OIB = 9.4). They also have Zr/Sm ratios (26.93–29.88) that are similar to the average OIB (Zr/Sm = 28). Moreover, the studied lavas exhibit elevated levels of incompatible trace elements (e.g., Rb, Pr, U, and Th), as well as higher Ta/Yb and Th/Yb ratios compared to normal OIB values, associated with a notable fluctuation in Nb/Ta and Zr/Hf ratios. The correlations between Th, La, U, and SiO2, coupled with the trend of the samples on Nb/Y vs. Rb/Y diagrams, indicate the influence of crustal contamination on the lavas' composition. The source of these lavas was a heterogeneous source with less than 4 % garnet that underwent partial melting of less than 2 %. The presence of a Pb depletion (Ce/Pb > 30) also implies that these magmas belong to the high μ (HIMU)-OIB type, attributed to lithospheric mantle metasomatism. The formation of these magmas involved partial melting of a mantle source evolving chemically and mineralogically over time with a HIMU composition at very low temperatures. Hydrous minerals, such as phlogopite or amphibole, may indicate modal metasomatism, supported by high Rb/Sr ratios or K2O high levels. Sr/Zr ratios (3.97–4.94) above OIB values (0.8–1.5) suggest Sr and Ba-rich fluid influence. Elevated Zr/Sm ratios (>28) and variations in Nb/Ta and Zr/Hf ratios point to metasomatic fluids or melts altering the mantle's composition. Therefore, the Moukoulvi lavas, like many CVL alkaline lavas, likely erupted from a metasomatized mantle source that was enriched in incompatible trace elements (Rb, Ba, Ce, Nb, and Zr). This enrichment is reflected in the elevated concentrations of these incompatible trace elements, as well as the relative enrichment in HFSE. The absence of temperature anomalies in the upper mantle beneath the CVL suggests that the magmatism originates from the lithospheric mantle source rather than a mantle plume.
Evaluating contaminant pathways in an altered vadose zone : a multidisciplinary approach in open-pit quarry environments
Van Wyk, Yazeed; Bodin, Jacques; Witthuser, Kai; Ubomba-Jaswa, Eunice; Dippenaar, Matthys Alois; Butler, Mike (Springer, 2025-06)
The closure of mining operations presents significant environmental challenges for groundwater protection and sustainable closure planning. Fractured and altered aquifers, which supply drinking water to nearly half the world’s population, are vulnerable to disruptions caused by mining. This study investigates groundwater flow and contaminant dynamics in an altered vadose zone and fractured rock environment at a quarry situated 20 km east of Pretoria, South Africa. The primary objective is to develop effective monitoring strategies for groundwater protection post-mine closure. The heterogeneous geological structures, including a network of fractures and a diabase sill, generate distinct water types and flow dynamics, with active groundwater circulation despite seasonal fluctuations. Field investigations and tracer analyses revealed seasonal variations in transport parameters. Blasting activities modified fracture characteristics, creating new pathways and increasing connectivity between fracture networks, complicating contaminant migration. Tracer tests analysed with the MDMi and MDP-2RNE analytical models identified variations in Péclet numbers and mean transit times, with higher transport velocities and lower retardation factors during the wet season. The MDMi model was more sensitive to fracture connectivity changes, while the MDP-2RNE model highlighted seasonal differences in flow velocities and dispersion. These findings highlight the challenges of parameterisation and the necessity for seasonal calibration in modelling contaminant transport. A conceptual site model (CSM) illustrates how mining has transformed groundwater flow patterns and contaminant transport mechanisms, providing critical insights into sustainable groundwater management and mine closure planning. This research highlights the importance of targeted monitoring strategies to protect groundwater in altered vadose zone environments post-mine closure.
Traversing the rift : a review of the evolution of the West and Central African Rift System and its economic potential
Lenhardt, Nils; Omietimi, Erepamo Job; Edegbai, Aitalokhai J.; Schwark, Lorenz; Catuneanu, Octavian; Fairhead, James D.; Goetz, Annette E. (Elsevier, 2025-02)
The Cretaceous to recent West and Central African Rift System is a major geological feature in Africa, extending 4000 km from the west to the east. Its formation is related to the breakup of Gondwana and the separation of Africa from South America, during which a complex network of extensional, wrench and pull-apart basins formed. These basins can be separated into two coeval rift sub-systems, the West African Rift System and the Central African Rift System. Both systems are genetically related but are physically separated and show significant structural as well as sedimentological differences. However, despite its great importance for the history of the African continent, our understanding of its origins and evolution is limited due to a scarcity of geophysical and sedimentological data. In this review paper, we examine the sedimentary and igneous basin-fill of the major West and Central African Rift System basins using literature data from the previous five decades. We analyse basin evolution, sequence stratigraphy, changing environmental and palaeoclimatic conditions, and economic aspects of the basins. Furthermore, we address future needs and challenges in research and collaboration between academia and industry to better understand the vast economic potential of the West and Central African Rift System basins. Ultimately, our findings shed light on the complicated geological history of the West and Central African Rift System and offer vital insights for future research and development in the region.
Geological and geochemical evaluation of shale gas potential of the Tanezzuft for-mation, Ghadames Basin, North Africa
Edegbai, Aitalokhai J.; Ogbe, O.B. (Slovnaft VURUP, 2024-02)
The Ghadames Basin is a poly-history Palaeozoic basin covering parts of Tunisia, Algeria and Libya. Exploration efforts in the past which targeted conventional hydrocarbon resources have been most successful in the Algerian segment. The aim of this research was to undertake a geological and geochemical assessment of the 'world class Silurian Tanezzuft Formation, model the timing of hydrocarbon generation and expulsion within the basin, all in a bid to evaluate its shale gas potential. Data from forty-nine (49) wells, which consist of total organic carbon (TOC), thermal maturity (Tmax), and kerogen (Hydrogen Index) were utilised for this study. TOC and Thermal maturity maps with cutoffs of 2wt.% and 1.0 Roequvalent which were generated show an increase of organic richness and maturity towards the West/NW. Subsequently integration of maps show favourable shale gas potential in a major 'sweet spot' area in the Western Ghadames Basin, with geological and geochemical characteristics that compare favourably with established similar aged gas shales in the US. Furthermore, 1-D basin models generated from an existing well and a pseudo well within the identified sweet spot area using a linear heat flow model reveal a good potential for thermogenic gas adsorption as well as an upside for shale oil. However, the risk and uncertainties associated with the shale gas development may be heightened due to non-technical issues such as political instability, access to technical support, water supply for fracking operations as well as potential environmental issues such as groundwater contamination with methane and induced seismicity arising from hydraulic fracturing.
Limited reactivity of pyroxene and plagioclase in batch experiments with supercritical CO2 in the presence of NaCl and NaHCO3 in the context of CO2 sequestration via carbonation
Nkosi, Zakhele H.; Altermann, Wladyslaw; Pölmann, Herbert; Doucet, Frédéric J. (Springer, 2025-02)
One-step high-pressure and high-temperature direct aqueous mineral carbonation of tailings derived from mining of Platinum Group Metals in South Africa requires a fundamental understanding of the reactivity of the most dominant mineral phases, i.e. pyroxene and plagioclase (66 wt. % and 12 wt. % of the bulk rock respectively) that are typically found in these tailings. The silicate minerals pyroxene and plagioclase were sampled from a pyroxenite footwall mined with the ore-bearing UG2 and from the Merensky Reefs outcropping in the eastern limb of the Bushveld Complex. These pyroxene and plagioclase grains were concentrated by gravity separation from the orthopyroxenite bulk rock and batch-reacted in a sodium chloride (NaCl) brine saturated with pure carbon dioxide (CO2) gas-only or seeded with sodium bicarbonate (NaHCO3; as an additional CO2 source) for 13 days at 100 °C and 10 MPa. Pyroxene dissolved slightly but no weathering features were observed in plagioclase. Analyses of the filtrates obtained from the pyroxene sample in the absence of NaHCO3 showed an increased concentration of magnesium and calcium ions in the solution. However, they had also reached a cation saturation sealing. On the other hand, liquid samples from reactions where both CO2 gas and NaHCO3 were added to the solution exhibited a pronounced decrease in dissolved magnesium and calcium ions. XRD patterns of some of the post-reaction solids collected from the cation-depleted solution aliquots showed peaks of newly formed secondary magnesite and vermiculite. Moreover, the presence of magnesite was further confirmed by Raman shift analysis of the dried solid products. The formation of secondary magnesite was observed only in the experiments seeded with NaHCO3, specifically where the pre-reaction solid was pyroxene rich. Some of the resultant fluid chemistry was corroborated by the geochemical model that simulated the reaction parameters using the Geochemist Work Bench (GWB) software. Overall, the results indicate low pyroxene dissolution, which leads to limited carbonation. These findings suggest that the carbonation of PGM tailings may be constrained under the evaluated physicochemical conditions.
Weathering profile of completely weathered rock from the Dullstroom Formation, South Africa
Swart, Duan; Dippenaar, Matthys Alois (Springer, 2025-05)
This study investigates the weathering profile of completely weathered rock derived from the Dullstroom Formation in South Africa. The research emphasizes the significance of the soil-rock interface, particularly the transition between completely weathered rock and residual soil, in understanding mechanical, chemical, and hydraulic behaviours. Field sampling and laboratory analyses, including particle size distribution, Atterberg limits, X-ray fluorescence (XRF), X-ray diffraction (XRD), and X-ray Computed Tomography (XRCT), were conducted. XRCT proved invaluable in visualizing pore geometry, density contrasts, and the persistence of relict rock structures in three dimensions. The findings highlight how structural prominence decreases with increasing weathering intensity, influencing compressibility and porosity. The compressibility of the material correlates better with chemical weathering indices than traditional geotechnical parameters like void ratio or dry density. These insights contribute to the geotechnical characterization of weathered rock profiles and propose structural prominence as a novel parameter for evaluating mechanical behaviour across weathering stages.
Downscaling and validating GLDAS groundwater storage anomalies by integrating precipitation for recharge and actual evapotranspiration for discharge
Viviers, Cindy; Van der Laan, Michael; Gaffoor, Zaheed; Dippenaar, Matthys Alois (Elsevier, 2024-08)
STUDY REGION : The Steenkoppies Catchment is located approximately 75 km southwest from Pretoria, South Africa (RSA). STUDY FOCUS : This study tested a framework for downscaling Global Land Data Assimilation System (GLDAS-2.2) groundwater storage anomaly (GWSA) estimates from 0.25◦ to 0.05◦. This was achieved in Google Earth Engine using the Random Forest algorithm with only precipitation and actual evapotranspiration (ETa) as input variables. Additionally, the study assessed whether accounting for temporal lags could minimise residuals and enhance model performance. NEW HYDROLOGICAL INSIGHTS FOR THE REGION : The greater range of downscaled GWSA values indicated that the product effectively captured local recharge (precipitation) and discharge (ETa) variations while maintaining conservation of mass. Optimising the temporal correlation (r) between input variables resulted in lower residuals and fewer outliers. Groundwater level measurements and downscaled estimates for the hard rock aquifer showed larger amplitudes and seasonality and yielded the highest r (0.6) and lowest RMSE (40 mm) and MAE (31 mm). Measurements near the spring and in the karst aquifer showed less evident amplitude and seasonality. The in situ derived and downscaled GWSA comparison demonstrated the effectiveness of the product for monitoring storage declines. When applied over aquifers experiencing significant land use change or belowaverage precipitation, the approach could monitor groundwater storage changes, even with limited in situ observations. The adaptable code is available for application in other study areas.
The subduction-related metavolcanic rocks of Maroua, northern Cameroon : new insights into a neoproterozoic continental arc along the northern margin of the Central African Fold Belt
Biakan à Nyotok, Pierre C.; Gountié Dedzo, Merlin; Djamilatou, Diddi H.; Lenhardt, Nils; Klamadji, Moussa N.; Fosso Tchunte, Periclex M.; Kamgang, Pierre (MDPI, 2024-11)
Please read abstract in article.
Multi-parameter investigation of Cretaceous to Palaeocene sedimentary sequences in the Anambra and Niger Delta Basins, Nigeria : organic matter characterisation, palynofacies and implications for palaeoclimate and sea-level changes
Omietimi, Erepamo Job; Lenhardt, Nils; Yang, Renchao; Götz, Annette E.; Edegbai, Aitalokhai J.; Bumby, Adam John (Wiley, 2025-01)
The Anambra Basin of Nigeria, part of the larger West and Central African Rift System (WCARS) across Africa, contains primarily Cretaceous to Palaeocene shallow to marginal marine and freshwater sedimentary deposits. The organic-rich deposits of the Cretaceous Nkporo and Mamu formations within the Anambra Basin and the Palaeocene Imo Formation of the Niger Delta Basin constitute important conventional source rocks. Despite its economic significance, research on organic matter characterisation, palynofacies, sea-level fluctuations, palaeoclimate, hydrogeography, basin restriction, palaeobathymetry and the factors controlling organic matter preservation remains largely undocumented. The here presented new inorganic and organic geochemical and organic petrography data of the Cretaceous to Palaeocene deposits serve to refine the regional interpretation at a basinal scale and within the supra-regional context of the WCARS. Geochemical palaeotemperature proxies suggest a warm and humid tropical palaeoclimate during the Late Cretaceous within the study area. Furthermore, the measured TOC values indicate poor to very good organic content. Palynofacies analysis revealed high abundances of opaque and translucent phytoclasts and low amounts of palynomorphs with negligible amorphous organic matter (AOM) in the studied mudrocks. Two palynofacies groups suggest shallow-marine conditions in a proximal shelf setting and a heterolithic oxic basin. The palynofacies of the upper Imo Formation reveal higher percentages of dinoflagellate cysts during the early highstand phase, with equidimensional, opaque phytoclasts representing the maximum flooding phase, accompanied by warmer conditions. Additionally, abundant terrestrial phytoclasts, Deltoidospora spp., Classopollis spp. and geochemical indicators collectively indicate warm tropical climatic conditions consistent with geochemical interpretations. The palaeobathymetry reconstructions suggest a shallow seaway during the Upper Cretaceous in the Anambra Basin.

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