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The Sanaga iron ore prospect within the Palaeoproterozoic Nyong Series in Cameroon is a magnetite‐dominated iron ore deposit hosted within granodioritic gneisses with an estimated resource of 82.9 Mt @ 32.1% Fe. The main ore mineral being magnetite, provides an opportunity to study the magnetite texture and iron‐oxygen isotope composition of the mineralization, which has heretofore not been reported. These offer insights into the nature and condition of formation of the mineralization thereby paving the way for better understanding the genesis and evolution of the mineralization as well as classifying it. The mineralization is characterized by Type I and Type II magnetite varieties based on their textural features. Type I magnetite is the dominant magnetite and is characterized by ilmenite oxy‐exsolution features with triple junction contacts, while Type II magnetite lacks these features. The presence of ilmenite oxy‐exsolution features in the Type I magnetite indicates a primary magmatic formation of the magnetite followed by re‐equilibration of primary Ti‐rich magnetite in the presence of a high‐temperature fluid. Oxygen isotope (δ18O) values for the magnetite range from +2.89% to 9.30‰ indicating precipitation from evolved ore‐forming fluids through reaction with country rocks. The iron isotope (δ56Fe) of the magnetite shows little variation, with positive values ranging from +0.49–0.66‰. These values plot within the magmatic and magmatic‐hydrothermal magnetite fields when compared to the published global range of δ56Fe values for different deposit types. A similar result is obtained by plotting the coupled Fe–O isotope pair, further buttressing the magmatic‐hydrothermal origin of the mineralization. Based on these data, the Sanaga iron mineralization is best explained as a magmatic‐hydrothermal deposit. [ABSTRACT FROM AUTHOR]

Stream water and associated bottom sediments were sampled within the Lom Basin, and their rare earth element (REE) concentrations have been used to decipher their provenance and environment of deposition. Stream waters in the lower Lom Basin have variable Post Archean Australian Shale-normalized REE concentrations (0.24–4978 ng/l), positive Ce anomalies (Ce/Ce* ranges from 1.08 to 8.03), a general positive Eu anomaly (Eu/Eu* varies from 0.9 to 15.2, average = 4.9) and are slightly enriched in the light rare earth elements (LREE/HREE varies from 1.7 to 10.3). Similarly, the sediments are slightly depleted in heavy rare earth elements (HREE), have a predominant negative Ce anomaly, but show a ubiquitous positive Eu anomaly. The dissolved REE content is controlled by the near-neutral pH of the stream water and adsorption onto Fe and Mn oxyhydroxides. The variable LREE/HREE ratios and Eu anomalies observed in the sediments indicate that these sediments are sourced mainly from felsic rocks with little mafic input. Moreover, Ce anomalies and redox-sensitive trace elemental ratios of Ni/Co, V/(V + Ni), V/Cr, Cu/Zn and V/Ni revealed the sediments were deposited under oxic to reducing conditions. Variations in the concentration of REE in the stream water and sediment indicate that Fe and Mn oxyhydroxides are important sinks for the HREE. The newly generated data will guide future studies and environmental policy makers. [ABSTRACT FROM AUTHOR]

Knowledge of groundwater recharge and apparent age constitutes a valuable tool for its sustainable management. Accordingly, shallow groundwater (n = 72) in the Ndop plain has been investigated using the stable isotopes of oxygen (118O) and hydrogen (2H or D) and tritium (2H) to determine the recharge process, timing and rate of recharge, and residence time. The shallow groundwater showed low variability in d18O values (-2.7 to - 4.1 %) and 3H content (2.4-3.1 TU). The low variability suggests a similar origin, homogenous aquifer, good water mixing and storage capacity of the groundwater reservoir. Like surface water, a cluster of groundwater along the Ndop Meteoric Water Line (NMWL) and Global Meteoric Water Line indicates meteoric origin/recharge. The rainfall recharge occurs under low relative humidity conditions and negligible evaporation effect. About 80 % of the recharge is from direct heterogeneous/diffuse local precipitation at low altitude (\1,260 m) within the Ndop plain. Approximately 20 % is from high altitude precipitation (localised recharge) or is recharged by the numerous inflowing streams and rivers from high elevations. A homogenous cluster of δ-values in groundwater (and surface water) between May and June monsoon rains on the NMWL suggests dominant recharge during these months. The recharge represents at least 16 % ([251 mm) of the annual rainfall (1,540 mm) indicating high annual recharge; high enough for development of the groundwater resource for agriculture. The 3H content ([2.4 TU) in groundwater indicates post-1952 recharged water with an estimated residence time \30 years, suggesting short subsurface circulation, and subsequently a renewable aquifer. [ABSTRACT FROM AUTHOR]