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The Mewengo iron deposit belongs to the Nyong series greenstone belt, which is located at the northwestern border of the Congo Craton in Cameroon. The amphibolites of Mewengo are associated to poorly documented banded iron formations (BIF) as layers and discontinuous pods; they are ortho-amphibolites having a basaltic protolith. They display granoblastic heterogranular texture, made up of garnet, amphibole, plagioclase, K-feldspar, and clinopyroxene, with accessory minerals such as zircon and iron oxides. Their major element contents are relatively low but they are enriched in alkalis and transition metals, (Na2O + K2O) comprised between 2.1 and 2.42 wt%, MgO (7.11–7.39 wt%), CaO (10.55–11.06 wt%), Fe2O3 (13.54–14.79 wt%), SiO2 (48.7–49.64%), Zr (45.3–55.5 ppm), V (320–340 ppm), Cu (126.5–179.3 ppm), Ni (85–109 ppm), Co (50.7–60.6 ppm). Their Mg# vary from 49.70 to 50.98 and the average value of Nb/Ta ratios is 19.4 characteristic of basaltic rocks from mantle; they are reminiscent of MORB from tholeiites series, generated by partial melting of upper mantle at the shallow depth in spinel-peridotite stability field, where slight metasomatism by subduction-derived fluids occur. Eu/Eu* (0.89–1.00) and Ce/Ce* (0.71–1.03) suggest a deep-sea environment with less input from pelagic sediments inferring the iron deposit setting. The U–Pb zircon dating yielded age of 2050 Ma for metamorphism within the Mewongo iron deposit. The results of this study compared with the previous data of metavolcanic rock-related BIFs in Nyong series suggest a deep-seated subduction setting related to an amphibolitic/granulitic metamorphism during the Transamozian/Eburnean (ca. 2050 Ma) orogeny.

The Kouambo iron deposit contains banded iron formations (BIFs) and is located in the northwestern margin of the Congo craton. The BIFs are hosted in Palaeoproterozoic Nyong series, a dominantly metasedimentary formations, which were metamorphosed into greenschist to granulite facies. The Kouambo BIFs are medium- to coarse-grained banded rocks consisting of alternation of Si-rich and Fe-rich mesobands, and belong to oxide facies iron formations. Geochemistry analyses reveal that these iron formations are composed of > 96 wt% Fe2O3 and SiO2 and have low concentrations of Al2O3, TiO2 and trace HFSE, suggesting chemical precipitates of silica and iron. Moreover, these BIFs have low concentrations of Al2O3, TiO2 and trace HFSEs (high field strength elements, e.g., Zr, Hf, Ta, Pb and Th), suggesting that terrigenous detrital materials contributed insignificantly to the sedimentation. The Post-Archean Australian Shale (PAAS)-normalized REE-Y patterns display seawater-like profile: minor LREE depletion and HREE enrichment, positive Y anomalies. However, they display positive Eu and negative Ce anomalies, and low Y/Ho ratio (average 29), which suggest the influence of the hydrothermal fluids. The weak positive Eu/Eu*(PAAS) ratio (average 1.5), associated with the low V (17.5 ppm), Co (6.1 ppm) and Ni (27.5 ppm) contents similar to other Superior-type BIFs worldwide, are consistent with the deposition of the Kouambo BIFs in continental marginal sea or back-arc basin environment. In summary, the Kouambo BIFs show a seawater-like REE + Y signature, however, the positive Eu anomalies and reduced Y/Ho ratios relative to seawater indicates a possible mixing with hydrothermal fluids (∼ 0.5%).

Banded iron-formations (BIFs) form an important part of the Archaean to Proterozoic greenstone belts in the Southern Cameroon. In this study, major, trace and REE chemistry of the banded iron-formation are utilized to explore the source of metals and to constraint the origin and depositional environment of these BIFs. The studied BIF belongs to the oxide facies iron formations composed mainly of iron oxide (mainly magnetite) mesobands alternating with quartz mesobands. The mineralogy of the BIF sample consists of magnetite and quartz with lesser amount of secondary martite, goethite and trace of gibbsite and smectite. The major element chemistry of these iron-formations is remarkably simple with the main constituents being SiO2 and Fe2O3 which constitute 95.6–99.5% of the bulk rock. Low Al2O3, TiO2, and HFSE concentrations show that they are relatively detritus-free chemical sediments. The Pearson’s correlation matrix of major element reveals that there is a strong positive correlation (r = 0.99) of Al with Ti and no to weak negative correlation of Ti with Mn, Ca and weak positive correlation of Si with Ca, suggesting the null to very minor contribution of detrital material to chemical sediment. The trace elements with minor enrichments are transition metals such as Zn, Cr, Sr, V and Pb. This is an indicator of direct volcanogenic hydrothermal input in chemical precipitates. The studied BIF have a low ΣREE content, ranging between 0.41 and 3.22 ppm with an average of 0.87 ppm, similar to that of pure chemical sediments. The shale-normalized patterns show depletion in light REE, slightly enrichment in heavy REE and exhibit weak positive europium anomalies. These geochemical characteristics indicate that the source of Fe and Si was the result of deep ocean hydrothermal activity admixed with sea water. The absence of a large positive Eu anomaly in the studied BIF indicates an important role of low-temperature hydrothermal solutions. The chondrite-normalized REE patterns are characterized by LREE-enriched (Mean LaCN/YbCN = 8.01) and HREE depletion (Mean TbCN/YbCN = 1.61) patterns and show positive Ce anomalies. With the exception of one sample (LBR133), all of the BIF samples analyzed during this study have positive Ce anomalies on both chondrite- and PASS-normalized plots. This may indicate that the BIFs within the Elom area were formed within a redox stratified ocean. The positive Ce anomalies in the studied samples likely suggest that the basin in which Fe formations were deposited was reducing with respect to Ce, probably in the suboxic or anoxic seawaters.

The west Bonguen area is located within latitudes 03°25’N to N03°39’N and longitudes 10°04’E to 10°09’ E in South Cameroon. It belongs to the Nyong Series which is the north-western extension of the Congo Craton in Cameroon. In order to highlight the extension of the Kribi-Campo shear zone, petrographic studies and structural analysis were carried out. Mylonitic metagranodiorite outcropping as a large dome in biotite gneiss basement rocks, it is the main rock type in the study area, it is made up of Kfs + Qtz + Bt + Pl + Op. Majority of the minerals shows deformation marks such as sigmoidal shape of Kfs, rolling extension of Qtz ribbons, Subgrains of Qtz and kink-band of Bt. Three (03) deformation phases (D1, D2, and D3) were denoted in Bonguen west. The D1 deformation developed S1 foliation in biotite gneiss basement rocks and is characterized by the alternation of parallel compositional bands and lithological units. The D2 deformation developed S2 mylonitic shistosity, Shear bands (C2-planes) develop oblique to the main S2 mylonitic schistosity (S2-plane) showing dextral ductile shear, V2 veins and B2 boudins. The D3 phase is exclusively highlighted by brittle features such as V3 veins, F3 joints and faults. The area consequently underwent a polyphases ductilo-fragile tectonism dominated by a dextral thrusting kinematics. Bonguen area is here considered as a segment of the northern extension of the Kribi-Campo fault.

Nlonako area belongs to Cameroon Volcanic Line. To determine the mineralization potentials of the area, stream sediment survey and geochemistry were carried out. The results show weak anomalies in Gold and Silver with threshold values of 0.001 and 0.073 respectively. Copper, Lead and Zinc have some relatively high values which are 690ppm, 182ppm and 378ppm with mean values statistically calculated to be 73.90, 46.51 and 198.58 respectively. The data analyzed using multivariate statistical methods yielded 5 factors from Principal Component Analysis (PCA). These five factors are; Factor 1 (Ce, La, Nb, Y), Factor 2 (W, Mo, Sr, As, Cd, Ni), Factor 3 (Pb, Sn, Zn, Sb), Factor 4 (Au, Ag, Cu) and Factor 5 (Cr, Co, Bi). These factors point mostly to a possible sulphide mineralization. Gold shows high correlation with Ag and Cu while Y correlates more highly and positively with Ce and La. There is a relatively high input of the light rare-earth elements which form the highest factor (34.363%) of the total PCA variance and possibly points to a granitic source rock. The existence of mafic–ultramafic igneous rocks in the study area underlies high correlations between Cr and Co and other factors gotten from PCA.