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![Major element geochemical classification plots for granitoid rocks from Bétaré Oya. (a) Na2O + K2O versus SiO2 diagram of [35], showing the subalkaline compositions of the rocks. (b) K2O versus SiO2 diagram of [37], the rocks plot in the high-K field. (c) A/NK versus A/CNK diagram of [38] showing aluminosity and alkalinity. (d) Discrimination diagram of [39], showing that the rocks were formed in a volcanic arc setting. A/NK = molar Al2O3/Na2O+K2O; A/CNK= molar Al2O3/CaO+Na2O+K2O, Syn-COLG, Syn-collisional granitoid; WPG, within-plate granitoid; VAG, volcanic arc granitoid; ORG, oceanic ridge granitoid](profile/Kevin-Ateh/publication/322078112/figure/fig2/AS:576138508083200@1514373532596/Major-element-geochemical-classification-plots-for-granitoid-rocks-from-Betare-Oya-a.png)
Major element geochemical classification plots for granitoid rocks from Bétaré Oya. (a) Na2O + K2O versus SiO2 diagram of [35], showing the subalkaline compositions of the rocks. (b) K2O versus SiO2 diagram of [37], the rocks plot in the high-K field. (c) A/NK versus A/CNK diagram of [38] showing aluminosity and alkalinity. (d) Discrimination diagram of [39], showing that the rocks were formed in a volcanic arc setting. A/NK = molar Al2O3/Na2O+K2O; A/CNK= molar Al2O3/CaO+Na2O+K2O, Syn-COLG, Syn-collisional granitoid; WPG, within-plate granitoid; VAG, volcanic arc granitoid; ORG, oceanic ridge granitoid
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A combination of whole rock geochemistry, Ti-in-zircon thermometry, geochronology and Lu-Hf isotope composition of zircon is employed in this study to depict the source of a granitoid from the Bétaré Oya Gold District, its formation temperature, age of emplacement and evaluate the role of petrogenesis and magmatic evolution of the granitic melt in...
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Context 1
... whole rock geochemical data for the studied granitoid samples alongside the Batouri granitoid [7] and the two mica granite [16] from Ekomédion are represented in Table 1 [35,36,37], the Bétaré Oya granitoid is sub-alkaline with a high-K calc- alkaline affinity (Figure 2a, Figure 2b). On the A/NK versus A/CNK classification plot [38], the granitoid is granodioritic to tonalitic in composition. ...
Context 2
... the A/NK versus A/CNK classification plot [38], the granitoid is granodioritic to tonalitic in composition. They are peraluminous with all samples clustering within the 'I- type' field ( Figure 2c). Nb -Y discrimination plot [39], reveals a volcanic arc setting for that the Bétaré Oya granitoid (Figure 2d). ...
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Citations
... Consequently, lithologic units within the domain bear pre-tectonic, syn-tectonic and posttectonic imprints. These are largely high-K, calc-alkaline rocks [9,10,30,31] interspersed with low-to medium-grade metamorphic rocks of volcano-sedimentary protoliths [32][33][34]. ...
... The gold grades within the granite alteration halo vary from 2 ppm to 103 ppm [8,9,13,14,35,36]. The granites are subduction-related and 640-620 Ma old [10], similar to those farther afield in the AYD [30,31,34,35,37] and southern Chad [38]. This class of granite-related gold deposits contributes to about 32% of the world's gold reserve [39][40][41][42][43]. Artisanal gold mining has been ongoing in the Batouri goldfield ( Figure 1b) since the 1930s [7]. ...
The identification of trace element anomalies in soils has been proven to assist semi-mechanized small-scale gold operations. This study employs soil geochemistry combined with the mi-crochemical signature of particulate gold from the Batouri goldfield to (1) vector possible golden -dowed lithologies introducing particulate gold into the overlying regolith, and (2) assess anthropo-genic Hg used in purification of both primary and alluvial/eluvial gold by artisans. The soil geo-chemistry shows irregularly distributed anomalies of elevated Cu especially in the saprolite soil layer. Whereas in the lateritic soil layer, a Au-Ag-Hg metal association is reported for the first time in this gold district and could be linked to anthropogenic Hg used in gold recovery. Particulate gold recovered from the soil varies in shape from euhedral and irregular to sub-rounded, indicating a proximal lode source. The gold grains range in size from nano-particles to >300 µm and are Au-Ag alloys. The gold particles reveal inclusions such as quar , silicate, zircon and ilmenite suggesting that the grains were dislodged from quar veins within the granitic basement. Systematic variation in the microchemical signature of the gold grains is suggestive of spatial and temporal evolution of the mineralizing fluid. These results are consistent with investigations from similar geologic se ings worldwide and validate the combined utility of gold fingerprinting and pathfinder elements in soil to examine deposit genesis in other gold districts globally. Citation: Vishiti, A.; Suh, C.E.; Ngatcha, R.B.; Melchiorre, E.B.; Shemang, E.M.; Omang, B.O.; Ngang, T.C.; Valdez, F.C.; Sekem,
... In Cameroon, most known primary gold occurrences are confined to regional scale NE-SW faults and shear zones which are aligned to the Central Cameroon Shear Zone system (e.g., Suh et al. 2006;Ateh et al. 2017;Vishiti et al. 2017). These deposits have largely been described as orogenic and are thought to have been emplaced during the Pan-African orogenic event (Suh et al. 2006;Ateh et al. 2017;Ndonfack et al. 2021a). ...
... In Cameroon, most known primary gold occurrences are confined to regional scale NE-SW faults and shear zones which are aligned to the Central Cameroon Shear Zone system (e.g., Suh et al. 2006;Ateh et al. 2017;Vishiti et al. 2017). These deposits have largely been described as orogenic and are thought to have been emplaced during the Pan-African orogenic event (Suh et al. 2006;Ateh et al. 2017;Ndonfack et al. 2021a). Suh et al. (2006) and Asaah (2010), respectively, observed that gold mineralization in the Dimako-Mboscoro and Batouri districts is hosted in steeply dipping quartz veins that display zoned alteration envelops consisting of quartz, sericite, hematite, and pyrite with an ore mineral association of gold, hematite, sphalerite, galena, pyrite, chalcopyrite, arsenopyrite, chalcocite, and covellite, prompting the conclusion that gold mineralization in the Precambrian mineral belt of Cameroon bears the hallmarks of orogenic gold systems, as described by Goldfarb et al. (2005). ...
The Galim-Legalgorou area, located along the north-western branch of the Cameroon Volcanic Line (CVL), is known for artisanal gold mining and primary gold exploration, but the style and origin of the mineralization has not been fully described in the scientific literature. The close spatial association of the mineralization with Tertiary volcanic rocks raises the question of whether or not this is an epithermal system in a region where all previously studied gold occurrences have been classified as orogenic. In this contribution, we use ore mineral and alteration assemblage and mineral microchemistry to constrain the origin and evolution of the mineralization. Gold is alloyed mainly with Ag (max. 53.1 wt%) and show fineness values that vary 379 and 721 with an average of 455. A cumulative percentile plot of Ag concentrations in the cores of all electrum particles, and the observed step-change from Au-rich cores to more Ag-rich mantles in zoned electrum particles, suggest that the mineralization was deposited by two distinct hydrothermal fluid influxes. The observed ore mineral association-electrum, Se/Tl-acanthite, pyrite, Fe-rich sphalerite, ± galena; the measured FeS contents of sphalerite (average 23.1 mol%), and the presence of colloform banded chalcedony and hydrothermal breccia are all consistent with features of low sulfidation epithermal deposits. This study, therefore, demonstrates for the first time, the presence of significant low sulfidation epithermal Ag–Au mineralization on the CVL, an intracontinental rift region only previously known for orogenic gold mineralization.
Graphical Abstract
... 620 Ma, using LA-ICP-MS U-Pb zircon dating, whereas Lemdjou et al. (2022) argued for a single magmatic pulse based on indistinguishable LA-ICP-MS zircon U-Pb ages of 641 ± 3 Ma and 638 ± 4 Ma for the Doumba Bello and Ngoura granitic plutons, respectively. In the Batouri area, located south of Colomines, auriferous monzogranite and granodiorite were dated using U-Pb and Ar-Ar geochronology at ca. 619 and 624 Ma and 640-620 Ma, respectively (Asaah et al., 2015;Ateh et al., 2017). The variety of proposed emplacement ages for intrusions in the region demonstrates a continuing need to refine the timing of magmatism and its temporal links with associated gold mineralization throughout Eastern Cameroon and the central domain of the PANEFB in a broader context. ...
... We do not find support in our U -Pb data for the extended duration of magmatism inferred by Gentry et al. (2021) based on K-Ar; instead, the younger K -Ar ages may reflect the timing of non-magmatic mineralization or reheating events. We also did not discover any rocks corresponding to the ~620 Ma magmatic pulse inferred by Azeuda , Asaah et al. (2015), and Ateh et al. (2017). ...
... As yet, no concrete evidence has genetically linked the gold mineralization in Eastern Cameroon to the Pan-African granitoids. Magmatic ages of 635 Ma and 620 Ma for plutons in the Bétaré-Oya and Batouri gold districts have been presented as constraints on the ages of gold mineralization in those districts (Asaah et al., 2015;Ateh et al., 2017). However, the gold mineralization in the area is in the form of lode gold in quartz veins, crossing almost all geologic units in the three recognized gold districts. ...
LA-ICP-MS zircon U-Pb geochronology was combined with field study, petrography, and whole rock geochemical data to constrain the age of the Ngoura-Colomines granitoid plutons in the central domain of the Pan-African North Equatorial Fold Belt (PANEFB) in Cameroon and to define the relationship between the plutons and gold mineralization in the area. In the field, small plutons of biotite granite, megacrystic leucogranite, and granodiorite are generally surrounded by a larger body of alkali feldspar granite, which in turn intrudes gneisses. Two granite samples yield crystallization ages of 629.8 ± 1.4 Ma and 630.9 ± 2.5 Ma, and a granodiorite sample was dated to 633.0 ± 2.4 Ma. All the granitoids exhibit a distinct I-type continental margin arc affinity, indicating their formation in a subduction zone environment, but deformation fabrics extending to intense mylonitization imply a syn-tectonic setting, which we associate with the onset of the Pan-African collisional orogeny in this area at or before 630 Ma. The gold-bearing quartz veins cross-cut the dated plutonic rocks, suggesting that the gold mineralization event is younger than 630 Ma. Concordant inherited zircon grains indicate a series of earlier magmatic events between 955 and 668 Ma, whereas a number of discordant inherited zircons reveal the influence of Paleoproterozoic (1960 ± 83 Ma) and Mesoarchean (3072 ± 13 Ma) reworked materials, likely from the Congo Craton, in producing the investigated Neoproterozoic granitoids.
... Cameroon are oxidized, I-type, sub-alkaline, high-K calc-alkaline to shoshonite in composition [20,[22][23][24][25]27]. This highlights the role the granitoids composition and redox conditions play in understanding the composition and characteristics of the exsolved ore-bearing aqueous fluids [28]. ...
... Zircon U-Pb age data revealed that granitoid intrusions were emplaced within an age bracket of ca. 670-620 Ma [20,27,57,58], with an average mean age of ca. 635 Ma obtained on syn-tectonic granitoid in the Bétaré Oya gold district [27], south of the present study. ...
... 670-620 Ma [20,27,57,58], with an average mean age of ca. 635 Ma obtained on syn-tectonic granitoid in the Bétaré Oya gold district [27], south of the present study. The granitoids recorded a metamorphichydrothermal overprint event between 600 and 550 Ma which could be related to the ore mineralizing fluids [58]. ...
Gold mineralization of the Upper Lom Basin in the eastern Cameroon goldfield is spatially associated with tourmaline. The goldfield belongs to the Adamawa-Yadé Domain of the Central African Fold Belt and is characterized by eluvial, alluvial and lode gold deposits of Pan-African age. This paper examines the chemistry and morphology of saprock gold and its link with tourmaline in the host rock. Tourmaline chemistry was obtained using the electron microprobe analysis (EMPA) technique while gold grains were examined for morphology and microchemistry using the EMPA equipped with scanning electron microscopy and energy dispersive spectrum instruments. The tourmaline compositional data plot in the dravite field, and belongs to the alkali group showing major element variations that are typical of tourmaline associated with granite-related orogenic gold deposits common along shear zones. Gold alloy composition (Ag, Cu) suggests multiple gold precipitation events due to episodic fluid influx, with a range of 572–1000 gold fineness. We infer that tourmaline development and gold deposition were coeval within the aureole around the pluton and involved reduced hydrothermal fluids with low salinity. The high δ¹¹B in the tourmaline also points to fluid derivation from the Pan African granitic basement widely recognized to be fertile in gold in eastern Cameroon. Tourmaline textural-chemical features such as low Na content and gold microchemistry point to granite-related hydrothermal style of primary gold mineralization, and has implications for exploration as tourmaline-rich rocks in the vicinity of the felsic plutons in the Lom Basin would be optimal target areas for future exploration.
... The association of the residual fraction with Pb is linked to formation of stable complexes [49]. Besides, high content of Pb in the residual fraction of tailings samples may be due to the presence of PbS (galena), the main form of an insoluble Pb occurring naturally in the study area [10,50]. This residual fraction of Pb is not available for plant uptake because it is associated with soil matrix and crystalline structure. ...
... Heavy metals in these forms are soluble and easily discharge into the biota [40]. In Bétaré Oya, the predominant Pb species is PbS [11,50], which is sensitive to environmental changes. The conversion of PbS to PbCO 3 is likely responsible for the significant concentration of Pb in exchangeable, carbonate and Fe-Mn bound fractions. ...
The Bétaré Oya gold district is situated in the Lom Basin, one of Cameroon’s Neoproterozoic volcano-sedimentary basins. The aim of this study was to evaluate the speciation, bioavailability and potential risk of metals in mine tailing of Bétaré Oya gold district. The metal content of the mine tailing samples collected is evaluated using an Inductive Coupled Plasma-Optical Emission Spectrometer. Speciation was performed according to the Tessier sequential extraction procedure. The low presence of clay in the tailings of the study area reduces the adsorption and mobilization of metals. Pyrite was the dominant sulphide mineral present in the study area. Metal speciation shows that greater portion of metals are bound to Fe–Mn oxide, and decrease progressively to inert fraction, organic fraction, carbonate and exchangeable forms. Relatively high mobility factors observed for Cd, Pb, Co, Fe, Zn and Mn at all sampling sites indicate high mobility, reactivity, susceptibility and bioavailability of these metals in the mine tailings studied. The enrichment of Ni, Cd, Cu, Pb, Co, Fe, Zn and Mn in soil and sediments when compared to metal bioavailability in mine tailings can be attributed to intense oxidation and dissolution of sulphide minerals linked to primary gold mineralization, intense weathering and anthropogenic activities. Contamination index, contamination degree, enrichment factor and geo-accumulation index indicate that Cd, La, As, Hg, and Pb may pose an ecological risk. The potential ecological risk assessment shows a low to very high level of ecological risk. The evaluation of metals content and chemical speciation in the study area is necessary to predict their mobility, bioavailability and potential risk to the ecosystem and this study represents the first metal speciation study in gold mines in Cameroon.
... The orogenic assemblage of Cameroon consists of three major geotectonic units ( Fig. 1): (i) Archean-Paleoproterozoic basement gneiss, migmatite and granulite with available ages ranging from ca. 3.09 to 2.49 Ga (e.g., Caen-Vachette 1988;Van Schmus et al. 2008;Chombong and Suh 2013;Chombong et al. 2017), (ii) Meso-to Neoproterozoic volcano-sedimentary sequences that were deformed and metamorphosed to various degrees and yield zircon detrital U-Pb ages from ~ 1100 to 950 Ma , and (iii) Pan-African granitic rocks that intruded the (i-ii) units at ~ 680-520 Ma (e.g., Asaah et al. 2015;Ateh et al. 2017;Li et al. 2017;Embui et al. 2020) (Fig. 1). ...
... This is an important research theme in the Neoproterozoic fold belt north of the Congo Craton, considering that granitic plutonism is ubiquitous throughout the various stages of the orogeny from subduction, collision to crustal thinning. In the neighbouring Batouri and Bétaré Oya gold districts (Fig. 2b) of eastern Cameroon, the granitoids were constrained to an age bracket of 635-620 Ma (zircon U-Pb dating) and this age bracket has been tentatively linked to magmatic activity associated to gold mineralisation (Asaah et al., 2014;Ateh et al., 2017). These ages need further scrutiny and form the basis of this contribution with a focus on the Colomine auriferous granitoids, which are poorly known in terms of the ages and crustal contribution to their petrogenesis. ...
... In this paper, we present new zircon U-Pb ages and Lu-Hf isotope data from preto syn-collisional granites of the Colomine gold district. We use these data in combination with previously published Lu-Hf zircon data from Bétaré Oya granitoids (Ateh et al., 2017) to place additional constraints on the timing of gold-associated Colomine granites, and the relative importance of basement sources (mantle/crustal) in the generation of the Neoproterozoic continental crust in SE Cameroon. ...
... This suggests that the magmas from which the zircons crystallised contained a significant contribution of old crustal material of Archean to Paleoproterozoic age (Fig. 6b). The zircon Hf isotopic signatures from this study are clearly distinct from those of the Bétaré Oya granitoids (ϵHf (t) ; − 18.9 to +0.3, Fig. 6) located about 100 km farther north (Ateh et al., 2017), indicating different source reservoirs. Colomine zircons show variations up to 9 ϵHf (t) units, excluding one outlier zircon grain BC08-05 with up to about 20 ϵHf (t) units difference. ...
The Neoproterozoic Pan-African Orogeny in the Adamawa-Yad´ e domain (AYD) of Cameroon is characterized by intense magmatism of metaluminous to weakly peraluminous I-type granites spatially associated with transcurrent shear zones. This domain provides a critical geological record that is important for unravelling the
regional tectonic evolution and geodynamic setting. We present new zircon U-Pb ages and Lu-Hf isotope data from pre-collisional biotite granite and porphyritic K-feldspar granite of the gold-producing Colomine district. Zircon U-Pb ages of biotite granite samples suggest emplacement at 727 ± 8 Ma and at 671 ± 6 for the porphyritic K-feldspar granite. Metamorphic-hydrothermal events between 600 and 550 Ma resulted in Pb-loss of most dated zircons. Lu-Hf isotope data of zircon grains form the porphyritic K-feldspar granite with ϵHf(t) values of − 28.7 to − 22.6 and Tc DM ages of 2.4–2.1 Ga overlap with those of the biotite granite (ϵHf(t) values of − 29.4 to − 19.6; Tc DM ages of 2.5–1.9 Ga). Depleted mantle model ages and ϵHf(t) values suggest that the granites were derived from crustal reworking of older Archean to Paleoproterozoic crust with minor mixing from a juvenile component during the Pan-African. The formation of these pre-collisional granites is interpreted as related to accretion tectonics that started around 750 Ma and incorporating tectonic domains of the Central African Fold belt, namely, the NW Cameroon domain, Mayo-Kebbi domain and the Adamawa-Yade domain.
... The East Metallogenic Province of the belt in Cameroon contains lode gold mineralization hosted by volcanic, sedimentary, and plutonic rocks that were formed and metamorphosed during the Neoproterozoic growth of Gondwana. Workers have undertaken a few granite petrogenetic and geochronological studies in the province (Fuh, 1990;Soba et al., 1991;Toteu et al., 2001Toteu et al., , 2006aAsaah et al., 2015;Ateh et al., 2017;Ngatcha et al., 2019;Fuh et al., 2021b). However, no systematic geochronological and isotopic investigations from the metavolcanicmetasedimentary and granitic rocks have been yet carried out to Kusky et al., 2003); and (b) Geological map of Cameroon showing the Neoproterozoic intercontinental basins and the Pan-African plutonic rocks associated with major litho-tectonic structures of the Central African Belt. ...
... Moreover, the previous studies are controversial regarding the timing of sediment deposition and granitoid emplacement along the Lom Belt, as well as, of the primary gold mineralization. Toteu et al. (2006a) interpreted the sediments of the Lom Belt as being deposited, deformed, and metamorphosed within the period of 613-600 Ma, while granitic intrusion within the belt was dated at ca. 635 Ma (Ateh et al., 2017). Furthermore, plutonic rocks ages of 635 Ma (Bétaré Oya district) and 620 Ma (Batouri district) were equated to the age of gold mineralization (Asaah et al., 2015;Ateh et al., 2017), but mineralized veins cut both metavolcanic-metasedimentary and plutonic rocks (Azeuda Ndonfack et al., 2021a,b). ...
... Toteu et al. (2006a) interpreted the sediments of the Lom Belt as being deposited, deformed, and metamorphosed within the period of 613-600 Ma, while granitic intrusion within the belt was dated at ca. 635 Ma (Ateh et al., 2017). Furthermore, plutonic rocks ages of 635 Ma (Bétaré Oya district) and 620 Ma (Batouri district) were equated to the age of gold mineralization (Asaah et al., 2015;Ateh et al., 2017), but mineralized veins cut both metavolcanic-metasedimentary and plutonic rocks (Azeuda Ndonfack et al., 2021a,b). These inconsistencies result in a poor understanding of the chronology of events such as sediment deposition, plutonic rock emplacement, and gold mineralization in eastern Cameroon. ...
The Bétaré Oya and Woumbou-Colomine-Kette gold districts, located in the East Metallogenic Province of Cameroon, are characterized by a complex Neoproterozoic history of metamorphism, polyphase deformation, and widespread crustal anatexis and magmatism. Controversy exists on the timing of the metamorphic and magmatic events, particularly within the area of the Lom Belt, and accurate absolute ages and even geodynamic chronology pertaining to the tectono-magmatism are yet to be well constrained. New LA-ICP-MS U-Pb zircon ages, Lu-Hf isotope data, and whole-rock geochemistry of granitoids and metavolcanic-metasedimentary rocks from the Woumbou-Colomine-Kette and Bétaré Oya districts better constrain the tectonic evolution of eastern Cameroon. The U-Pb age data of 646.5 ± 2.0 Ma, 643.7 ± 1.8 Ma, 641.3 ± 4.4 Ma, 641.4 ± 3.5 Ma, and 620.9 ± 2.6 Ma revealed that the granitoids from the Woumbou-Colomine-Kette district were emplaced during two main magmatic events at ca. 650-635 Ma and ca. 620 Ma. The zircon Hf(t) values between − 13.80 and − 6.20 with Hf TDM model ages of 1.9-2.4 Ga, coupled with geochemical signatures show that granitoids were generated by partial melting of Paleoproterozoic supracrustal metasedimentary units and meta-igneous rocks during subduction and orogenic convergence. Metamorphic zircons from the actinolite-chlorite schist of the Lom Belt gave ages between ca. 655 and 585 Ma, implying that the metavolcanic-metasedimentary rocks of the belt were deposited prior to 655 Ma, then metamorphosed and deformed between ca. 655 and 585 Ma. Two age peaks of detrital zircons were measured at ca. 1035 Ma and ca. 784 Ma with the εHf (t) values of-14.60 and-18.37 and +2.97 and +8.60, respectively. These data, coupled with those from previous studies, suggest that the Lom Belt may represent a suture zone between the Central and Southern Cameroon domains with an early rifting at ca. 784 Ma. In general, our U-Pb ages indicate compressional to transpressional deformational phases in the two districts at ca. 660-635 Ma (D1), 630-610 Ma (D2), and 600-580 Ma (D3). The latter D3 transpressional event was also associated with the formation of the widespread occurrences of orogenic gold, although the precise timing of gold deposition needs to be constrained.
... Plutonic rocks in the district are syn-tectonic (see below section 3.2) and show heterogeneous deformation features varying from undeformed to strongly deformed mineral grains within a single pluton (Ngako et al., 2003). The Bétaré Oya peraluminous, calc-alkaline granitic stock was emplaced into the chlorite-sericite schist and has a granodioritic to tonalitic affinity (Ateh et al., 2017). The pluton shows evidence of D2 sinistral deformation along its NW and NE margins when examined by aeromagnetic and radiometric images (Ateh et al., 2017), but the total amount of displacement along the Bétaré Oya Shear Zone is unknown. ...
... The Bétaré Oya peraluminous, calc-alkaline granitic stock was emplaced into the chlorite-sericite schist and has a granodioritic to tonalitic affinity (Ateh et al., 2017). The pluton shows evidence of D2 sinistral deformation along its NW and NE margins when examined by aeromagnetic and radiometric images (Ateh et al., 2017), but the total amount of displacement along the Bétaré Oya Shear Zone is unknown. The intrusion was dated at ca. 635 Ma and formed in a subduction-related magmatic arc setting (Ateh et al., 2017). ...
... The pluton shows evidence of D2 sinistral deformation along its NW and NE margins when examined by aeromagnetic and radiometric images (Ateh et al., 2017), but the total amount of displacement along the Bétaré Oya Shear Zone is unknown. The intrusion was dated at ca. 635 Ma and formed in a subduction-related magmatic arc setting (Ateh et al., 2017). Mafic dikes occur in the belt (Fig. 3e, 3i) and underwent the same regional greenschist facies metamorphism. ...
The Bétaré Oya district has a substrate composed of the Neoproterozoic metavolcanic-metasedimentary rocks of the Lom Belt in eastern Cameroon. The district is well-known for alluvial gold mining activities, however, the primary gold mineralization has received little attention. In the current study, we newly report geological, ore mineralogy, fluid inclusion microthermometric, laser Raman spectroscopy, and stable isotope data from auriferous veins of the Lom Belt to characterize the style of gold mineralization and to constrain the origin of the ore-forming fluids. The auriferous quartz veins are laminated, fractured, N- to NE-trending, and spatially associated with the Bétaré Oya Shear Zone. Fieldwork coupled with microscopic examination and the textural relationships of ore minerals revealed two stages of mineralization. The first stage is characterized by the presence of pyrite, sphalerite, galena, chalcopyrite, pyrrhotite, hematite, petzite, hessite, wolframite, electrum, and gold, while the second stage is characterized by the presence of a later deposition of galena and pyrite, as well as minor greenockite. The gangue minerals are quartz, sericite, muscovite, chlorite, calcite, ankerite, and barite, whereas the supergene assemblage (stage 3) includes goethite, hematite, covellite, and enargite. Two fluid inclusion assemblages containing three types of inclusions are identified in mineralized quartz veins. Assemblage 1 consists of gold-related types 1 and 2 with daughter minerals consisting of nahcolite, magnesite, and arsenolamprite (black native arsenic), whereas assemblage 2 consists of post-gold type 3 fluid inclusions. Type 1 has H2O-NaCl-CO2±N2±CH4 primary fluid inclusions (FI), with a TmCO2 ranging from −59.8 to −56.6 °C, salinities from 0.5 to 10.8 wt% NaCl eq., densities from 0.87 to 1.00 g.cm⁻³, and total homogenization temperatures between 280 and 360 °C. Type 2 contains CO2 (±H2O-NaCl)±N2±CH4 FI that exhibit TmCO2 ranging between −60.0 and −56.7 °C, ThCO2 from 13 to 25 °C, and densities between 0.73 and 0.85 g.cm⁻³. Type 3 shows H2O-NaCl FI with salinities between 0.2 and 10.1 wt% NaCl eq., densities between 0.82 and 0.98 g.cm⁻³, and total homogenization temperatures from 160 to 235 °C. Measured δ¹⁸O for gold-bearing quartz (+11.5 to +16.0‰), δD from FI (−50.6 to −21.8‰), δ¹³C from FI (−5.8 to −5.5‰), and δ³⁴S from galena and pyrite grains (+5.3‰ and +8.2‰, respectively) suggest a metamorphic source as most likely for the ore-forming fluids and sulfur, although a mantelic CO2 contribution cannot be ruled out.
The gold deposition probably took place by fluid-rock interaction and fluid unmixing at ∼310 °C and at a depth of about 6-9 km. The ore-forming fluid was a low salinity (∼6.2 wt% NaCl eq.) H2O-NaCl-CO2±N2±CH4 solution. These data revealed that the Lom Belt gold mineralization is best classified as a mesozonal orogenic gold deposit.
... The PC2-FIL and PC3-FIL anomaly B coincides with the mineralized veins NW of the maps (Fig. 12b, c). This anomaly highlights two potential phases of mineralization: The first being linked to PC3-FIL with the Au-Rb-As association representing a mineralization linked to the placement of granitoids as shown by (Asaah et al. 2015;Ateh et al. 2017). These authors associate the placement of granitoids dating from 620 to 640 Ma with gold mineralization in the Batouri gold district (to the south of the study area) and Betare Oya gold district (located to the north-west part of the study area), respectively. ...
Gold enrichment and other metals usually occur during fractional crystallization in granitoids. In this study, the spatial analysis of multi-element associations from stream sediments is proposed to identify the characteristics and distributions of lithological units and mineralized pegmatite vein with associated stream sediments in the Lingbim-Zimbi gold field for mineral exploration purposes. The sampling campaign was carried out both on rocks and in exploration wells. Principal component analysis and the phased array approach have allowed distinguishing the chemical elements linked to the mineralized structure from those linked to the geology of the area. Then, two potential gold mineralization phases were identified along with the anomalies observed and the spatial distribution of the elemental associations; the first one being linked to the emplacement of granitoids and the second linked to the formation of the Central Cameroonian Shear Zone (CCSZ) oriented NE-SW
