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Bulk geochemistry,Rb-Sr,Sm-Nd,and stable O-H isotope systematics of the Metzimevin high-grade iron ore deposit,Mbalam iron ore district,southern Cameroon

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Acta Geochimica 2024年第4期43卷 677-706页

作者： Samndong Cyril Tufoin cheo emmanuel suh Tabod Charles Tabod George Lemewihbwen Ngiamte Department of Geology Mining and Environmental ScienceThe University of BamendaB.P.39BambiliNorth West RegionCameroon Economic Geology Unit Department of GeologyUniversity of BueaP.O.63BueaSouth West RegionCameroon Department of Physics Faculty of ScienceThe University of BamendaB.P.39BambiliNorth West RegionCameroon Department of Geology Pan-African University Life and Earth Sciences Institute(PAULESI)University of IbadanIbadanNigeria

Bulk geochemistry,Sr,Nd,and O-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the northwestern segment of Congo Craton(CC).Located in Mbalam iron ore district,Southern Cameroon,Metzimevin iron ore deposit is a hematite-magnetite BIF system,dominated by SiO_(2)+Fe_(2)O_(3)(97.1 to 99.84 wt%),with low concentrations of clastic elements e.g.,Al_(2)O_(3),TiO_(2),and HFSE,depicting a nearly pure chemical *** REE+Y signature of the iron deposit displays strong positive Eu anomaly,strong negative Ce anomaly,and chondritic to superchondritic Y/Ho ratios,suggestive of formation by mixed seawater-high temperature hydrothermal fluids in oxidising ***^(87)Sr/^(86)Sr ratios of the BIF are higher than the maximum^(87)Sr/^(86)Sr evolution curves for all Archean reservoirs(bulk silicate earth,Archean crust and Archean seawater),indicating involvement of continentally-derived components during BIF formation and ***Ɛ_(Nd)(t)(+2.26 to+3.77)and Nd model age indicate that chemical constituents for the BIF were derived from undifferentiated crustal source,between 3.002 and 2.88 *** variable and diverse O and H isotope data(−1.9‰to 17.3‰and−57‰to 136‰respectively)indicate that the Metzimevin iron ore formed initially from magmatic plumes and later enriched by magmatic-metamorphic-modified meteoric *** balance calculations indicate mineralisation by combined leaching and precipitation,with an average iron enrichment factor of>2.67 and SiO_(2)depletion factor of>*** is associated with an overall volume reduction of 28.27%,reflecting net leaching and volume collapse of the BIF protholith.

关键词： Bulk geochemistry Rb-Sr Sm-Nd Mitzimevin High-grade iron ore

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Land Use and Land Cover Dynamics in the Eseka Alluvial Gold Mining District, Centre Region, Cameroon

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Journal of Geographic Information System 2024年第4期16卷 289-305页

作者： Shu Vejiline Lum-Ndob Fonge Beatrice Ambo Ambe Godlove Neba Ateh Kevin Ijunghi Enerst Tata cheo emmanuel suh Department of Plant Science Faculty of Science University of Buea Buea Cameroon Department of Mining and Mineral Engineering National Higher Polytechnic Institute The University of Bamenda Bambili Cameroon Economic Geology Unit Department of Geology Faculty of Science University of Buea Buea Cameroon Department of Geology Mining and Environmental Science The University of Bamenda Bambili Cameroon

Local populations in Cameroon thrive on forest resources and the flow of ecosystem services they provide are pivotal in sustaining national economy, improving people’s lives, safeguarding biodiversity, and mitigating the impacts of environmental changes. The exploitation of these resources invariably leads to deforestation and forest degradation. This study was designed to evaluate land use land cover change (LULCC) in the Eseka alluvial gold mining district with the aid of Landsat images. In the investigation of forest cover change, four Landsat satellite images for (1990, 2002, 2015 and 2022) were used. Ground-truthing also helped to identify the activities carried out by the local population and to determine agents, drivers and pressures of land use and land cover change. Four main land cover classes namely: forest, agricultural land, settlement/mining camps and water bodies were selected. Between 1990 and 2022, the proportion of forest decreased from 98% to 34% while those of agricultural land and settlement/mining camps increased from 2% to 60% and 0.54% to 6% respectively. Analysis showed ongoing deforestation with forest cover loss of ~98,263 ha in 32 years giving a cover change percentage of 63.94%. Kappa coefficient for the study period ranged from 0.92 to 0.99. Forest cover loss could be attributed to farming activities, wood extraction and alluvial gold mining activities. Economic motives notably the need to increase household income from a frequent demand for farm and wood products in neighbouring towns and the quest for gold were the main drivers of these activities. Hence, this study assesses the impact of human activities from the mining sector on the forest ecosystem in a bid to inform mitigation policies.

关键词： Land Use and Land Cover Changes Biodiversity Alluvial Gold Mining Drivers Landsat Images Ground-Truthing Mitigation

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Petrogenetic characterization of the host rocks of the Sanaga iron ore prospect,southern Cameroon

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Acta Geochimica 2023年第2期42卷 195-220页

作者： Tasin Godlove Bafon Anthony Temidayo Bolarinwa cheo emmanuel suh Temesgen Oljira Bekele Ayele Bedada Gilles Nyuyki Ngoran Kevin Ijunghi Ateh Boris Martial Keuko Djoumbissie Cho Terence Ngang Department of Geology Pan African University Life and Earth Science InstituteUniversity of IbadanIbadanNigeria Department of Geology Mining and Environmental ScienceUniversity of BamendaP.O.Box 39BambiliCameroon Explorers 33 Consulting Group Sarl P.O.Box 6666YaoundeCameroon Department of Earth Sciences Faculty of ScienceUniversity of Yaounde IP.O.Box 812YaoundeCameroon

The Sanaga iron ore prospect is a recent discovery in the Nyong Series with a resource estimated at 82.9 Mt at 32.1%Fe and whose origin remains *** mineralization occurs as NE-SW oriented discontinuous lenticular bodies of magnetite-bearing pyroxenegneisses(MPG)hosted by ortho-derived *** amphibolites are *** MPG mineral assemblage consists of quartz-magnetite-orthopyroxene-garnet-tremolite/actinolite exhibiting a granoblastic texture,which is characteristic of granulite facies *** granodioritic gneisses show compositional features of the tonalite-trondhjemite-granodiorite *** trace and REE element geochemistry indicate their protolith melt resulted from the partial melting of a subducted oceanic slab,with interaction with the overlying mantle wedge during *** amphibolites show enrichment in LILE with negative Ta–Nb and Zr–Hf indicating arc-related magmas generated by partial melting of a sub-continental lithospheric mantle source with metasomatism by subduction-related *** MPG exhibits oxidation-exsolution features characterized by ilmenite lamellae,with hematite fracture-fillinginmagnetite,andlacksfeatures characteristic of typical BIF such as LREE depletion relative to HREE,positive Eu,La,and Y *** on the results of this study,we interpret the Sanaga MPG as a possible skarn-type mineralization formed by the metamorphism/metasomatism of a possible BIF *** results of this study compare with similar magnetite-rich mineralization in the Sa o Francisco craton in northeastern Brazil and enhance the correlation of pre-drift reconstructions of the Sa o Francisco–Congo Cratons.

关键词： Magnetite-pyroxene-gneiss Metasomatism Ilmenite exsolution Hematite fracture-filling Skarn type mineralization Nyong Series

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Application of Electrical Resistivity and Chargeability Data on a GIS Platform in Delineating Auriferous Structures in a Deeply Weathered Lateritic Terrain, Eastern Cameroon

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International Journal of Geosciences 2012年第5期3卷 960-971页

作者： Albert Nih Fon Vivian Bih Che cheo emmanuel suh Economic Geology Unit Department of Geology Faculty of Science University of Buea Buea Cameroon Remote Sensing Unit Department of Geology Faculty of Science University of Buea Buea Cameroon

Exploration for primary gold in tropical settings is often problematic because of deep weathering and the development of a thick soil cover. In this paper we present the results of both chargeability and resistivity surveys carried out over the Belikombone hill gold prospect (14?00' - 14?25'E, 5?25' - 6?00'N) in the Betare Oya area (eastern Cameroon), where previous soil sampling had identified gold anomalies. The geophysical data were obtained using Syscal Junior 48 resistivity meter and the Schlumberger configuration array for both the vertical electrical soundings (VES) and horizontal profiling. These data were further built into a GIS framework and the continuity of favourable gold-bearing structures at depth modeled using WINSEV, RED2INV and SURFER extensions softwares. IP (Induced Polarization)-chargeability and resistivity data combined, have identified irregular anomalous zones trending NE-SW. This trend is consistent with the attitude of most auriferous quartz veins exposed in artisanal pits and parallel to the regional shear zone system and foliations. The high resistivity anomalies correspond to quartz veins while the relatively high IP anomalies correspond to low sulphide ± gold concentrations in the quartz veins. Modeling IP-chargeability and resistivity data prepared as contours and 3D maps, culminated to the development of an inferred, irregular and discontinuous mineralized body at depths of up to 95 m. The size and shape of this mineralized body can only later be tested by drilling to ascertain the resource.

关键词： Gold Exploration Tropical Settings Deep Weathering IP-Chargeability and Resistivity Betare Oya 3D Maps Cameroon

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Textures and Rare Earth Elements Composition of Banded Iron Formations (BIF) at Njweng Prospect, Mbalam Iron Ore District, Southern Cameroon

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International Journal of Geosciences 2013年第1期4卷 146-165页

作者： Dieudonne Charles Isidore Ilouga cheo emmanuel suh Ghogomu Richard Tanwi Department of Earth Sciences Faculty of Science University of Yaoundé I Yaoundé Cameroon Economic Geology Unit Department of Geology and Environmental Science University of Buea Buea Cameroon

The REE signature of banded iron formations (BIF) and martite-goethite mineralization of the Njweng ridge (South Cameroon) are used here to decipher the nature of the ocean during the period of BIF precipitation. The textures of typical BIF categories are also presented as the only sedimentary feature. Two types of BIF facies are present at Njweng: the oxide and silicate facies. These facies show two stages of phase transformations. The first is the transformation of the original magnetite mineral into martite by oxidation resulting in trellis texture;the second is a simultaneous transformation by hydration into goethite and dehydration into martite. The samples typically show LREE depleted patterns relative to HREE, a characteristic similar to that of modern seawater. Also the strong positive Eu anomalies from the samples indicate the involvement of hydrothermal plumes of volcanic origin such as at mid ocean ridges (MOR). Yttrium (Y) has a strong positive anomaly pointing to the transportation of REEs as aqueous complexes within these ancient seas. The BIF samples have no positive Ce anomalies, suggesting that the oceans at that time were more reducing with no Ce fractionation than in present day oceans. The martite-goethite mineralization rather shows a positive Ce anomaly that derived from the enrichment in REE during the weathering of REE-bearing minerals. These results are integrated into existing literature on REE in BIFs worldwide and provide new insights into these heretofore unstudied BIFs of the northern edge of the Congo Craton.

关键词： REE BIF Martite Magnetite Alteration Njweng Cameroon

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Na-Metasomatism and Uranium Mineralization during a Two-Stage Albitization at Kitongo, Northern Cameroon: Structural and Geochemical Evidence

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International Journal of Geosciences 2012年第1期3卷 258-279页

作者： Arnaud Patrice Kouske cheo emmanuel suh Richard Tanwi Ghogomu Vincent Ngako Laboratory of Applied Geology-Metallogeny Department of Earth Sciences University of Yaoundé 1 Yaoundé Cameroon

Mapping and documentation of lithological varieties and their corresponding geochemistry at the Kitongo uranium mineralization were concerned. The Kitongo U occurrence is hosted by granitic rocks that include interleaved sequences of metasedimentary and metavolcanic rocks of the collectively termed Poli Group. U-mineralization and Na-metasomatism are related and structurally controlled. The most promising uraniferous bodies are intimately related to intersections between the ductile ENE-trending faults and the brittle conjugate R' faults postdating the shearing event. The con- centration of uranium at fault intersections rather than along individual faults suggests that these zones that are dilatational in nature were also highly permeable and therefore the hydrothermal fluids ponded there could readily precipitate U therein. A two-stage albitization has altered the foliated granitic host rock and the second albitization that has over-printed the first one is more effective at fault intersections. Whole rock geochemistry was performed by using ICP-MS and ICP-AES respectively for major oxides, trace and REE. The U-bearing rock suite exhibits restricted range in SiO2 concentration (62.89% - 70.91%) and Al2O3 (13.16% - 18.59%) and it is poor in MgO (0.02% - 1.03%), CaO (0.24% - 1.88%) and K2O (0.08% - 5.32%). The mineralized rocks are however comparatively richer in Na2O (4.33% - 10.92%) compared to their barren counterparts. The host granite and associated granodioritic rocks in the area are weakly metaluminous, peralkaline, and are calc-alkaline. They are moderately to strongly fractionated and have tholeiitic and shoshonitic affinities with moderate to high HFSE (high field strength elements) and LILE (large ion lithophile elements) enrichment. The Rb/Sr, Rb/Ba and Sr/Ba ratios are 0.31, 0.14 and 1.48, respectively. U content in the mineralized granite is up to 651 ppm while the non-mineralized rock has only 2.4 ppm U. The REE patterns of the granite show LREE enric

关键词： Uranium Kitongo Granite Albitization Strike Slip Fault Cameroon

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Geochemistry of Sedimentary Rocks from the Nkapa Formation, North Western Part of the Douala Basin, Cameroon: Implications for Provenance, Tectonic Setting and Paleoenvironmental Conditions

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International Journal of Geosciences 2021年第9期12卷 739-762页

作者： Florence Njinto Kwankam Christopher Mbaringong Agyingi Josepha Foba-Tendo cheo emmanuel suh Department of Petroleum Engineering National Higher Polytechnic Institute (NAHPI) The University of Bamenda Bambili North West Region Cameroon Department of Geology Faculty of Science The University of Bamenda Bambili North West Region Cameroon Department of Chemistry University of Buea Buea South West Region Cameroon Department of Geology University of Buea Buea South West Region Cameroon

The Douala sedimentary basin in Cameroon is the main gas prospective basin in the country and has witnessed a number of investigations in this regard. The Nkapa Formation is one of the basin’s principal rock units and here we analyzed samples from sediments comprising this formation in order to constrain their provenance, tectonic setting and depositional environment using geochemical traits. Major and trace elements were analyzed by inductively coupled plasma mass spectrometry. Elemental ratios provide information on geochemical signatures of Eu/Eu ratios of the sandstones and shales, suggesting the provenance of the sediments was felsic from continental rock protoliths. Calculated K2O/Na2O ratios > 1 is reminiscent of quartz-rich sediments deposited in passive margin (PM) environments with significant terrigenous input. The elemental ratios La/Sc, La/Ca, Th/Sc, and Th/Co suggest that the sediment sources are felsic and mafic in nature. The clastic sediments were normalized using North American Shale Composite (NASC). The Ni/Co and V/(V + Ni) ratios reveal that the sediments were deposited under variable conditions including euxinic, dysoxic and anoxic. Overall, the evidence from discrimination diagrams using major and trace elements suggest that the sediments were derived from mostly Passive margins (PM) and continental island arc (CIA) with minor Oceanic island arch (OIA) sources. Limestones from the studied area at Kompina, rich in calcium carbonate

关键词： Geochemistry Sedimentary Rocks Nkapa Formation Provenance Depositional Environment

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Hydrothermal Alteration of Basaltic Rocks at Eruptive Vents on Mount Cameroon Volcano, West Africa

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International Journal of Geosciences 2018年第9期9卷 513-527页

作者： Akumbom Vishiti Taboko Armstrong Elisha Mutum Shemang Jacques Etame cheo emmanuel suh Department of Civil Engineering The University Institute of Technology (IUT) University of Douala Douala Cameroon Economic Geology Unit Department of Geology University of Buea Buea Cameroon Department of Earth and Environmental Science Botswana International University of Science and Technology Palapye Botswana Laboratory of Geosciences Natural Resources and Environment Department of Earth Science University of Douala Douala Came-roon Department of Geology Mining and Environmental Science The University of Bamenda Bambili Cameroon

The study of changes in rocks due to interaction with hydrothermal fluids at active volcanoes provides insights into wall rock alteration associated with ore deposits formed in the geological past. Therefore, the nature of mineral alteration and chemical changes experienced by wall rocks can be investigated at eruptive sites on active volcanoes and the results used to better constrain ore-forming processes. In this study, we investigated the alteration at eruptive sites at Mount Cameroon volcano. These eruptive vents lie along NE-SW-trending fissures that define the Mount Cameroon rift. The vents are surrounded by cones composed largely of pyroclastic materials and to a lesser extent lava. Fumaroles (volcanic gases) rising through the vents during and after the 1999 eruption have resulted in the alteration of the pyroclastic robble along the fissures and the inner walls of the cones. Consequently, altered basaltic materials are covered with thin films of reddish, yellowish to whitish secondary minerals. These coatings result from an interaction between the surfaces of the basaltic glass with volcanically-derived acidic fluids. Petrographic investigations and XRD analysis of the basalts have identified primary mineral phases, such as olivine, pyroxene (mainly augite) and feldspars. Alteration products revealed include ubiquitous silica as well as gypsum, magnetite, feldspar, alunite and jarosite. Jarosite occurrence indicates that SO2 is the primary volcanically-derived acid source involved in coating formation. High contents of sulfur identified in the basalts indicate that melts at Mount Cameroon can be sulfur saturated as backed by previous melt inclusion data. Whole rock geochemical analysis shows a gain in silica in the altered samples and this ties with the mass balance calculations although minor gains of Al2O3, , MgO, MnO, CaO and K2O are shown by some samples.

关键词： Mount Cameroon 1999 Eruption Fumarole Wall Rock Alteration Mass Bal-ance

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Mineralogy and Texture of the Weathered Products from Silicic Lavas in the Sabga Area, North West Cameroon

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International Journal of Geosciences 2021年第6期12卷 605-624页

作者： Edith Etakah Bate Tibang Gideon Anoma Waji Elisha Mutum Shemang cheo emmanuel suh Department of Geology Mining & Environmental Science Faculty of Science University of Bamenda Bambili North West Region Cameroon Economic Geology Unit Department of Geology University of Buea Buea South West Region Cameroon Department of Earth and Environmental Sciences Botswana International University of Science and Technology Palapye Botswana

Products of weathering usually clay minerals, are commonly characterized through mineralogical, chemical and geochemical analysis, emphasizing their implications in industrial applications, initiation of landslides and their impact on surface water geochemistry. In this study the vertical variations in textural characteristics and clay mineral type within weathered profiles in the Sabga area were investigated. Two exposed weathered profiles were logged from bed rock to topsoil and each horizon was sampled separately. Granulometric analysis on the samples indicated mixtures of clay, silt and sand size particles in all horizons. Smectite and kaolinite were identified by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The two logs show that the lower horizons display whitish colors with fine laminations, middle horizons are brownish and the upper horizons display dark brown colors. Graphic mean values for both sections gave values that range between 2.02 - 3.7f with an average standard deviation value of 1.9

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Petrochemistry of Two Magnetite Bearing Systems in the Precambrian Belt of Southern Cameroon

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International Journal of Geosciences 2016年第4期7卷 501-517页

作者： Gilles Nyuyki Ngoran cheo emmanuel suh Dunkan Bowker Raymond Beri Verla Godlove Tasin Bafon Ministry of Mines Industry and Technological Development Yaounde Cameroon Explorers 33 Consulting Group Yaounde Cameroon Economic Geology Unit Department of Geology University of Buea Buea Cameroon West African Minerals Cooperation Compagnie Minière du Cameroon Yaoundé Cameroon

In the past decades, several iron ore occurrences have been discovered in the Precambrian Belt of southern Cameroon, with focus on their economic potential, and little attention on the deposit type. However, few studies have been geared towards understanding the different deposit types within this region. This paper seeks to provide new insight on the different styles of iron ore mineralisation of two potential, yet least studied iron ore deposits in this region in addition to enhancing exploration efforts within the different prospects. Petrology and geochemistry of rock samples from the Binga and Djadom iron prospects in southern Cameroon are investigated. The structural disposition of the prospects was mapped and cores described, sampled and subsequently analysed to enhance the understanding of the alteration mineralogy, ore mineralogy and textural features of the iron-bearing lithologies. Polished thin sections were studied by standard microscopy while the bulk rock geochemistry was determined by X-ray fluorescence (XRF) for major and trace elements. At Binga, the main rock types are magnetite gneisses, amphibolites, quartz-biotite gneisses, and mafic intrusions, while the main rocks encountered at Djadom are magnetite gneisses, amphibolitic BIFs, quartz-biotite gneisses, amphibolites and fault rocks. At both prospects, the target lithology for iron ore is the magnetite gneiss. The magnetite gneisses at the Binga prospect are weakly to moderately foliated, but strongly foliated at Djadom, and both contain fractures that are healed by irregular magnetite. Magnetite is anhedral to euhedral in outline and it is closely associated with amphibole, garnet and pyroxene. Iron content of the magnetite gneisses ranges from 17.44 - 33.40 wt% (at Binga) and 27.73 - 43.39 wt% (at Djadom) and the ore enrichment process involved progressive loss of silica and aluminium. Trace element concentrations show high contents of Ba, Zn, Cu and V but lower abundances of Sr and Zr, as we

关键词： Magnetite Gneiss Amphibolitic BIF Skarn Hydrothermal Enrichment

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