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The Bafoussam volcanic series:origin and evolution of the volcanism along the Cameroon volcanic line

Acta Geochimica 2022年第6期41卷 1049-1068页

作者： Philippe Essomba Gilles Chazot Nicaise Blaise Tchuimegnie Ngongang Arnaud Agranier pierre Kamgang HervéBellon Philippe Nonnotte pierre wotchoko Innocent Badriyo Département Des Sciences de La Terre FacultéDes SciencesUniversitéde YaoundéIB.P.812YaoundéCameroun Geo-Ocean CNRSIfremerUMR6538Univ Brest29280PlouzaneFrance Département Des Sciences de La Terre FacultéDes SciencesUniversitéde DoualaDoualaCameroun Department of Geology Higher Teacher Training CollegeUniversity of BamendaBambiliBamendaCameroon Département de Séismologie et Géologie Observatoire Volcanologique de Goma-RDCGomaRépublique Démocratique du Congo

The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic *** rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and *** age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 *** alkaline volcanism is younger,with ages ranging from10 to 4.5 *** evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing *** the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic *** lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional *** La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the *** cannot be used for discussing the mantle source of the volcanic rocks from this *** elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle *** magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic *** mantle source is present in all the oldest lavas from the *** magmas formed from an HIMU-like mantle sourc

关键词： Cameroon Volcanic Line Bafoussam Mafic volcanic rocks Felsic volcanic rocks Mantle source

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Remineralization of a Dystric Ferralsol Using Basalt and Tephra Dusts,Effective Microorganisms Manure and NPK 20-10-10 for Radish(Raphanus sativus)Production in Bamougoum(Cameroon Western Highlands)

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Journal of Environmental & Earth Sciences 2021年第1期3卷 1-15页

作者： pierre wotchoko Primus Azinwi Tamfuh Margaret Awah Tita Alice Magha Glory Anonchuh Wonyi Fritz Oben Tabi Dieudonne Bitom Department of Geology Higher Teacher Training College BambiliUniversity of BamendaP.O.Box.39BambiliCameroon Department of Soil Science Faculty of Agronomy and Agricultural SciencesUniversity of DschangP.O.Box.222DschangCameroon Departmentment of Mining and Mineral Engineering National Higher Polytechnic InstituteUniversity of BamendaP.O.Box.39BambiliCameroon Department of Biology Higher Teacher Training CollegeUniversity of BamendaP.O.Box.39BambiliCameroon

This paper studies the effect of basalt and tephra dusts,as alternatives to chemical fertilizers,on soil fertility and Radish(Raphanus sativus)*** experiment was conducted in the field and in the laboratory in the years 2017 and 2018 on two separate plots so as to annul residual effects of fertilizers).The experimental design in the field was a randomized complete block design(56 m^(2)),including five treatments and three replications:control(T_(0)),basalt dust(T_(1)),tephra dust(T_(2)),effective micro-organism(EM)fertilizer(T_(3))and NPK 20-10-10(T_(4)).The main results show the following decreasing trend based on yield:T_(1)>T_(3)>T_(0)>T_(4)>T_(2).The best yields appear in T_(1) and T_(3) probably because they supplied the highest levels of soil nutrients to match the needs of the *** T_(2) plants performed poorly,soil properties like pH.H_(2)O(6.14 to 6.49),sum of exchangeable bases,base saturation,available phosphorus and cation balance were improved after tephra treatment.T_(2) plants might have performed poorly due to intrinsic properties of the tephra dust like low availability of trace elements compared to T_(1) and T_(3).T_(4) plants show the highest number of leaves,leaf area index and plant *** Fe,Mn,Cu and Zn levels in bulbs and leaves will not pose danger of toxicity to human upon consumption and could serve as nutrient supplement for children and expectant *** most profitable treatment is T_(1) permitting to recommend the popularization of basalt dust for radish cultivation as an alternative to chemical fertilizers.

关键词： Raphanus sativus Soil remineralisation Micronutrients Revenue-to-cost ratio Cameroon Western Highlands

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Petrochemical Characterization of Two Distinct Types of Dolerites from Bafoussam Area, West Cameroon

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International Journal of Geosciences 2013年第8期4卷 1131-1144页

作者： Gus Djibril Kouankap Nono pierre wotchoko Sylvestre Ganno Divine Ngong Njinchuki Jean Paul Nzenti 1Department of Geology HTTC University of Bamenda Bamenda Cameroon 2Laboratory of Petrology and Structural Geology Faculty of Science University of Yaoundé I Yaoundé Cameroon Department of Geology HTTC University of Bamenda Bamenda Cameroon Economic Geology Unit Department of Geology University of Buea Buea Cameroon Laboratory of Petrology and Structural Geology Faculty of Science University of Yaoundé I Yaoundé Cameroon

Two petrochemical types of doleritic dykes have been distinguished in Bafoussam area: 1) the olivine-bearing dolerites which are the most representative are dark green, showing characteristics of alkaline basalts and, 2) the calcite-bearing dolerites are grayish green, showing characteristics of tholeiitic basalts. The studied dolerites are less differentiated (1 FeOt/MgO 2);they present the evolution of a subalkaline magma following a calc-alkaline series (alkaline dolerites) and the tholeiitic series (tholeitiic dolerite). The chondrite normalized multielement spider diagrams of all the dolerites show a pronounced depletion in Ba, Th, and enrichment in Rb. Their geotectonic context is inferred to be intraplate and the contrast between the two types is probably due to a diverse source: crustal source for calcite-bearing dolerites and mantle source for olivine-bearing dolerites.

关键词： Doleritic Dyke Petrochemical Alkaline Tholeiitic Intraplaque Bafoussam

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Assessment of Groundwater Quality for Domestic and Irrigation Purposes in Northern Bamenda (Cameroon)

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Journal of Water Resource and Protection 2021年第1期13卷 1-19页

作者： Alice Magha Margaret Tita Awah Gus Djibril Kouankap Nono Primus Azinwi Tamfuh pierre wotchoko Mercy Adoh Veronique Beyala Kamgang Kabeyene Department of Geology Higher Teacher Training College University of Bamenda Bambili Cameroon Department of Biology Higher Teacher Training College University of Bamenda Bambili Cameroon Department of Soil Science Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Mining and Mineral Engineering National Higher Polytechnic Institute University of Bamenda Bambili Cameroon Department of Earth Sciences Higher Teacher Training College University of Ngaoundere Bertoua Cameroon

Safe and reliable drinking water availability constitutes a nightmare in many towns of developing countries and is usually appreciated from its physical appearance without prior knowledge of its chemical and biological properties. This study investigates the suitability of groundwater for domestic and irrigational purposes through physico-chemical and bacteriological analyses in the Northern part of Bamenda Town (Cameroon). Thus, 20 groundwater samples were collected from hand-dug wells and spring sources in September 2018 (rainy season) and February 2019 (dry season) and physico-chemical and bacteriological characteristics were determined. The results revealed that pH ranged from 5.5 to 6.6, thus enabling the classification of the water as slightly acidic. Electrical conductivity varied between 0.01 - 0.06 μS/cm. The relative abundance of ions was such that Ca2+ > K+ > Mg2+ > Na+ for cations and HCO-3 > Cl- > NO-3 > SO-4 for anions. The water types were Ca-Mg-NO3 in both dry and rainy seasons. The results revealed that the mechanisms controlling groundwater chemistry are rock weathering and atmospheric precipitation. Indicator bacteria such as E. coli, Shigella, Enterobacteria, Vibrio, Streptococcus and Staphylococcus were detected in the studied groundwater samples, thus the water sources may pose a threat to public health.

关键词： Reliable Drinking Water Groundwater Quality Spring Sources Chemical Characteristics Bacteriological Characteristics

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The Twin Bambili Maars (Bamenda Mountains, Cameroon Volcanic Line): Simulative Model of Formation

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Open Journal of Geology 2017年第4期7卷 443-456页

作者： wotchoko pierre Takojio Nguemo Rose Eugenie Kouankap Nono Gus Djibril Guedjeo Christian Suh Nkouathio David Guimollaire Bobga Stanley Babila Chenyi Marie-Louise Vohnyui Tchokona Seuwi dieudonne Suh Emmanuel Cheo Department of Geology Higher Teacher Training College University of Bamenda Bambili Cameroon Institut de Recherche Géologique et Minière Laboratoire de Traitement des Minerais Yaoundé Cameroon Department of Earth Sciences Faculty of Sciences University of Dschang Dschang Cameroon Department of Earth Sciences Faculty of Sciences University of Yaoundé 1 Yaoundé Cameroon Economic Geology Unit Department of Geology and Environmental Science University of Buea Buea Cameroon

The Bambili maars are twin contemporaneous maars embedded in trachytic rocks. The two maars are separated by a low lying inter-Maar dome whose inner walls dip towards the Southern Maar. The Bambili Northern Maar (BNM) contains water and its floor is found at an altitude lower than the Bambili Southern Maar (BSM) (50 m) which is swampy and drains into the BNM. Both maars have very steep vertical walls. Three different units are identified in the area. Unit 1 is 1 m thick sequence, characterize by the presence of matrix supported fine-grained fallouts (ash and lapilli size) with stratified diffused bedding planes. This unit is further subdivided into three different layers: L1, L2 and L3 from bottom to top with increasing sizes of particles respectively. This layer shows reverser grading and its grain sizes rarely exceed 2 cm and this unit shows no depositional structures. Unit 2 is an unstratified unit predominantly made up of tephra deposits. Within these deposits are found blocks of sizes ranging between 2 and 10 cm of different petrographic types. They include scoria, basalts, trachyte, and granite cognate. The last unit, Unit 3 is distinctly stratified characterized by well sorted, heterolithologic, graded bedding layers which are matrix supported. Base on the composition and grain sizes, this unit was subdivided into 7 horizons: h1 - h7. Within this unit, two sequences of deposits are distinguished: U1 and U2. Both sequences are characterized by alternation of lapilli and tuff beds. The clast comprises of juvenile materials, mudstone which are highly vesicular and altered rock fragments. Other products identified within the area are ferolithic volcanic bombs (5 - 20 cm), xenocrystals (2 - 4 cm) within finer deposits. They are elongated and show visible twinned planes. Explosion breccias are equally identified occurring as bolders. Along the inner walls of the maars are also found large basaltic and trachytic blocks which are remnants of pre-maar unit within maar

关键词： Maar Bambili Dynamisms Model

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