A comparative review of petrogenetic processes beneath the Cameroon Volcanic Line: Geochemical constraints

查看全文 作　　者：Asobo [1,2]N.E.Asaah;Tetsuya [1]Yokoyama;Festus [3]T.Aka;Tomohiro [1]Usui;Mengnjo [4]J.Wirmvem;Boris Chako [4]Tchamabe;Takeshi [4]Ohba;Gregory [3]Tanyileke;[3]J.V.Hell

机构地区：[1]Department of Earth & Planetary Sciences, Tokyo Institute of Technology,2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan;[2]Department of Mines, Ministry of Mines, Industry and Technological Development, Yaoundé, Cameroon;[3]Institute of Mining & Geological Research, P.O. Box 4110, Yaoundé, Cameroon;[4]Department of Chemistry, School of Science, Tokai University,Hiratsuka 259-1211, Japan

出　　处：《Geoscience Frontiers》索引2015年第6卷第4期,共14页

基　　金：supported by Science and Technology Research Partnership for Sustainable Development(SATREPS)project titled:Magmatic Fluid Supply into Lakes Nyos and Monoun;Mitigation of Natural Disasters through capacity building in Cameroon;financial support is being provided by the Japan Science and Technology Agency(JST);Japan International Cooperation Agency(JICA);the Institute of Geological and Mining Research(IRGM)of the Cameroon Ministry of Scientific Research and Innovation(MINRESI) 摘　　要：The origin and petrogenesis of the Cameroon Volcanic Line(CVL),composed of volcanoes that form on both the ocean floor and the continental crust,are difficult to understand because of the diversity,heterogeneity,and nature of available data.Major and trace elements,and Sr-Nd-Pb isotope data of volcanic rocks of the CVL spanning four decades have been compiled to reinterpret their origin and petrogenesis.Volcanic rocks range from nephelinite,basanite and alkali basalts to phonolite,trachyte and rhyolite with the presence of a compositional gap between Si O258e64 wt.%.Similarities in geochemical characteristics,modeled results for two component mixing,and the existence of mantle xenoliths in most mafic rocks argue against significant crustal contamination.Major and trace element evidences indicate that the melting of mantle rocks to generate the CVL magma occurred dominantly in the garnet lherzolite stability field.Melting models suggest small degree(<3%)partial melting of mantle bearing(6e10%)garnet for Mt.Etinde,the Ngaoundere Plateau and the Biu Plateau,and<5%of garnet for the oceanic sector of the CVL,Mt.Cameroon,Mt.Bambouto,Mt.Manengouba and the Oku Volcanic Group.The Sr-Nd-Pb isotope systematics suggest that mixing in various proportions of Depleted MORB Mantle(DMM)with enriched mantle 1 and 2(EM1 and EM2)could account for the complex isotopic characteristics of the CVL lavas.Low Mg number(Mg#100 Mg O/(Mg O t Fe O))and Ni,Cr and Co contents of the CVL mafic lavas reveal their crystallization from fractionated melts.The absence of systematic variation in Nb/Ta and Zr/Hf ratios,and Sr-Nd isotope compositions between the mafic and felsic lavas indicates progressive evolution of magmas by fractional crystallization.Trace element ratios and their plots corroborate mantle heterogeneity and reveal distinct geochemical signatures for individual the CVL volcanoes. 关键词：地球化学特征火山岩喀麦隆成岩过程石榴石二辉橄榄岩地幔捕虏体同位素组成审查

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A comparative review of petrogenetic processes beneath the Cameroon Volcanic Line: Geochemical constraints

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