Geochemical characteristics and origin of the Neoproterozoic high-K calc-alkaline granitoids in the northern part of Mandara hills,northeastern Nigeria  

作　　者：Musa B.Girei Tavershima Najime Paul O.Ogunleye 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources,Faculty of Earth Resources,China University of Geosciences,Wuhan 430074,China [2]Department of Geology,Faculty of Earth and Environmental Sciences.Bayero University,Kano,Nigeria [3]Department of Geology,Ahmadu Bello University,Zaria,Nigeria [4]Centre for Energy Research and Training,Ahmadu Bello University,P.M.B.1014,Zaria,Nigeria

出　　处：《Acta Geochimica》2020年第3期337-354,共18页地球化学学报（英文）

摘　　要：The high-K calc-alkaline granitoids in the northern part of the Mandara Hills are part of the wellexposed post-collisional plutons in northeastern Nigeria.The calc-alkaline rock association consists of quartz monzodiorite,hornblende biotite granite,biotite granites and aplite which intruded the older basement consisting mainly of low-lying migmatitic gneisses and amphibolites during the Neoproterozoic Pan-African Orogeny.Petrological and geochemical studies have revealed the presence of hornblende,iron oxide,and metaluminous to slightly peraluminous characteristics in the granitoids which is typical of I-type granite.The granitoids are also depleted in some high field strength elements(e.g.Nb and Ta) as well as Ti.Plots of Mg#versus SiO2 indicate that the granite was derived from partial melting of crustal sources.Lithospheric delamination at the waning stage of the PanAfrican Orogeny possibly triggered upwelling of hot mafic magma from the mantle which underplated the lower crust.This,in turn,caused partial melting and magma generation at the lower to middle-crustal level.However,the peculiar geochemical characteristics of the quartz monzodiorite especially the enrichment in compatible elements such as MgO,Cr,and Ni,as well as LILE element(e.g.K,Ce,Cs,Ba,and Sr),signify that the rock formed from an enriched upper mantle source.The emplacement of high-K granites in the Madara Hill,therefore,marked an important episode of crustal reworking during the Neoproterozoic.However,further isotopic work is needed to confirm this model.

关 键 词：CALC-ALKALINE I-type granitoids PAN-AFRICAN Mandara hills NIGERIA 

分 类 号：P534.3[天文地球—古生物学与地层学] P588.121[天文地球—地质学] P59