eng Science and Education Publishing Journal of Geosciences and Geomatics 2373-6704 2021-09-07 9 4 160 176 10.12691/jgg-9-4-1 JGG2021941 article Z¨¦non Itiga zenonitiga@yahoo.fr 1 Beno?t Joseph Mbassa 2 Rose No?l Ngo Belnoun 3 Pierre Wotchoko 4 Dieudonn¨¦ Tchokona Seuwui 5 S¨¦bastien Owona 5 Jacques-Marie Bardintzeff 6 Pierre Wandji 6 Herv¨¦ Bellon 7 Department of Earth Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon Institute for Geological and Mining Research, Laboratory of Ore mineral Processing, P.O. Box 4110, Yaound¨¦, Cameroon Department of Earth Sciences, University of Yaound¨¦, P.O. Box 812, Yaound¨¦, Cameroon Higher Teacher Training College, University of Bamenda I, P.O. Box 39, Yaound¨¦, Cameroon Higher Teacher Training College, University of Yaound¨¦ I, P.O. Box 47, Yaound¨¦, Cameroon Universit¨¦ Paris-Saclay, Sciences de la Terre, Volcanologie, Plan¨¦tologie, UMR CNRS, 8148 GEOPS, bat 504, F-91405, Orsay, France Universit¨¦ europ¨¦enne de Bretagne, CNRS UMR, 6538 Domaines oc¨¦aniques, UBO-IUEM, 6 avenue Le Gorgeu, CS 93837, F-29238, Brest cedex 3, France The Cretaceous Ngaou Boh anorogenic complex (NBAC) located in the far North Adamawa Plateau, the centre domain of the Cameroon Line constitutes a plutonic-volcanic ring association. The whole rock K-Ar datation yields a crystallization age of ca. 74 Ma. Plutonic rocks comprise abundant alkali feldspar granites, scarce clinopyroxene-amphibole gabbros and alkali feldspar syenites. Alkali feldspar granites are leucocratic, coarse to fine-grained; quartz and K-feldspars are the major rock-forming mineral, besides minor oligoclase, biotite and accessory phases as sphene, zircon and opaques. Alkali feldspar syenites are mesocratic coarse-grained, mainly composed of K-feldspars with small amounts of quartz and biotite. Volcanic rocks consist of a basanite-trachyte-rhyolite suite. Basanites contain olivine and diopside phenocrysts and a groundmass essentially composed of plagioclase and titanomagnetite. Biotite-clinopyroxene trachytes and clinopyroxene-amphibole rhyolites have an almost homogeneous modal composition, mainly made up of sanidine and anorthoclase microliths, scarce phenocrysts of quartz, and minor crystals of biotite, clinopyroxene (augite) amphibole (pargasite, sandagaite); Fe-Ti oxides (ilmenite, titanomagnetite) and fibreglass are often isolated in the groundmass. Plutonic rocks are alkaline, weakly metaluminous with some alkali feldspar granites displaying agpaitic or peralkaline feature. Incompatible Trace elements (HFSE and LILE) distribution and chondrite-normalized REE patterns evidence a significant petrogenetic link between clinopyroxene-amphibole gabbros, alkali feldspar syenites and alkali feldspar granites. All the analysed samples are enriched in incompatible elements, indicating melts from spinel and garnet-bearing mantle source close to OIB component. Indeed, the (Tb/Yb)N ratios of both basanites (2.3-2.5) and clinopyroxene-amphibole gabbros (1.4-1.9) suggest different parental magma sources. Alkali feldspar granites appear as residue of magma differentiation led by crystal fractionation of liquid derived from the partial melting of spinel peridotite mantle. Clinopyroxene-amphibole rhyolites and biotite-clinopyroxene trachytes (Mg#=0.0-15.4) derive through fractional crystallization from basanites (Mg#=64.3-60.1), the most primitive mafic parental melt. Both plutonic rocks and lavas trends evidence a bimodality highlighted by a pronounced ¡°Daly gap¡±. http://pubs.sciepub.com/jgg/9/4/1/jgg-9-4-1.pdf Ngaou Boh Cameroon Line Adamawa Plateau anorogenic complex magma differentiation K/Ar age dating