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Abstract: The felsic lavas of the Bamenda Mountains, in the main part of the Cameroon Volcanic Line, are mainly represented by trachytes, with subordinated benmoreites and alkaline to peralkaline rhyolites. New K–Ar geochronological data define two main volcanic episodes, the first one between 18 and 22Ma, and the second one from 12.5 to 13.5Ma. Geochemical data indicate that these felsic rocks mainly originated through a fractional crystallization process from mafic magmas. Crustal contamination also occurred during the magma evolution. These new data confirm that there is no time evolution of the volcanism along the Cameroon Volcanic Line and show a similar magma genesis process through space and time. [Copyright &y& Elsevier]

Abstract: Basaltic lavas of the Kumba Plain contain mantle-spinel peridotite xenoliths. Mineralogical characteristics, together with major and trace element compositions, both in bulk rocks and clinopyroxenes, point out that the upper mantle beneath the Kumba volcanic plain has an essentially lherzolitic composition. This mantle is fertile or only affected by a very low degree of partial melting and cryptic metasomatism. The Kumba upper mantle appears to be homogeneous and very different from the other mantle peridotite occurrences from the Cameroon Line, especially those from the upper mantle beneath the Nyos volcanic plain. [Copyright &y& Elsevier]

Abstract: Camptonites have been discovered at Mount Cameroon. They contain phenocrysts of olivine + clinopyroxene + plagioclase ± kaersutite ± bi and ocelli of nepheline or analcite and carbonates. 87Sr/86Sri values are similar to those of the basalts of Mount Cameroon . The camptonites are interpreted as resulting from fractional crystallization of a basaltic magma generated by a low degree of melting of an infra-lithospheric metasomatized mantle tapped by huge lithospheric cracks. To cite this article: I. Ngounouno et al., C. R. Geoscience 338 (2006). [Copyright &y& Elsevier]

Abstract: Mount Bangou, an Eocene volcano (40K–40Ar ages between 44.7 and 43.1±1 Ma) is the oldest dated volcano of the Cameroon Line. In this region, two magmatic series, evolving by fractional crystallization, show transitional affinities that are exceptionally known in this sector. Mineral compositions of basaltic rocks (scarce modal olivine and occurrence of normative hypersthene) as well as geochemical characteristics (low Ba, La, Ta contents and high Y/Nb ratios) are in agreement with this trend. The succession of magmas evolving in time from transitional to more typical alkaline compositions is evidenced in a continental setting. To cite this article: J. Fosso et al., C. R. Geoscience 337 (2005). [Copyright &y& Elsevier]

Dykes of monchiquites of Cainozoic age (37.5±2.3 Ma) are intrusive in Cretaceous sandstones in the Tchircotche´ area, Upper Benue valley (northern Cameroon). The differentiation of the monchiquites is explained by crystal fractionation of olivine, clinopyroxene, magnetite, ilmenite and apatite. A studied rock has low Sr-isotope ratio (0.703 69±10), which is similar to those of the alkali basalts of the Cameroon Line. Therefore the continental crust appears to have no significant role in the genesis of the monchiquites. [Copyright &y& Elsevier]