Mineralogy, geochemistry and petrogenesis of the recent magmatic formations from Mbengwi, a continental sector of the Cameroon Volcanic Line (CVL), Central Africa

Benoît Joseph Mbassa, Emmanuel Njonfang, Mathieu Benoit, Pierre Kamgang, Michel Grégoire*, Stephanie Duchene, Pierre Brunet, Bekoa Ateba, Félix M. Tchoua

*Corresponding author for this work

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The Mbengwi recent magmatic formations consist of volcanics and syenites belonging to the same magmatic episode. Lavas form a bimodal basanite-rhyolite alkaline series with a gap between 50 and 62 wt.% SiO 2. Mafic lavas (basanite-hawaiite) are sodic while felsic rocks (trachyte-rhyolite-syenites) are sodi-potassic, slightly metaluminous to peralkaline. The geochemical and isotopic characteristics (0. 7031 < ( 87Sr/ 86Sr) initial < 0. 7043; 1. 03 < ε Ndi < 5. 17) of these rocks are similar to those of other rocks from the CVL. The main differentiation process is fractional crystallization with two trends of fractionation. Their Rb/Sr isochron age of 28. 2 Ma, almost similar to 27. 40 ± 0. 6 Ma K/Ar age obtained in a trachyte from neighboring Bamenda Mountains system, precludes any local age migration of an hypothetic hotspot. Mafic lavas have OIB features displaying an isotopic signature similar to that of HIMU mantle source different from FOZO known as source of most parental magmas along the CVL.

Original languageEnglish
Pages (from-to)217-242
Number of pages26
JournalMineralogy and Petrology
Volume106
Issue number3-4
DOIs
Publication statusPublished - Nov 2012
Externally publishedYes

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