Petrology and geochemical framework of dolerites dykes of Temté, North Cameroon,Central Africa

The Temté basement in North Cameroon is crosscut by dyke swarms with N 20°–40° trending,including dykes 15–30 m wide, up to 3 km-long. Representative rocks exhibit intersertal to sub-ophitic textures.Electron microprobe analyses identified diopside, augite,pargasite, biotite, Ti-magnetite, plagioclase, and sanidine.Whole-rock ICP-MS and ICP-AES chemical analyses showed compositions of basaltic andesite, basaltic trachyandesite and trachyandesite in composition. Igneous differentiation was likely governed by fractional crystallization associated with limited fluid metasomatism. Some lavas could have been moderately contaminated by crustal materials during feeding of local cracks through turbulent magma flows. Discrimination geochemical diagrams and immobile trace and REE element ratios show that the mantle source of Temté dolerites was a deep phlogopitebearing EMII mantle component and has undergone moderate to high partial melting rate. Correlations of fieldwork and analytical data with previous results evidence the Temté dolerite dyke swarms as fingerprints of crustal extension accompanying regional uplift in an active continental margin when early rifting led to the formation of the Poli marginal basin.