Petrogenesis of Basaltic Rocks in the Cameroon Volcanic Line Extension in Taraba State

Basaltic volcanic rocks occurring in Taraba State, North East Nigeria, represent the northwestward extension of the Cameroon Volcanic Line into Nigerian territory, yet their petrogenesis and mantle source characteristics have received limited attention compared to the better-studied Cameroon sections of this lineament. This study investigates the petrogenesis of basaltic rocks at three volcanic centres in Taraba State through integrated major element, trace element, and isotopic geochemistry. Fresh to moderately altered basalt samples were collected from identified scoria cones and lava flows, with petrographic characterisation of mineral assemblages conducted prior to geochemical analysis. Whole-rock major and trace element compositions were determined by X-ray fluorescence and inductively coupled plasma mass spectrometry. Rare earth element patterns and multi-element spidergrams were constructed to characterise source region fertility and melting degree. Sr-Nd-Pb isotope ratios were measured by thermal ionisation mass spectrometry to characterise mantle source components. The study evaluates the relative contributions of enriched mantle 1, enriched mantle 2, and high-mu mantle components to the observed isotopic signatures, testing the hypothesis that Taraba basalts preserve a lithospheric mantle component absent from Cameroon equivalents owing to differences in sub-lithospheric thinning along the lineament. Keywords: petrogenesis, basaltic rocks, Cameroon Volcanic Line, Taraba State, mantle source.