Petrogenesis and tectonic setting of the mafic rocks from the Mfengou-Manki area, Central Cameroon Shear Zone: constraints from petrology and bulk-rock geochemistry

In the Central Cameroon Shear Zone, several studies were focused on granitoids and very few on mafic rocks. Here we report the petrography, geochemistry and mineralogy of the Mfengou-Manki mafic rocks in order to constrain their petrogenesis and tectonic settings and the role of lithospheric and ast...

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Published in:Discover applied sciences 2024-02, Vol.6 (3), p.100, Article 100
Main Authors: Nchouwet, Zakari, Ntieche, Benjamin, Yongue Fouateu, Rose, Ntoumbe, Mama, Mounjouohou, Mahomed Aziz, Atsalang, Chimene Grace Staelle, Abomo Olomo, Marcelle Nathalie, Amidou, Moundi
Format: Article
Language:English
Subjects:
Asthenosphere
Basalt
Crystallization
Delamination
Depletion
Geochemistry
Geology
Lanthanum
Lithosphere
Magma
Mineralogy
Niobium
Pan-Africanism
Petrogenesis
Petrography
Petrology
Rock intrusions
Rocks
Shear zone
Tantalum
Tectonics
Transition zone
Zirconium
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Summary:In the Central Cameroon Shear Zone, several studies were focused on granitoids and very few on mafic rocks. Here we report the petrography, geochemistry and mineralogy of the Mfengou-Manki mafic rocks in order to constrain their petrogenesis and tectonic settings and the role of lithospheric and asthenospheric mantle sources in their genesis. The studied mafic rocks are subdivided into columnar jointed basalts and mafic dykes. Clinopyroxene thermobarometry indicates that the mafic dykes crystallized at a temperature of 1071 to 1193 °C and a pressure of 4 to 12 kbar while the columnar jointed basalts emplaced at a temperature of 1064 to 1152 °C and 2 to 13 kbar pressure. The mafic dykes and columnar jointed basalts present high La/Sm, Sm/Yb, Nb/Yb and Th/Yb ratios, indicating garnet to spinel transition zone mantle source. The multi-element diagram of the mafic dykes display enrichment in Nb, Ta, Pb and Ti and depletion in Th, U, Ce and Zr compared to that of the columnar jointed basalts (slight depletion in Nb and Ta and pronounced depletion in U, Pb and Zr and enrichment in Cs, Ba and Rb) indicating the little involvement of the sub-continental lithospheric mantle to the formation of the columnar jointed basalts. The Nb/La ratio > 1 for the mafic dykes and 
ISSN:3004-9261
2523-3963
3004-9261
2523-3971
DOI:10.1007/s42452-024-05635-5