TITLE:
Petrography and Geochemistry of the Mbip Granitic Massif, SW Tcholliré (Central North Cameroon): Petrogenetic and Geodynamic Implication
AUTHORS:
Emmanuel Nomo Negue, Rigobert Tchameni, Olivier Vanderhaeghe, Pierre Barbey, Periclex Martial Fosso Tchunte, Jonas Didero Takodjou Wambo, Brice Yanick Lemdjou, Nicaise Alliance Saha Fouotsa
KEYWORDS:
Central African Fold Belt, Granitic Rocks, Mafic Rocks, Transitional Regime, Active Margin.
JOURNAL NAME:
International Journal of Geosciences,
Vol.6 No.7,
July
30,
2015
ABSTRACT: In this article, we discussed about
the petrography and geochemistry of magmatic rocks of theMbip massiflocated
SW of Tcholliré, in Central North Cameroon (Central African Fold Belt).
Petrographic study shows that this massif is made of granodiorite,
amphibole-biotite granite, and biotite granite which often contain enclave of
mafic rocks (gabbro). Granodiorites and granites show porphyritic texture and
consist dominantly of plagioclase and alkaline feldspar phenocrysts, quartz,
biotite and often few amphibole. The gabbro enclaves are characterized by a
granular porphyroid texture constituted of amphibole, plagioclase and olivine
phenocrysts, all in a matrix of small crystals of plagioclase, olivine,
amphibole, pyroxene and opaque minerals. All the analyzed rocks provide
geochemical features of sublkaline serie and have nothing to do with the
alkaline nature previously signaled in the former works. Granodiorites and
granites are shoshonitic to calc-alkaline strongly potassic affinity consistent
with emplacement in the continental collision setting. They present positive
anomalies in Rb, Th, U; negative anomalies in Sr, P, Ti, Nb, Ta and some facies
contain hydrated minerals such as amphibole. These characters are consistent
with crustal and mantle contribution in their genesis. The mafic rocks (gabbro)
have geochemical characteristics conferring a mantle origin, as confirmed by
the high Mg# value (49.9). On the whole, the fractional crystallization of the
magma formed by melting of crustal material and the magmatic mixing are the
main petrogenetic process in the Mbip massif. Petrographic studies and
geochemical data shows that the Mbip massif was emplaced in an active
continental margin, into transitional regime from the end of maximum
compression to the beginning of relaxation.