Host: The Japanese Association of Mineralogists, Petrologists and Economic Geologists
The Ntem Complex is situated at the north-western border of the Congo Craton in the south of Cameroon. It makes up the Archean basement and extends over its contact with the North Equatorial Mobile Belt represented by the Yaounde group. This group overthrusted the Ntem Complex during the Pan-African orogeny (650-500 Ma) and is affected by high pressure syn-tectonic metamorphism. The Sangmelima region belongs to the Ntem Complex made up of three main lithologic groups: the intrusive complex (TTG, Granodiorites and Granites), the banded series and greenstone belts or iron trenches, so has undergone several magmatic episodes. The first is linked with the beginning of the major deformation phase (D1) faced by the region, associated with a granulite facies metamorphism. It corresponds to the successive diapiric emplacement of charnockitic rocks (TTG suite) during Meso to Neoarchean (2.9-2.8 Ga). The intense migmatization of TTG and the emplacement of Potassic Granitoids which marked the second magmatic episode, correspond to the period between 2.6-2.5 Ga. TTG and Orthogneisses are of Trondhjemitic affinity whereas Potassic Granitoids are high-K acid rocks of typical Calc-alkaline differentiation series. This Archean-Proterozoic transition granitic magmatism (2.6-2.5 Ga) is one of the important stages in the evolution of the Ntem Complex (Congo Craton) since it marks a crustal reworking event.
