Geochemistry and <SUP>40</SUP>ar/<SUP>39</SUP>ar Geochronology of Amphibolites from Banefo-Mvoutsaha Area, Central Domain of the Pan-African Fold Belt in Cameroon

The Banefo-Mvoutsaha area lies along the Central Cameroon Shear Zone and belongs to the Central Domain of the Pan-African Fold Belt in Cameroon. The amphibolites of the study area are of two types: The banded amphibolites which are associated with migmatites and composed of Hbl + Bt + Qtz + Kfs + Pl ± Grt + Op; and the massive amphibolites which outcrops as discontinuous bands within the garnet bearing-gneisses; its mineral assemblage is made up of Hbl + Qtz + Kfs ± Grt ± Op. The studied amphibolites are ortho-derived, their SiO2 contents range from 48 to 52 wt%, they are enriched in LREEs and LILEs relatively to HREE, and display negative Eu anomalies (0.65 ≤ Eu/Eu* ≤ 0.96), characteristics of alkali basaltic rocks, which belong to intraplate tholeiitic series. The banded amphibolites samples yield an Ar-Ar age of 618.14 ± 11.43 Ma, while the massive amphibolites samples ages are 547.50 ± 3.15 Ma. The 618 Ma age coincide with the emplacement age of granitoids that intruded the metamorphic basement of the area. The age of 547.50 ± 3.15 Ma is correlated to amphibolitic metamorphism events that mark the end of the Pan-African orogeny in the study area. These new Ar-Ar ages therefore point out at least two phases of amphibolitic metamorphism in the Central domain of the Pan-African Fold Belt in Cameroon.