The Gondwana pre-break up related formations in Bafoussam area are transitional calc-alkaline doleritic dykes exhibiting high Alumina and low Ti-Mg contents. Their REE compositions are similar to those of E-MORB (Nd/Nb≈1, Zr/Nb≤20). A high partial melting of about 20% of Garnet peridotites source having primitive mantle composition, is inferred to the studied rocks. They are slightly evolved 50<Mg#<54, and its clinopyroxenes are augite of high temperature (600°C-1100°C). The studied dykes were emplaced in a within-plate tectonic setting and yield a 40Ar-39Ar plateau ages of 229±7Ma. These ages are slightly different from those of dolerites from the Oban-Obudu massif (Nigeria), from the basaltic dyke of the Cameroon Volcanic Line and from the Karoo-Ferrar mafic magmatism, all interpreted as magmatism that preceded the break-up of Gondwana. The emplacement age of 229±7Ma of dolerites from Bafoussam area relates them to the very early stage of Gondwana pre-break up magmatism in central Africa.
The Bangangte area belongs to the Cameroon Volcanic Line. The volcanic rocks exposure in the area consist of fine microlitic porphiritic Basalts which still poorly surveyed. Petrographically, the studied rocks are made up of minerals like plagioclase, clinopyroxene, olivine phenocrysts and a lot of opaque minerals within a very fine grained matrice. The Bangangte basalts are quartz normative free and are olivine, Diopside, Hypersthene normative. Alkaline (Na 2 O + K 2 O) contents vary from 2.247% to 5.46%. These rocks are low-Mg basalts with the Mg# values vary from 42.86 to 45.95 which are characteristic of primitive mantle source. The studied rocks are alkali to transitional basalts with Nb/Y ratio>1.5. Chondrite normalized spider diagram pattern of REE shows uniform patterns with enrichment in LREE and a relative depletion in HREE. While MORB normalized spider diagram pattern of multi elements reveals a negative anomaly with K 2 O, with enrichement in LILE and depletion in HREE. The Eu anomalies are positive to nulle and are typical of alkali basalts. The Bangangté transitional alkali basalts were formed in intraplate setting of continental part of the CVL. They are the products of partial melting of about 13% of an asthenosphere made up of garnet peridotite. Geochemically, the studied basalts are similar to alkali basalts from Mount Bamenda.
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