Geology

Biography

Biography: Saleh Ibrahim Bute

Abstract

The major rock units in the Wuyo-Gubrunde Horst, northeastern Nigeria are gneisses, porphyritic granite, altered granite, sheared granite, basalts and sandstone. Uranium has been reported in rhyolite and sheared rocks within the area. Petrogenetic evolution of the uranium-mineralized granitoids and associated rocks in the area were evaluated in the light of new geochemical data, which showed that uranium mineralization is within the altered granite rock and hydrothermal related. The granitoids are metaluminous, sub-alkaline, S-type granite that evolved by partial melting of crustal material emplaced at moderate depth of 20-30 km in a syn-to late-collisional within plate tectonic setting. The negative Eu/Eu* anomaly and higher (La/Yb)N ratio of the granitoids are indicative of magma fractionation. The lower SiO2 (<53%) and higher Fe2O3 (10%) of the altered granite compared to other similar rock units suggested pervasive alteration. The associated basalts are tholeiitic, emplaced within continental plate and enriched in Ni (122 ppm), V (169 ppm), Nb (39 ppm), Sr (570) and Light Rare Earth Elements (LREEs). The uranium content, P2O5, Fe2O3, TiO2, MnO, Co, Nb, Sr and V of the altered granites are higher while the Na2O, K2O, SiO2, Th and Rb contents are lower than those of the other rock units in the area. This supported hydrothermal source for the uranium mineralization. The basaltic rocks have similar SiO2, Fe2O3, V, Th and Co contents with the mineralized altered granite suggesting rock-fluid interactions and element mobilization. The uranium mineralization in the area was through secondary enrichment, hydrothermally sourced and remobilized by induced post-magmatic volcanic events.