Abstract
Trace and Rare Earth Elements (REEs) data are used to constrain the geochemical evolution of the amphibolites from Ifewara in the Ife-Ilesha schist belt of southwestern Nigeria. The amphibolites can be grouped into banded and sheared amphibolites. Major element data show SiO2 (48.34%), Fe2O3 (11.03-17.88%), MgO (5.76-9.90%), CaO (7.76-18.6%) and TiO2 (0.44-1.77%) contents which are similar to amphibolites in other schist belts in Nigeria. The Al2O3 (2.85-15.55%) content is varied, with the higher values suggesting alkali basalt protolith. Trace and rare earth elements composition reveal Sr (160-1077ppm), Rb (0.5-22.9ppm), Ni (4.7-10.2ppm), Co (12.2-50.9 ppm) and Cr (2-7ppm). Chondrite-normalized REE patterns show that the banded amphibolites have HREE depletion and both negative and positive Eu anomalies while the sheared variety showed slight LREE enrichment with no apparent Eu anomaly. The study amphibolites plot in the Mid Oceanic Ridge Basalts (MORB) and within plate basalt fields on the Zr/Y vs Zr discriminatory diagrams. They are further classified as volcanic arc basalt and E-type MORB on the Th- Hf/3- Ta and the Zr-Nb-Y diagrams. The amphibolites precursor is considered a tholeiitic suite that suffered crustal contamination, during emplacement in a rifted crust.
Highlights
The amphibolites of Ifewara in the Ife-Ilesha schist belt (Figure 1) in southwestern Nigeria constitute a major rock unit within the amphibolite complex, with which placer gold and disseminated sulphide mineralization have been associated (Elueze, 1981)
The amphibolites of the Ifewara area in the Ife-Ilesha schist belt belong to the Precambrian basement complex of southwestern Nigeria, which consist of Archean to Early Proterozoic migmatite gneissic-quartzite complex that bear the imprint of early to late Precambrian metamorphic episodes
Geochemical data showed that the protoliths of the amphibolites were tholeiitic basalts which were emplaced in a rifted crust within an environment of active sedimentation
Summary
The amphibolites of Ifewara in the Ife-Ilesha schist belt (Figure 1) in southwestern Nigeria constitute a major rock unit within the amphibolite complex, with which placer gold and disseminated sulphide mineralization have been associated (Elueze, 1981). The area is located within the N-S trending schist belt of the Nigerian Basement Complex. The geology of Ife-Ilesa schist belt (Figure 1) has been studied by Hubbard (1975), Ajayi (1980), Elueze (1981) and Rahaman et al (1988). They recognized two contrasting lithologies separated by the NNE trending Ifewara faults. Mineralization is not strongly developed in the Ife-Ilesa schist belts unlike most well known greenstone belts in the Canadian, Indian, Australian, and South African Precambrian shields
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
