Abstract
The Idofin-Osi-Eruku area occur in the south-eastern margin of the southwestern sector of the Nigerian Basement Complex. Granitic rocks and early gneiss samples were studied geologically and geochemically using ICP-MS. The study focuses on the trace elements and rare earth elements geochemistry in determining the geochemical characteristics and geotectonic processes of formation of the granitic rocks. Geologically, Idofin-Osi-Eruku area is underlain by early gneiss, quartzite and marble which have been intruded by granite gneiss, porphyritic granite and fine to medium-grained granite of probable Pan-African (ca. 600Ma) age. Geochemical data indicate that the granitic rocks are Fe-rich potassic granites. The varying ratios of the incompatible elements of Rb/Sr ratios (0.664-1.388) in porphyritic granite, (0.338-2.390) in the fine to medium-grained granite and (0.593-1.509) in granite gneiss are higher than Rb/Sr ratio (0.029) in the early gneiss. Also, Ba/Sr ratios (2.815-5.424) in porphyritic granite, (3.463-4.636) in fine to-medium grained granite and (2.132-4.734) in granite gneiss are higher than Ba/Sr ratio (0.912) in the early gneiss. And Ba/Rb ratios (2.486-6.192) in porphyritic granite, (1.473-1.520) in the fine to-medium grained granite and (3.183-3.595) in the granite gneiss are lower than Ba/Rb ratio (31.02) in the early gneiss. Higher ratios of Rb/Sr and Ba/Sr, and lower ratio of Ba/Rb in the granitic rocks than the early gneiss indicate high fractionation associated with magmatic differentiation. The granite rocks have fractionated REE patterns characterized by enrichment in the LREE which is confirmed by high values of the normalized ratios of La/Yb, Ce/Yb and La/Sm, with negative europium anomalies and varying degrees of HREE depletion which is typical of the crust and also of calc-alkaline rocks. Based on the overall abundances of REE, the similarities in the REE patterns of the granitic rocks suggest the same origin. Geotectonically, the granite gneiss, fine to medium-grained granite and porphyritic granite plot as syncollisional and volcanic arc granites. The granitic rocks are products of volcanic arc magmatism emplaced in the late phase of the Pan-African Orogeny.
Highlights
The Idofin-Osi-Eruku area forms part of the southeastern margin of the southwestern sector of the Nigerian Basement Complex (Figure 1)
The granite rocks have fractionated Rare-Earth Elements (REE) patterns characterized by enrichment in the Light Rare-Earth Elements (LREE) which is confirmed by high values of the normalized ratios of La/Yb, Ce/Yb and La/Sm, with negative europium anomalies and varying degrees of Heavy Rare-Earth Elements (HREE) depletion which is typical of the crust and of calc-alkaline rocks
The present study focuses on the trace elements and rare earth elements geochemistry with the aim of determining the geochemical characteristics and geotectonic processes of formation of the granitic rocks
Summary
The Idofin-Osi-Eruku area forms part of the southeastern margin of the southwestern sector of the Nigerian Basement Complex (Figure 1). This Basement Complex comprises of gneisses and migmatites with supracrustal relics, which have yielded Archean The migmatitic rocks include both high-grade migmatites and injection-type migmatites These metamorphic rocks form the host into which the intrusive granitoids i.e. Older Granites were emplaced [3]. Variations in the abundance of trace elements, rare earth elements and their distribution patterns are useful in tracing the evolution of granitic and basaltic rocks.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
