Petrogenesis and Geotectonic Settings of the Granitic Rocks of Idofin-osi-eruku Area, Southwestern Nigeria using Trace Element and Rare Earth Element Geochemistry

Abstract

The Idofin-Osi-Eruku area occurs in the southeastern 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 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 also of calc-alkaline rocks. Based on the overall abundances of Rare-Earth Elements (REE), the similarities in the Rare-Earth Elements (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.

Geochemical Classification and Geotectonic Setting of Granitic Gneisses from Southeastern Margin of Western Nigeria Basement

“…The granitic gneisses are sensu sricto granite gneiss and granodiorite gneiss. This observation is similar to those of other workers on the granitic gneisses in various parts of the basement complex of Nigeria [4,[22][23][24][25][26][27] .…”

Petrology and Geochemistry of Basement Gneissic Rocks Around Oka-Akoko, Southwestern, Nigeria

“…The Oka-Akoko grey gneiss is similar in composition to the Kabala gneiss which is granodioritic [19]. The granite gneiss of Oka-Akoko is similar to Idofin-Osi-Eruku and Jebba granite gneisses which are also peraluminous, potassic, calcic to alkalic and silica-rich and inferred to be products of partial melting of crustal rocks [16,17].…”

Adsorption Equilibrium, Physicochemical Parameters and Colour Deactivation Effects of Activated Carbon for Dye for Waste Water Treatment

“…It is obvious that the amount of maize cobs overshadows that of guinea corn husk in the sample C. the results in Table 1 entails that the burn ability of guinea corn husk is better than that of maize cobs, due to size difference, moisture content and texture. Odewumi and coresearchers [33] reported close values for porphyritic granite, medium grained granite, granite mneiss, early gneiss and average granite rocks with a dominance of SiO 2 .…”