The Neoproterozoic charnockite-granite association of Okpella intrudes metasedimentary and migmatite-gneiss complex rocks in the eastern Igarra Schist Belt, southwestern Nigeria. In order to unravel the complex processes involved in the formation and tectonic evolution of the Igarra Schist Belt during the Neoproterozoic, detailed field, petrographic and whole-rock geochemical study of the charnockite-granite association and metasedimentary rocks around Okpella was conducted. Published data on the metasedimentary rocks and Pan-African granitoids in different sectors of the belt were also compiled for detailed interpretations. Results of the study revealed that the charnockites and granites of Okpella show primary magmatic mineralogy and geochemical characteristics. They are silicic ( 63 wt. % SiO2), metaluminous to peraluminous, high-K calcalkaline, ferroan, post-collisional granitoids. The garnet-biotite schist, calc-silicate gneiss and quartzite in the area have paragenesis characteristic of low-medium grade metasedimentary rocks. The mineralogy and geochemistry of the charnockites suggest that the charnockitic melt was derived by partial melting of underplated basaltic (mantle-derived) magma and assimilation-fractionation processes at lower crustal levels.The granites probably originated from mixed melts derived from lower-to mid-crustal tonalites-trondhjemitesgranodiorites and/or subducted metagreywackes and mantle-derived magmas (probably the charnockitic melt progenitor). The granites and charnockites are coeval and were presumably emplaced during the post-collisional stages of the Pan-African Orogeny. The garnet-biotite schist, calc-silicate gneiss and quartzite represent 1 metamorphosed immature to slightly mature sedimentary rocks, probably greywacke, marl and subarkose, respectively, that were sourced from intermediate-acidic rocks which underwent low-moderate chemical weathering with minor contribution from recycled sediment sources and deposited in active continental environments. The Neoproterozoic evolution of the Igarra Schist Belt, therefore, involved deposition and infolding of sediments in active continental margin during the early Pan-African followed by upwelling of basaltic magma from the mantle which underplated the lower crust to generate the charnockitic and granitic melts through mantle-crust interaction during the late Pan-African.

An active gold mining area in Okpella, Edo State, Nigeria was studied to assess the contribution of gold mining to the concentrations of potentially toxic elements (PTEs) in stream sediments. Standard geochemical sampling and sample method. The concentrations of arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead I geo) were calculated-ate enrichment of Cu, minor enrichment of As and Pb, and no enrichment of Co, Cr, Ni and Zn in the sediments. The I geo also showed that the sediments were extremely polluted with Hg, moderately polluted with Cu but there was no evidence of pollution from other PTEs. Extreme pollution of the sediments by Hg and its enrichments in Cu, As and Pb are due to indiscriminate active artisanal gold mining in the area. It is recommended that immediate remediation measures should be enforced to mitigate the possible environmental health hazards to humans and livestock in the area.

The aim of the study is to identify and record the taxonomic notes on species of Genus Globigerinoides from the study area located in Kafe field of the offshore western Niger Delta area of Nigeria. 550 ditch cuttings samples were retrieved at 18.29 metres intervals from the five wells studied (Kafe-1, Kafe-2, Kafe-4, Kafe-5 and Kafe-6). The standard micropaleontological preparation technique for foraminiferal samples was employed. The foraminiferal contents were identified under binocular microscope and recorded. The species of the Genus Globigerinoides identified are Globigerinoides obliquus BOLLI, Globigerinoides extremus BOLLI and BERMUDEZ, Globigerinoides quadrilobatus D'ORBIGNY, Globigerinoides subquadrilobatus (BRÖNNIMANN), Globigerinoides trilobus REUSS and Globigerinoides sacculifer BRADY and their taxonomic notes were documented accordingly.

Okpella area is the eastern extension of the Igarra Schist Belt, Southwestern Nigerian Basement Complex. The area comprises granite gneiss, metasedimentary rocks and Pan-African intrusives. Metasedimentary rocks occurring in the area include garnet-biotite schist, marble and calc-silicate gneiss, quartzite and Banded Iron Formation (BIF). The Pan-African intrusives include granite, charnockite, hybrid rocks, pegmatite, aplite and basic dykes. Structural data of rocks in the area suggest the presence of two contrasting structural trends. The older one which appears restricted to the granite gneiss, calc-silicate gneiss and garnet-biotite schist trends ENE-WSW to EW with moderate dips to the south. The latter NW-SE to NS trend is pervasive and occurs in all the metasediments and granite gneiss. These two trends are related to two deformational episodes and probably two orogenic periods. All the metasediments show affinity for sedimentary parentage, the granite gneiss is probably of igneous origin while the intrusives are magmatic. The charnockite-granite hybrid rock probably represents a zone of magma mixing between two contrasting magmas that were emplaced contemporaneously. The occurrence of metacarbonates in association with deformed metapelites as well as the complete absence of metavolcanics in the area suggests deposition of their protoliths in a continental environment along which crustal distention occurred. A sequence of nine geological events is suggested for the evolution of the area as deduced from field observation.

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