Geochemical and Petrographic Studies of Some Quartz Mica Schists in Igarra and Environs, Southwestern Nigeria

  • Ovie Odokuma-Alonge Department of Geology, Faculty of Physical Sciences, University of Benin, Benin City, Edo State, Nigeria
  • Susan Chioma Dibani
Keywords: Petrography, Schist, Chemical, Analysis, Facies


Five schist samples from Igarra and Environs in Akoko Edo area of Southwestern Nigeria were obtained with the aim of determining their geochemical properties using XRF techniques and also for petrographic analysis. Results from the geochemical analysis revealed the presence of SiO2 (54.65-59.01wt.%), Al2O3 (21.98-25wt.%), Fe2O3 (3.77-5.67wt.%), MgO (0.56-1.68wt.%), K2O (4.62-6.56wt.%) and Na2O (0.48-0.96wt.%).  The geochemical evaluation revealed that the schists were probably generated from the metamorphism of shale. Discrimination diagrams show peraluminous character and plots within the metasedimentary field which also supports a sedimentary protolith. The A-CN-K plot reflects that the shale suffered moderate chemical weathering before being subjected to metamorphism. The petrographic studies also revealed the characteristics of the minerals present in the rock which shows the alignment of platy minerals in a preferred direction that aided the characteristic features of the rock foliation. Modal composition shows mineralogical assemblages of quartz + plagioclase + microcline + biotite + muscovite + hornblende which indicates that the schist belong to the greenschist facies grade.


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