Malaysian Journal of Geosciences (MJG)

Charnockites could be of magmatic, metamorphic, or metasomatic origin and formed in varying tectonic settings. Lack of detailed geological mapping of plutonic charnockites around Ikare necessitated this work. Hence, this study was designed to investigate the petrography of plutonic charnockites, in order to infer post-cystallization event that prevailed in the area. Ten (10) chip rock samples purposively collected were prepared into thin and polished sections for petrographic studies using petrological microscope. The mineral assemblages observed are quartz, plagioclase feldspar, alkali feldspar, horhblende, biotite, orthopyroxene ± clinopyroxene. The accessory minerals are apatite, magnetite, ilmenite and zircon. Anti-perthite and myrmekite intergrowth are common. BSE images show close association between alkali feldspar and barium suggesting that barium is replacing potassium in the feldspar. Also,hornblende are found enclosing orthopyroxene suggesting a retrograde event. Relicts of quartz and alkali feldspars are found in biotite grain suggesting partial melting of the rock under high temperature conditions. Based on petrographic evidence, the charnockite magma that produced these charnockites must have been emplaced at deep crustal level under granulite facies conditions and followed by strong ductile deformation.