摘要
The geology,geochemistry of Iroko-granites have been studied and reported in this paper.The study area has been described as of Archaean-Early Proterozoic terrain underlain by migmatite-gneiss-quartzite complex with supracustal rocks.Large number of granites which outcrops in Iroko-Ekiti represent a typical occurrence of granitoids sporadically distributed in the basement and are known to belong to the Older Granite suites,which are attributable to the Pan-African Orogeny(750±150Ma).The rocks occur,mostly as flat and low lying within sparse vegetation.Structures common on and around the outcrops include quartz vein,veinlets,pegmatite dykes which trend North-south,discrete exfoliated surfaces and xenoliths of older rocks.This study reveals that the granites belong to calc-alkalic suites,demonstrate metaluminous nature,and exhibit characteristics of I-type granites.The granite is a distinctive type in that it is relatively highly potassic,has high FeO/(FeO+MgO)ratio,and high average Zr(299.75ppm)concentration with other high field strength elements.The trace elements study implicates pronounced fractional crystallization during evolution of the granites and thus petrogenetically discriminates as Syn-collision provenance.
