| Abstract |
Nigeria lies very close to the equator on the west coast Africa between latitude 4-14° N and longitude 2-15° E. The country is located at the northern end of the eastern branch of the African rift system. Geologically, Nigeria is comprised of sedimentary formations and crystalline basement complex, which occur more or less in equal proportion all over the country. The sediment is mainly Upper Cretaceous to recent in age while the basement complex rocks are thought to be Precambrian. The studied area lies between latitude 12.4-11.11°N and longitude 13.81-14.13° S. The studied area is underlain by Precambrian basement complex of southern western Nigeria. The major rock in the area is charnokite and granite rock. The granite rocks which are members of the older granite suite occupy about 65% of the total area of Akure. Three principal petrographic varieties are recognized, the fine-grained biotite granite, the medium to coarse-grained non-porphyritic biotite-hornblende granite, and the coarse-grained porphyritic biotite-hornblade granite. Also three main textural type of Charnokitic rock are also distinguished including coarse grained, massive fine grained and gneissic fine grained. The charnokitic rocks appear to have three modes of occurrence in the area, (1) the first occurrence is within what seems to be the ‘core’ of the granite rock as exemplified by Akure body and few smaller bodies. (2) The second is along the margins of the granite bodies as seem in Ijare and Uro Edemo-Idemo charnokitic bodies. (3) The last mode of occurrence is represented by the discrete bodies of the gneissic fine-grained charnokitic rocks within the country gneisses as seen in Ilara and also near Iju and Emirin villages. All the Charnokite in the region are dark-greenish to greenish-gray rocks with bluish quartz and greenish feldspar. |