ABSTRACT
PETROLOGICAL IMPLICATIONS OF 1.065 GA ZIRCONU-PB AGE OF MIGMATITE-GNEISS IN THE BASEMENT COMPLEX OF IDANRE, SOUTHWESTERN NIGERIA
Journal: Malaysian Journal of Geosciences (MJG)
Author: Akinola Oluwatoyin Olagoke, Adeoye Aderemi Sunday
This is an open access article distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
DOI: 10.26480/mjg.02.2024.108.114

This research investigates and report zircon U-pb age of a migmatite-gneiss in Idanre, southwestern Nigeria and the petrological implications of this U-Pb age. Field geology reveals Idanre migmatite isa diatexite withnebulitic structures and the gneiss,a metatexite with perverse deformation. The migmatite-gneiss which forms the country rockis a low-lying geomorphologic unitintruded by granite plutons and batholiths. Zircon grains recovered from the migmatite-gneiss have variable sizes and morphology. Geochemicalinvestigation of the zircon revealed Uranium contents range between 80.838 to 116.736 ppm, Th contents between 25.647 ppm and 38.227 ppm while Th/U ratio falls between 0.299 and 0.365. 206Pb/207Pb age of the migmatite-gneiss ranges from 1051 to 1082 Ma with weighted average 1065.1 ± 7.1 Ma (MSWD = 0.28).The age of migmatite-gneiss fallsoutside the Archean-Early Proterozoic (3200-1600 Ma) age bracket reported for migmatite-gneissin other parts of Nigeria.Even though, the 1.065 Ga age of the migmatite-gneissis comparableto granite-gneiss from central Zambezi which crystallized around 1005–1018 million years ago and Phyllite from the Maru schist belt of north central Nigeria which yielded 1110 Ma.However,the migmatite-gneiss age is uncommonin neighbouring Pan-African belt, it is older than the Bayudian event (~0.92 Ga) of the Bayuda Desert of Sudan. This suggests the Idanre migmatite-gneiss probably represents anatectic product of yet another ancient Archean protolith.