Petrography, Structural Characteristics and Mineral Resources of Igue Oke Igarra Area Southwestern Nigeria

Abstract

Igue Oke is located in the SW of Igarra Auchi sheet 266 SW, southwest basement complex of Nigeria. The rock types are made up of meta-sediments which includes marbles, migmatitic schists, meta-conglomerates, amphibolites, calc-silicate rocks which have undergone several deformations, metamorphism and also intruded by syn-tectonic plutonic granitic rocks in Pan-African time. This orogeny is the longest and lasted for about 300 million years. Minerals in the rocks consists of quartz, k-feldspar, biotite, albite-plagioclase, micas, dolomite and calcite as the major minerals while the opaque minerals are major accessory. There are two phases of deformational episodes which have been identified in the rocks of this area. A regional foliation F1 with open, close, tight to isoclinal folds. Secondly, deformation followed which gave rise to shear zones, slickensides and fault features in an environment of extensional tectonics. The dominant major folding in the area is the NW-SE trend and the foliation F2 is associated with slickensides and faults superimposed on the earlier formed structures. The structural element in the study area shows multidirectional orientations. Rocks in the area have a general and consistent trend as revealed by the statistical data on rose diagrams and stereographic projection plots in NNW–SSE, and a few N-S to NE-SW directions. There is also an E-W and EEN-WWE orientation which are probably relicts of Pre-Pan-African orogeny. Exploitation of granites for aggregates has been going on with established quarrying firms for granites, while mining of marble by small-scale miners has been going on without proper design or plan for Health, Safety and Environment HSE causing badland topography, a three bench mine design with reclamation procedures will be appropriate for the area.