Petrostructural and Mineralogical Assessment of the Precambrian Rocks in Ikere Area, Southwestern Nigeria

Petrological and mineralogical evaluation of the basement rocks in Ikere Ekiti, southwestern Nigeria was carried out with the aim of determining the petrological characteristics and mineral composition of the various rock units dominating the study area in an attempt to unravel the pattern of deformation on the rocks. The method of investigation includes systematic geologic mapping to determine the underlying rock units, petrographic studies of the thin sections using light transmitting Petrological Microscope and; analysis and interpretation of the structural elements inherent in the rocks using rosette diagrams. Seventeen (17) rock samples were collected on the field out of which ten (10) fresh rock samples were selected and prepared for thin section studies using standard procedures. Geologic mapping of the studied area revealed that the rocks occured as plutons (older granite) while the charnockites and granites occur as pegmatitic intrusions into the older rock sequence. The granites and charnockites were extensively dissected by a network of intersecting or crosscutting quartzo-feldspathic stringers or veins/veinlets of various widths and dykes, which is an indication of the relevant post-tectonic deformation episodes and deuteric alteration in the evolutionary history of the rocks. Also, the rocks are rich in quartz and feldspar with significant amounts of heavy minerals such as zircon, tantalite, tourmaline, heamatite, topaz and opaque minerals such as casiterite, chalcopyrite, sulphide and pyrrhotite.