Study’s Excerpt The lithological and structural composition of the Ikara North-Central Basement Complex in Nigeria is investigated. Detailed field and petrographic analyses were carried out to identify the rock types of the area. The geological map of the area is updated. Full Abstract The lithological and structural architecture to unravel the compositions and tectonic evolution of the Nigerian Basement Complex has not been fully documented by geoscientists. As such, this research aimed to investigate the lithological and structural characteristics of the Ikara North-Central Basement Complex. Detailed petrographic and field analysis reveals the prevalence of gneiss and granite lithologies characterized by significant structural features such as fractures, folds, and foliations. These findings offer new understandings of the tectonic evolution of the region. The study area mapped is the Ikara Sheet 103 Federal Survey Topographic Sheet to a scale of 1:100,000. The major lithological units underlying the study area are gneisses and granites. However, these major rock types have varieties, namely migmatitic gneiss, granite gneiss, migmatitic (augen) gneiss, porphyroblastic gneiss, medium to coarse-grained granites, and porphyritic granites. These rock types were intruded by quartzites, pegmatitic dykes, quartz, and aplite veins. Rock samples were observed and studied based on their mineralogical composition, color, and texture. The results of the petrographic analysis showed that the rocks are mainly composed of quartz, plagioclase feldspars, alkali feldspars, mica (biotite and muscovite), hornblende, garnet, and accessory minerals like zircon and magnetite. Geological structures were also observed during the field study, namely fractures (joints and fractures), foliations, lineations, veins, dykes, and various landforms. Photomicrographs from thin section analyses revealed micro-structures like myrmekites, micro-folds, and micro-fractures were also observed. Mineralization such as amethyst and cassiterite were hosted by quartz veins and pegmatites in porphyritic granites, respectively. A litho-structural map was produced, exhibiting the lithological units and regional structures cross-cutting the area of research.
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