Geological and structural analysis using remote sensing for lineament and lithological mapping

Abstract

The study area forms part of the precambrian to early paleozoic Nigerian Basement Complex. The Nigerian Basement Complex is a polycyclic assemblage of heterogeneous migmatites and gneisses, metasediments and granites that have undergone a complex evolutionary history spanning through Archaean to Pan-African (Late Proterozoic) times. Multispectral images from Landsat 7 ETM+ were utilized to complement field mapping, elucidate lineaments and clearly outline alteration zones. The dominant rock types in the area are gneiss, granites and metasediments with minor lithologies such as aplite dykes, quartzo-feldspathic and quartz veins, pegmatites and xenolith. Petrographic studies have shown that the granite comprises of porphyritic and medium to coarse grained varieties that are composed mainly of quartz, feldspar, biotite ± muscovite. The metasediments include pelitic schist and composed of quartz, biotite, feldspar, ± muscovite, ± chlorite and quartzites. These rocks have been deformed, sheared and foliated. The dominant NW-SE to N-S structural trend, follows the general trend of structures resulting from both Pre-Pan-African and Pan-African Orogenies. The geological and structural maps of the study area on a scale of 1:50,000 have been updated.