Analysis of the Lineaments Extracted from LANDSAT TM Image of the Area around Okemesi, South-Western Nigeria

摘要

Lineament analysis of the area around Okemesi were carriedout using a remotely sensed LANDSAT THEMATIC MAPPER ( LANDSAT TM ) imagery of scale 9.2km to delineate groundwater productive zones in the areas around okemesi, based on the frequency and density of lineaments on the lithologies that make up the area. 260 lineaments comprising 157 on the quartzite, 82 on the granite and 21 on the schist and migmatite were extracted from the image with their corresponding directions and lengths. The results show that the highest pecentage lineament density (17.20%) occur on the quartzite at 041° -050° azimuth and having the longest lineament length of 46.47km. This is closely followed by the granite with (20.73%) of the lineament density occuring at 041° -050° azimuth, while the schist and the migmatite and the gneiss which constitute the other rocks on the imagery also have the lowest density of lineaments (19.20%) occuring at 120 0 -130 0 azimuth and the shortest lineament length of 9.75km. The lineaments on the granites are intersected and long, while those on the quartzites are shorter and mostly in E-W direction. The overall results show a polymodal distribution of lineament lengths and frequencies on the quartzites, granites than the schists. Other lithologies, such as gneisses and migmatites, have fewer lineaments because of their ductile nature.