Abstract

An attempt was made to use remote sensing technique to analyze some structural components of the metamorphic basement complex of the Ikare area in the SW Nigeria. Multiple data sets coupled with application of directional filtering techniques were used to extract linear features from Landsat ETM+ image with a view to improving on already produced regional structural map of the area and also determine a fast and cost effective approach to lineament mapping when handling multiple datasets. Band 7 (2.080 - 2.35) µm of the ETM+ image was used as a single band to visually extract linear feature while Principal Component Analysis (PCA) technique was employed in generating a multi-band enhanced image used to extract linear features. Four standard directional filters, Sobel (NS, EW, NW_SE and NE_SW) were further applied to enhance visual interpretation. The result shows that the area was affected by both ductile and brittle deformations at a regional scale, at least two episodes of deformations. A first episode of deformation (D1) produced the NW - SE tight to isoclinal fold in style (F1) and a second episode of deformation (D2) which affected the axial trace of the first episode to produce a N - S gentle to open fold (F2). Furthermore, the result shows that spatial domain filtering significantly improves the amount of lineaments that can be mapped and single band analysis is a rather fast and cost effective method of lineament extraction.

Key words: Lineament mapping, directional filters, Ikare,