LITHOLOGICAL AND STRUCTURAL MAPPING OF FIDITI AREA, SOUTH-WESTERN NIGERIA USING REMOTE SENSING TECHNIQUES

Abstract

Geological mapping involve plotting the location of the various rock units, folds and faults on a base map. The aim of this study is to carry out lithological and structural analysis using remote sensing techniques. LANDSAT ETM imagery was combined in a 745 band combination using a RGB format. Lineaments were picked and analysis from LANDSAT ETM, ASTER and SRTM dataset. Lithological mapping of the area were carried out using the principal component analysis (PCA) and the minimum noise fraction (MNF) techniques while geological field mapping techniques were used to groundthruth information generated from these data. Structural analysis involved the plotting of stereographic projections and the plane to pole diagram for fractures and folds data. From the results of the analysis, field mapping revealed that quartzite, granite and granite gneiss are the major rock types in this area. These rock types were easily recongnised using PCA and MNF techniques. Petrographic analysis shows that quartz, feldspar, biotite, amphibole are the common minerals found in these rock types. Structural analysis of lineaments in the area shows that they trend mostly in the NE to SW and NW to SE directions. This is possibly due the effect of pan African orogeny in the area. Field mapping of fractures in the area also shows similar trends which confirms the results obtained from the satellite imageries. Other structures found in the area are folds and microfaults. Shear zones were also observed. Conclusively, it can be said that remotely sensed imageries can be used to update the geological map of the area.