LITHOLOGICAL MAPPING AND LINEAMENT ANALYSIS IN ZARIA AND ITS ENVIRONS USING REMOTE SENSING TECHNIQUE.

Ishaku, Y.M. and Abubakar, Y.I.*

The study area is underlain by Precambrian rocks which lie in the mobile zone between the West African and Congo Craton. Detail remote sensing analysis was carried out using landsat ETM⁺ data set and SRTM DEM to map lithological units and understand regional structural pattern of the study area. Lithological and structural map of the area was produced using a false colour composite image from band 7, 4 and 1 in RGB. Three main lithological units were mapped in the area include older granite, biotite gneiss and metasedimentary rocks. Lineament analysis was carried through a semi-automatic process. Result indicates variations in lithological units and revealed a dominant NW-SE trend accompanied by a less dominant N-S and E-W direction. Lineament length ranged from 0.807km to 10.0535km. Areas of high lineament length are observed in the North and Southern part of the study area. The mean lineament length ranges from 0.6-0.9km. Correlation between lineament length and orientation show a close correlation between NW-SE and NE-SW, and NE-SW and E-W lineament specie. From the lineament density map, areas of extremely high lineament density are located in the western part occupying an area extent of 2.90km², very high lineament density occurs in the eastern to northern to southeastern parts and has an area extent of 26.73km², high lineament density occur in the western, south eastern and c north central parts of the study area, occupying an area extent of 150.4 km² and low density has an area extent of 329.2km². Areas of short lineament length cover a total area of 387.3km². Areas of very short lineaments cover a total area of 104km², while extensive lineament length covers a surface area of 217.7km². The present study has shown that ETM⁺ and SRTM DEM are powerful tools in lithological and lineament mapping and can be effectively used in reconnaissance study. There is no standard on selection of the optimum band for manual lineament extraction. Therefore, it is recommended that the geologic, topographic properties and vegetation cover of the selected area should be taken into the consideration.

Key words: ETM⁺, Lineament, Lithological Mapping, Remote Sensing, SRTM DEM, Zaria.