Mapping of Lineament Structures for Groundwater Study using Aeromagnetic Data:

Case Study of a part of Ilorin and its Adjoining Areas, Central Nigeria

Abstract

Lineaments mapping over the Basement Complex rocks of southwestern Nigeria at Ilorin, Central Nigeria was carried out. It was aimed at identification of the structural features responsible for the hydrogeology of the area. This work involved the qualitative and quantitative analysis of aeromagnetic data using Oasis MontajTM and the geological information obtained from the area. The analyses made on the IGRF corrected aeromagnetic data acquired was used to estimate depth to anomalous sources using 3-D Euler deconvolution. The 3D Euler Deconvolution was used to estimate and examine the shape, type of magnetic field within a window and calculate 3-D source locations based on its structural index. The results obtained from aeromagnetic data analysis augmented with geological information obtained from literature were employed in the lineaments extraction and interpretation works. The results have shown that the identified faults and lineament features obtained from geophysical data generally coincide with the river channels on the geologic maps which indicate a structural control of the drainage system in the study area. The orientation of the extracted faults and lineament features showed a preponderance of NE-SW trend followed by NW-SE trend, which corroborate the fact that the Pan African in Nigeria was followed by conjugate strike slip fault systems which averaged in the NE-SW and NW-SE directions and showed dextral and sinistral sense of displacement which cut across the earlier Pan African structures.