Geological And Structural Interpretation Of Ado-Ekiti Southwest And Its Adjoining Areas Using Aeromagnetic Data

Abstract

Airborne magnetic datasets was processed to interpret the geology of part of the basement complex of Ado-Ekiti SW, Sheet 244 and estimate the depth to basement of magnetic sources in the area in order to evaluate and deduce the basement topography, delineating structural lineaments and their trends using the aeromagnetic geophysical method. Aeromagnetic dataset were collected, filtered, inverted and enhanced using appropriate software packages and subsequently employed to generate model of the subsurface basement topography. The data processing steps involved were Butterworth filtering, reduction to the equator, analytic signal, upward continuation, Tilt angle derivative, Average power spectrum, Euler deconvolution and Window Euler solution. The magnetic intensity from Butterwort ranges from 171.647 to 188.405nT; Reduction to the Equator varies from -162.5 to 194.1nT; upward continuation at 4km ranges from 7.6 to 91.7nT and analytical signal varies from 0.007 to 0.564nT. The magnetic intensity distribution was found to depend on the size, depth of burial and the thickness of low susceptibility superficial material overlying the magnetite rich crystalline rocks. Tilt angle derivative revealed the presence of fold, shearing and lineaments with its orientations. Lineament analysis using the rose diagram showed that the area is dominated by NNE-SSW trend. Window Euler solution varies from 0.132km to 2.23km with the percentage variation in the depth estimation ranging from 5.56% at shallow depth to 0.90% at deeper depth. The average radial power analysis delineated shallow sources ranging from 0.36km - 0.50km with 95.2nT - 134.9nT magnetic intensity and deeper sources ranging from 0.88 - 1.35km with magnetic intensity -37.4nT to -162.5nT. Maps of upward continuation, analytical signal, tilt derivative, average power spectrum, Window Euler solution and Rose diagram revealed the basement topography including structural lineaments with its orientations and the depth to the magnetic sources of the study area.

AAPG Datapages/Search and Discovery Article #90215 © 2015 Pacific Section AAPG Convention, Oxnard, California, May 3-6, 2015