Precambrian Basement Architecture and Lineaments Mapping of Ado-Ekiti Region Using Aeromagnetic Dataset Cyril C. Okpoli and Michael A. Oladunjoye Department of Earth Sciences, Faculty of Science, Adekunle Ajasin University, PMB 1, Akungba- Akoko, Ondo State, Nigeria Department of Geology, University of Ibadan, Ibadan, Nigeria Email: cyril.okpoli@aaua.edu,ng; okpolicyril@gmail.com Abstract. Aeromagnetic dataset over Ado-Ekiti Southwest (sheet 244) was processed to interpret the geology structure and estimate the depth to bedrock of magnetic sources as well as to deduce the basement architecture and their trends. Aeromagnetic dataset were collected, filtered, inverted, and enhanced using appropriate software packages and subsequently employed to generate a 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 and Euler/Werner deconvolution. The result shows that magnetic intensity from Butterwort ranges from -173.3 to 150.8 nT; Reduction to the pole varies from -213.1 to 314.1 nT; upward continuation at 100m ranges from 156.1 to 142.4 nT and analytical signal varies from 0.0 to 0.4 nT. 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 disclose the presence of fold, shearing, contacts, lineaments with its orientations while the 3D Euler deconvolution > 2000 and dike model fits the Werner function. The average radial power analysis delineated shallow sources ranging from 0.34 km - 0.49 km and deeper sources ranging from 0.45 – 1.25 km. Pseudogravity result is 0.103g/cc which trends in NE-SW direction. The lineaments directions are in NE-SW, NW-SE and E-W directions which are Pan-African, Kibaran and Liberian Orogenies that occurred in the region. Modeled maps of upward continuation, analytical signal, tilt derivative, pseudo gravity average power spectrum and 3D Euler /Werner deconvolution revealed the basement architecture including structural lineaments with its orientations and the depth to the magnetic sources of the study area. Keywords: Aeromagnetic, 3D Euler/Werner deconvolution, pseudogravity, Ado-Ekiti, derivatives, basement architecture. 1 Introduction High-resolution aeromagnetic data were recently collected in an Ado- Ekiti area and its surrounding towns to improve the regional geologic understanding of the subsurface geology (Reeves, 1985; Grant, 1985). Qualitative and quantitative analyses of the data were integrated to obtain a preliminary interpretation. The primary sources of aeromagnetic anomalies are interpreted as magnetite and intrusive with dominantly reversed-polarity remanent magnetization, weakly to moderately magnetic Precambrian crystalline basement, and magnetic Tertiary intrusions. High resolution aeromagnetic surveys, in particular terms, map the magnetite in the rocks beneath the aircraft. Aeromagentic surveys are comprehensively used as reconnaissance tools and there has been a growing recognition of their value for appraising prospective areas by virtue of the unique information they provide. Highlights of the function of aeromagnetic surveys are: identification and interpretation of faulting, shearing, and fracturing not only as potential hosts for a variety of minerals, but also an indirect guide to epigenetic, stress related mineralization in the surrounding rocks (Reeves, 2005) Aeromagnetic survey used in direct detection of deposit of certain rocks rich in iron ores. Identification and delineation of post-tectonic intrusive: typical of such targets are zoned Syenite or Carbonatite Geosciences Research, Vol. 2, No. 1, February 2017 https://dx.doi.org/10.22606/gr.2017.21005 27 Copyright © 2017 Isaac Scientific Publishing GR