Magnetic Basement Depth Re-Evaluation of Naraguta and Environs North Central Nigeria, Using 3-D Euler Deconvolution

Abstract

This paper presents a detailed geological interpretation of the aeromagnetic data over Naraguta and environs using 2-D spectral inversion and 3-D Euler deconvolution techniques. The objectives of the study are to re-evaluate the depth to the magnetic basement and to delineate associated structural features in the study area. Data enhancement was carried out to separate residual features relative to the strong regional gradients and the more intense anomalies due to basement features and igneous intrusives. Results of the 2-D spectral analysis revealed a two layer depth source model. The deeper magnetic source bodies (d<SUB>2</SUB>) varies from 1.672km to 2.3km with an average depth of 1.999km while the depth to the shallower magnetic source bodies (d<SUB>1</SUB>) ranges from 0.55km to 0.897km with an average depth of 0.711km. The shallower magnetic anomalies are believed to be as the result of basement rocks which intruded into the sedimentary rocks while the deeper layer may be attributed to magnetic basement surface and intra-basement discontinuities like faults, fractures and lineations. Structural analysis of these shallow anomalies using 3-D Euler deconvolution with structural index values ranging from 0-3, revealed three main structural models which include spheres, horizontal pipes/cylinders and sills/ dikes. Similarly, magnetic basement depth estimates using 3-D Euler deconvolution revealed a magnetic basement depth range of 0.5 - 2.5km. Finally, the average sedimentary thickness of 1.999km estimated from the study area is unfavorable for hydrocarbon generation and accumulation. However, the area is more viable for solid mineral exploitation based on the presence of several intrusive and linear features which may have acted as conduits for mineralization.