Structures and Depth to Magnetic Source Assessment of Auchi Sheet 266, South-Eastern Nigeria

The current study was designed to provide a consistent and detailed understanding of the Structural disposition and magnetic source depth of Sheet 266, south-east Nigeria in the Auchi region by applying three source edge mapping techniques: horizontal gradient magnitude; tilt derivative and Euler deconvolution to aeromagnetic data obtained from Nigeria Geological Survey Agency Abuja (NGSA). To achieve the above objective, there was a need to correct the latitudinal effect on data obtained at low latitudes just as the present case, the total magnetic intensity (TMI) data was reduced to the pole (RTP) and regional magnetic anomalies were extracted from the RTP data to obtain the residual anomaly data using the upward continuation technique. To establish the boundaries of the magnetic sources, various source edge mapping techniques such as Analytic signal (AS), Horizontal Gradient Magnitude (HGM) and Tilt Derivative (TDR) were applied. A strong correlation between these techniques has been found, suggesting that their incorporation may contribute to delineating the structural mechanism of the study area. A comprehensive structural map based on the findings was therefore built. The key tectonic patterns in the study region are typically interpreted to predominantly ENE-WSW trend followed by WNW-ESE trend. In the study area, depth to magnetic source estimation using 3D Euler deconvolution and source parameter imaging (SPI) has also shown that the two techniques complement each other with depth estimation and general depth to magnetic source was 50 m in the basement portion of the study area and >2000 m in sedimentary portion as seen from both SPI and 3D Euler deconvolution techniques.