Qualitative Interpretation of Recently Acquired Aeromagnetic Data of Naraguta Area, North Central Nigeria

Abstract

This study on Qualitative Interpretation of recently acquired aeromagnetic data of Naraguta, sheet 168 was aimed at analysing and interpreting the data, identifying the subsurface structures and the mineralized zones. Using some software packages, the data was analysed using the following processes; Total Magnetic Intensity (TMI), Reduced-To-Equator (RTE), Upward Continuation and First Vertical Derivative (FVD). Results from the analysis show that the magnetic intensity range for TMI map varies from -696.9 to 599.2 nT/m, RTE varies from -430.1 to 346.4 nT/m both showing anomalies in circular to near circular closures which could be associated with granitic intrusions, long narrow features which could be dykes or long ore bodies and dislocations which could be due to subsurface fractures. Upward continuation map at 3 km deep revealed a basement trending mostly in the NE-SW and ENE-WSW directions with the latter being the major trend direction. The first vertical derivative sharpened the anomaly edges which were extracted to produce the lineament map and to obtain the rose plot. The rose plot shows the dominant lineament trend to be in the NE-SW direction. Finally, the analytic signal maxima may represent the edges of circular, elliptical or polygonal porphyritic ring dykes that characterize many of the complexes in the studyarea. Comparison of this study with previous research done using an old data of Naraguta sheet 168, shows similarities with few differences noticed especially in the TMI map which may be attributed to sophistication in equipment used or the effects of temporal variation on the geomagnetic field of the earth which helped in making visible anomalies that were hidden in the former data of Naraguta sheet 168.