Interpretation of Aeromagnetic Data of Part of Gwagwalada Abuja Nigeria for Potential Mineral Targets

This study analyzes aeromagnetic data over a section of Gwagwalada in Abuja. The data were obtained from the Nigerian Geological Survey Agency acquired at 100 m terrain clearance. The study area spans longitudes 7.0875 E to 7.1458 E and latitude 8.9625 N to 9.0 N (about 27 km2). The dataset was reduced to the equator (RTE) and downward continued by 50 m. Analytic signal filter was applied on TMI-RTE grid to detect the edges of the magnetic bodies present. The structure was observed to trend NE-SW. The CET lineament map reveals intersections such as junctions and corners on the map. This revealed structure liable for potential mineralization zone. Euler deconvolution technique applied over the transformed dataset ascertain the location and depth of the structure,having a maximum depth of about 421 m and a minimum of about 59 m.Variation in magnetic depth and susceptibility contrast is specified by the gridded SPI depth map.

Analytic Signal Depth from High Resolution Aeromagnetic Data over the Gongola Basin Upper Benue Trough Northeastern Nigeria

The study of high-resolution aeromagnetic data was carried out over the Gongola basin, upper Benue trough, northeastern Nigeria, for analytic signal depth determination. Total intensity magnetic map obtained from the data using the Oasis Montaj TM programming software was used to get the residual map by polynomial fitting, from where the analytic signal was obtained with the use of anomaly width at half the amplitude (X1/2). This was used to carry out depth estimations over the study area. The results showed that it peaks over the magnetic structure with local maxima over its edges (boundaries or contact), and the amplitude is simply related to magnetization, likewise results also showed that the depth estimates were in the range of 1.2 to 5.9 km and were calculated for contact, dyke/sill and horizontal cylinder respectively. The lowest values are from DD profiles, while the highs are from AA profiles. This work is important in identifying dykes, contacts and intrusives over an area.

Quantitative depth estimation using analytic signal at low-latitude for ground gravity survey of Gbede, Oyo State

This paper presents the insitu gravity survey of basement complex rock in Southwestern Nigeria. In the E-W direction, LaCoste and Romberg Gravity Meter type G309 was used to carry out a ground gravity survey where ten traverses were established over a distance of 1000 m by 500 m with station spacing of 20m and a traverse interval of 50 m. Observed gravity values were corrected, analyzed and interpreted quantitatively. The corrected bouguer gravity data were presented as bouguer anomaly graphs. Analytic Signal at low-latitude was adopted to compute the depth to source of iron-ore for a contact, a thin sheet (dyke) and a horizontal cylinder. The result revealed a depth range of 5.45 m-8.25 m for a contact, 9.44 m-14.29 m for a thin sheet (dyke) while a depth range of 12.31 m-18.05 m was estimated for a horizontal cylinder respectively. An average depth of 11.81±3.64 m was estimated for the entire area irrespective of the structural model, this was compared with published magnetic results of the study area and a small disparity of potential field measurements was recorded. The overall computed results signified the existence of iron mineral deposits at low depths across the study area.

Geophysical Investigation of a Fault Zone from Aeromagnetic Data over the Ageva Area of Okene Kogi State, Nigeria

High-resolution aeromagnetic data over a part of Ageva fault zone in Nigeria have been analyzed with a view to estimate sedimentary thicknesses within the studied area. The data set of this study area, was subjected to various corrections and interpretation techniques. Regional residual correction was done and the noise level of the data was reduced via upward continuation to a height of 250 m thereby enhancing the reliability of the results obtained. Qualitative interpretation techniques which include: Second Vertical Derivative, Analytic Signal, Tilt derivative were used to delineate the trending pattern of the anomalies in the study area which are in the E-W, NE-SW, NW-SE, and N-S directions. The result suggests that fault zone within Ageva and Owo may be mineralized and also that the faults within Ageva and Ibilo extend by a quarter of their exposed length. The Werner solutions revealed that inferred faults within Owo and Ibilo may have relatively low susceptibilities as compared with others in the study area and the range of the depth extent of linear features is 401.5 m – 982.5 m.