Subsurface Structural Mapping over Koton Karifi and Adjoining Areas, Southern Bida Basin, Nigeria, using High-Resolution Aeromagnetic Data

In this current work, we aim to delineate the subsurface structural trends, determine the depth to basement surface, and provide an illustrative 3D model for its subsurface structure. Four digitized aeromagnetic maps were acquired from the Nigerian Geological Survey Agency, Abuja. The total field aeromagnetic anomalies over Koton Karifi and adjoining areas have been evaluated. In order to map the subsurface structures and estimate the depth to basement surface the spectral analysis method was applied. To achieve such goals, a detailed analysis of the aeromagnetic data for the study area was performed. 2D interpretation was carried out for the aeromagnetic data. The processes used include contouring of the Total Magnetic Intensity (TMI) data, separation of regional and residual anomalies, structural detection methods such as analytic signal, vertical derivatives, and magnetic lineament mapping were used to map the contacts and faults within the study area. The first vertical derivative and the magnetic lineament maps show major geologic lineaments trending in East-West with minor ones trending Northeast-Southwest. In the south-eastern part of the study area, there is a dome-shaped linear feature. The result obtained using the spectral analysis method reveals two source depth models. The depths to deeper magnetic sources range from 2.81 km to 3.24 km with an average depth of 2.90 km. The deeper magnetic source bodies are identified with the magnetic basement. The shallower magnetic sources which range from 0.45 km to 1.81 km with an average depth of 1.13 km could be attributed to near surface magnetic sources which are magnetic rocks that intruded into the sedimentary formations or magnetised bodies within the sedimentary cover. Based on the sedimentary thickness range of 0.45 to 3.24 km, there is an indication that the possibility of hydrocarbon generation in the study area is feasible.

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Estimation of The Structural Pattern and Sedimentary Thickness Over Part Of Anambra Basin, Nigeria Using Aeromagnetic Data

Pakistan Journal of Geology ◽

10.2478/pjg-2021-0002 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Priscilla E. Ikioda ◽

Charles O. Ofoegbu ◽

Etim D. Uko ◽

Olatunji S. Ayanninuola

Keyword(s):

Spectral Analysis ◽

Analytical Techniques ◽

Average Depth ◽

Intensity Data ◽

Aeromagnetic Data ◽

Structural Pattern ◽

Near Surface ◽

Anambra Basin ◽

Potential Depth ◽

Magnetic Basement

AbstractAeromagnetic data acquired over part of the Anambra Basin is analyzed to determine the structural pattern and sedimentary thickness of the basin. The study area is covered by high resolution aeromagnetic data on sheets 301 (Udi), 302 (Nkalagu), 312 (Okigwe) and 313 (Afikpo), and lies between latitudes 5o30’0’‘-6o30’0’‘ and longitudes 7o0’0”-8o0’0”. The whole area was divided into 25 overlapping blocks of 37.2km2 each and a 2D energy spectral analysis was carried out. Total magnetic intensity data was subjected to filtering and analytical techniques to determine the structural pattern, mineralization potential, depth to the basement, variation in the sedimentary thickness. The structural map generated using the vertical derivatives shows that the major structural orientation of the area is in the ENE-WSW trend and the minor trend is the NW to SE direction widespread all over the area. These structures are as a result of the various near-surface magnetic intrusion within the study area. The spectral analysis result shows two depth layers, the deep and the shallow depth, the depth to magnetic basement for the deep anomalous source ranges from 3.3km to 4.8 4km with an average depth of 3.99km, while the depth to shallow magnetic sources ranges between 0.46km to 0.67km and an average of 0.56km within the area. The mineralization pattern in this area follows the ENE-WSW direction.

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