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Abstract
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Article Information:
Depth Estimation of Digitized Aeromagnetic Data of the Western Part of the Younger Granite Rocks of North Central Nigeria, West Africa
S.C. Alkali, S. Gaiya and B. Abba Musa
Corresponding Author: S.C. Alkali
Submitted: March 02, 2012
Accepted: March 24, 2012
Published: August 01, 2012 |
Abstract:
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The present study is aimed at estimating the depths extents of aeromagnetic anomalies over the
younger granite rocks and their associates in the western part of North Central Nigeria. The Younger Granites
rocks of North Central Nigeria are characterized by total magnetic intensity values ranging from 32670 to
33070 nanoTesla (nT). Most of the anomalous features trend in the northeast-southwest direction. Medium to
higher magnetic intensity values occupy more than three quarter of the area. Third order polynomial trend
surface fitting performed by least squares produced positive regional field without preferred direction. Higher
regional field values are observed along the southern region and lower ones around the northeast. The surface
residual anomaly has values between 32660 and 33061 nT. E-W, NE-SW and NNW-SSE are the main
structural directions of the residual anomalies. Individual anomalies suggest discontinuity of the rock units.
Residual anomalies of the total magnetic intensity fields fitted with third degree polynomial regional curves
along four profiles produced both negative and positive values. Segments of the profiles with little variations
are considered magnetic ‘quiet’ environments and those showing considerable variation are ‘noisy’ and indicate
magnetic sources in the subsurface. Two and a half dimensional models of the subsurface structures suggest
deep seated fault along the profiles that attained maximum depths of 12.0 km each along sections Mag1 and
Mag2; 13.0 km along Mag3 and 26.6 km along Mag4. The steepness of the magnetic sources suggest possible
relative displacement of the blocks of the rock bodies of these magnitudes. The fault correlate with Romanche
fracture zone which, if extrapolated into Nigerian landmass will pass through the area diagonally in a NE-SW
striking direction.
Key words: Fault, magnetic intensity, polynomial, residual anomaly, rock units, ,
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Cite this Reference:
S.C. Alkali, S. Gaiya and B. Abba Musa, . Depth Estimation of Digitized Aeromagnetic Data of the Western Part of the Younger Granite Rocks of North Central Nigeria, West Africa. Research Journal of Applied Sciences, Engineering and Technology, (15): 2444-2450.
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ISSN (Online): 2040-7467
ISSN (Print): 2040-7459 |
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