SPECTRAL ANALYSIS AND INTERPRETATION OF AEROMAGNETIC ANOMALIES OVER THE UPPER BENUE TROUGH, NIGERIA

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Date
1987-08
Authors
NWOGBO, NWOGBO
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Abstract
Aeromagnetic data of the Upper Benue Trough have been analysed by one- and two-dimensional spectral analysis to determine the lateral variation in sedimentary thickness and structure under the basin. A two-dimensional standard model interpretation of an aeromagnetic profile was also presented as a supplementary technique. The area investigated covers the portion of the trough from 09° 00' - 12° 60'N and 009° 30' - 012° 30'E. Spectral depth determinations to magnetic sources in the region give four depth ranges namely: 9.40km to 31.52km, 4.37km to 5.10km, 2.0km to 2.83km, and 0.04km to 0.96km. Deep source depths occuring at 9.40km and 31.52km refer respectively to some layer of intra-crustal source structures, and to the lithologic interface corresponding to the crust-mantle boundary. The intermediate mean depths varying between 4.37km and 5.10km may represent the top of some intrusive material occuring within the basement. Some of these intrusions as indicated by the two-dimensional model interpretation occur at depths of up to 6.0km. Mean depth values in the range of 2.0km to 2.83km agree with previous estimates from gravity data and may relate to the magnetic level corresponding to the true basement surface. This depth range indicate clearly the magnitude of the undulation of the basement topography in the study area. Variations in the depth
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A thesis submitted to the Postgraduate School, Ahmadu Bello University, Zaria in partial fulfilment of the requirements for the award of the degree of Master of Science in Applied Geophysics.
Keywords
SPECTRAL, ANALYSIS, INTERPRETATION, AEROMAGNETIC, ANOMALIES, OVER, UPPER, BENUE, TROUGH, NIGERIA
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