Spectral Transformation of Aeromagnetic data for Local Sub-Basin Delineation within Parts of the Cretaceous Middle Benue Trough
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Abstract
Spectral valuation of aeromagnetic data was undertaken within segments of the Middle Benue trough in order to delineate local sub-basin structures favourable to hydrocarbon accumulation; determine the depths to magnetic sources and hence estimate the thickness of the sedimentary materials within them. Standard processing and interpretation procedure involving coordinate system reprojection; regional-residual separation by means of least square polynomial smoothening and application of discrete Fourier Transform for the Spectral Analysis of (25) blocks carefully chosen to ensure inclusion of essential and interesting anomaly signatures were undertaken. Findings from the analysis show models with two-depth solutions, deep and shallow depth solution models. The deep depth-source model showed depth solutions varying between 0.65 km and 5.02 km and the shallow depth-source model revealed depth solutions ranging from 0.3 Km to 0.5 Km with the average magnetic source depth for the study area being 2.48 km. The deep depth sources are probably due to presence of thick sedimentary sequences with the thickest sedimentary sequences found around Tsuwa sub basins, SW of the study location and around Igbor sub basin, NW of the study location and on this basis; the two sub-basin structures were identified as most promising for hydrocarbon prospects. The shallow depth sources are hypothesized to be due to metallic ore deposits widely reported within the general vicinity. The results obtained have important implications for petroleum and mineral exploration.
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