Prospectivity study of mineral and geothermal energy resources in parts of SouthEastern Nigerian Sedimentary Basin
Date
2021-09
Authors
Journal Title
Journal ISSN
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Publisher
Federal University of Technology, Owerri
Abstract
There has been an open search for clean/renewable energy and mineral resources for economic growth using airborne geophysical surveys. High resolution airborne magnetic and radiometric data, five scenes of Landsat 8 remote sensing, SP and VES Schlumberger data of parts of Southeastern Nigerian sedimentary basin were analysed and interpreted with a view to delineate regimented mineral colonies and anomalous zones of geothermal gradient. Reduction to Equator and Vertical Derivative filters were applied to the airborne magnetic data to centre anomaly peaks over causative bodies, define shapes and edges of magnetic sources and map magnetic lineaments. Fast Line-in-sight Atmospheric Analysis for Spectral Hypercube (FLAASH) and subsequent post FLAASH band maths were applied to the remote sensing data to generate the surface reflectance data from which ratio composite and lineament maps were generated. Results showed dominant NE-SW and E-W lineament trends from Landsat and Magnetic data with subordinate NW-SE trend. 50% overlapping data windows selected for spectral analysis were used to delineate anomalous geothermal gradients. The vertical, horizontal and NTilt derivative maps were used to reveal boundaries of mafic intrusives and inclusions which are most likely controlled by the trends of deep-seated magnetic lineaments. The derivative maps were also used to enhance edges of shallow structures. Alteration zones, lithologic/geologic boundaries were revealed by radioelement ratio, ternary and total count maps and Landsat ratio map composites 4/2, 6/5 and 6/7 and PCA plots. The Source Parameter Imaging, 3D Euler Deconvolution and Magnetic Vector Inversion modelling depth estimate filters established depths to, and geometry of, subsurface magnetic structures. Results revealed shallow to deep-seated structures in the depth range of 80 m asl to >7 km bsl which must have aided development of veins and hosted lodes of intrusives and ore bodies. Shallow Curie Point Depth (< 10km), geothermal gradient > 42°C/km and heat flow > 88mW/m2 from spectral analysis procedure have been earmarked for good geothermal reservoirs. VES geoelectric sections and 2D imaging results beneath two zones of anomalous geothermal gradient between 35 to 45 (°C/km), proposed approximate models of geothermal resources as Hot Dry Rock (HDR) for Alok and geo-pressured model for Amagunze. Cylindrical/lenticular sills, inclined dykes, sparse nodules and spheres were identified from probed windows of the RTE-TMI map as surface to deep-seated models. Ground-truthing these findings, field image and double dipole results indicated mineralization of the study area as true, hence, making it a viable mineral and geothermal prospect environment.
Description
This thesis is for the award of Doctor of Philosophy in Geophysics
Keywords
Airborne, magnetics, radiometrics, landsat, geothermal, lineaments, mineralization, Department of Geology
Citation
Okiyi, I. M. (2021). Prospectivity study of mineral and geothermal energy resources in parts of SouthEastern Nigerian Sedimentary Basin (Unpublished Doctoral Thesis). Federal University of Technology Owerri, Nigeria