Geological Interpretation Using Derivatives of Magnetic Signal from Ground Survey over a Granitoid Bedrock Area in part of South-Western Nigeria
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Abstract
Few researchers located and identified granitoid rocks in the course of determining the thickness of the clay deposits with the use of electrical resistivity method of geophysics in the Basement Complex of Southwestern Nigeria. Another set of researchers have related elemental abundances were to tectonic evolution of certain granitoid rocks from the Precambrian rocks of Southeastern Nigeria. It was also established that their ferromagnesian phase oriented clots followed the magmatic flux direction. However, the analysis, modification and synthesis of magnetic signal in the interpretation of magnetic anomalies granitoid bodies are rare in the geophysics literature of Southwestern Nigeria. This study is aimed at deciphering the physical and geometric limitations from magnetic causative body. In this study, ground magnetic data was acquired using advanced GSM 19T Proton Precision Magnetometer. Quantitative data was transformed to magnetic signal. Carefully chosen derivatives include the Total Magnetic Intensity (TMI), Regional Magnetic Intensity (RMI), Residual Anomaly (RA), Tilt Derivative (TD), HTD, Euler Deconvolution, Analytical Signal (AS), Pseudo-gravity data, 2-D Power Spectrum. Results clarified doubts on the structural trend and tectonics of the igneous bodies. It was established that granitoid rocks which underlain Idofe-Oru area experienced crustal thickening during the period of Pan African orogeny, and were related to convergent boundaries.
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