Analytic Signal Depth from High Resolution Aeromagnetic Data over the Gongola Basin Upper Benue Trough Northeastern Nigeria

H Musa,N.E Bassey,R Bello

doi:10.4314/jasem.v25i4.15

Abstract

The study of high-resolution aeromagnetic data was carried out over the Gongola basin, upper Benue trough, northeastern Nigeria, for analytic signal depth determination. Total intensity magnetic map obtained from the data using the Oasis Montaj TM programming software was used to get the residual map by polynomial fitting, from where the analytic signal was obtained with the use of anomaly width at half the amplitude (X1/2). This was used to carry out depth estimations over the study area. The results showed that it peaks over the magnetic structure with local maxima over its edges (boundaries or contact), and the amplitude is simply related to magnetization, likewise results also showed that the depth estimates were in the range of 1.2 to 5.9 km and were calculated for contact, dyke/sill and horizontal cylinder respectively. The lowest values are from DD profiles, while the highs are from AA profiles. This work is important in identifying dykes, contacts and intrusives over an area.

Highlights

High-resolution aeromagnetic data collected over the Gongola basin were analyzed for analytic signal depth using the Oasis Montaj TM programming software
Residual map of the region investigated was generated by polynomial fitting from where the analytic signal was obtained using the anomaly width at half the amplitude (X1/2), this was used to carry out depth estimations over the region investigated
The aim of this research was to analyze high resolution aeromagnetic data obtained over the Gongola Basin using the Oasis Montaj TM software, in order to get the total magnetic intensity map as well as the residual map from where the analytic signal was obtained using the anomaly

Summary

Introduction

High-resolution aeromagnetic data collected over the Gongola basin were analyzed for analytic signal depth using the Oasis Montaj TM programming software. Epuh et al (2011) researched on the basement depth estimation using second vertical derivative data as input anomaly profile in the Gongola Basin. Their findings showed depths of 5.2 km for the SE part and 7.0 km for the NE part. The aim of this research was to analyze high resolution aeromagnetic data obtained over the Gongola Basin using the Oasis Montaj TM software, in order to get the total magnetic intensity map as well as the residual map from where the analytic signal was obtained using the anomaly. The fast Fourier transforms technique was used in calculating the derivatives, for a 2-D magnetic contact at (x=0) and at depth (h) the analytic signal anomaly is described by the expression of Nabigian,

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Conclusion