Angular spectral analysis of aeromagnetic data over the middle Benue Trough, Nigeria

Abstract

Aeromagnetic field over an area is a sum of the total or inducing field and the remanent field produced by complex distributions of magnetization in the earth's crust. For proper interpretation of a magnetic data set or anomaly, it is imperative that both the external and remanent magnetization directions be known. Most interpretation tools assume that the induced magnetization in the ambient field direction is the only or primary component of the total magnetization and its direction is known. This can lead to erroneous interpretation as in many cases remanence can be present strongly as to affect the true magnetization direction. In this paper, the use of angular spectrum of magnetic data can assist in delineating angular features of both regional and local significance and so capable of removing such angular assumptions. Application of the angular spectral analysis on a synthetic example and a real data set from the Middle Benue Trough, Nigeria gives spectral peaks in the frequency bands that correspond to measured lineation. One of the major drawbacks in this method is that there may be some peaks in the angular spectrum that can be caused by other factors such as direction of polarization and the data window used in tapering.