Regional-residual separation and automatic interpretation of aeromatic data

Abstract

Two key areas in aeromagnetic interpretation are discussed. Firstly, the problem of separating geologically useful information from measurements which contain contributions due to instrument malfunction, regional trends and magnetic sources not of interest. Secondly, the rapid interpretation of aeromagnetic data by means of automatic computer analysis. The theory of spectral analysis is discussed as it has wide application in the processing and interpretation of aeromagnetic data. Spectral analysis is used in the separation and interpretation techniques dealt with in this study. Regional-residual separation of aeromagnetic data may be carried out by means of a linear transformation in the frequency domain. Mathematical filters are designed by an analysis of the frequency spectrum of the data. Different regional-residual filter functions are tested on data generated by a theoretical model. It is concluded that the matched filtering gives the best results. Examples of regional-residual separation of aeromagnetic data with these filters are presented. The theory of automatic interpretation by Werner deconvolution is derived from first principles. The method makes use of an equation for the magnetic anomaly due to a thin sheet derived by Werner (1953). The method scans aeromagnetic profiles and provides position1 depth and dip estimates for a thin sheet and edge model at each anomaly recognised. The program is tested on both theoretical and actual aeromagnetic data1 and is found to produce reliable results. The computer program is listed in Appendix A.