Quality assurance of aeromagnetic data using lineament analysis

Lineament analysis is typically applied to geoscientific data to identify lithological contacts, faults, fractures and dyke swarms. We implement lineament analysis as a method for quantifying the adequacy of pre-processing of airborne magnetic datasets. This is accomplished through the identification of noise due to inappropriate levelling. Lineament analysis involves the extraction of linear features from a dataset using visual and/or automatic interpretation techniques and the statistical and directional analyses of these extracted lineaments. We apply lineament analysis to a levelled high resolution aeromagnetic dataset from the Northwest Territories, Canada, to assess the levelling quality. A priori knowledge will include geology defining regional tectonic trends such as fault systems and dyke swarms. Analysis of a lineament’s azimuth separates assumed geologic sources and noise associated with data acquisition or processing artefacts. The lineament azimuths are assessed as rose diagrams. This is an alternative method to standard computation of 2D radially averaged power spectrums in the frequency domain and sunshading orthogonal to flight path. The rose diagrams are compared with the 2D power spectrums which both provide quantitative directional information; however, the power spectrum provides spectral frequency content and rose diagrams provide frequency of occurrence. Calculation of the number of lineaments along a particular azimuth before and after pre-processing quantifies the degree to which flight-line variations have been suppressed and geological signal more apparent.