3D Euler Deconvolution Research Articles

Microlevelling procedures applied to regional aeromagnetic data: an example from the Transantarctic Mountains (Antarctica)

The extensive application of digital enhancement and filtering as a powerful tool for aeromagnetic interpretation, not only of high resolution but also of regional data, requires an improved levelling. Two microlevelling techniques were thus compared in order to find an effective but relatively simple procedure to remove, or at least to reduce, residual magnetic errors remaining after standard levelling processes. This study was carried out on regional aeromagnetic data recently acquired at high magnetic latitudes along the Transantarctic Mountains in Antarctica, where it is particularly critical to remove time‐dependent magnetic variations. Two‐dimensional FFT filters applied to the gridded data, namely the Butterworth and a directional cosine filter, proved to be more effective than previously proposed one‐dimensional space‐domain filters in the reduction of the ‘residual corrugation’ not removed by statistical levelling. Tectonic interpretation of trends detected in the total field magnetic anomaly map and in the 3D analytic signal improved after application of frequency‐domain microlevelling. However, we also show that when interpreting microlevelled data, two factors must be considered: (i) the possible presence of real geological trends aligned along the flight lines; (ii) modifications in the results yielded by depth estimates of magnetic sources due to the FFT filters applied during the microlevelling procedure. Such changes were seen both in the well‐established 2D FFT method, based on the slope of the energy spectrum, and in the more recent 3D Euler deconvolution technique. Overall our results indicate that microlevelling could profitably be applied to older gridded aeromagnetic data sets in Antarctica, thus improving the accuracy and geological significance of future regional magnetic compilations, as already seen in other continents.

Analytical Techniques in Interpretation of Regional Aeromagnetic Data

Regional aeromagnetic interpretation includes an important mapping component as well as location of possible economic targets. Given these varied requirements, objective interpretation techniques based on spectral analysis and application of specialised filters play a major role. Recent improvements in computer hardware, particularly microcomputers, have made it possible to analyse more data and it is now feasible to perform quantitative analysis on complete blocks of aeromagnetic data. Quantitative analysis may be applied to profile or grid data or both, depending on the interpretation objectives and the data quality. Results are presented for two analytical interpretation techniques, location of the maxima of the pseudo-gravity gradient and 3D Euler deconvolution. These results together with apparent susceptibility mapping provide objective information on geological boundaries, depths and lithologies.