Amplitude of the magnetic anomaly vector for interpretation at low latitudes

We propose the use of the amplitude of the magnetic vector (B) for qualitative interpretation at low latitudes. The B is computed from transforming the total-field anomaly into the three orthogonal components in the x-, y-, and z-directions. The B generates a maximum over the source, allowing the definition of the horizontal projection of the source. We perform tests in synthetic data simulating a main geomagnetic field (main field) with vertical incidence and at low latitudes. The sources that give rise to the simulated anomalies have both induced and strong remanent magnetizations. The synthetic tests show that for defining the geologic sources’ horizontal projections the B performs better than the total gradient amplitude (TGA) of total-field anomaly. By comparing the maps of B and of the simulated gravity data, we show their good correlation, even for sources with negative density contrast. We applied both the B and the TGA to the real total-field anomaly from the Amazonian Craton, Brazil, and compared with Bouguer data. The result shows that the B can be a useful tool for qualitative interpretation at low latitudes and suggests studies to update the geologic knowledge.