Multiscale analysis of potential fields: reconstruction of magnetized complex basements

We demonstrate the effectiveness of the potential-field multiscale approach when used as a tool for analyzing and characterizing geological features such as magnetized complex basements. This approach allows estimations of the source structural index and depth by methods analyzing a 3D dataset obtained by upward continuation of the original data. These data can be analysed by: 1) a geometrical approach (Multiridge Geometric Method, Fedi et al., 2009), looking for the intersection, in the source domain, of the field ridges (i.e.: lines defined by the position of the extreme points of the field at different scales); 2) the numerical analysis of the values of the field along ridges through the scaling function method (Fedi and Florio, 2006, Fedi, 2007; Florio et al., 2009) or the Euler method (Florio and Fedi, 2014); the DEXP transformation of the field (Fedi, 2007). The mentioned methods enjoy a good stability and resolution due to the inherent properties of a smoothing-enhancing filter which is applied to the original data to obtain the 3D dataset. It was shown that, when properly tuned, this filter (including upward continuation and vertical differentiation) can effectively act as a band-pass filter, controlling the noise amplification as well as the interference. Our approach may be employed to effectively analyze different datasets of magnetized basements. As an example, for the Bishop complex basement model (Williams et al., 2005) the analysis of the field ridges of different nth-order derivatives lead to structural index estimates in agreement with the basement structure morphology and allowed a good reconstruction of the complex basement relief.