Multiscale derivative analysis of the gravity and magnetic fields of Southern Apennines (italy)

A multiscale analysis of the gravity and magnetic fields of the Southern Apennines (Italy) is performed. The method, called Multiscale Derivative Analysis (MDA), is based on the good resolution properties of the Enhanced Horizontal Derivative (EHD) and allows the potential field to be explored at different scales. The task of separating the different scale-related effects is traditionally accomplished by classical filtering methods, based on Fourier or wavelet expansion, but some distortion is likely to occur. MDA, instead, does not apply sharp component separations, but simply enhances the contributions at different resolution which are really present in the field. From a morphological point of view, Southern Italy is characterized by the presence of a main structural element represented by the southern sector of the Apennine chain. This consists in a thrust and fold belt system primarily, with a rather complex geological structure, and represents the geodynamic evolution, developed from Lower Cretaceous up to the Quaternary, resulting from the convergence between the African and European plates. MDA was performed at three resolutions to highlight regional, intermediate and local trends, for interpreting the gravity and aeromagnetic fields in the area of the Apennine belt and surrounding regions, just in terms of geological structures. MDA of gravity data provided an almost complete representation of the structural framework of Southern Italy at three different scales. Most of the known geological elements of the Apennine system are clearly shown at intermediate and short scales, together with several trends indicating structures that do not have any reference at the surface. This is, for instance, the case of some regional linear trends in the foredeep area, which in some cases may be related to hidden thrust systems at depth. MDA of magnetic data allowed localization of several linear and closed trends, identifying anomaly sources the presence of which was not previously detected, even by MDA of gravity data. In addition, interpretation of some magnetic structures may support the hypothesis that within the sedimentary cover of the Apulian foreland, at a first sight considered as relatively non-magnetic, several sources of detectable magnetization are present.