GNGTS 2016 - Atti del 35° Convegno Nazionale

508 GNGTS 2016 S essione 3.1 method. The homogeneity degree we found ranges between -3.3 and -3.5. So, considering k =3 because of the 3 rd order derivative, the respective average structural index is 0.4, value typical for finite fault or sill structures. These kinds of idealized models can be approximately adopted for explaining the most complex features of the morphology of an interface or a basement (for instance, Li, 2005). The results of the structural index evaluation, then, were used to employ the DEXP method in order to represent the source distribution beneath the magnetic anomaly (Fig. 3C). The DEXP representation has good correspondence with the geometric method results. In particular, we observe clearly a progressive uplift of the source distribution toward NE as retrieved in the Multiridge section. The results obtained by scaling function and DEXPmethods provided interesting information about the nature and the distribution of sources with depth. By this, we can fill the singular points obtained from the Multiridge analysis in order to reconstruct the trend of the magnetic basement beneath the Adriatic anomaly allowing a lateral extension of previous interpretative models, obtained with no data available onshore and, partly, offshore Croatia (Fig. 3D). These results, so, allowed confirming the interpretation of the main source generating the wide Adriatic magnetic anomaly by using very fast and stable methods with a multiscale approach. The uplift of the magnetic basement appears as the most important contribution to the magnetic anomaly field at several altitudes and could be considered as the effect of a complex geodynamic setting of the area, characterized mainly of graben and horsts formed during the evolution of the Apennines–Adriatic–Dinarides system. Conclusions. We presented a newmodel of the main magnetic source generating theAdriatic magnetic anomaly using the Multiridge and DEXP methods. A multiscale dataset was built by upward continuing the high-resolution grid of the total magnetic field up to 20 km altitude. We employed the multiridge method along a profile and used a geometric approach to obtain the depth of the deep sources by considering the high-altitude portion of the ridges. The singular points retrieved from profileAA’were compared with previous magnetic model showing a good agreement of the depth of the basement top. The source parameters were evaluated by using the scaling function method which provided the structural index values needed to employ the DEXP method. The structural index evaluated is typical of finite fault or sill structures suitable to interpret the shape of a basement or a magnetic interface. The DEXP method was applied to the Multiridge profile and the results are fairly well coincident to the depth carried out by the geometric approach. By fitting the depth solution of the Multiridge section we modeled the trend of the basement beneath the Adriatic magnetic anomaly confirming that the uplift of such magnetic structure is to be assigned as the main source contribution to the magnetic anomaly field up to high altitude. References Battaglia, M., Murray M. H., Serpelloni E., and R. Burgmann, (2004). TheAdriatic region: An independent microplate within the AfricaEurasia collision zone, Geophys. Res. Lett., 31, L09605, doi:10.1029/2004GL019723. Bertotti G, Picotti V, Cloetingh S, (1998). Lithospheric weakening during ‘‘retro-foreland’’ basin formation:tectonic evolution of the central South Alpine foredeep. Tectonics 17(1):131–142 Carminati E, Doglioni C, Scrocca D, (2003). ��������� ������������������ ���������� �� ������� ������� ��� ���� Apennines subduction-related subsidence of Venice. ������� ��� ���� Geophys Res Lett 30. doi:10.1029/2003GL017001 Cuffaro M., Riguzzi F., Scrocca D., Antonioli F., Carminati E., Livani M., Doglioni C., (2010). �� ��� ����������� �� On the geodynamics of the northern Adriatic plate. Rend. Fis. Acc. Lincei, 21 (Suppl 1): S253–S279 DOI 10.1007/s12210-010-0098-9. Di Stefano R, Kissling E, Chiarabba C, Amato A, Giardini D (2009). ������� ���������� ������� ������ ������ Shallow subduction beneath Italy: Three- dimensional images of the Adriatic–European–Tyrrhenian lithosphere system based on highquality P wave arrival times. J Geophys Res 114. doi:10.1029/2008JB005641 Fedi, M. (2007). DEXP: A fast method to determine the depth and the structural index of potential fields sources, Geophysics, 72(1), I1–I11, doi:10.1190/1.2399452. Fedi, M., Florio G., and T. Quarta (2009), Multiridge analysis of potential fields: Geometrical method and reduced Euler deconvolution, Geophysics, 74(4), L53–L65.