GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.2 GNGTS 2024 suggestng fuids upwelling, while the phase-related atribute makes more evident the interrupton of the contnuity of all horizons across the highly atenuated facies. It is remarkable to point that the GPR signature and response to the atributes analysis we performed on the GPR profles of CALM grid, fnd a match with the outcomes described in Forte et al., 2016 for other Antarctc coastal lakes. As a mater of fact, the accuracy of the match in terms of spectral behaviour and EM facies further validate the applicability of GPR as a low-tme consuming method to identfy hidden brines pockets. However, it is essental to point out that in some cases the signal is so atenuated that prevents the applicaton of atributes analysis. Such situaton occurs for instance on the GPR profles of Lake n.16 where atributes analysis gave no remarkable results. Therefore, the integraton of FDEM and GPR, allows to be more accurate and favourable about the presence of buried brines pockets. Fig. 3 – Exemplary GPR profles on Lake n.16 (A, B) and on CALM grid (C, C’, C’’), both represented with white lines. C’ and C’’ display dominant frequency and chaos atributes, respectvely, of profle C. Yellow dot marks the crossing point between A and B. Locaton of each GPR profle is highlighted by a coloured line: C, C’, C’’ with a blue line, while A and B with pink and magenta lines, respectvely. Pink triangle marks the locaton of BC1. Conclusion We proposed a detailed analysis of the geophysical signature of Antarctc brines pockets, validated through boreholes. The integraton of FDEM and GPR surveys allowed to characterize brines pockets in terms of high electrical conductvity and a peculiar EM facies, respectvely. The high conductvity (up to more than 12 mS/m in the investgated area) related to the brines strongly afects the propagaton of the EM wave generatng an atenuated EM facies which is characterized, in additon to the low refectvity, by a spectral shif to lower frequencies, horizons contnuity