GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.2 GNGTS 2024 Integrated GPR and FDEM to detect brines pockets in Contnental Antarctca I. Santn 1 , E. Forte 1 , M. Guglielmin 2 1 Department of Mathematcs, Informatcs and Geosciences (University of Trieste, Italy) 2 Department of Theoretcal and Applied Science (University of Insubria, Italy) Introducton The extreme environmental conditon of Antarctca and the presence of subcryospheric saline waters makes it one of the most relevant planetary analogues for Mars, especially since hypersaline brines were found on the red planet ( Martnez and Renno, 2013 ). As a consequence, the interest on Antarctc brines have increased, especially to determine the lifeforms in these environments and their adaptability to extreme environmental conditons. From the geophysical point of view, brines are peculiar materials whose characteristcs are strictly correlated with their salinity, density, temperature and pressure. Considering that, at liquid state, brines are hypersaline and therefore high-conductve solutons, electromagnetc (EM)-based methods, such as Ground Penetratng Radar (GPR) can be successfully exploited to detect and image brines pockets, although their EM signature on GPR data is not unequivocally defned ( Forte et al., 2020 ). However, recently also Frequency-Domain Electromagnetc (FDEM) inductve methods are increasing their applicatons to glaciology, even though their efectveness is not always fully demonstrated and, up to now, no applicatons to Antarctc brines detecton have been reported. We focus on Boulder Clay Glacier area (Victoria Land, East Antarctca), i.e. a coastal zone characterized by a glacier, its moraines and some perennially frozen lakes ( Guglielmin et al., 2009 ). The area is located about 6 km SW from the Italian Antarctc Staton (MZS in FIG.1A), close to the southern side of a gravel landing strip, built in 2019. Several boreholes have been dug both on the moraine, the glacier and some lakes, and at least three detected brines pockets have been sampled to study their prokaryotc ( Azzaro et al., 2021 ) and fungal ( Sannino et al., 2020 ) communites. In partcular, Lake n.16 is neighbour with a CALM permafrost grid (FIG.1B), which is part of the CALM program aiming at the observaton of the response of the actve layer to climate change over mult-decadal tme scales ( Guglielmin et al., 2009 ). Such a grid has been relocated in its actual positon in 2019 due to the landing strip building, and now it lies near a borehole discussed in Sannino et al., 2020 . In this work, startng from the borehole dug in 2014 in which a liquid brine pocket was discovered, we proposed an integrated geophysical approach to defne the EM signature of brine pockets, combining GPR and FDEM inducton surveys. The geophysical characterizaton of brines pockets allows to deepen the investgaton about the complex geomorphological setngs of the area, providing a more constrained methodology to optmize the