Interpolation of the subsurface structural pattern of the icy satellites through multiscale comparison with terrestrial analogues

The surfaces of the icy satellites in the outer Solar System show landforms and features that testify an intense geologic activity. Kilometric-scale tectonic structures shape the majority of their icy crusts showing complex patterns that mostly refer to extensional and strike-slip regimes. Such stress-related structures (i.e., fractures/faults) represent weakness zones that provides insights to the dynamics and the mechanical properties of the crusts. Additionally, these structures are potential conduits for fluid propagation within the icy crusts that can connect the surface with the sub-crustal layers, including the internal liquid ocean. Therefore, tectonic structures of the icy satellites are pivotal for the understanding of both internal processes and also for astrobiology research. In view of upcoming missions, such as JUICE and Europa Clipper, the knowledge about such icy bodies requires support to better understand their geology and tectonics, whose investigations are constrained to regional-scale remote sensing detection.

The contribute of terrestrial analogues has always represented a strong aid to unravel planetary surfaces issues. On Earth, glaciers and ice sheets are optimal analogues, since they show deformation styles similar to the shear zones in the icy satellite surfaces. Although the formation processes differ, the similarity of their structures allows to unravel and predict the state of deformation in icy satellites at different scales. Moreover, the comparison with glacier deformation allows to better understand the local-scale environment and target areas for future exploration.

In this contribution we propose a multiscale analysis in four glaciers in the Argentinean Southern Patagonia Ice Field. Deformation structures of glaciers in the Tierra del Fuego province, named Martial, Vinciguerra, Ojo del Albino and Alvear gl., have been detected at both local- and regional-scale, through fieldwork and remote sensing investigation, respectively. The investigations allowed to achieve two datasets of the structures attribute measurements (i.e., azimuth, dip, length, spacing, width and sinuosity). Therefore, the datasets have been compared to acquire knowledge that has been then transferred to the surfaces of the icy satellites.

The data have been stored on GIS and Digital Outcrop Modeling tool to better unravel the structural settings and their relation at both surface and subsurface, in the third dimension. In this way, we produced 3D models that show the glacier structures development from the surface to the subsurface and have been used to infer models of the deep structural setting of shear zones in the icy satellites. Such models show the occurrence and development of deep low-angle structures, including the compressional ones, which are challenging to detect on icy satellite surfaces by remote sensing investigation.

Therefore, this work attempts i) to identify scaling laws between deformation structures measured at local-scale in the glacier outcrops and those mapped at regional-scale on satellite images; ii) to relate and compare such scaling laws with structures of shear zones of the icy satellites and in turn iii) to infer their local and deep structural setting.

Acknowledgments: This work is part of the EVIDENCE project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 871149. The activity has been realized under the ASI-INAF contract 2023-6-HH.0. We gratefully acknowledge funding from INAF through the Mini Grant DISCOVERIES.