First subsurface characterization of periglacial areas in the Yendegaia National Park, Southern Tierra del Fuego Island, Chile

Remote high-latitude regions remain among the least explored on Earth, yet they hold crucial records of past and ongoing climate dynamics. The Tierra del Fuego archipelago, at the southern margin of the Andes, represents a key area to investigate the extent and characteristics of periglacial and potential permafrost conditions in the southern hemisphere. This study presents the first integrated geomorphological and geophysical analysis of periglacial environments in a remote sector of the Valdivieso Sierra, westards from Darwin Cordillera, in the Yendegaia National Park. Field observations identified diverse landforms—such as patterned ground, creeping slopes, cryogenic polygons, and hummocky thúfur -like structures—indicative of active periglacial processes. Complementary geophysical investigations conducted with Electrical Resistivity Tomography and Seismic Refraction Tomography revealed subsurface signatures consistent with partially frozen ground above 750 m asl. These results suggest the presence of mountain permafrost near its southernmost distributional limit in the Southern Cone and emphasize the importance of periglacial processes in shaping the regional landscape. The findings have broader implications for paleoclimate reconstruction, ecosystem dynamics, and infrastructure planning in the context of accelerating climate change. This work provides essential baseline data from previously unstudied areas and highlights the effectiveness of integrating geomorphological mapping with non-invasive geophysical techniques in data-scarce environments. • First integrated periglacial study in remote southern Tierra del Fuego Island • Active processes and frozen ground detected above ~750 m a.s.l. • Geophysical and petrophysical data suggest mountain permafrost presence • Provides baseline for future climate and environmental monitoring