Permafrost Hydrogeology of Taylor Valley, Antarctica: Insights From Deep Electrical Resistivity Tomography.

Global warming has prompted globally widespread permafrost thawing, resulting in enhanced greenhouse gas release into the atmosphere. Studies conducted in the Northern Hemisphere reveal an alarming increase in permafrost thawing. However, similar data from Antarctica are scarce. We conducted a 2‐D Deep Electrical Resistivity Tomography (DERT) survey in Taylor Valley, Antarctica, to image the distribution of permafrost, its thicknesses, lower boundaries, and hydrogeology. Results show resistive, discontinuous domains that we suggest represent permafrost units. We also find highly conductive layers (5–10 Ω·m), between 300–350 m and 600–650 m below ground level and a shallower (∼50–100 m depth) conductive layer. The combined data set reveals a broad brine system in Taylor Valley, implying multi‐tiered groundwater circulation: a shallow, localized system linked with surface water bodies and a separate deeper, regional circulation system. The arrangement of these brines across different levels, coupled with the uneven permafrost distribution, underscores potential interplay between the two systems. Plain Language Summary: Permafrost (perennially frozen ground) and its increasing thaw is a key indicator of climate change. The gradual increase of global temperature accelerates permafrost thawing at high latitudes, resulting in enhanced carbon release into the atmosphere, ultimately exacerbating global warming. During the austral summer of 2020, we conducted an electrical resistivity survey in Taylor Valley, McMurdo Dry Valleys, Antarctica, to map the thickness of permafrost, determine its lower boundaries and identify the presence and connectivity of saline groundwater at depth. The ice‐free Dry Valleys are the only place in Antarctica where it is possible to study the permafrost directly. Results show a complex distribution of permafrost, with layers of saline groundwater at different levels. We recognized two distinct zones: one of low resistivity around Lake Fryxell, related to the presence of two systems of brines at different depths, and the other displaying typical ice‐rich frozen ground resistivity values near Coral Ridge. These findings reveal variations in permafrost thickness and brine depth along the valley, both horizontally and vertically. Our research identifies a multi‐level groundwater circulation system: a shallow, local network, connected to surface water bodies like Lake Fryxell, above a deeper, regional system. Key Points: Resistivity data show a complex hydrogeological scenario, with uneven permafrost distribution and different levels of brinesResults show a multi‐tiered system of groundwater circulation of brines: a shallow system connected to the surface and a deeper regional systemObservations are consistent with a model of upwelling of over pressured deep brines enhancing permafrost thawing from beneath [ABSTRACT FROM AUTHOR]