A dynamic saline groundwater system mapped beneath an Antarctic ice stream

Area of Science:

• Geophysics
• Glaciology
• Hydrogeology

Background:

• Antarctica's ice streams are crucial for ice sheet drainage and are influenced by subglacial water.
• Existing knowledge of subglacial water systems is limited to shallow regions near the ice-bed interface.
• The potential role of deeper groundwater in modulating ice stream velocity remains largely unexplored.

Purpose of the Study:

• To investigate the presence and characteristics of deep groundwater beneath Antarctica's Whillans Ice Stream.
• To determine if deep groundwater reservoirs influence subglacial water systems and ice stream dynamics.

Main Methods:

• Utilized magnetotelluric and passive seismic geophysical techniques.
• Collected data from Whillans Ice Stream in West Antarctica.
• Analyzed data to image deep subsurface structures and identify groundwater presence.

Main Results:

• Provided the first direct observations of deep groundwater beneath an Antarctic ice stream.
• Identified a substantial groundwater volume within a >1-kilometer-thick sedimentary basin, exceeding known subglacial water systems by over an order of magnitude.
• Detected a vertical salinity gradient, suggesting interaction between ancient seawater and modern basal meltwater.

Conclusions:

• Deep groundwater systems represent a significant, previously unrecognized component of Antarctic subglacial hydrology.
• These deep systems likely play a critical role in regulating ice stream velocity and associated biogeochemical processes.
• Findings necessitate revised models of subglacial water flow and ice sheet dynamics.