Topographic Controls on Channelized Meltwater in the Subglacial Environment

Realistic characterization of subglacial hydrology necessitates knowledge of the range in form, scale, and spatiotemporal evolution of drainage networks. A relict subglacial meltwater corridor on the deglaciated Antarctic continental shelf encompasses 80 convergent and divergent channels, many of which are hundreds of meters wide and several of which lack a definable headwater source. Without significant surface-melt contributions to the bed like similarly described landforms in the Northern Hemisphere, channelized drainage capacity varies non-systematically by three orders of magnitude downstream. This signifies apparent additions and losses of basal water to the bed-channelized system that relates to bed topography. Larger magnitude grounding-line retreat events occurred while the channel system was active than once channelized drainage had ceased. Overall, this corridor demonstrates that meltwater drainage styles co-exist in time and space in response to bed topography, with prolonged impacts on grounding-line behavior. Plain Language Summary Water drainage beneath glacial ice can impact flow of the overlying ice, sediment transport underneath the ice toward the glacier's terminus, and the stability of glacial ice as it transitions from resting on the geologic terrain to floating in the ocean. Despite being an important component of glacial systems, the full range of possible modes of water delivery and how these interact and vary across time and space is not well resolved. We describe a relict subglacial meltwater network preserved on the Antarctic seafloor, representing a persistent pathway for water drainage when the East Antarctic Ice Sheet was much larger. The landforms within the drainage network implicate substantial changes in how subglacial water drainage was influenced by the shape of the underlying terrain and demonstrate the prolonged impacts that meltwater corridors have on the retreat of glacial ice.

Automated summary

A study on a relict subglacial meltwater corridor on the Antarctic continental shelf reveals significant variations in drainage capacity due to basal water additions and losses related to bed topography. The channel system's behavior is influenced by the shape of the underlying terrain, with larger retreat events occurring while the system was active. This demonstrates the complex interactions between subglacial water drainage and bed topography, highlighting their prolonged impacts on grounding-line behavior.