Morphometry of bedrock meltwater channels on Antarctic inner continental shelves

• Published in: Geomorphology
• Main Authors: Kirkham, James D., Hogan, Kelly A., Larter, Robert D., Arnold, Neil S., Nitsche, Frank O., Kuhn, Gerhard, Gohl, Karsten, Anderson, John B., Dowdeswell, Julian A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2020
• Subjects: Antarctic; The Antarctic; Antarctic Peninsula; Amundsen Sea; Antarc*; Ice Sheet
• Online Access: http://nora.nerc.ac.uk/id/eprint/527820/; https://nora.nerc.ac.uk/id/eprint/527820/1/1-s2.0-S0169555X20303421-main.pdf; https://www.sciencedirect.com/science/article/pii/S0169555X20303421

Expanding multibeam bathymetric data coverage over the last two decades has revealed extensive networks of submarine channels incised into bedrock on the Antarctic inner continental shelf. The large dimensions and prevalence of the channels implies the presence of an active subglacial hydrological system beneath the past Antarctic Ice Sheet which we can use to learn more about inaccessible subglacial processes. Here, we map and analyse over 2700 bedrock channels situated across >100,000 km2 of continental shelf in the western Antarctic Peninsula and Amundsen Sea to produce the first inventory of submarine channels on the Antarctic inner continental shelf. Morphometric analysis reveals highly similar distributions of channel widths, depths, cross-sectional areas and geometric properties, with subtle differences between channels in the western Antarctic Peninsula compared to those in the Amundsen Sea. At 75–3400 m wide, 3–280 m deep, 160–290,000 m2 in cross-sectional area, and typically 8 times as wide as they are deep, the channels have similar morphologies to tunnel valleys and meltwater channel systems observed from other formerly glaciated landscapes despite differences in substrate geology and glaciological regime. We propose that the Antarctic bedrock channels formed over multiple glacial cycles through the episodic drainage of at least 59 former subglacial lakes identified on the inner continental shelf.