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Bedrock erosion in subglacial channels.
Sergio Fagherazzi1, Luca Baticci1,2, Christine M Brandon1,3
1Department of Earth & Environment, Boston University, Boston, Massachusetts, United States of America.
Plos One
|September 9, 2021
Summary
Bedrock abrasion in Antarctic subglacial channels peaks at intermediate distances from the glacier snout. This finding explains concave-up channel profiles and constrictions, suggesting abrasion over glacial scour.
Area of Science:
- Geomorphology
- Glaciology
- Sedimentology
Background:
- The Labyrinth in Antarctica features large bedrock channels formed by subglacial processes.
- Understanding subglacial channel morphodynamics is crucial for interpreting glacial landscapes.
Purpose of the Study:
- To investigate the morphodynamics of bedrock abrasion in Antarctic subglacial channels.
- To determine the factors controlling bedrock erosion beneath glaciers.
Main Methods:
- Development of a numerical model for subglacial channel morphodynamics.
- Incorporation of classical subglacial channel theory and bedrock abrasion by saltating bed load.
- Simulation of pressurized subglacial flow and sediment transport dynamics.
Main Results:
- Bedrock abrasion intensity exhibits a non-monotonic relationship with distance from the glacier snout.
- Abrasion is maximized at intermediate distances due to optimal sediment mobilization and impact.
- Close to the snout, low velocities limit sediment transport; far from the snout, suspension transport reduces basal abrasion.
Conclusions:
- The model explains concave-up bottom profiles and cross-section constrictions observed in The Labyrinth's channels.
- These landforms are indicative of bedrock abrasion, not solely glacial scour.
- Subglacial channel evolution is governed by the interplay of transport rate, sediment load, and transport capacity.
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