Bedrock erosion in subglacial channels.

The Labyrinth in the McMurdo Dry Valleys of Antarctica is characterized by large bedrock channels emerging from beneath the margin of Wright Upper Glacier. To study the morphodynamics of large subglacial channels cut into bedrock, we develop herein a numerical model based on the classical theory of...

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Autores principales:	Sergio Fagherazzi, Luca Baticci, Christine M Brandon, Maria Cristina Rulli
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/3943a16281754af7aee6c8a99a1c649e
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spelling	oai:doaj.org-article:3943a16281754af7aee6c8a99a1c649e2021-12-02T20:08:25ZBedrock erosion in subglacial channels.1932-620310.1371/journal.pone.0253768https://doaj.org/article/3943a16281754af7aee6c8a99a1c649e2021-01-01T00:00:00Zhttps://doi.org/10.1371/journal.pone.0253768https://doaj.org/toc/1932-6203The Labyrinth in the McMurdo Dry Valleys of Antarctica is characterized by large bedrock channels emerging from beneath the margin of Wright Upper Glacier. To study the morphodynamics of large subglacial channels cut into bedrock, we develop herein a numerical model based on the classical theory of subglacial channels and recent results on bedrock abrasion by saltating bed load. Model results show that bedrock abrasion in subglacial channels with pressurized flow reaches a maximum at an intermediate distance up-ice from the glacier snout for a wide range of sediment grain sizes and sediment loads. Close to the snout, the velocity is too low and the sediment particles cannot be mobilized. Far from the snout, the flow accelerates and sediment is transported in suspension, thus limiting particle impacts at the channel bottom and reducing abrasion. This non-monotonic relationship between subglacial flow and bedrock abrasion produces concave up bottom profiles in subglacial channels and potential cross-section constrictions after channel confluences. Both landforms are present in the bedrock channels of the Labyrinth. We therefore conclude that these geomorphic features are a possible signature of bedrock abrasion, rather than glacial scour, and reflect the complex interplay between transport rate, sediment load, and transport capacity in subglacial channels.Sergio FagherazziLuca BaticciChristine M BrandonMaria Cristina RulliPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 16, Iss 9, p e0253768 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Sergio Fagherazzi Luca Baticci Christine M Brandon Maria Cristina Rulli Bedrock erosion in subglacial channels.
description	The Labyrinth in the McMurdo Dry Valleys of Antarctica is characterized by large bedrock channels emerging from beneath the margin of Wright Upper Glacier. To study the morphodynamics of large subglacial channels cut into bedrock, we develop herein a numerical model based on the classical theory of subglacial channels and recent results on bedrock abrasion by saltating bed load. Model results show that bedrock abrasion in subglacial channels with pressurized flow reaches a maximum at an intermediate distance up-ice from the glacier snout for a wide range of sediment grain sizes and sediment loads. Close to the snout, the velocity is too low and the sediment particles cannot be mobilized. Far from the snout, the flow accelerates and sediment is transported in suspension, thus limiting particle impacts at the channel bottom and reducing abrasion. This non-monotonic relationship between subglacial flow and bedrock abrasion produces concave up bottom profiles in subglacial channels and potential cross-section constrictions after channel confluences. Both landforms are present in the bedrock channels of the Labyrinth. We therefore conclude that these geomorphic features are a possible signature of bedrock abrasion, rather than glacial scour, and reflect the complex interplay between transport rate, sediment load, and transport capacity in subglacial channels.
format	article
author	Sergio Fagherazzi Luca Baticci Christine M Brandon Maria Cristina Rulli
author_facet	Sergio Fagherazzi Luca Baticci Christine M Brandon Maria Cristina Rulli
author_sort	Sergio Fagherazzi
title	Bedrock erosion in subglacial channels.
title_short	Bedrock erosion in subglacial channels.
title_full	Bedrock erosion in subglacial channels.
title_fullStr	Bedrock erosion in subglacial channels.
title_full_unstemmed	Bedrock erosion in subglacial channels.
title_sort	bedrock erosion in subglacial channels.
publisher	Public Library of Science (PLoS)
publishDate	2021
url	https://doaj.org/article/3943a16281754af7aee6c8a99a1c649e
work_keys_str_mv	AT sergiofagherazzi bedrockerosioninsubglacialchannels AT lucabaticci bedrockerosioninsubglacialchannels AT christinembrandon bedrockerosioninsubglacialchannels AT mariacristinarulli bedrockerosioninsubglacialchannels
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Bedrock erosion in subglacial channels.

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