The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica
An elevated erosional trimline in the heart of West Antarctica in the Ellsworth Mountains tells of thicker ice in the past and represents an important yet ambiguous stage in the evolution of the Antarctic Ice Sheet. Here we analyse the geomorphology of massifs in the southernmost Heritage Range wher...
Published in: | Earth and Planetary Science Letters |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Online Access: | https://nrl.northumbria.ac.uk/id/eprint/30529/ https://doi.org/10.1016/j.epsl.2017.04.006 https://nrl.northumbria.ac.uk/id/eprint/30529/8/million-year%20evolution.pdf https://nrl.northumbria.ac.uk/id/eprint/30529/1/jwoodward%20EPSL_14401%202017.pdf |
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ftunivnorthumb:oai:nrl.northumbria.ac.uk:30529 2023-05-15T13:56:54+02:00 The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica Sugden, David Hein, Andrew Woodward, John Marrero, Shasta Rodés, Ángel Dunning, Stuart Stuart, Finlay Freeman, Stewart Winter, Kate Westoby, Matt 2017-07-01 text https://nrl.northumbria.ac.uk/id/eprint/30529/ https://doi.org/10.1016/j.epsl.2017.04.006 https://nrl.northumbria.ac.uk/id/eprint/30529/8/million-year%20evolution.pdf https://nrl.northumbria.ac.uk/id/eprint/30529/1/jwoodward%20EPSL_14401%202017.pdf en eng Elsevier https://nrl.northumbria.ac.uk/id/eprint/30529/8/million-year%20evolution.pdf https://nrl.northumbria.ac.uk/id/eprint/30529/1/jwoodward%20EPSL_14401%202017.pdf Sugden, David, Hein, Andrew, Woodward, John, Marrero, Shasta, Rodés, Ángel, Dunning, Stuart, Stuart, Finlay, Freeman, Stewart, Winter, Kate and Westoby, Matt (2017) The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica. Earth and Planetary Science Letters, 469. pp. 42-52. ISSN 0012-821X cc_by_4_0 CC-BY F800 Physical and Terrestrial Geographical and Environmental Sciences Article PeerReviewed 2017 ftunivnorthumb https://doi.org/10.1016/j.epsl.2017.04.006 2022-09-25T06:05:32Z An elevated erosional trimline in the heart of West Antarctica in the Ellsworth Mountains tells of thicker ice in the past and represents an important yet ambiguous stage in the evolution of the Antarctic Ice Sheet. Here we analyse the geomorphology of massifs in the southernmost Heritage Range where the surfaces associated with the trimline are overlain by surficial deposits that have the potential to be dated through cosmogenic nuclide analysis. Analysis of 100 rock samples reveals that some clasts have been exposed on glacially moulded surfaces for 1.4 Ma and perhaps more than 3.5 Ma, while others reflect fluctuations in thickness during Quaternary glacial cycles. Modelling the age of the glacially moulded bedrock surface based on cosmogenic 10Be, 26Al and 21Ne concentrations from a depth-profile indicates a minimum exposure age of 2.1–2.6 Ma. We conclude that the glacially eroded surfaces adjacent to the trimline predate the Last Glacial Maximum and indeed the Quaternary. Since erosion was by warm-based ice near an ice-sheet upper margin, we suggest it first occurred during the early glaciations of Antarctica before the stepped cooling of the mid-Miocene at ∼14 Ma. This was a time when the interior Antarctic continent had summers warm enough for tundra vegetation to grow and for mountain glaciers to consist of ice at the pressure melting point. During these milder conditions, and subsequently, erosion of glacial troughs is likely to have lowered the ice-sheet surface in relation to the mountains. This means that the range of orbitally induced cyclic fluctuations in ice thickness have progressively been confined to lower elevations. Article in Journal/Newspaper Antarc* Antarctic Antarctica Ice Sheet Tundra West Antarctica Northumbria University, Newcastle: Northumbria Research Link (NRL) Antarctic Ellsworth Mountains ENVELOPE(-85.000,-85.000,-78.750,-78.750) Heritage Range ENVELOPE(-82.000,-82.000,-80.000,-80.000) The Antarctic West Antarctica Earth and Planetary Science Letters 469 42 52 |
institution |
Open Polar |
collection |
Northumbria University, Newcastle: Northumbria Research Link (NRL) |
op_collection_id |
ftunivnorthumb |
language |
English |
topic |
F800 Physical and Terrestrial Geographical and Environmental Sciences |
spellingShingle |
F800 Physical and Terrestrial Geographical and Environmental Sciences Sugden, David Hein, Andrew Woodward, John Marrero, Shasta Rodés, Ángel Dunning, Stuart Stuart, Finlay Freeman, Stewart Winter, Kate Westoby, Matt The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica |
topic_facet |
F800 Physical and Terrestrial Geographical and Environmental Sciences |
description |
An elevated erosional trimline in the heart of West Antarctica in the Ellsworth Mountains tells of thicker ice in the past and represents an important yet ambiguous stage in the evolution of the Antarctic Ice Sheet. Here we analyse the geomorphology of massifs in the southernmost Heritage Range where the surfaces associated with the trimline are overlain by surficial deposits that have the potential to be dated through cosmogenic nuclide analysis. Analysis of 100 rock samples reveals that some clasts have been exposed on glacially moulded surfaces for 1.4 Ma and perhaps more than 3.5 Ma, while others reflect fluctuations in thickness during Quaternary glacial cycles. Modelling the age of the glacially moulded bedrock surface based on cosmogenic 10Be, 26Al and 21Ne concentrations from a depth-profile indicates a minimum exposure age of 2.1–2.6 Ma. We conclude that the glacially eroded surfaces adjacent to the trimline predate the Last Glacial Maximum and indeed the Quaternary. Since erosion was by warm-based ice near an ice-sheet upper margin, we suggest it first occurred during the early glaciations of Antarctica before the stepped cooling of the mid-Miocene at ∼14 Ma. This was a time when the interior Antarctic continent had summers warm enough for tundra vegetation to grow and for mountain glaciers to consist of ice at the pressure melting point. During these milder conditions, and subsequently, erosion of glacial troughs is likely to have lowered the ice-sheet surface in relation to the mountains. This means that the range of orbitally induced cyclic fluctuations in ice thickness have progressively been confined to lower elevations. |
format |
Article in Journal/Newspaper |
author |
Sugden, David Hein, Andrew Woodward, John Marrero, Shasta Rodés, Ángel Dunning, Stuart Stuart, Finlay Freeman, Stewart Winter, Kate Westoby, Matt |
author_facet |
Sugden, David Hein, Andrew Woodward, John Marrero, Shasta Rodés, Ángel Dunning, Stuart Stuart, Finlay Freeman, Stewart Winter, Kate Westoby, Matt |
author_sort |
Sugden, David |
title |
The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica |
title_short |
The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica |
title_full |
The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica |
title_fullStr |
The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica |
title_full_unstemmed |
The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica |
title_sort |
million-year evolution of the glacial trimline in the southernmost ellsworth mountains, antarctica |
publisher |
Elsevier |
publishDate |
2017 |
url |
https://nrl.northumbria.ac.uk/id/eprint/30529/ https://doi.org/10.1016/j.epsl.2017.04.006 https://nrl.northumbria.ac.uk/id/eprint/30529/8/million-year%20evolution.pdf https://nrl.northumbria.ac.uk/id/eprint/30529/1/jwoodward%20EPSL_14401%202017.pdf |
long_lat |
ENVELOPE(-85.000,-85.000,-78.750,-78.750) ENVELOPE(-82.000,-82.000,-80.000,-80.000) |
geographic |
Antarctic Ellsworth Mountains Heritage Range The Antarctic West Antarctica |
geographic_facet |
Antarctic Ellsworth Mountains Heritage Range The Antarctic West Antarctica |
genre |
Antarc* Antarctic Antarctica Ice Sheet Tundra West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Tundra West Antarctica |
op_relation |
https://nrl.northumbria.ac.uk/id/eprint/30529/8/million-year%20evolution.pdf https://nrl.northumbria.ac.uk/id/eprint/30529/1/jwoodward%20EPSL_14401%202017.pdf Sugden, David, Hein, Andrew, Woodward, John, Marrero, Shasta, Rodés, Ángel, Dunning, Stuart, Stuart, Finlay, Freeman, Stewart, Winter, Kate and Westoby, Matt (2017) The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica. Earth and Planetary Science Letters, 469. pp. 42-52. ISSN 0012-821X |
op_rights |
cc_by_4_0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1016/j.epsl.2017.04.006 |
container_title |
Earth and Planetary Science Letters |
container_volume |
469 |
container_start_page |
42 |
op_container_end_page |
52 |
_version_ |
1766264488156200960 |