Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica
Abstract Mount Achernar moraine is a terrestrial sediment archive that preserves a record of ice-sheet dynamics and climate over multiple glacial cycles. Similar records exist in other blue ice moraines elsewhere on the continent, but an understanding of how these moraines form is limited. We propos...
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crcambridgeupr:10.1017/jog.2019.83 2024-06-23T07:47:49+00:00 Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica Kassab, Christine M. Licht, Kathy J. Petersson, Rickard Lindbäck, Katrin Graly, Joseph A. Kaplan, Michael R. 2019 http://dx.doi.org/10.1017/jog.2019.83 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143019000832 en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by/4.0/ Journal of Glaciology volume 66, issue 255, page 49-60 ISSN 0022-1430 1727-5652 journal-article 2019 crcambridgeupr https://doi.org/10.1017/jog.2019.83 2024-06-05T04:04:07Z Abstract Mount Achernar moraine is a terrestrial sediment archive that preserves a record of ice-sheet dynamics and climate over multiple glacial cycles. Similar records exist in other blue ice moraines elsewhere on the continent, but an understanding of how these moraines form is limited. We propose a model to explain the formation of extensive, coherent blue ice moraine sequences based on the integration of ground-penetrating radar (GPR) data with ice velocity and surface exposure ages. GPR transects (100 and 25 MHz) both perpendicular and parallel to moraine ridges at Mount Achernar reveal an internal structure defined by alternating relatively clean ice and steeply dipping debris bands extending to depth, and where visible, to the underlying bedrock surface. Sediment is carried to the surface from depth along these debris bands, and sublimates out of the ice, accumulating over time (>300 ka). The internal pattern of dipping reflectors, combined with increasing surface exposure ages, suggest sequential exposure of the sediment where ice and debris accretes laterally to form the moraine. Subsurface structure varies across the moraine and can be linked to changes in basal entrainment conditions. We speculate that higher concentrations of debris may have been entrained in the ice during colder glacial periods or entrained more proximal to the moraine sequence. Article in Journal/Newspaper Antarc* Antarctica Ice Sheet Journal of Glaciology Cambridge University Press Achernar ENVELOPE(160.933,160.933,-84.200,-84.200) Mount Achernar ENVELOPE(160.933,160.933,-84.200,-84.200) Transantarctic Mountains Journal of Glaciology 66 255 49 60 |
institution |
Open Polar |
collection |
Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract Mount Achernar moraine is a terrestrial sediment archive that preserves a record of ice-sheet dynamics and climate over multiple glacial cycles. Similar records exist in other blue ice moraines elsewhere on the continent, but an understanding of how these moraines form is limited. We propose a model to explain the formation of extensive, coherent blue ice moraine sequences based on the integration of ground-penetrating radar (GPR) data with ice velocity and surface exposure ages. GPR transects (100 and 25 MHz) both perpendicular and parallel to moraine ridges at Mount Achernar reveal an internal structure defined by alternating relatively clean ice and steeply dipping debris bands extending to depth, and where visible, to the underlying bedrock surface. Sediment is carried to the surface from depth along these debris bands, and sublimates out of the ice, accumulating over time (>300 ka). The internal pattern of dipping reflectors, combined with increasing surface exposure ages, suggest sequential exposure of the sediment where ice and debris accretes laterally to form the moraine. Subsurface structure varies across the moraine and can be linked to changes in basal entrainment conditions. We speculate that higher concentrations of debris may have been entrained in the ice during colder glacial periods or entrained more proximal to the moraine sequence. |
format |
Article in Journal/Newspaper |
author |
Kassab, Christine M. Licht, Kathy J. Petersson, Rickard Lindbäck, Katrin Graly, Joseph A. Kaplan, Michael R. |
spellingShingle |
Kassab, Christine M. Licht, Kathy J. Petersson, Rickard Lindbäck, Katrin Graly, Joseph A. Kaplan, Michael R. Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica |
author_facet |
Kassab, Christine M. Licht, Kathy J. Petersson, Rickard Lindbäck, Katrin Graly, Joseph A. Kaplan, Michael R. |
author_sort |
Kassab, Christine M. |
title |
Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica |
title_short |
Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica |
title_full |
Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica |
title_fullStr |
Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica |
title_full_unstemmed |
Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica |
title_sort |
formation and evolution of an extensive blue ice moraine in central transantarctic mountains, antarctica |
publisher |
Cambridge University Press (CUP) |
publishDate |
2019 |
url |
http://dx.doi.org/10.1017/jog.2019.83 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143019000832 |
long_lat |
ENVELOPE(160.933,160.933,-84.200,-84.200) ENVELOPE(160.933,160.933,-84.200,-84.200) |
geographic |
Achernar Mount Achernar Transantarctic Mountains |
geographic_facet |
Achernar Mount Achernar Transantarctic Mountains |
genre |
Antarc* Antarctica Ice Sheet Journal of Glaciology |
genre_facet |
Antarc* Antarctica Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 66, issue 255, page 49-60 ISSN 0022-1430 1727-5652 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1017/jog.2019.83 |
container_title |
Journal of Glaciology |
container_volume |
66 |
container_issue |
255 |
container_start_page |
49 |
op_container_end_page |
60 |
_version_ |
1802637999766241280 |