Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica
We collected a debris-rich ice core from a buried ice mass in Ong Valley, located in the Transantarctic Mountains in Antarctica. We measured cosmogenic nuclide concentrations in quartz obtained from the ice core to determine the age of the buried ice mass and infer the processes responsible for the...
Published in: | The Cryosphere |
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Copernicus Publications
2022
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fttriple:oai:gotriple.eu:oai:doaj.org/article:bcd92eb9a5914900a5d23f5dc7f837d4 2023-05-15T13:53:01+02:00 Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica M. Bergelin J. Putkonen G. Balco D. Morgan L. B. Corbett P. R. Bierman 2022-07-01 https://doi.org/10.5194/tc-16-2793-2022 https://tc.copernicus.org/articles/16/2793/2022/tc-16-2793-2022.pdf https://doaj.org/article/bcd92eb9a5914900a5d23f5dc7f837d4 en eng Copernicus Publications doi:10.5194/tc-16-2793-2022 1994-0416 1994-0424 https://tc.copernicus.org/articles/16/2793/2022/tc-16-2793-2022.pdf https://doaj.org/article/bcd92eb9a5914900a5d23f5dc7f837d4 undefined The Cryosphere, Vol 16, Pp 2793-2817 (2022) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2022 fttriple https://doi.org/10.5194/tc-16-2793-2022 2023-01-22T19:11:31Z We collected a debris-rich ice core from a buried ice mass in Ong Valley, located in the Transantarctic Mountains in Antarctica. We measured cosmogenic nuclide concentrations in quartz obtained from the ice core to determine the age of the buried ice mass and infer the processes responsible for the emplacement of the debris currently overlaying the ice. Such ice masses are valuable archives of paleoclimate proxies; however, the preservation of ice beyond 800 kyr is rare, and therefore much effort has been recently focused on finding ice that is older than 1 Myr. In Ong Valley, the large, buried ice mass has been previously dated at > 1.1 Ma. Here we provide a forward model that predicts the accumulation of the cosmic-ray-produced nuclides 10Be, 21Ne, and 26Al in quartz in the englacial and supraglacial debris and compare the model predictions to measured nuclide concentrations in order to further constrain the age. Large downcore variation in measured cosmogenic nuclide concentrations suggests that the englacial debris is sourced both from subglacially derived material and recycled paleo-surface debris that has experienced surface exposure prior to entrainment. We find that the upper section of the ice core is 2.95 + 0.18 / −0.22 Myr old. The average ice sublimation rate during this time period is 22.86 + 0.10 / −0.09 m Myr−1, and the surface erosion rate of the debris is 0.206 + 0.013 / −0.017 m Myr−1. Burial dating of the recycled paleo-surface debris suggests that the lower section of the ice core belongs to a separate, older ice mass which we estimate to be 4.3–5.1 Myr old. The ages of these two stacked, separate ice masses can be directly related to glacial advances of the Antarctic ice sheet and potentially coincide with two major global glaciations during the early and late Pliocene epoch when global temperatures and CO2 were higher than present. These ancient ice masses represent new opportunities for gathering ancient climate information. Article in Journal/Newspaper Antarc* Antarctic Antarctica ice core Ice Sheet The Cryosphere Unknown Antarctic Ong Valley ENVELOPE(157.617,157.617,-83.233,-83.233) The Antarctic Transantarctic Mountains The Cryosphere 16 7 2793 2817 |
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Open Polar |
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fttriple |
language |
English |
topic |
geo envir |
spellingShingle |
geo envir M. Bergelin J. Putkonen G. Balco D. Morgan L. B. Corbett P. R. Bierman Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica |
topic_facet |
geo envir |
description |
We collected a debris-rich ice core from a buried ice mass in Ong Valley, located in the Transantarctic Mountains in Antarctica. We measured cosmogenic nuclide concentrations in quartz obtained from the ice core to determine the age of the buried ice mass and infer the processes responsible for the emplacement of the debris currently overlaying the ice. Such ice masses are valuable archives of paleoclimate proxies; however, the preservation of ice beyond 800 kyr is rare, and therefore much effort has been recently focused on finding ice that is older than 1 Myr. In Ong Valley, the large, buried ice mass has been previously dated at > 1.1 Ma. Here we provide a forward model that predicts the accumulation of the cosmic-ray-produced nuclides 10Be, 21Ne, and 26Al in quartz in the englacial and supraglacial debris and compare the model predictions to measured nuclide concentrations in order to further constrain the age. Large downcore variation in measured cosmogenic nuclide concentrations suggests that the englacial debris is sourced both from subglacially derived material and recycled paleo-surface debris that has experienced surface exposure prior to entrainment. We find that the upper section of the ice core is 2.95 + 0.18 / −0.22 Myr old. The average ice sublimation rate during this time period is 22.86 + 0.10 / −0.09 m Myr−1, and the surface erosion rate of the debris is 0.206 + 0.013 / −0.017 m Myr−1. Burial dating of the recycled paleo-surface debris suggests that the lower section of the ice core belongs to a separate, older ice mass which we estimate to be 4.3–5.1 Myr old. The ages of these two stacked, separate ice masses can be directly related to glacial advances of the Antarctic ice sheet and potentially coincide with two major global glaciations during the early and late Pliocene epoch when global temperatures and CO2 were higher than present. These ancient ice masses represent new opportunities for gathering ancient climate information. |
format |
Article in Journal/Newspaper |
author |
M. Bergelin J. Putkonen G. Balco D. Morgan L. B. Corbett P. R. Bierman |
author_facet |
M. Bergelin J. Putkonen G. Balco D. Morgan L. B. Corbett P. R. Bierman |
author_sort |
M. Bergelin |
title |
Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica |
title_short |
Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica |
title_full |
Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica |
title_fullStr |
Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica |
title_full_unstemmed |
Cosmogenic nuclide dating of two stacked ice masses: Ong Valley, Antarctica |
title_sort |
cosmogenic nuclide dating of two stacked ice masses: ong valley, antarctica |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-2793-2022 https://tc.copernicus.org/articles/16/2793/2022/tc-16-2793-2022.pdf https://doaj.org/article/bcd92eb9a5914900a5d23f5dc7f837d4 |
long_lat |
ENVELOPE(157.617,157.617,-83.233,-83.233) |
geographic |
Antarctic Ong Valley The Antarctic Transantarctic Mountains |
geographic_facet |
Antarctic Ong Valley The Antarctic Transantarctic Mountains |
genre |
Antarc* Antarctic Antarctica ice core Ice Sheet The Cryosphere |
genre_facet |
Antarc* Antarctic Antarctica ice core Ice Sheet The Cryosphere |
op_source |
The Cryosphere, Vol 16, Pp 2793-2817 (2022) |
op_relation |
doi:10.5194/tc-16-2793-2022 1994-0416 1994-0424 https://tc.copernicus.org/articles/16/2793/2022/tc-16-2793-2022.pdf https://doaj.org/article/bcd92eb9a5914900a5d23f5dc7f837d4 |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-16-2793-2022 |
container_title |
The Cryosphere |
container_volume |
16 |
container_issue |
7 |
container_start_page |
2793 |
op_container_end_page |
2817 |
_version_ |
1766257975166500864 |