Where is the 1-million-year-old ice at Dome A?
Ice fabric influences the rheology of ice, and hence the age–depth profile at ice core drilling sites. To investigate the age–depth profile to be expected of the ongoing deep ice coring at Kunlun station, Dome A, we use the depth-varying anisotropic fabric suggested by the recent polarimetric measur...
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Copernicus Publications
2018
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Online Access: | https://doi.org/10.5194/tc-12-1651-2018 https://www.the-cryosphere.net/12/1651/2018/tc-12-1651-2018.pdf https://doaj.org/article/db21c11404f74b74a47a4596f570356b |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:db21c11404f74b74a47a4596f570356b 2023-05-15T16:39:23+02:00 Where is the 1-million-year-old ice at Dome A? L. Zhao J. C. Moore B. Sun X. Tang X. Guo 2018-05-01 https://doi.org/10.5194/tc-12-1651-2018 https://www.the-cryosphere.net/12/1651/2018/tc-12-1651-2018.pdf https://doaj.org/article/db21c11404f74b74a47a4596f570356b en eng Copernicus Publications doi:10.5194/tc-12-1651-2018 1994-0416 1994-0424 https://www.the-cryosphere.net/12/1651/2018/tc-12-1651-2018.pdf https://doaj.org/article/db21c11404f74b74a47a4596f570356b undefined The Cryosphere, Vol 12, Pp 1651-1663 (2018) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2018 fttriple https://doi.org/10.5194/tc-12-1651-2018 2023-01-22T19:23:19Z Ice fabric influences the rheology of ice, and hence the age–depth profile at ice core drilling sites. To investigate the age–depth profile to be expected of the ongoing deep ice coring at Kunlun station, Dome A, we use the depth-varying anisotropic fabric suggested by the recent polarimetric measurements around Dome A along with prescribed fabrics ranging from isotropic through girdle to single maximum in a three-dimensional, thermo-mechanically coupled full-Stokes model of a 70 × 70 km2 domain around Kunlun station. This model allows for the simulation of the near basal ice temperature and age, and ice flow around the location of the Chinese deep ice coring site. Ice fabrics and geothermal heat flux strongly affect the vertical advection and basal temperature which consequently control the age profile. Constraining modeled age–depth profiles with dated radar isochrones to 2∕3 ice depth, the surface vertical velocity, and also the spatial variability of a radar isochrones dated to 153.3 ka BP, limits the age of the deep ice at Kunlun to between 649 and 831 ka, a much smaller range than previously inferred. The simple interpretation of the polarimetric radar fabric data that we use produces best fits with a geothermal heat flux of 55 mW m−2. A heat flux of 50 mW m−2 is too low to fit the deeper radar layers, and 60 mW m−2 leads to unrealistic surface velocities. The modeled basal temperature at Kunlun reaches the pressure melting point with a basal melting rate of 2.2–2.7 mm a−1. Using the spatial distribution of basal temperatures and the best fit fabric suggests that within 400 m of Kunlun station, 1-million-year-old ice may be found 200 m above the bed, and that there are large regions where even older ice is well above the bedrock within 5–6 km of the Kunlun station. Article in Journal/Newspaper ice core The Cryosphere Unknown The Cryosphere 12 5 1651 1663 |
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English |
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geo envir L. Zhao J. C. Moore B. Sun X. Tang X. Guo Where is the 1-million-year-old ice at Dome A? |
topic_facet |
geo envir |
description |
Ice fabric influences the rheology of ice, and hence the age–depth profile at ice core drilling sites. To investigate the age–depth profile to be expected of the ongoing deep ice coring at Kunlun station, Dome A, we use the depth-varying anisotropic fabric suggested by the recent polarimetric measurements around Dome A along with prescribed fabrics ranging from isotropic through girdle to single maximum in a three-dimensional, thermo-mechanically coupled full-Stokes model of a 70 × 70 km2 domain around Kunlun station. This model allows for the simulation of the near basal ice temperature and age, and ice flow around the location of the Chinese deep ice coring site. Ice fabrics and geothermal heat flux strongly affect the vertical advection and basal temperature which consequently control the age profile. Constraining modeled age–depth profiles with dated radar isochrones to 2∕3 ice depth, the surface vertical velocity, and also the spatial variability of a radar isochrones dated to 153.3 ka BP, limits the age of the deep ice at Kunlun to between 649 and 831 ka, a much smaller range than previously inferred. The simple interpretation of the polarimetric radar fabric data that we use produces best fits with a geothermal heat flux of 55 mW m−2. A heat flux of 50 mW m−2 is too low to fit the deeper radar layers, and 60 mW m−2 leads to unrealistic surface velocities. The modeled basal temperature at Kunlun reaches the pressure melting point with a basal melting rate of 2.2–2.7 mm a−1. Using the spatial distribution of basal temperatures and the best fit fabric suggests that within 400 m of Kunlun station, 1-million-year-old ice may be found 200 m above the bed, and that there are large regions where even older ice is well above the bedrock within 5–6 km of the Kunlun station. |
format |
Article in Journal/Newspaper |
author |
L. Zhao J. C. Moore B. Sun X. Tang X. Guo |
author_facet |
L. Zhao J. C. Moore B. Sun X. Tang X. Guo |
author_sort |
L. Zhao |
title |
Where is the 1-million-year-old ice at Dome A? |
title_short |
Where is the 1-million-year-old ice at Dome A? |
title_full |
Where is the 1-million-year-old ice at Dome A? |
title_fullStr |
Where is the 1-million-year-old ice at Dome A? |
title_full_unstemmed |
Where is the 1-million-year-old ice at Dome A? |
title_sort |
where is the 1-million-year-old ice at dome a? |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-12-1651-2018 https://www.the-cryosphere.net/12/1651/2018/tc-12-1651-2018.pdf https://doaj.org/article/db21c11404f74b74a47a4596f570356b |
genre |
ice core The Cryosphere |
genre_facet |
ice core The Cryosphere |
op_source |
The Cryosphere, Vol 12, Pp 1651-1663 (2018) |
op_relation |
doi:10.5194/tc-12-1651-2018 1994-0416 1994-0424 https://www.the-cryosphere.net/12/1651/2018/tc-12-1651-2018.pdf https://doaj.org/article/db21c11404f74b74a47a4596f570356b |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-12-1651-2018 |
container_title |
The Cryosphere |
container_volume |
12 |
container_issue |
5 |
container_start_page |
1651 |
op_container_end_page |
1663 |
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