Bubbles and Bubble Pressures in Antarctic Glacier Ice
Application of the gas law to fourth-place density measurements of ice samples from two deep drill holes at “Byrd” station and “Little America V”, Antarctica, shows that virtually all density increase beyond the pore close-off density (0.830 g cm −3 ) can be attributed to compression of the entrappe...
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Cambridge University Press (CUP)
1968
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crcambridgeupr:10.1017/s0022143000030975 2024-03-03T08:38:34+00:00 Bubbles and Bubble Pressures in Antarctic Glacier Ice Gow, Anthony J. 1968 http://dx.doi.org/10.1017/s0022143000030975 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030975 en eng Cambridge University Press (CUP) Journal of Glaciology volume 7, issue 50, page 167-182 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1968 crcambridgeupr https://doi.org/10.1017/s0022143000030975 2024-02-08T08:37:11Z Application of the gas law to fourth-place density measurements of ice samples from two deep drill holes at “Byrd” station and “Little America V”, Antarctica, shows that virtually all density increase beyond the pore close-off density (0.830 g cm −3 ) can be attributed to compression of the entrapped bubbles of air. Data from “Byrd” station also indicate that the lag between overburden pressure and bubble pressure, initially 4–5 kg cm −2 at pore close-off, diminishes to less than 1.0 kg cm −2 at about 200 m depth. By substituting the overburden pressure for the bubble pressure in the pressure-density relationship based on the gas law, one can determine ice densities below 200 m more accurately than they can be measured per se on cores, because of the relaxation that occurs in samples recovered from high confining pressures. This relaxation, resulting in a progressive increase in the bulk volume of the ice with time, is generally attributed to decompression of the entrapped air bubbles following removal of the ice from high confining pressures. However. calculations of the stress in ice due to bubble pressure, together with measurements of bubble sizes in cores from various depths at “Byrd” station, both tend to indicate that there has been negligible decompression of the inclosed bubbles. It is suggested that most of this relaxation may be due to the formation of micro-cracks in the ice. Anomalous bubble pressure–density relations at “Little America V” tend to confirm abundant petrographic evidence of the existence of considerable deformation in the upper part of the Ross Ice Shelf. Studies of crystal–bubble relations at “Byrd” station revealed that the concentration of bubbles in ice remains remarkably constant at approximately 220 bubbles/cm 3 . Bubbles and crystals were found to be present in approximately equal numbers at pore close-off at 64 m depth, at which level the average bubble diameter was 0·95 mm, decreasing to 0.49 mm at 116 m and to 0·33 mm at 279 m. Despite a ten-fold increase in the size of ... Article in Journal/Newspaper Antarc* Antarctic Antarctica Ice Shelf Journal of Glaciology Ross Ice Shelf Cambridge University Press Antarctic Ross Ice Shelf Byrd Byrd Station ENVELOPE(-119.533,-119.533,-80.017,-80.017) Little America ENVELOPE(-164.050,-164.050,-78.667,-78.667) Little America V ENVELOPE(-162.367,-162.367,-78.317,-78.317) Journal of Glaciology 7 50 167 182 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Gow, Anthony J. Bubbles and Bubble Pressures in Antarctic Glacier Ice |
topic_facet |
Earth-Surface Processes |
description |
Application of the gas law to fourth-place density measurements of ice samples from two deep drill holes at “Byrd” station and “Little America V”, Antarctica, shows that virtually all density increase beyond the pore close-off density (0.830 g cm −3 ) can be attributed to compression of the entrapped bubbles of air. Data from “Byrd” station also indicate that the lag between overburden pressure and bubble pressure, initially 4–5 kg cm −2 at pore close-off, diminishes to less than 1.0 kg cm −2 at about 200 m depth. By substituting the overburden pressure for the bubble pressure in the pressure-density relationship based on the gas law, one can determine ice densities below 200 m more accurately than they can be measured per se on cores, because of the relaxation that occurs in samples recovered from high confining pressures. This relaxation, resulting in a progressive increase in the bulk volume of the ice with time, is generally attributed to decompression of the entrapped air bubbles following removal of the ice from high confining pressures. However. calculations of the stress in ice due to bubble pressure, together with measurements of bubble sizes in cores from various depths at “Byrd” station, both tend to indicate that there has been negligible decompression of the inclosed bubbles. It is suggested that most of this relaxation may be due to the formation of micro-cracks in the ice. Anomalous bubble pressure–density relations at “Little America V” tend to confirm abundant petrographic evidence of the existence of considerable deformation in the upper part of the Ross Ice Shelf. Studies of crystal–bubble relations at “Byrd” station revealed that the concentration of bubbles in ice remains remarkably constant at approximately 220 bubbles/cm 3 . Bubbles and crystals were found to be present in approximately equal numbers at pore close-off at 64 m depth, at which level the average bubble diameter was 0·95 mm, decreasing to 0.49 mm at 116 m and to 0·33 mm at 279 m. Despite a ten-fold increase in the size of ... |
format |
Article in Journal/Newspaper |
author |
Gow, Anthony J. |
author_facet |
Gow, Anthony J. |
author_sort |
Gow, Anthony J. |
title |
Bubbles and Bubble Pressures in Antarctic Glacier Ice |
title_short |
Bubbles and Bubble Pressures in Antarctic Glacier Ice |
title_full |
Bubbles and Bubble Pressures in Antarctic Glacier Ice |
title_fullStr |
Bubbles and Bubble Pressures in Antarctic Glacier Ice |
title_full_unstemmed |
Bubbles and Bubble Pressures in Antarctic Glacier Ice |
title_sort |
bubbles and bubble pressures in antarctic glacier ice |
publisher |
Cambridge University Press (CUP) |
publishDate |
1968 |
url |
http://dx.doi.org/10.1017/s0022143000030975 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030975 |
long_lat |
ENVELOPE(-119.533,-119.533,-80.017,-80.017) ENVELOPE(-164.050,-164.050,-78.667,-78.667) ENVELOPE(-162.367,-162.367,-78.317,-78.317) |
geographic |
Antarctic Ross Ice Shelf Byrd Byrd Station Little America Little America V |
geographic_facet |
Antarctic Ross Ice Shelf Byrd Byrd Station Little America Little America V |
genre |
Antarc* Antarctic Antarctica Ice Shelf Journal of Glaciology Ross Ice Shelf |
genre_facet |
Antarc* Antarctic Antarctica Ice Shelf Journal of Glaciology Ross Ice Shelf |
op_source |
Journal of Glaciology volume 7, issue 50, page 167-182 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000030975 |
container_title |
Journal of Glaciology |
container_volume |
7 |
container_issue |
50 |
container_start_page |
167 |
op_container_end_page |
182 |
_version_ |
1792506972652699648 |