Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps.
"Craigite," the mixed-air clathrate hydrate found in polar ice caps below the depth of air-bubble stability, is a clathrate mixed crystal of approximate composition (N2O2).6H2O. Recent observations on the Byrd Station Antarctic core show that the air hydrate is present at a depth of 727 m,...
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ftpubmed:oai:pubmedcentral.nih.gov:47993 2023-05-15T13:58:40+02:00 Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps. Craig, H Shoji, H Langway, C C 1993-12-01 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC47993 http://www.ncbi.nlm.nih.gov/pubmed/11607442 en eng http://www.ncbi.nlm.nih.gov/pmc/articles/PMC47993 http://www.ncbi.nlm.nih.gov/pubmed/11607442 Research Article Text 1993 ftpubmed 2013-08-29T08:12:15Z "Craigite," the mixed-air clathrate hydrate found in polar ice caps below the depth of air-bubble stability, is a clathrate mixed crystal of approximate composition (N2O2).6H2O. Recent observations on the Byrd Station Antarctic core show that the air hydrate is present at a depth of 727 m, well above the predicted depth for the onset of hydrate stability. We propose that the air hydrate occurs some 100 m above the equilibrium phase boundary at Byrd Station because of "piezometry"--i.e., that the anomalous depth of hydrate occurrence is a relic of a previous greater equilibrium depth along the flow trajectory, followed by vertical advection of ice through the local phase-boundary depth. Flowline trajectories in the ice based on numerical models show that the required vertical displacement does indeed occur just upstream of Byrd Station. Air-hydrate piezometry can thus be used as a general parameter to study the details of ice flow in polar ice caps and the metastable persistence of the clathrate phase in regions of upwelling blue ice. Text Antarc* Antarctic PubMed Central (PMC) Antarctic Byrd Byrd Station ENVELOPE(-119.533,-119.533,-80.017,-80.017) |
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English |
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Research Article |
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Research Article Craig, H Shoji, H Langway, C C Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps. |
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Research Article |
description |
"Craigite," the mixed-air clathrate hydrate found in polar ice caps below the depth of air-bubble stability, is a clathrate mixed crystal of approximate composition (N2O2).6H2O. Recent observations on the Byrd Station Antarctic core show that the air hydrate is present at a depth of 727 m, well above the predicted depth for the onset of hydrate stability. We propose that the air hydrate occurs some 100 m above the equilibrium phase boundary at Byrd Station because of "piezometry"--i.e., that the anomalous depth of hydrate occurrence is a relic of a previous greater equilibrium depth along the flow trajectory, followed by vertical advection of ice through the local phase-boundary depth. Flowline trajectories in the ice based on numerical models show that the required vertical displacement does indeed occur just upstream of Byrd Station. Air-hydrate piezometry can thus be used as a general parameter to study the details of ice flow in polar ice caps and the metastable persistence of the clathrate phase in regions of upwelling blue ice. |
format |
Text |
author |
Craig, H Shoji, H Langway, C C |
author_facet |
Craig, H Shoji, H Langway, C C |
author_sort |
Craig, H |
title |
Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps. |
title_short |
Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps. |
title_full |
Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps. |
title_fullStr |
Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps. |
title_full_unstemmed |
Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps. |
title_sort |
nonequilibrium air clathrate hydrates in antarctic ice: a paleopiezomdter for polar ice caps. |
publishDate |
1993 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC47993 http://www.ncbi.nlm.nih.gov/pubmed/11607442 |
long_lat |
ENVELOPE(-119.533,-119.533,-80.017,-80.017) |
geographic |
Antarctic Byrd Byrd Station |
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Antarctic Byrd Byrd Station |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC47993 http://www.ncbi.nlm.nih.gov/pubmed/11607442 |
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1766267020018450432 |