Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica
The texture and physical properties of an ice core, recovered to 215 m depth from the Ronne Ice Shelf, Antarctica, have been studied with regard to formation and transformation of the ice. At a depth of 152.8 m, a sharp discontinuity marks the transition between meteoric ice accumulated from above a...
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ftawi:oai:epic.awi.de:719 2023-09-05T13:12:37+02:00 Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica Eicken, H. Oerter, Hans Miller, Heinrich Graf, W. Kipfstuhl, J. 1994 https://epic.awi.de/id/eprint/719/ https://hdl.handle.net/10013/epic.11302 unknown Eicken, H. , Oerter, H. , Miller, H. , Graf, W. and Kipfstuhl, J. (1994) Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica , Journal of Glaciology, Vol. 40, No. 135, pp. 386-398 . hdl:10013/epic.11302 EPIC3Journal of Glaciology, Vol. 40, No. 135, pp. 386-398, ISSN: 0022-1430 Article isiRev 1994 ftawi 2023-08-22T19:42:09Z The texture and physical properties of an ice core, recovered to 215 m depth from the Ronne Ice Shelf, Antarctica, have been studied with regard to formation and transformation of the ice. At a depth of 152.8 m, a sharp discontinuity marks the transition between meteoric ice accumulated from above and marine ice accreted from below, as testified by electrolytical conductivity and stable-isotope measurements as well as geophysical field surveys. Automated image analysis of thin sections indicates that the decrease in grain-boundary density and the increase in grain cross-sectional area with depth is commensurate with though not necessarily caused bythermodynamically driven grain growth down to 120m depth, corresponding to a vertical strain of roughly 65% as computed with a simple temperature-history, particle-path model. The observed increase of grain-boundary density (i.e. a decrease of grain-size) with age in the marine ice is in part explained by the thermal history of this layer. Sediment inclusions at the top of the marine-ice layer affect the observed grain-boundary density profile by inhibiting grain growth and dynamic recrystallization. This may allow some conclusions on the role of temperature, particulate inclusions, stress and strain rate in controlling the grain-size evolution of deforming ice, supplementing earlier laboratory experiments conducted at much shorter time-scales. Salinities (0.026 parts per thousand), brine volumes (0.09-0.2 parts per thousand) and solid-salt concentrations have been computed from electrolytical conductivity measurements (mean of 51.0 x 10(-6)S cm(-1)) for the marine ice. An assessment of salt incorporation and desalination rates shows that these low salinities can at present only be explained by a unique densification mechanism of under-water ice crystals at the base of the ice shelf. Article in Journal/Newspaper Antarc* Antarctica Antarctica Journal ice core Ice Shelf Journal of Glaciology Ronne Ice Shelf Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Ronne Ice Shelf ENVELOPE(-61.000,-61.000,-78.500,-78.500) |
institution |
Open Polar |
collection |
Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
The texture and physical properties of an ice core, recovered to 215 m depth from the Ronne Ice Shelf, Antarctica, have been studied with regard to formation and transformation of the ice. At a depth of 152.8 m, a sharp discontinuity marks the transition between meteoric ice accumulated from above and marine ice accreted from below, as testified by electrolytical conductivity and stable-isotope measurements as well as geophysical field surveys. Automated image analysis of thin sections indicates that the decrease in grain-boundary density and the increase in grain cross-sectional area with depth is commensurate with though not necessarily caused bythermodynamically driven grain growth down to 120m depth, corresponding to a vertical strain of roughly 65% as computed with a simple temperature-history, particle-path model. The observed increase of grain-boundary density (i.e. a decrease of grain-size) with age in the marine ice is in part explained by the thermal history of this layer. Sediment inclusions at the top of the marine-ice layer affect the observed grain-boundary density profile by inhibiting grain growth and dynamic recrystallization. This may allow some conclusions on the role of temperature, particulate inclusions, stress and strain rate in controlling the grain-size evolution of deforming ice, supplementing earlier laboratory experiments conducted at much shorter time-scales. Salinities (0.026 parts per thousand), brine volumes (0.09-0.2 parts per thousand) and solid-salt concentrations have been computed from electrolytical conductivity measurements (mean of 51.0 x 10(-6)S cm(-1)) for the marine ice. An assessment of salt incorporation and desalination rates shows that these low salinities can at present only be explained by a unique densification mechanism of under-water ice crystals at the base of the ice shelf. |
format |
Article in Journal/Newspaper |
author |
Eicken, H. Oerter, Hans Miller, Heinrich Graf, W. Kipfstuhl, J. |
spellingShingle |
Eicken, H. Oerter, Hans Miller, Heinrich Graf, W. Kipfstuhl, J. Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica |
author_facet |
Eicken, H. Oerter, Hans Miller, Heinrich Graf, W. Kipfstuhl, J. |
author_sort |
Eicken, H. |
title |
Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica |
title_short |
Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica |
title_full |
Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica |
title_fullStr |
Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica |
title_full_unstemmed |
Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica |
title_sort |
textural characteristics and impurity content of meteoric and marine ice in the ronne ice shelf, antarctica |
publishDate |
1994 |
url |
https://epic.awi.de/id/eprint/719/ https://hdl.handle.net/10013/epic.11302 |
long_lat |
ENVELOPE(-61.000,-61.000,-78.500,-78.500) |
geographic |
Ronne Ice Shelf |
geographic_facet |
Ronne Ice Shelf |
genre |
Antarc* Antarctica Antarctica Journal ice core Ice Shelf Journal of Glaciology Ronne Ice Shelf |
genre_facet |
Antarc* Antarctica Antarctica Journal ice core Ice Shelf Journal of Glaciology Ronne Ice Shelf |
op_source |
EPIC3Journal of Glaciology, Vol. 40, No. 135, pp. 386-398, ISSN: 0022-1430 |
op_relation |
Eicken, H. , Oerter, H. , Miller, H. , Graf, W. and Kipfstuhl, J. (1994) Textural characteristics and impurity content of meteoric and marine ice in the Ronne Ice Shelf, Antarctica , Journal of Glaciology, Vol. 40, No. 135, pp. 386-398 . hdl:10013/epic.11302 |
_version_ |
1776201022866194432 |