scholarly journals Basement Ige, Ward Hunt Ice Shelf, Ellesmere Island, Canada

1971 ◽  
Vol 10 (58) ◽  
pp. 93-100 ◽  
Author(s):  
J.B. Lyons ◽  
S.M. Savin ◽  
A.J. Tamburi
Keyword(s):  
Grain Boundary ◽  
Sea Ice ◽  
Small Angle ◽  
Brackish Water ◽  
Main Part ◽  
Ellesmere Island ◽  
Ice Shelf ◽  
The West ◽  
Vertical Orientation ◽  
Brackish Ice

Oxygen-isotope and chlorinity determinations, as well as petrographie observations, indicate that the basement we of the Ward Hunt Ice Shelf is largely composed of a unique brackish ice, which interdigitates with sea ice. Some iced firn occurs near the top of the Basement Ice, below an unconformity. stratification in brackish and sea ice represents annual increments to the bottom of the ice shelf The c-axis vertical orientation and small-angle grain-boundary relations in brackish ice are explained by nucleation and floating of ice dendrites from the undercooled brackish water zone to the bottom of the ice shelf, where they attach themselves sub-parallel to the plane of the undersurface. Ice island T-3 did not come from a break-up of the main part of the Ward Hunt Ice Shelf, but probably originated in a nearby area to the west.

scholarly journals Basement Ice, Ward Hunt Ice Shelf, Ellesmere Island, Canada

1971 ◽  
Vol 10 (58) ◽  
pp. 93-100 ◽  
Author(s):  
J.B. Lyons ◽  
S.M. Savin ◽  
A.J. Tamburi
Keyword(s):  
Grain Boundary ◽  
Sea Ice ◽  
Small Angle ◽  
Brackish Water ◽  
Main Part ◽  
Ellesmere Island ◽  
Ice Shelf ◽  
The West ◽  
Vertical Orientation ◽  
Brackish Ice

AbstractOxygen-isotope and chlorinity determinations, as well as petrographie observations, indicate that the basement we of the Ward Hunt Ice Shelf is largely composed of a unique brackish ice, which interdigitates with sea ice. Some iced firn occurs near the top of the Basement Ice, below an unconformity.stratification in brackish and sea ice represents annual increments to the bottom of the ice shelf The c-axis vertical orientation and small-angle grain-boundary relations in brackish ice are explained by nucleation and floating of ice dendrites from the undercooled brackish water zone to the bottom of the ice shelf, where they attach themselves sub-parallel to the plane of the undersurface.Ice island T-3 did not come from a break-up of the main part of the Ward Hunt Ice Shelf, but probably originated in a nearby area to the west.

scholarly journals Stratigraphy, stable isotopes and salinity in multi-year sea ice from the rift area, south George VI Ice Shelf, Antarctic Peninsula

1991 ◽  
Vol 37 (127) ◽  
pp. 357-367
Author(s):  
J.-L. Tison ◽  
E. M. Morris ◽  
R. Souchez ◽  
J. Jouzel
Keyword(s):  
Stable Isotopes ◽  
Sea Ice ◽  
Fresh Water ◽  
Large Scale ◽  
Sea Water ◽  
Ice Core ◽  
Ice Shelf ◽  
The Core ◽  
Brackish Ice ◽  
Ice Production

AbstractResults from a detailed profile in a 5.54 m multi-year sea-ice core from the rift area in the southern part of George VI Ice Shelf are presented. Stratigraphy, stable isotopes and Na content are used to investigate the growth processes of the ice cover and to relate them to melting processes at the bottom of the ice shelf.The thickest multi-year sea ice in the sampling area appears to be second-year sea ice that has survived one melt season. Combined salinity/stable-isotope analyses show large-scale sympathetic fluctuations that can be related to the origin of the parent water. Winter accretion represents half of the core length and mainly consists of frazil ice of normal sea-water origin. However, five major dilution events of sea water, with fresh-water input from the melting base of the ice shelf reaching 20% on two occasions, punctuate this winter accretion. Two of them correspond to platelet-ice production, which is often related to the freezing of ascending supercooled water from the bottom of the ice shelf.Brackish ice occurs between 450 and 530 cm in the core. It is demonstrated that this results from the freezing of brackish water (Jeffries and others, 1989) formed by mixing of normal sea water with melted basal shelf ice, with dilution percentages of maximum 80% fresh water.

scholarly journals Massive, ancient sea-ice strata and preserved physical-structural characteristics in the Ward Hunt Ice Shelf

1991 ◽  
Vol 15 ◽  
pp. 125-131 ◽  
Author(s):  
Martin O. Jeffries
Keyword(s):  
Sea Ice ◽  
Structural Characteristics ◽  
Ice Core ◽  
Gravity Drainage ◽  
Physical Processes ◽  
Ice Shelf ◽  
The West ◽  
Time Intervals ◽  
Long Time ◽  
Equilibrium Thickness

Two sea-ice layers, one measured as 9 m thick, the other at least 12 m thick and estimated to be 24.5 m thick, have been located by ice core drilling in the west Ward Hunt Ice Shelf. To examine the preservation of physical-structural characteristics over long time intervals, the crystal structure and brine volumes in the sea ice, which possibly dates back to about 3000 BP, have been studied. The structural characteristics are immediately recognizable as those of undeformed congelation sea ice accreted by Stefan growth. Brine volumes in the ancient sea ice are higher than those in modern multi-year ice at the same temperature. The preservation of brine over a time span of hundreds to thousands of years is attributed to an absence of surface meltwater to effect brine flushing and the very slow, even negligible action of gravity drainage, brine pocket migration and brine expulsion. The congelation structures indicate that sea ice can grow by the Stefan accretion mechanism to thicknesses exceeding the equilibrium thickness (2.5–5 m) of most undeformed multi-year ice. The observed physical-structural characteristics of the Ward Hunt sea ice strongly suggest that many of the properties attained by sea ice are permanent and not affected by slow-acting physical processes.

scholarly journals Stratigraphy, stable isotopes and salinity in multi-year sea ice from the rift area, south George VI Ice Shelf, Antarctic Peninsula

1991 ◽  
Vol 37 (127) ◽  
pp. 357-367 ◽  
Author(s):  
J.-L. Tison ◽  
E. M. Morris ◽  
R. Souchez ◽  
J. Jouzel
Keyword(s):  
Stable Isotopes ◽  
Sea Ice ◽  
Fresh Water ◽  
Large Scale ◽  
Sea Water ◽  
Ice Core ◽  
Ice Shelf ◽  
The Core ◽  
Brackish Ice ◽  
Ice Production

AbstractResults from a detailed profile in a 5.54 m multi-year sea-ice core from the rift area in the southern part of George VI Ice Shelf are presented. Stratigraphy, stable isotopes and Na content are used to investigate the growth processes of the ice cover and to relate them to melting processes at the bottom of the ice shelf.The thickest multi-year sea ice in the sampling area appears to be second-year sea ice that has survived one melt season. Combined salinity/stable-isotope analyses show large-scale sympathetic fluctuations that can be related to the origin of the parent water. Winter accretion represents half of the core length and mainly consists of frazil ice of normal sea-water origin. However, five major dilution events of sea water, with fresh-water input from the melting base of the ice shelf reaching 20% on two occasions, punctuate this winter accretion. Two of them correspond to platelet-ice production, which is often related to the freezing of ascending supercooled water from the bottom of the ice shelf.Brackish ice occurs between 450 and 530 cm in the core. It is demonstrated that this results from the freezing of brackish water (Jeffries and others, 1989) formed by mixing of normal sea water with melted basal shelf ice, with dilution percentages of maximum 80% fresh water.

scholarly journals Some measurements and observations of very old sea ice and brackish ice, Ward Hunt Ice Shelf, N.W.T.

1989 ◽  
Vol 27 (3) ◽  
pp. 553-564 ◽  
Author(s):  
Martin O. Jeffries ◽  
William M. Sackinger
Keyword(s):  
Sea Ice ◽  
Ice Shelf ◽  
Very Old ◽  
Brackish Ice

scholarly journals Survey and Mapping of Recent Ice Shelf Changes and Landfast Sea Ice Growth Along the North Coast of Ellesmere Island, NWT, Canada

1986 ◽  
Vol 8 ◽  
pp. 96-99 ◽  
Author(s):  
M.O. Jeffries ◽  
H.V. Serson
Keyword(s):  
Sea Ice ◽  
Ellesmere Island ◽  
North Coast ◽  
Ice Shelf ◽  
Negative Mass ◽  
Ice Shelves ◽  
The North ◽  
Landfast Ice ◽  
Melt Water ◽  
Landfast Sea Ice

Ground and aerial surveys along the north coast of Ellesmere Island confirm that a considerable area of shelf ice remains, although it is not as extensive as it once was due to periodic ice island calvings. However, the lost ice shelf is quickly replaced by landfast sea ice. The sea ice often persists for many years and thickens sufficiently to be considered as the restoration of former ice shelf. The landfast ice quickly assumes an undulating topography, similar to the ice shelves, the development of which is encouraged by melt water and wind action. Even under the present conditions of negative mass balance, the sea ice reaches considerable, undeformed thicknesses. The thick sea ice forming today could be the precursor of an expansion of the ice shelves.

scholarly journals Water Circulation and Ice Accretion Beneath Ward Hunt Ice Shelf (Northern Ellesmere Island, Canada), Deduced From Salinity and Isotope Analysis of Ice Cores

1988 ◽  
Vol 10 ◽  
pp. 68-72 ◽  
Author(s):  
Martin O. Jeffries ◽  
William M. Sackinger ◽  
H. Roy Krouse ◽  
Harold V. Serson
Keyword(s):  
Sea Ice ◽  
Fresh Water ◽  
Sea Water ◽  
Ice Core ◽  
Isotope Analysis ◽  
Ice Cores ◽  
Water Circulation ◽  
Ice Shelf ◽  
The West ◽  
Water Ice

Ice-core drilling and ice-core analysis (electrical conductivity–salinity, 18O, 3H, density) reveal that the internal structure of the west Ward Hunt Ice Shelf contrasts sharply with that of the east ice shelf. The west ice shelf contains a great thickness (≥22 m) of sea ice (mean salinity, 2.22‰; mean δ18O, -0.8‰), whereas the east ice shelf is entirely of meteoric or fresh-water ice (mean salinity 0.01‰; mean δ18O, -29.7‰). High tritium activities are found only in ice from near the bottom of the east and west ice shelves. The contrasting ice-core data is considered to be a proxy record of variations in water circulation and bottom freezing beneath the ice shelf. The west shelf is underlain by sea water flowing into Disraeli Fiord. Sea ice accretes on to the bottom of the west ice shelf from the sea-water flowing into the fiord. Sea-water flowing out of the fiord is directed below the east ice shelf. However, the east ice shelf is not underlain directly by sea-water but by a layer of fresh water from the surface of Disraeli Fiord. In this region, ice growth resulting from the presence of this stable fresh-water layer has been accompanied by surface ablation over a period of perhaps the last 450 years. As a result, fresh-water ice has completely replaced any sea ice that originally grew in the region of the east ice shelf. Whereas the west and east shelves are underlain almost exclusively by sea-water and fresh water, ice in the south shelf is the result of freezing of fresh, brackish or sea water. This is attributed to mixing of the inflowing and outflowing waters.

scholarly journals Water Circulation and Ice Accretion Beneath Ward Hunt Ice Shelf (Northern Ellesmere Island, Canada), Deduced From Salinity and Isotope Analysis of Ice Cores

1988 ◽  
Vol 10 ◽  
pp. 68-72 ◽  
Author(s):  
Martin O. Jeffries ◽  
William M. Sackinger ◽  
H. Roy Krouse ◽  
Harold V. Serson
Keyword(s):  
Sea Ice ◽  
Fresh Water ◽  
Sea Water ◽  
Ice Core ◽  
Isotope Analysis ◽  
Ice Cores ◽  
Water Circulation ◽  
Ice Shelf ◽  
The West ◽  
Water Ice

Ice-core drilling and ice-core analysis (electrical conductivity–salinity, 18O, 3H, density) reveal that the internal structure of the west Ward Hunt Ice Shelf contrasts sharply with that of the east ice shelf. The west ice shelf contains a great thickness (≥22 m) of sea ice (mean salinity, 2.22‰; mean δ18O, -0.8‰), whereas the east ice shelf is entirely of meteoric or fresh-water ice (mean salinity 0.01‰; mean δ18O, -29.7‰). High tritium activities are found only in ice from near the bottom of the east and west ice shelves. The contrasting ice-core data is considered to be a proxy record of variations in water circulation and bottom freezing beneath the ice shelf. The west shelf is underlain by sea water flowing into Disraeli Fiord. Sea ice accretes on to the bottom of the west ice shelf from the sea-water flowing into the fiord. Sea-water flowing out of the fiord is directed below the east ice shelf. However, the east ice shelf is not underlain directly by sea-water but by a layer of fresh water from the surface of Disraeli Fiord. In this region, ice growth resulting from the presence of this stable fresh-water layer has been accompanied by surface ablation over a period of perhaps the last 450 years. As a result, fresh-water ice has completely replaced any sea ice that originally grew in the region of the east ice shelf. Whereas the west and east shelves are underlain almost exclusively by sea-water and fresh water, ice in the south shelf is the result of freezing of fresh, brackish or sea water. This is attributed to mixing of the inflowing and outflowing waters.

scholarly journals Survey and Mapping of Recent Ice Shelf Changes and Landfast Sea Ice Growth Along the North Coast of Ellesmere Island, NWT, Canada

1986 ◽  
Vol 8 ◽  
pp. 96-99 ◽  
Author(s):  
M.O. Jeffries ◽  
H.V. Serson
Keyword(s):  
Sea Ice ◽  
Ellesmere Island ◽  
North Coast ◽  
Ice Shelf ◽  
Negative Mass ◽  
Ice Shelves ◽  
The North ◽  
Landfast Ice ◽  
Melt Water ◽  
Landfast Sea Ice

Ground and aerial surveys along the north coast of Ellesmere Island confirm that a considerable area of shelf ice remains, although it is not as extensive as it once was due to periodic ice island calvings. However, the lost ice shelf is quickly replaced by landfast sea ice. The sea ice often persists for many years and thickens sufficiently to be considered as the restoration of former ice shelf. The landfast ice quickly assumes an undulating topography, similar to the ice shelves, the development of which is encouraged by melt water and wind action. Even under the present conditions of negative mass balance, the sea ice reaches considerable, undeformed thicknesses. The thick sea ice forming today could be the precursor of an expansion of the ice shelves.

scholarly journals Massive, ancient sea-ice strata and preserved physical-structural characteristics in the Ward Hunt Ice Shelf

1991 ◽  
Vol 15 ◽  
pp. 125-131 ◽  
Author(s):  
Martin O. Jeffries
Keyword(s):  
Sea Ice ◽  
Structural Characteristics ◽  
Ice Core ◽  
Gravity Drainage ◽  
Physical Processes ◽  
Ice Shelf ◽  
The West ◽  
Time Intervals ◽  
Long Time ◽  
Equilibrium Thickness

Two sea-ice layers, one measured as 9 m thick, the other at least 12 m thick and estimated to be 24.5 m thick, have been located by ice core drilling in the west Ward Hunt Ice Shelf. To examine the preservation of physical-structural characteristics over long time intervals, the crystal structure and brine volumes in the sea ice, which possibly dates back to about 3000 BP, have been studied. The structural characteristics are immediately recognizable as those of undeformed congelation sea ice accreted by Stefan growth. Brine volumes in the ancient sea ice are higher than those in modern multi-year ice at the same temperature. The preservation of brine over a time span of hundreds to thousands of years is attributed to an absence of surface meltwater to effect brine flushing and the very slow, even negligible action of gravity drainage, brine pocket migration and brine expulsion. The congelation structures indicate that sea ice can grow by the Stefan accretion mechanism to thicknesses exceeding the equilibrium thickness (2.5–5 m) of most undeformed multi-year ice. The observed physical-structural characteristics of the Ward Hunt sea ice strongly suggest that many of the properties attained by sea ice are permanent and not affected by slow-acting physical processes.

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