scholarly journals Ice-Coring At Mizuho Station, Antarctica, and Core Analyses: A Contribution from the Glaciological Research Program in East Dronning Maud Land, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 213-213
Author(s):  
H. Narita ◽  
S. Mae ◽  
M. Nakawo ◽  
Y. Fujii ◽  
M. Yoshida ◽  
...  
Keyword(s):  
Research Program ◽  
Ice Core ◽  
Gas Content ◽  
List Type ◽  
Air Bubbles ◽  
The Core ◽  
Core Recovery ◽  
Burn Out ◽  
Dronning Maud Land ◽  
Antarctic Research

Between May 1983 and July 1984 glaciological parties of the 24th and 25th Japanese Antarctic Research Expeditions (JARE–24 and 25) carried out ice-core drilling using a thermal drill, down to 700.5 m depth at Mizuho Station (70°41'53"S, 44°19'54"E), as a part of the Glaciological Research Program in east Dronning Maud Land, Antarctica.The thermal drill, 3.9 m long and capable of taking a core 1.5 m long and 130 mm in diameter, is an improved version of a drill used by JARE–15 in 1975. The most important improvement was the monitoring system during drilling, for which a micro-computer was fitted in the drill. By using this system, such accidents as heater burn-out, tank overflow and failure of water suction would immediately be brought to our attention. The drilling speed was about 1.6 m/h, when the optimum output was 3.6 kW. The core recovery rate was above 99%.The core quality was good down to a depth of 80 m. Between 80 and 120 m, cracks were found at intervals of 0.15–0.5 m, and horizontal cracks were found continuously at intervals of 0.01 m or less.Immediately after the core was pulled, the stratigraphy was observed and bulk density was measured. A dust band, presumably volcanic particles, was seen at only 500.2 m depth during stratigraphic observation. The following analyses were carried out at Mizuho Station within a month of recovery: (1)Density determination by the hydrostatic method.(2)Measurement of total gas content.(3)Thin-section analyses, including observation of cracking around air bubbles and the crystalline texture, and ice-fabric studies.The 700.5 m core has been brought to Japan, and the following analyses are now under way: (1)Oxygen-isotope ratio.(2)Concentration of microparticles.(3)Electric conductivity.(4)Chemistry of soluble impurities.

scholarly journals Ice-Coring At Mizuho Station, Antarctica, and Core Analyses: A Contribution from the Glaciological Research Program in East Dronning Maud Land, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 213 ◽  
Author(s):  
H. Narita ◽  
S. Mae ◽  
M. Nakawo ◽  
Y. Fujii ◽  
M. Yoshida ◽  
...  
Keyword(s):  
Research Program ◽  
Ice Core ◽  
Gas Content ◽  
List Type ◽  
Air Bubbles ◽  
The Core ◽  
Core Recovery ◽  
Burn Out ◽  
Dronning Maud Land ◽  
Antarctic Research

Between May 1983 and July 1984 glaciological parties of the 24th and 25th Japanese Antarctic Research Expeditions (JARE–24 and 25) carried out ice-core drilling using a thermal drill, down to 700.5 m depth at Mizuho Station (70°41'53"S, 44°19'54"E), as a part of the Glaciological Research Program in east Dronning Maud Land, Antarctica. The thermal drill, 3.9 m long and capable of taking a core 1.5 m long and 130 mm in diameter, is an improved version of a drill used by JARE–15 in 1975. The most important improvement was the monitoring system during drilling, for which a micro-computer was fitted in the drill. By using this system, such accidents as heater burn-out, tank overflow and failure of water suction would immediately be brought to our attention. The drilling speed was about 1.6 m/h, when the optimum output was 3.6 kW. The core recovery rate was above 99%. The core quality was good down to a depth of 80 m. Between 80 and 120 m, cracks were found at intervals of 0.15–0.5 m, and horizontal cracks were found continuously at intervals of 0.01 m or less. Immediately after the core was pulled, the stratigraphy was observed and bulk density was measured. A dust band, presumably volcanic particles, was seen at only 500.2 m depth during stratigraphic observation. The following analyses were carried out at Mizuho Station within a month of recovery: (1) Density determination by the hydrostatic method. (2) Measurement of total gas content. (3) Thin-section analyses, including observation of cracking around air bubbles and the crystalline texture, and ice-fabric studies. The 700.5 m core has been brought to Japan, and the following analyses are now under way: (1) Oxygen-isotope ratio. (2) Concentration of microparticles. (3) Electric conductivity. (4) Chemistry of soluble impurities.

scholarly journals A Stratigraphic Record of an Ice Core from the Yamato Meteorite Ice Field, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 126-129
Author(s):  
Masayoshi Nakawo ◽  
Masayasu Nagoshi ◽  
Shinji Mae
Keyword(s):  
Electrical Conductivity ◽  
Pressure Difference ◽  
Ice Core ◽  
Gas Content ◽  
Volume Relaxation ◽  
Overburden Pressure ◽  
The Core ◽  
Core Recovery ◽  
Bubble Pressure ◽  
Surface Ice

Measurements of density, total gas content, δ18O, and electrical conductivity were carried out along a core 100 m long. A profile of in-situ bubble pressure was obtained from the data on density and total gas content, taking into account the volume relaxation of the core in the period between core recovery and density determination. The bubble pressure was appreciably higher than the overburden pressure at corresponding depths. It was considered that the pressure difference was caused by the continuous lifting of the ice, since ice flow was obstructed in the blue-ice area. From the profile of the pressure difference, the vertical distribution of the upward velocity was calculated, which provided a time-scale for the core. It was found that the 100 m long core represented a record of about 104–105a. Since the surface ice was considered to represent a few tens of thousand years B.P., the data obtained on total gas content, δ18O, and electrical conductivity would describe the variations in the climate as well as in the ice sheet during the last glacial period.

scholarly journals A Stratigraphic Record of an Ice Core from the Yamato Meteorite Ice Field, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 126-129 ◽  
Author(s):  
Masayoshi Nakawo ◽  
Masayasu Nagoshi ◽  
Shinji Mae
Keyword(s):  
Electrical Conductivity ◽  
Pressure Difference ◽  
Ice Core ◽  
Gas Content ◽  
Volume Relaxation ◽  
Overburden Pressure ◽  
The Core ◽  
Core Recovery ◽  
Bubble Pressure ◽  
Surface Ice

Measurements of density, total gas content, δ18O, and electrical conductivity were carried out along a core 100 m long. A profile of in-situ bubble pressure was obtained from the data on density and total gas content, taking into account the volume relaxation of the core in the period between core recovery and density determination. The bubble pressure was appreciably higher than the overburden pressure at corresponding depths. It was considered that the pressure difference was caused by the continuous lifting of the ice, since ice flow was obstructed in the blue-ice area. From the profile of the pressure difference, the vertical distribution of the upward velocity was calculated, which provided a time-scale for the core. It was found that the 100 m long core represented a record of about 104–105a. Since the surface ice was considered to represent a few tens of thousand years B.P., the data obtained on total gas content, δ18O, and electrical conductivity would describe the variations in the climate as well as in the ice sheet during the last glacial period.

scholarly journals Studies on microparticles contained in medium-depth ice cores retrieved from east Dronning Maud Land, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 73-79
Author(s):  
Akira Higashi ◽  
Yoshiyuki Fujii
Keyword(s):  
Elemental Composition ◽  
Depth Profile ◽  
Volcanic Ash ◽  
Ice Core ◽  
Compositional Analysis ◽  
Ice Cores ◽  
Cold Climates ◽  
Dronning Maud Land ◽  
Antarctic Research ◽  
South Sandwich Islands

SEM observations of microparticles in ice-core samples retrieved by the Japanese Antarctic Research Expedition in east Dronning Maud Land have been carried out since 1987. Morphology and elemental composition by EDS of many microparticles taken from various depths of the 700 m Mizuho ice core were compared with each other and with those of stratospheric microparticles in NASA Cosmic Dust Catalogs and microparticles hitherto found in deep ice cores retrieved in Antarctica. Number concentrations of microparticles were measured on all samples throughout the 700 m Mizuho ice core. Remarkable fluctuations found in the depth profile of the concentration seem to coincide with cold climates indicated by δ18O of the same core. Compositional analysis of volcanic ash at a depth of 500.7 m in the Mizuho ice core, dated at approximately 6000 years BP, indicates that the ash originated from the South Sandwich Islands.

scholarly journals Ice Flow Along an I.A.G.P. Flow Line and Interpretation of Data From an Ice Core in Terre Adélie, Antarctica

1979 ◽  
Vol 24 (90) ◽  
pp. 103-115 ◽  
Author(s):  
D. Raynaud ◽  
C. Lorius ◽  
W. F. Budd ◽  
N. W. Young
Keyword(s):  
Flow Line ◽  
Ice Core ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Gas Content ◽  
Ice Flow ◽  
The Core ◽  
The Past ◽  
Terre Adélie ◽  
Inland Ice

AbstractAn ice core has been obtained to the bedrock about 300 m deep in Terre Adélie, 5 km inland from the coast. Stable isotopes and gas content have been measured over the length of the core. The results have been interpreted in terms of the temperature and elevation of origin of the ice further inland on the ice sheet from the data obtained along an 800 km traverse towards Dome “C”, and from Dome “C”, at an elevation of about 3 200 m. The flow of the ice from Dome “C“ to the coast has been modelled to determine the ages and particle trajectories of the ice for present conditions.It has been found that the upper isotope and gas-content values in the core can be matched with the present regime using a base for ice flow above the present bed which is suggested by moraine in the ice core. The ice in the layer from the 200 m depth, where the age is apparently more than 5 000 years, to the 250 m depth, appears to have originated from conditions which differ substantially from those existing on the present inland ice-sheet surface. The results give an indication of a colder climate and greater ice-sheet thickness in the past.

scholarly journals Deep Drilling at Base Roi Baudouin, Dronning Maud Land, Antarctica

1962 ◽  
Vol 4 (31) ◽  
pp. 101-110 ◽  
Author(s):  
E. Tongiorgi ◽  
E. Picciotto ◽  
W. de Breuck ◽  
T. Norling ◽  
J. Giot ◽  
...  
Keyword(s):  
Coarse Grained ◽  
Ice Formation ◽  
Deep Drilling ◽  
Fine Grained ◽  
The Core ◽  
Core Recovery ◽  
Morphological Studies ◽  
Antarctic Expedition ◽  
Dronning Maud Land ◽  
Air Circulation

Abstract A drilling operation and core investigations at Base Roi. Baudouin (lat. 70° 25′ 5″ S., long. 24° 18′ 38″ E.) in January 1961 are discussed. The drilling, undertaken with light equipment, attained a depth of 115.72 m. From the start serious difficulties were encountered so that it was decided to use a SIPRE auger driven by the mechanism of the drilling machine. Core recovery was close to 100 per cent. Below a depth of 43.70 m., since the drill had reached the zone of high ice density (0.85 g./cm.3), a 3 m. double core barrel was used with air circulation. A depth of 79.33 m. was reached with a core yield close to 100 per cent. From this level downwards to the final depth of 115.72 in. the core yield was only 55 per cent. Preliminary observations were made at the site. A stratigraphie profile of the first 43 m. showed an al terna-ion of coarse-grained summer layers with ice formation and fine-grained winter deposits. From the seasonal alternations of the last six years, an average annual accumulation of 38.3 cm. of water was calculated. No coloured or dust layers were observed. Between 9 and 16 m. and between 41 and 44 m. an intense formation of ice was noticed. The depth-density curve is similar to those found by the. Norwegian-British-Swedish Antarctic Expedition at Maudheim and by the Americans at Little America V. If an average annual accumulation of 38 cm. of water is assumed, the whole depth drilled corresponds to approximately 240 yr. Temperature measurements could not he carried out b;rcause of the limited time available. Detailed stratigraphie and morphological studies of the cores, which are stored at −15°C. in Brussels, are planned, as well as chemical and isotopic investigations.

scholarly journals Ice Structure and Crystal Fabrics of the 2200 M Ice Core at Vostok Station, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 223-223
Author(s):  
N.I. Barkov ◽  
V.Ya. Lipenkov ◽  
V.N. Petrov
Keyword(s):  
Ice Core ◽  
Three Dimensional ◽  
Air Bubbles ◽  
The Core ◽  
Polycrystalline Ice ◽  
Vostok Station ◽  
Dimensional Parameters ◽  
The Mean ◽  
Ice Fabrics

Both the ice structure and the ice fabric along the 2200 m ice core at Vostok Station were investigated during the 25th, 29th and 30th Soviet Antarctic Expeditions.Several kinds of three-dimensional parameters of polycrystalline ice were measured, e.g. the mean diameter and size distribution of ice crystals and air bubbles, and specific volumeThe variation in most of these parameters along the core reflects not only the process of metamorphism in ice but also changes in the environmental conditions at the surface. The causes of these variations are discussed, in order to estimate the possibility of a paleoclimatic interpretation.The evolution of c-axis fabrics with depth is discussed in relation to the ice-deformation conditions.A comparison of ice fabrics at Vostok, Byrd Station and Camp Century shows that similar mechanisms cause the reorientation of crystals. The role of temperature in fabric development is discussed.

scholarly journals Atmospheric CO2 Concentration During the Last Glaciation

1984 ◽  
Vol 5 ◽  
pp. 160-164 ◽  
Author(s):  
B. Stauffer ◽  
H. Hofer ◽  
H. Oeschger ◽  
J. Schwander ◽  
U. Siegenthaler
Keyword(s):  
Ice Core ◽  
Co2 Concentration ◽  
Temporal Variations ◽  
Air Bubbles ◽  
The Core ◽  
Last Glaciation ◽  
Time Period ◽  
Core Section ◽  
Glacier Ice ◽  
Short Time

Analyses of atmospheric air extracted from air bubbles in polar glacier ice provide a measure of past CO2concentrations and their temporal variations. Earlier measurements have shown that the atmospheric CO2concentration was significantly lower during the late Wisconsin stage and that the change from low to high CO2concentration occurred in a relatively short time period.We measured the CO2concentration of ice samples from the deep ice core recently drilled at Dye 3 (south Greenland). The core section investigated represents ice from about 40 to 30 ka BP. The air extracted from the ice samples shows large variations of CO2concentration which are correlated with δ18O values of the ice samples. A probable explanation of the results is that corresponding changes of the atmospheric CO2concentration occurred during that glacial period. These changes could have had a significant influence on the climate. Possible reasons for the variations of the atmospheric CO2concentration are discussed.

scholarly journals Studies on microparticles contained in medium-depth ice cores retrieved from east Dronning Maud Land, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 73-79
Author(s):  
Akira Higashi ◽  
Yoshiyuki Fujii
Keyword(s):  
Elemental Composition ◽  
Depth Profile ◽  
Volcanic Ash ◽  
Ice Core ◽  
Compositional Analysis ◽  
Ice Cores ◽  
Cold Climates ◽  
Dronning Maud Land ◽  
Antarctic Research ◽  
South Sandwich Islands

SEM observations of microparticles in ice-core samples retrieved by the Japanese Antarctic Research Expedition in east Dronning Maud Land have been carried out since 1987. Morphology and elemental composition by EDS of many microparticles taken from various depths of the 700 m Mizuho ice core were compared with each other and with those of stratospheric microparticles in NASA Cosmic Dust Catalogs and microparticles hitherto found in deep ice cores retrieved in Antarctica. Number concentrations of microparticles were measured on all samples throughout the 700 m Mizuho ice core. Remarkable fluctuations found in the depth profile of the concentration seem to coincide with cold climates indicated by δ18O of the same core. Compositional analysis of volcanic ash at a depth of 500.7 m in the Mizuho ice core, dated at approximately 6000 years BP, indicates that the ash originated from the South Sandwich Islands.

scholarly journals Ice Structure and Crystal Fabrics of the 2200 M Ice Core at Vostok Station, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 223 ◽  
Author(s):  
N.I. Barkov ◽  
V.Ya. Lipenkov ◽  
V.N. Petrov
Keyword(s):  
Ice Core ◽  
Three Dimensional ◽  
Air Bubbles ◽  
The Core ◽  
Polycrystalline Ice ◽  
Vostok Station ◽  
Dimensional Parameters ◽  
The Mean ◽  
Ice Fabrics

Both the ice structure and the ice fabric along the 2200 m ice core at Vostok Station were investigated during the 25th, 29th and 30th Soviet Antarctic Expeditions. Several kinds of three-dimensional parameters of polycrystalline ice were measured, e.g. the mean diameter and size distribution of ice crystals and air bubbles, and specific volume The variation in most of these parameters along the core reflects not only the process of metamorphism in ice but also changes in the environmental conditions at the surface. The causes of these variations are discussed, in order to estimate the possibility of a paleoclimatic interpretation. The evolution of c-axis fabrics with depth is discussed in relation to the ice-deformation conditions. A comparison of ice fabrics at Vostok, Byrd Station and Camp Century shows that similar mechanisms cause the reorientation of crystals. The role of temperature in fabric development is discussed.

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