Gas studies: ice from Allan Hills meteorite site and Byrd ...
in the late winter or early spring. However, the actual mechanisms of storage and release of saline water are likely to be affected by glaciological and climatic variations which are poorly known. Special thanks are due to R. L. Armstrong, R. F. Black, G. L. Lyon, W. C. McIntosh, J . M. Nankervis, P. H. Robinson, T. Toni, and Y. Yusa for their assistance in the field or in the compilation of tables 1 and 2. Logistic support was provided by the NZ Antarctic Research Programme and the U.S. Antarctic Research Program. This research was supported by the NZ University Grants Committee and by National Science Foundation grant DPP 77-21590.
References
Hamilton, W. L., I. C. Frost, and P. T. Hayes. 1962. Saline features of a small ice platform in Taylor Valley, Antarctica.
US Geological Survey, Professional Paper, no. 450B, article 28, pp. B73-76.
Lorius, C., L. Merlivat, and R. Hagemann. 1969. Variations in the mean deuterium content of precipitations in Antarctica.
Journal of Geophysical Research, 74: 7027-7031. McGinnis, L. D., and T. E. Jensen. 1971. Permafrost-hydrogeologic regimen in two ice-free valleys, Antarctica, from electrical depth sounding. Quaternary Research, 1(3): 389409. Nakai, N., Y. Kiyosu, H. Wada, R. Nagae, and T. Nishiyama. 1978. Stable isotope studies: the evidence of relative sea level fluctuations and the environmental changes in Wright and Taylor Valleys. Dry Valley Drilling Project Bulletin, no. 8: pp. 64-65.
Picciotto, E. E. 1967. Geochemical investigations of snow and
Angino, E. E., K. B. Armitage, and J . C. Tash. 1964. Physicochemical limnology of Lake Bonney, Antarctica. Limnology and Oceanography, 9(2): 207-17. Black, R. F. 1969. Saline discharges from Taylor Glacier, Victoria Land, Antarctica. Antarctic Journal of the United States, 4(3): 89-90. Black, R. F., M. L. Jackson, and T. E. Berg. 1965. Saline discharge from Taylor Glacier, Victoria Land, Antarctica.Journal of Geology, 73(1): 175-81. Decker, E. R., and G. J . Bucher. 1977. Geothermal studies in Antarctica. Antarctic Journal of the United States, 12(4): 102-
urn samples from East Antarctica. Antarctic Journal of the United States, 2(6): 236-40. Sofer, Z., and J . R. Gat. 1972. Activities and concentrations of oxygen-18 in concentrated aqueous salt solutions: analytical and geophysical implications. Earth and Planetary Science Letters, 15: 232-8. Stephens, G. C., and F. R. Siegel. 1969. Calcium salts from Taylor Glacier, Southern Victoria Land. Antarctic Journal of the United States, 4(4): 133. Sverdrup, H. U., M. W. Johnson, and R. H. Fleming. 1942. The
Epstein, S., R. P. Sharp, and I. Goddard. 1963. Oxygen-isotope ratios in antarctic snow, firn and ice. Journal of Geology, 71: 698-720.
Taylor, T. G. 1922. The Physiography of the McMurdo Sound and Granite Harbour Region. British Antarctic (Terra Nova) Expedition 1910-1913. London: Harrison and Sons Ltd.
104.
Oceans. New York: Prentice-Hall, Inc.
Gas studies: Ice from Allan Hills meteorite site and Byrd Station E. L.
FIREMAN
Smithsonian Astrophysical Observatory Cambridge, Massachusetts 02138
We are in the process of analyzing ice samples taken near Allan Hills (figure 1), one of two blue ice regions in Antarctica where meteorites lie exposed on the surface. This site was discovered in 1976 (Cassidy, 1977; Nagata, 1977) The other site-located near the Queen Fabiola (or Yamato) Mountains-was found in 1969 by a Japanese glaciological party (Nagata, 1975). During the past three field seasons, W. A. Cassidy and his associates (Cassidy, 1978) have recovered more than 600 meteorites from the approximately 100-square-kilometer Allan Hills blue ice area. The rare-gas isotopic contents of ten Allan Hills meteorites have been measured (H. W. Weber and L. Schultz, 1978) and no paired falls have been found. This indicates that a large fraction of the meteorites are from different falls. The terrestrial ages of about 20 specimens have been measured as being
\A NO
0 1 00
/
/. 91^
/'
-
V 1+
Figure 1. Locations of meteorite finds at the Allan Hills site. Rock outcrops are shaded and bare ice patches are outlined. Monocline in ice surface runs from southwest of Allan Hills toward Battlements Nunatak but flattens out before reaching nunatak. (Surrounding features can be located on USGS Convoy Range map ST 57-60/li.) 85
between 30,000 and 300,000 years (Fireman, Rancitelli, and Kirsten, 1979; Evans and Rancitelli, 1979). However, there are three individual specimens that have ages of 700,000, 800,000, and probably 1.5 million years. These terrestrial ages are interesting time markers and indicate that the meteorite collection process has been going on for a long time. The ages of the ice underneath the specimens and near Allan Hills are not known. But some of this ice may also be 1 million years old. The ice contains bubbles of gas under pressure and also dissolved gas. The gas in the ice may constitute unique samples of the atmosphere during an important period of time-the million year epoch that contains the evolution of man. During the past field season, John 0. Annexstad, a member of Cassidy's field party, axed ice samples, each of approximately 25 kilograms in weight, from three Allan Hills locations for our study (locations are identified in figure 2 as #1, #2, and #3). Ice sample #1 was taken from directly underneath meteorite 291 (Annexstad's meteorite number designation; it will eventually receive a permanent ALHA78-- number). It was in the region with the highest meteorite concentration; the ice had the appearance of being stagnant. Ice sample #2 was taken from the top of the prominent monocline, which dominates the meteorite collection site. This ice was very difficult to chop out; Annexstad said it was the hardest ice he had encountered. At the place where ice sample #3 was removed, the ice had the appearance of being fast-moving because it was heavily crevassed with many pressure ridges. The remainder of this article describes our apparatus, experimental procedures, and analysis of a Byrd Station test sample. Measurements on the Allen Hills ice are currently in progress. C. C. Langway at the State University of New York-Buffalo is supplying us with wellstudied ice from Byrd Station for interlaboratory comparisons. Measurements of the N 2 , 02, Ar, G02 , and carbon-14 abundances in an li-kilogram core of ice from a depth of 362 meters at Byrd Station are under way. According to studies by Oeschger et al. (1977), this ice is 2,500 years old. We are employing the following procedures with the Byrd test ice. The ice is put into the 6-inch-diameter glass pipe. A glass cap is bolted to the glass pipe and joined to the rest of the extraction unit. The entire system, including the glass pipe containing the ice, is evacuated to a pressure of 25 u. The glass pipe is then purged of the air remnant with helium. The glass pipe unit is filled to a pressure of 1.2 atmospheres and closed off; the ice is then allowed to melt at room temperature. The air that was trapped in the ice is now either with the helium or dissolved in the melt water. The chromatographic column is cooled to -196° C and the glass pipe is opened to the rest of the extraction system. A helium flow of about 100 cubic centimeters per minute is started through the melt water and the chromatographic column. The helium exits into the room. After a helium sweep of about 1 hr, the exit flow is closed; then the helium is made to exit through a mechanical pump. This helium evacuation is continued until there is a pressure of less than 1 torr in the system. The chromatographic column and the charcoal trap are then closed off and contain the gas from the ice. The air 86
159000'E #3 WEST
#2 #1 EAST
..s-2.
KM
I
ALLAN % HILLS '
MONOCL I NE
Figure 2. Locations of Ice samples #1, #2, and #3 taken during 1978-79 field season, as viewed in sketch of plane perpendicular to the ice, 3.5 kilometers north of latitude 76°45'S.
minus its carbon dioxide content is removed from the chromatographic column by raising its temperature to 25° C. The amount of air is measured and stored for later analyses. The carbon dioxide is removed from the chromatographic column by raising its temperature to 250° C. The accompanying table gives results for three successive extractions that were done in order to test the completeness of our extraction method. This work has been supported by National Science Foundation grant DPP 78-0573. Table 1. Gas from 5.5 kg of 1187-ft depth Byrd core Melt-water temperature Air CO2 Extraction (°C) (cm3 SIP) (cm3 SIP) 1st 2nd 3rd
24 475.0 0.27 24 24.6 0.03 55 2.5 0.01
Total
- 502.1 0.31 References
Cassidy, W. A. 1977. Antarctic search for meteorites. Antarctic Journal of the United States. 12: 96-98. Cassidy, W. A. 1978. Antarctic search for meteorites during the 1977-78 field season. Antarctic Journal of the United States, 13: 39-40. Evans, J . C., and L. A. Rancitelli. 1979. Non-destructive Al measurements on Antarctic meteorites. Lunar and Planetaiy Science, 10: 373-75. Fireman, E. L., L. A. Rancitelli, and T. Kirsten. 1979. Terrestrial ages of four Allan Hills meteorites: Consequences for Antarctic ice. Science, 203: 453-55. Nagata, T. 1975. Yamato meteorites collected in Antarctica in 1969. Tokyo: National Institute of Polar Research. Nagata, T. 1977. Japanese scientific activities in the McMurdo region, 1976-1977. Antarctic Journal of the United States, 12: 95-96. Oeschger, H., B. Stauffer, P. Bucher, and H. H. Loosli. 1977. Extraction of gases and dissolved and particulate matter from ice in deep boreholes. In Proceedings of the Grenoble Symposium, 1975, on Isotopes and Impurities in Snow and Ice. IAHS publication no. 118, pp. 307-11. Weber, H. H., and L. Schultz. 1978. Noble gases in 10 stony meteorites from Antarctica and their exposure ages. Meteoritics, 13: 658-60.
References
Hamilton, W. L., I. C. Frost, and P. T. Hayes. 1962. Saline features of a small ice platform in Taylor Valley, Antarctica.
US Geological Survey, Professional Paper, no. 450B, article 28, pp. B73-76.
Lorius, C., L. Merlivat, and R. Hagemann. 1969. Variations in the mean deuterium content of precipitations in Antarctica.
Journal of Geophysical Research, 74: 7027-7031. McGinnis, L. D., and T. E. Jensen. 1971. Permafrost-hydrogeologic regimen in two ice-free valleys, Antarctica, from electrical depth sounding. Quaternary Research, 1(3): 389409. Nakai, N., Y. Kiyosu, H. Wada, R. Nagae, and T. Nishiyama. 1978. Stable isotope studies: the evidence of relative sea level fluctuations and the environmental changes in Wright and Taylor Valleys. Dry Valley Drilling Project Bulletin, no. 8: pp. 64-65.
Picciotto, E. E. 1967. Geochemical investigations of snow and
Angino, E. E., K. B. Armitage, and J . C. Tash. 1964. Physicochemical limnology of Lake Bonney, Antarctica. Limnology and Oceanography, 9(2): 207-17. Black, R. F. 1969. Saline discharges from Taylor Glacier, Victoria Land, Antarctica. Antarctic Journal of the United States, 4(3): 89-90. Black, R. F., M. L. Jackson, and T. E. Berg. 1965. Saline discharge from Taylor Glacier, Victoria Land, Antarctica.Journal of Geology, 73(1): 175-81. Decker, E. R., and G. J . Bucher. 1977. Geothermal studies in Antarctica. Antarctic Journal of the United States, 12(4): 102-
urn samples from East Antarctica. Antarctic Journal of the United States, 2(6): 236-40. Sofer, Z., and J . R. Gat. 1972. Activities and concentrations of oxygen-18 in concentrated aqueous salt solutions: analytical and geophysical implications. Earth and Planetary Science Letters, 15: 232-8. Stephens, G. C., and F. R. Siegel. 1969. Calcium salts from Taylor Glacier, Southern Victoria Land. Antarctic Journal of the United States, 4(4): 133. Sverdrup, H. U., M. W. Johnson, and R. H. Fleming. 1942. The
Epstein, S., R. P. Sharp, and I. Goddard. 1963. Oxygen-isotope ratios in antarctic snow, firn and ice. Journal of Geology, 71: 698-720.
Taylor, T. G. 1922. The Physiography of the McMurdo Sound and Granite Harbour Region. British Antarctic (Terra Nova) Expedition 1910-1913. London: Harrison and Sons Ltd.
104.
Oceans. New York: Prentice-Hall, Inc.
Gas studies: Ice from Allan Hills meteorite site and Byrd Station E. L.
FIREMAN
Smithsonian Astrophysical Observatory Cambridge, Massachusetts 02138
We are in the process of analyzing ice samples taken near Allan Hills (figure 1), one of two blue ice regions in Antarctica where meteorites lie exposed on the surface. This site was discovered in 1976 (Cassidy, 1977; Nagata, 1977) The other site-located near the Queen Fabiola (or Yamato) Mountains-was found in 1969 by a Japanese glaciological party (Nagata, 1975). During the past three field seasons, W. A. Cassidy and his associates (Cassidy, 1978) have recovered more than 600 meteorites from the approximately 100-square-kilometer Allan Hills blue ice area. The rare-gas isotopic contents of ten Allan Hills meteorites have been measured (H. W. Weber and L. Schultz, 1978) and no paired falls have been found. This indicates that a large fraction of the meteorites are from different falls. The terrestrial ages of about 20 specimens have been measured as being
\A NO
0 1 00
/
/. 91^
/'
-
V 1+
Figure 1. Locations of meteorite finds at the Allan Hills site. Rock outcrops are shaded and bare ice patches are outlined. Monocline in ice surface runs from southwest of Allan Hills toward Battlements Nunatak but flattens out before reaching nunatak. (Surrounding features can be located on USGS Convoy Range map ST 57-60/li.) 85
between 30,000 and 300,000 years (Fireman, Rancitelli, and Kirsten, 1979; Evans and Rancitelli, 1979). However, there are three individual specimens that have ages of 700,000, 800,000, and probably 1.5 million years. These terrestrial ages are interesting time markers and indicate that the meteorite collection process has been going on for a long time. The ages of the ice underneath the specimens and near Allan Hills are not known. But some of this ice may also be 1 million years old. The ice contains bubbles of gas under pressure and also dissolved gas. The gas in the ice may constitute unique samples of the atmosphere during an important period of time-the million year epoch that contains the evolution of man. During the past field season, John 0. Annexstad, a member of Cassidy's field party, axed ice samples, each of approximately 25 kilograms in weight, from three Allan Hills locations for our study (locations are identified in figure 2 as #1, #2, and #3). Ice sample #1 was taken from directly underneath meteorite 291 (Annexstad's meteorite number designation; it will eventually receive a permanent ALHA78-- number). It was in the region with the highest meteorite concentration; the ice had the appearance of being stagnant. Ice sample #2 was taken from the top of the prominent monocline, which dominates the meteorite collection site. This ice was very difficult to chop out; Annexstad said it was the hardest ice he had encountered. At the place where ice sample #3 was removed, the ice had the appearance of being fast-moving because it was heavily crevassed with many pressure ridges. The remainder of this article describes our apparatus, experimental procedures, and analysis of a Byrd Station test sample. Measurements on the Allen Hills ice are currently in progress. C. C. Langway at the State University of New York-Buffalo is supplying us with wellstudied ice from Byrd Station for interlaboratory comparisons. Measurements of the N 2 , 02, Ar, G02 , and carbon-14 abundances in an li-kilogram core of ice from a depth of 362 meters at Byrd Station are under way. According to studies by Oeschger et al. (1977), this ice is 2,500 years old. We are employing the following procedures with the Byrd test ice. The ice is put into the 6-inch-diameter glass pipe. A glass cap is bolted to the glass pipe and joined to the rest of the extraction unit. The entire system, including the glass pipe containing the ice, is evacuated to a pressure of 25 u. The glass pipe is then purged of the air remnant with helium. The glass pipe unit is filled to a pressure of 1.2 atmospheres and closed off; the ice is then allowed to melt at room temperature. The air that was trapped in the ice is now either with the helium or dissolved in the melt water. The chromatographic column is cooled to -196° C and the glass pipe is opened to the rest of the extraction system. A helium flow of about 100 cubic centimeters per minute is started through the melt water and the chromatographic column. The helium exits into the room. After a helium sweep of about 1 hr, the exit flow is closed; then the helium is made to exit through a mechanical pump. This helium evacuation is continued until there is a pressure of less than 1 torr in the system. The chromatographic column and the charcoal trap are then closed off and contain the gas from the ice. The air 86
159000'E #3 WEST
#2 #1 EAST
..s-2.
KM
I
ALLAN % HILLS '
MONOCL I NE
Figure 2. Locations of Ice samples #1, #2, and #3 taken during 1978-79 field season, as viewed in sketch of plane perpendicular to the ice, 3.5 kilometers north of latitude 76°45'S.
minus its carbon dioxide content is removed from the chromatographic column by raising its temperature to 25° C. The amount of air is measured and stored for later analyses. The carbon dioxide is removed from the chromatographic column by raising its temperature to 250° C. The accompanying table gives results for three successive extractions that were done in order to test the completeness of our extraction method. This work has been supported by National Science Foundation grant DPP 78-0573. Table 1. Gas from 5.5 kg of 1187-ft depth Byrd core Melt-water temperature Air CO2 Extraction (°C) (cm3 SIP) (cm3 SIP) 1st 2nd 3rd
24 475.0 0.27 24 24.6 0.03 55 2.5 0.01
Total
- 502.1 0.31 References
Cassidy, W. A. 1977. Antarctic search for meteorites. Antarctic Journal of the United States. 12: 96-98. Cassidy, W. A. 1978. Antarctic search for meteorites during the 1977-78 field season. Antarctic Journal of the United States, 13: 39-40. Evans, J . C., and L. A. Rancitelli. 1979. Non-destructive Al measurements on Antarctic meteorites. Lunar and Planetaiy Science, 10: 373-75. Fireman, E. L., L. A. Rancitelli, and T. Kirsten. 1979. Terrestrial ages of four Allan Hills meteorites: Consequences for Antarctic ice. Science, 203: 453-55. Nagata, T. 1975. Yamato meteorites collected in Antarctica in 1969. Tokyo: National Institute of Polar Research. Nagata, T. 1977. Japanese scientific activities in the McMurdo region, 1976-1977. Antarctic Journal of the United States, 12: 95-96. Oeschger, H., B. Stauffer, P. Bucher, and H. H. Loosli. 1977. Extraction of gases and dissolved and particulate matter from ice in deep boreholes. In Proceedings of the Grenoble Symposium, 1975, on Isotopes and Impurities in Snow and Ice. IAHS publication no. 118, pp. 307-11. Weber, H. H., and L. Schultz. 1978. Noble gases in 10 stony meteorites from Antarctica and their exposure ages. Meteoritics, 13: 658-60.
