Byrd-Station ice core

Palais JM (1985) Tephra layers and ice chemistry in the Byrd-Station ice core, Antarctica. Ph.D. dissertation. Dept. Geol. Minertil., The Ohio State University, Columbus, OH... 

The Byrd-Station ice core was drilled through the West Antarctic ice sheet in 1968 and reached bedrock at a depth of 2,164 m (Gow et al. 1968). This core contains about 2,000 layers of volcanic ash or tephra (Gow and Williamson 1971 Gow 1971). The term includes all volcanic ejecta regardless of the diameters of the particles. These tephra were subsequently described by Kyle and Jezek (1978), Gow et al. (1979), and Kyle et al. (1981). In addition, Epstein et al. (1970) and Johnsen et al. (1972) demonstrated by means of the values of the ice that the Byrd-Station core contains a record of the transition from the cold climate of the Wisconsinan ice age to the present Holocene interglacial. 

The Byrd-Station ice core confirmed and extended conclusions reached previously from the study of the Camp-Century core drilled in northwestern Greenland in 1966 (Dansgaard et al. 1969, 1971 Johnsen et al. 1972 Morner 1972, 1974 Langway et al. 1985). The ice of the Camp-Century core also contains tephra that originated from volcanic eruptions in Iceland (Hammer and Clausen 1981 Hammer 1984). 

Palais and Legrand (1985) concluded that the ice of the Byrd Station core contains sodium chloride (NaCl) and sodium sulfate (Na SO ) of marine origin. The interactions of ions during transport from the surface of the ocean to the interior of Antarctica permits elemental fractionation which causes an excess of Cl" in some places and an excess of Na+in others. The data in Table 17.12 indicate that the Byrd-Station ice core contains an excess of Cl" over Na+(not shown) but an excess of Na+as Na SO occurs in the ice of the Vostok core (deAngelis et al. 1984). 

Kyle PR, Jezek PA, Mosley-Thompson E, Thompson LG (1981) Tephra layers in the Byrd Station ice core and the Dome C ice core, Antarctica, and their climatic importance. J Volcanol Geotherm Res 11 29-39... 

Figure 11. Camp Century, Greenland and Byrd Station, Antarctica ice cores COs contents of the first gas extraction fraction and S1S0 profiles (50). The S,sO profiles are from Dansgaard and coworkers, and the ages are calculated according to Ref. 54.

Figure 14.13 shows C02 concentrations measured in ice cores at the Byrd Station in Antartica from 5000 years before the present (bp) to 40,000 years bp (Anklin et al., 1997). The use of ice core data for elucidating atmospheric composition is discussed by Delmas (1992) and in more detail in Section E.l. As seen in Fig. 14.13, atmospheric C02 concentrations about 5000 years ago were only 280 ppm. (Note that interpretation of such ice core data must be carried out with care since there is evidence that in some cases, C02 can be produced in the ice from decomposition of carbonate e.g., see Smith et al., 1997.)... 

FIGURE 14.13 Concentrations of atmospheric C02 measured using gases trapped in ice cores from Byrd Station, Antarctica, from 5000 to 40,000 years before the present (bp) (adapted from Anklin et al., 1997). 

Ice cores have been drilled at several places in the Antarctic, including the research outposts at Vostok and Byrd Station. What they tell us is largely consistent with the climate records obtained from the Greenland ice sheets on the other side of the world, as well as with those from marine sediment cores. One can double-check these ice-core records because the ratio of H to deuterium in the water molecules of the ice also acts as an atmospheric thermometer (Fig. 156). 

Epstein S. and Sharp R. P. (1970) Antarctic ice sheet stable isotope analyses of Byrd station cores and interhemispheric climatic implications. Science 16, 1570-1572. 

The ice sheet was penetrated by drilling at Vostok Station (Russia) on the East Antarctic ice sheet and at Byrd Station (USA) in West Antarctica. The resulting cores contain valuable records of past climatic conditions, but only the core at Byrd Station recovered samples of the subglacial bedrock. The climate record contained in these cores and in the core that was recently recovered at Dome C will be featured in a later section of this chapter. 

The chemical composition of ice in the long cores that were recovered in East Antarctica at Dome C (74°39 S, 2A° 0 E), Vostok (78- 30 S, 106 54 E) and South Pole (90 S) were determined by Petit et al. (1981), deAngehs et al. (1984), and Delmas et al. (1982a), respectively. The ice in the core drilled at Byrd Station in West Antarctica was analyzed by Palais (1985) and Palais and Legrand (1985). 

The concentrations of cations Na+, Mg +, K+, NH, and H+and anions CL, NO, and SOl in ice of the Byrd-Station core were determined by Palais (1985) and by Palais and Legrand (1985) who divided the core into four segments based on climate criteria derived from the profile. The average concentrations of the ions in each of the segments are summarized in Table 17.12. 

The study of microparticles in Antarctic ice cores by L.G. Thompson and E. Mosley-Thompson at The Ohio State University (Thompson et al. 1975, 1981 Thompson 1977a, b Mosley-Thompson 1979 Thonpson and Mosley-Thompson 1981) indicated that the concentration of dust particles in ice cores from the South Pole and Dome C in East Antarctica, from Byrd Station in West Antarctica, as well as from Camp Century in northwestern Greenland have certain common characteristics identified in Table 17.13. The conclusions that are derivable from the data include ... 

Layers of ice containing disseminated particles of volcanic origin (i.e., tephra) are a common feature of blue ice areas and in the vicinity of volcanic vents in the Transantarctic Mountains. Volcanic tephra have also been found in the ice cores drilled at South Pole Station, Dome C, Vostock Station, and at Byrd Station, as well as in the glacial deposits that cover the floor of Wright Valley (Jones et al. 1973b Boger and Faure 1988). 

Fig. 17.44 The chemical compositions of coarse tephra at different depths in the Byrd-Station core classify them as alkali-rich tra-chytes/phonolites. The points labeled 1 and 2 are volcanic rocks from Mt. Takahe and Mt. Sidley, respectively, in Marie Byrd Land. The chemical compositions of the fine tephra in the Byrd-Station core scatter widely and are not shown on this diagram. The tephra from South Pole, the Yamato Mountains, and Vostok Station are andesites that could have originated from volcanoes in the South Sandwich Islands (3 = Candlemas Island, 4 = Bellingshausen Island). Tephra from the Lewis Cliff ice tongue are composed of...

The ice core drilled in 1983/84 at South Pole Station contained a 3-mm tephra layer at a depth of 303.44 m (Palais et al. 1987). The tephra are composed of vesic-nlar glass with crystals of quartz, pyroxene, and pla-gioclase. The bulk chemical composition of these tephra plots close to the boundary between the andesite and benmoreite fields in Fig. 17.44 in strong contrast to the tephra in the cores at Byrd Station and Dome C (See also Koeberl 1990, Table 1). 

Long cores extracted from the ice sheets in East and West Antarctica contain layers of dirty ice composed of particles of volcanic ash called tephra. The tephra in the core drilled at Byrd Station in West Antarctica consist of alkali-rich volcanic ash almost certainly erupted by Mt. Takahe in Marie Byrd Land. The tephra in the ice at South Pole, Vostok, and the Yamato Mountains are composed of andesite that matches the composition of volcanic rocks erupted in the South Sandwich Islands 4,500 km from Vostok. Tephra in a core at Dome C are composed of trachyte like those in the Byrd-Station core and could have originated from the... 

Epstein S, Sharp RP, Gow AJ (1970) Antarctic ice sheet stable isotope analysis of Byrd Station cores and interhemispheric climatic implications. Science 168 1570-1572 Eugster HP (1966) Sodium carbonate-bicarbonate minerals as indicators of Pco. J Geophys Res 71 3369-3377 Faure G (1990a) Origin of stranding surfaces. Lunar Planet. Inst. 

Thompson LG (1977b) Variations in microparticle concentration, size distribution, and elemental composition found in Camp Century, Greenland, and Byrd Station, Antarctica, deep ice cores. Proceedings of Grenoble Symposium, 1975. lAHS-AISH Pub. No. 118 351-364 Thompson LG, Mosley-Thompson E (1981) Temporal variability of microparticle properties in polar ice sheets. J Volcanol Geotherm Res 11 11-27... 

Thompson LG, Hamilton WL, BuU C (1975) Climatological implications of microparticle concentrations in the ice core from Byrd Station, Western Antarctica. J Glaciol 14 433 44 Thompson LG, Mosley-Thompson E, Petit JR (1981) Glaciological and climatological interpretation of microparticle concentrations from the French 905-meter Dome C, Antarctica, core. In Sea level, ice, and chmate. lAHS Pub. No. 131 227-234 Thompson, S.L. and S.H. Schneider, 1981. Carbon dioxide and climate ice and ocean. Nature, 290 9-10 Thornton I (ed) (1983) Applied environmental geochemistry. Academic Press, London... 

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