Vostok core

Figure 3.16 compares 8 0 profiles from Antarctica and Greenland. The dramatic 5-shifts observed in Greenland cores are less pronounced in the 5-record along the Vostok core, probably because the shifts in Greenland are connected to rapid ocean/atmosphere circulation changes in the North Atlantic (for more details, see Sect. 3.12.1). 

Petit J. R., Mounier L., Jouzel J., Korotkevich Y. S., Kotyakov V. I., and Lorius C. (1990) Paleoclimatological and chronological implications of the Vostok core dust record. Nature 343, 56-58. 

Either 6D or profiles can be indifferently used as a climatic record. Different choices have been made by various teams. The climate reconstruction is based on the interpretation of the 6D profile for Vostok, Dome B, old Dome C and EPICA Dome C, and on for all the other cores. Interestingly, measuring both isotopes on the same core brings additional information about the changes affecting the oceanic sources of Antarctic precipitation through the deuterium-excess parameter. Most of the ice core projects now include measurements of both isotopes. Based on the Vostok core results, we illustrate in Section 4.08.8 how this co-isotopic approach can be used. 

In this review, dealing with the temperature interpretation of isotopic ice core records, we will focus mainly on the Vostok core in central East Antarctica and on the GRIP and GISP 2 cores from central Greenland. The reason is that the effort undertaken to calibrate the isotopic paleothermometer through other estimates of... 

Greenland (Grootes and Stuiver 1997 Johnsen et al. 1997), from the Vostok core of central East Antarctica (Fig. 1) (Petit et al. 1999), and from other ice cores (e.g. Thompson et al. 1998). Typically, isotopic composition of water is reported as or 5D, respectively the per mil deviation of or D H from an approximation of the... 

FIGURE 2 Climate and atmospheric composition over the past 420,000 years from the Vostok core (Petit et tiL, 1999). 

Drilling resumed in 1980 and reached a depth of 2,083 m where the depositional age of the ice was estimated to be 150,000 years (Lorius et al. 1985). The 5 0 and 6D values of the ice were measured at the Laboratoire de Geochemie Isotopique in Saclay, Gif-sur-Yvette, in France. The resulting 5 0 and 8D profiles of the Vostok core were interpreted by Lorius et al. (1985) and by Jouzel et al. (1982), respectively. In addition, the concentrations of carbon dioxide and of chemical impurities in this core were measured in Russian and French laboratories. 

The 5 0 profile of the Vostok core in Fig. 17.28 includes four intervals of low temperature when the ice was strongly depleted in 0 and reached 5 0 values of -62%c (SMOW). Lorius et al. (1985) used these cold intervals to subdivide the core into eight sections which they identified by the letters A-H. The depths in the core and the ages of these intervals are indicated in Table 17.7. Accordingly, the core extends from the Holocene (A) (Present) to the Wisconsinan glacial... 

The information derivable from the Vostok core is summarized in Table 17.8... 

The climatic history derivable from the Vostok core was later extended by Petit et al. (1999) to 488,000 years. 

Fig. 17.29 The thickness of the annual layers of ice in the Vostok core (Fig. 17.28) decreases with increasing depth in the upper part of the core and approaches a constant value below a depth of about 1,600 m. This property causes the age of ice in a long core to vary non-linearly with depth (Derived from Figure 1 of Lorius et al. 1985)...

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). 

The Vostok tephra are very similar in composition to the tephra in the South-Pole core and closely resemble the andesite in Candlemas and Bellingshausen islands of the South Sandwich Islands in Fig. 17.46 (57°45 S, 026°30 W) (Tomblin 1979 Baker 1978). The distance between these islands and Vostok station is about 4,500 km (Palais et al. 1987 Kyle et al. 1984). In spite of the dispersion during transport through the atmosphere, the thickness of the tephra layer in the Vostok core is 5 cm at a depth of 101 m giving it an assigned age of 3,300 years. Therefore, the volcanic ash erupted by volcanoes in the South Sandwich Islands may have formed a large plume over East Antarctica. If so, this ash layer may be a useful stratigraphic marker in the East Antarctic ice sheet (Kyle et al. 1984). 

Petit, J.R., Jouzel, J., Raynaud, D. and 16 others. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok core, Antarctica. Nature 399,429-436. Petrochemistry Net. 2004. What is Petrochemistry www.Detrochemistrv.net Pfeiffer, P. 2004. Eating Fossil Fuels, www.copvcia.com Pfizer. 2003. Viagra, www.viagra.com... 

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