The Vostok Core

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 Holocene interglacial has lasted about 13,000 years which is about one half the duration of the Sangoman interglacial. 

The average annual temperatures of the Wisconsin and Illinoian glaciations at Vostok were about 15°C colder than the present average annual temperature. 

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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). 

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... 

Fig. 1-2 Chemical data from the Vostok ice core. The graph of 5D can be taken as a proxy for temperature changes, as described in Chapter 18. CO2 and CH4 are greenhouse gases and vary in the same direction as temperature. Non-seasalt sulfate and methane sulfonic acid are both sulfur species existing in the particle phase, and are positively correlated with each other, but negatively with T. Major variations for all of these variables seem to correlate either positively or negatively with each other, indicating a coupled system. <5D, non-seasalt sulfate, and methane sulfonic acid data kindly provided by Dr Eric Saltzman. CO2 data are from Bamola et al. (1987) and Jouzel et al. (1993). CH4 data are from Chappellaz et al. (1990) and Jouzel et al. (1993). (ppmv = parts per million by volume ppbv = parts per billion by volime)...

Chappellaz, ]., Barnola, J. M., Raynaud, D., Korotkevich, Y. S., and Lorius, C. (1990). Atmospheric methane record over the last climatic cycle revealed by the Vostok ice core. Nature 345,127-131. 

Fig. 18-12 Record of atmospheric CO2 over the past 220 000 years from the Vostok ice core (Jouzel et al., 1993 Bamola et al., 1987), and the corresponding deuterium isotope record temperature proxy (Jouzel et al., 1993) (see Section 18.3.2).

Fig. 18-21 The last 250 000 years of environmental history, recorded in the central Antarctic ice sheet. Bottom three panels are data from the Vostok ice core (Lorius et al., 1990 Jouzel et at., 1993). Top panel is marine data representing global ice volume (Shackle-ton el al., 1990).

Jouzel, J., Barkov, N. 1., Barnola, J. M. et al. (1993). Extending the Vostok ice-core record of paleoclimate to the penultimate glacial period. Nature 364, 407-412. 

The characteristics of the changes in several species discussed in this chapter are shown in Fig. 19-3. This figure depicts the changing composition of the atmosphere on three time scales. Figures 19-3a-c show the simultaneous variation of CO2, CH4, temperature, and SO from the Vostok ice core (see also Fig. 1-2). These records also clearly demonstrate that the Earth functions as a coupled system. Temperature, CO2 and CH4 are positively correlated with one another, but each is negatively correlated with (for reasons that are not yet known). This time period covers 160000 years including the... 

Fig. 9.6 Climate records from the Vostok Antarctic ice core and the tropical carbonate seafloor sediment core V19-30 (Shakleton, N. J. and Pisais, N. Am. Geophys. Union, Geophys. Mon. 3, 303 (1985))...

The 8 N- and 8 0-values of atmospheric N2O today, range from 6.4 to 7.0%c and 43 to 45.5%c (Sowers 2001). Terrestrial emissions have generally lower 8-values than marine sources. The 8 N and 8 0-values of stratospheric N2O gradually increase with altitude due to preferential photodissociation of the lighter isotopes (Rahn and Wahlen 1997). Oxygen isotope values of atmospheric nitrous oxide exhibit a mass-independent component (Cliff and Thiemens 1997 Clifif et al. 1999), which increases with altitude and distance from the source. The responsible process has not been discovered so far. First isotope measurements of N2O from the Vostok ice core by Sowers (2001) indicate large and 0 variations with time (8 N from 10 to 25%c and 8 0 from 30 to 50%c), which have been interpreted to result from in situ N2O production via nitrification. 

Peterson BJ, Fry B (1987) Stable isotopes in ecosystem studies. Ann Rev Ecol Syst 18 293-320 Petit JR, et al. (1999) Qimate and atmospheric history of the past 420000 years from the Vostok ice core, Antarctica. Nature 399 429 36... 

Sowers T, Bender M, Raynaud D, Korotkevich YS, Orchardo J (1991) The 6 0 of atmospheric O2 from air inclusions in the Vostok ice core timing of CO2 and ice volume changes during the Penultimate degladation. Paleoceanography 6 679-696... 

Fig. 15a comes from N. J. Shackleton, A. Berger, and W. R. Peltier, An Alternative Astronomical Calibration of the Lower Pleistocene Timescale Based on ODP Site 677 , Transactions of the Royal Society of Edinburgh Earth Sciences, 81 (1990), 251. Fig. 156 comes from J. Jouzel et al., Extending the Vostok Ice-Core Record of Palaeocllmate to the Penultimate Glacial Period , Nature, 364 (1993), 407. 

Figure 10.36. The CO2 content of air bubbles trapped in Antarctic glacial ice at the Vostok station as a function of depth in the ice core. Two ages of the ice are shown. (After Barnola et al., 1987.)...

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