Vostok Ice Core Timescales

• Ruddiman and Raymo 2003 "RR03", Quaternary Science Reviews, 22, 141-155
• Petit et al. 1999 "GT4", Nature, 399, 429-436
• Jouzel et al. 1996
• Lorius et al. 1985
• Lorius et al. 1985 Extended Glaciological Timescale
• Sowers et al. 1985

Different timescales have been used for the interpretation of Vostok ice core records. They are reported in ky BP.

- The Ruddiman and Raymo (2003) Methane-Based Time Scale was developed by tuning the Vostok methane signal to mid-July 30°N insolation.

- The Petit et al. GT4 timescale extends the glaciological timescale of Jouzel et al.

- The Lorius et al. timescale (column 2) has been derived by combining a glaciological model, fully described in Ritz (1992) and an accumulation model in which past accumulation is derived from the temperature record reconstructed from the deuterium isotopic profile (see Lorius et al., 1985).

- Sowers et al. correlated the d18O of paleoatmospheric O2 derived from the Vostok 3G and 4G cores, into a record of changes in the d18O of sea water derived from records of the d18O of foraminifera (see Sowers et al., 1993). This timescale is given in column 3.

- The glaciological timescale of Lorius et al. (1985) has been extended accounting for a linear increase of modern accumulation upstream of Vostok. This Extended Glaciological Timescale (EGT; column 4) is described in Jouzel et al. (1993).

- Jouzel et al. (1996) have used a modified version of EGT (column 4) assuming that this timescale overestimates the increase of age with depth by 12% for gas ages older than 112 ky BP.