Characterization of subglacial Lake Vostok as seen from physical and isotope properties of accreted ice

Abstract

Deep drilling at the Vostok Station has reached the surface of subglacial Lake Vostok (LV) twice-in February 2012 and January 2015. As a result, three replicate cores from boreholes 5G-1, 5G-2 and 5G-3 became available for detailed and revalidation analyses of the 230 m thickness of the accreted ice, down to its contact with water at 3769 m below the surface. The study reveals that the concentration of gases in the lake water beneath Vostok is unexpectedly low. A clear signature of the melt water in the surface layer of the lake, which is subject to refreezing on the icy ceiling of LV, has been discerned in the three different properties of the accreted ice: the ice texture, the isotopic and the gas content of the ice. These sets of data indicate in concert that poor mixing of the melt (and hydrothermal) water with the resident lake water and pronounced spatial and/or temporal variability of local hydrological conditions are likely to be the characteristics of the southern end of the lake. The latter implies that the surface water may be not representative enough to study LV's behaviour, and that direct sampling of the lake at different depths is needed in order to move ahead with our understanding of the lake's hydrological regime.

Pingo drilling reveals sodium–chloride‐dominated massive ice in Grøndalen, Spitsbergen

“…Yet it is clear that salt expelled from stage A ice must have been incorporated into later stage ice and some of it was left in brine water (i.e., brine encountered at 19 m bs) because permafrost temperatures were not low enough for complete freezing of the NaCl solution. Higher mineralization in stage B might be explained by the process of freezing liquid water pockets captured in the ice as was found by drilling of Antarctic Lake Vostok 46 accompanied by later salt migration down‐core. Due to the frozen state of sediments and the absence of a water lens below the Nori pingo at present and no sign of spring outflow, it can be postulated that the process of ice accretion stopped at some time in the past and the Nori pingo is now inactive.…”

Fifty-five years of Russian radio-echo sounding investigations in Antarctica

“…Ice thickness in the drilling site vicinity was predicted to be 3760 ± 30 m based on the seismic data, and 3775 ± 15 m based on RES data (Popov and others, 2003). During the penetration of Lake Vostok on 5 February 2012, the ice thickness was 3758.6 ± 3 m (Lipenkov and others, 2016). Therefore, the reflection seismic data were extremely accurate in comparison to the RES data which was less accurate than expected.…”

Development of a clean hot water drill to access Subglacial Lake CECs, West Antarctica

“…The first accessing of an Antarctic subglacial lake took place in February 2012 at Lake Vostok in central East Antarctica (Lukin and Vasiliev, 2014; Lipenkov and others, 2016). Refrozen lake water samples were later recovered using an ice core drill, although contamination from the hydrocarbon-based drilling fluids remains an issue (Alekhina and others, 2018).…”