Thermobaric Conditions at Ice-Water Interface in Subglacial Lake Vostok, East Antarctica

P G Тalalay,A N Markov

doi:10.4236/nr.2015.66040

Abstract

Thermobaric conditions of subglacial Antarctic environment remain poorly understood, despite recent advances in radar and seismic surveying. The direct accessing to the largest subglacial lake, Lake Vostok, was carried out twice by Russian scientists in February 2012 and January 2015, opening new opportunities for assessing the thermobaric conditions at ice-water interface. According to the assumption that ice sheet is “floating” on the lake, it was predicted that the water would rise 30 - 40 m in the bottom part of the borehole, but in fact the water rose from the lake to a height of more than 500 m. To explain this phenomenon we assume that the pressure in Lake Vostok results from the external pressure of the entire mass of ice above it and the pressure of the water column that is overlaid above the point being considered. Extrapolation of temperature measurements from the deep bore-holes drilled at Vostok Station also confirmed that the bed of the ice sheet is at pressure melting point. As a result of accessing Lake Vostok, the pressure in the lake is reduced that would lead to the formation of a new additional layer of accretion ice on the lower ice sheet surface.

Highlights

It is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheet
Where ρi is the average ice density, kg/m3; g is the acceleration of gravity, 9.81 m/s2; ZV is the thickness of the ice sheet at Vostok station, m; zf is the firn correction accounting for the air content in the upper snow-firn zone
Assuming that the pressure in the Lake Vostok is composed of the external pressure of the entire mass of ice above the lake and the pressure of the water column that is overlaid above the point being considered, we obtain: ( ) P=II

Summary

Introduction

It is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheet. (2015) Thermobaric Conditions at Ice-Water Interface in Subglacial Lake Vostok, East Antarctica. Drilling a deep Hole 5G started in February 1990 six years before the large subglacial lake under Vostok station was officially recognized [7]. After 22 years Russian team made contact with the Lake Vostok water February 5, 2012 at a depth 3769.3 m (Figure 2). On January 2013, the drill deployment found the first signs of frozen lake water (cork of bright white hard material) at the depth of 3181.9 m at distance of ∼587 m from the bottom of ice sheet [10]. Deeper than 3406.1 m the drill began to recover the continuous full diameter core composed from outside frozen water ice and hydrate core. 34.1 m long core with frozen lake water was recovered

Pressure at Ice Sheet-Lake Vostok Interface

Temperature at the Ice-Water Interface

Findings

Conclusions