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

摘要

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.