Role of the Antarctic ice sheet in the genesis and evolution of subglacial Lake Vostok
V.V. LUKIN1,2, A.N. MARKOV3,4
1Arctic and Antarctic Research Institute, St. Petersburg, Russia
2St. Petersburg State University, St. Petersburg, Russia
3China University of Geosciences, School of Geophysics and Information, Beijing, China
4Jilin University, Polar Research Center, Changchun, China
Keywords: Antarctica, ice sheet above Lake Vostok, layered glacier structure, lake water body, numerical modeling of the processes of glacier melting, pre-glacial lake origin
Abstract
The world’s largest Antarctic ice sheet has a significant influence on the formation and variability of climate, the system of circulation of oceanic water, biodiversity and surface and subglacial lakes of this region. Appearance of the water strata of land hydrology bodies of Antarctica is usually connected with the processes of snow and ice melting. In the case of subglacial lakes this process occurs on the glacier bed under the influence of thermal isolation of the geothermal flow by a large ice strata, energy of friction forces due to the movement of the glacier over bedrocks and large pressure values, which allows melt water to accumulate in hollows of the subglacial relief. In the case of Lake Vostok, however, the genesis of its water body is connected with accumulation of atmospheric precipitation and discharge of ancient rivers that existed on this continent at the time of its location in the temperate climatic belt before the epoch of its glaciation, i. e. before the beginning of formation of one whole continental glacial cover. We distinguish the layered structure of the glacier above Lake Vostok explaining the genesis of all layers by different stages of glaciation of the sixth continent. Analysis of geological, geophysical, glaciological and biological studies in the area of location of the valley of Lake Vostok convincingly proves that the water body of this subglacial lake existed on the surface before the onset of multiyear glaciation of Antarctica while the glacier has only a role of the cover isolating the water body. This conclusion is confirmed by the results of numerical modeling of the processes of glacier freezing/melting proving that the lake water strata could never freeze through to the bottom due to water adfreeze at the glacier bottom surface. Thus the water body and bottom sediments of Lake Vostok are more ancient natural bodies than the Antarctic ice sheet.
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