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Non-belspo (2000-ongoing)

Basal Ice at Lake Vostok

Project description

Our laboratory is actively involved in the interpretation of the physico-chemical properties of the basal ice of the Vostok ice core. A geochemical investigation of the deepest part of the Vostok ice core between 3310 m, the depth at which the palaeoenvironmental record present in the ice above is lost, and the bottom of the core about 130 m above subglacial Lake Vostok reveals two contrasted sections.
The upper section (3310- 3539 m depth) still consists of ice of meteoric origin but subjected to widespread complex deformation. This deformation has been analyzed in light of a δD- deuterium excess diagram and information on microparticles, crystal sizes and chemical elements distributions in that part of the core. Such ice deformation occurred when the ice was still grounded upstream from Vostok Station, in a region with subfreezing temperatures.
The lower section from 3539 m to the bottom of the core at3623 m depth is lake ice formed by freezing of subglacial Lake Vostok waters. This is indicated by the isotopic properties (δD, δ180 and deuterium excess), by electrical conductivity measurements (ECM), crystallography and gaz content of the ice. These ice core data together with data on ionic chemistry favor an origin of the lake ice by frazil ice generation in a supercooled (below pressure melting point) water plume existing in the lake followed by accretion and consolidation by subsequent freezing of the host water.

Project team

Coordinator:

Prof Dr. Roland Souchez

Involved research group:

Involved Partners:

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