Isotopic examination at depth of an Antarctic glacier

The authors made two drillings in the ice of Adelie Land, near a moraine. Two bore samples of ice were taken at 98 m (G1) and 105 m (G2). The deuterium contents of the samples from this ice core are between δD -370 per mille and δD = -40 per mille. Between the surface and +54 m, the value of δD varies around -145 per mille for the two bore samples, which corresponds to the coastal precipitation in that part of the continent. From this, it can be deduced that this layer of ice results from the transformation of the local granular ice. Between +54 and +34 m, δD drops rapidly from -145 per mille to -350 per mille. Down to -9m (G1) and +7.5 m (G2) δD fluctuates around -350 per mille. On the basis of the topographical data for the area, and the relationship between δD and the annual mean temperature, the authors explain the origin of this ice on the polar plateau, about 900 km from the coast. Finally, the ice layer in contact with the sediment has a very high δD-value reaching -40 per mille and it is believed to be of marine origin. It is assumed from study of the deuterium that there is an ice flow from the polar cap which passes between a layer of local ice and a layer of marine ice. (author)