Titre du document / Document title
The microstructure of meteoric ice from Vostok, Antarctica
Auteur(s) / Author(s)
OBBARD Rachel (1) ;
BAKER Ian (1) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755-8000, ETATS-UNIS
Résumé / Abstract
The 3623 m long, 5G core collected at Vostok station, Antarctica, contains alternating layers of meteoric ice with two distinctly different microstructures. In this paper, we present the microstructure and impurity content of a number of specimens ranging in depth from 97 to 3416m, describe in detail the characteristics of the different layers and propose a mechanism for their microstructural development. Digital image analysis, ion chromatography, scanning electron microscopy and energy dispersive X-ray spectroscopy were used to measure texture and the location and type of impurities; electron backscatter diffraction was used to determine crystal orientation. The ice associated with interglacial periods is characterized by relatively coarse grains and a strong preferred orientation of the caxes in a plane encompassing the coring direction, producing a vertical-girdle fabric. In contrast, ice from glacial periods is characterized by a much smaller grain size and a strong single-maximum fabric, where the c axes are clustered around the vertical. Calcium is uniquely present in the grain boundaries of the fine-grained glacial layers, and its effect on grain-boundary mobility and the misorientation dependence of mobility can explain the development of the discontinuous microstructure seen in glacial ice at Vostok station.
Revue / Journal Title
Journal of Glaciology
ISSN
0022-1430
CODEN JOGLAO
Source / Source
2007, vol. 53, n
o180, pp. 41-62 [22 page(s) (article)] (1 p.1/4)
Langue / Language
Anglais
Editeur / Publisher
International Glaciological Society, Cambridge, ROYAUME-UNI
(1947)
(Revue)
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Localisation / Location
INIST-CNRS, Cote INIST : 5524, 35400014352133.0040
Nº notice refdoc (ud4) : 18682954
