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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, no180, pp. 41-62 [22 page(s) (article)] (1 p.1/4)

Langue / Language

Anglais

Editeur / Publisher

International Glaciological Society, Cambridge, ROYAUME-UNI  (1947) (Revue)

Mots-clés anglais / English Keywords

polar regions

;

Vostok Station

;

Antarctica

;

interglacial periods

;

glacial periods

;

ion chromatography

;

Electron backscattering

;

Dispersive spectrometry

;

X-ray spectroscopy

;

scanning electron microscopy

;

image analysis

;

impurities

;

Crystal orientation

;

textures

;

microstructures

;

ice

;

drill cores

;

Core boring

;

ice sheets

;

Polar Cap

;

Mots-clés français / French Keywords

Région Polaire

;

Station Vostok

;

Antarctique

;

Période interglaciaire

;

Période glaciaire

;

Chromatographie ionique

;

Rétrodiffusion électron

;

Spectrométrie dispersive

;

Spectrométrie RX

;

Microscopie électronique balayage

;

Analyse image

;

Impureté

;

Orientation cristalline

;

Texture

;

Microstructure

;

Glace

;

Carotte

;

Carottage

;

Inlandsis

;

Calotte polaire

;

Mots-clés espagnols / Spanish Keywords

Antártico

;

Período interglaciario

;

Período glaciario

;

Cromatografía iónica

;

Espectrometría dispersiva

;

Espectrometría RX

;

Análisis imagen

;

Impureza

;

Orientación cristalina

;

Textura

;

Microestructura

;

Hielo

;

Testigo

;

Extracción testigo

;

Masa de hielo

;

Casquete polar

;

Localisation / Location

INIST-CNRS, Cote INIST : 5524, 35400014352133.0040

Nº notice refdoc (ud4) : 18682954



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