文章基本信息

标题：The microstructure of meteoric ice from Vostok, Antarctica
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作者：Rachel Obbard ; Ian Baker
期刊名称：Journal of Glaciology
印刷版ISSN：0022-1430
电子版ISSN：1727-5652
出版年度：2007
卷号：53
期号：180
页码：41-62
DOI：10.3189/172756507781833901
出版社：Cambridge University Press
摘要：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 3416 m, 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 c axes 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 singlemaximum 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.