Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2016-247
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
30 Nov 2016
Review status
This discussion paper is under review for the journal The Cryosphere (TC).
Location and distribution of micro-inclusions in the EDML and NEEM ice cores using optical microscopy and in-situ Raman spectroscopy
Jan Eichler1,2, Ina Kleitz1, Maddalena Bayer1, Daniela Jansen1, Sepp Kipfstuhl1, Wataru Shigeyama3,4, Christian Weikusat1, and Ilka Weikusat1,2 1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 27568 Bremerhaven, Germany
2Department of Geosciences, Eberhard Karls University Tübingen, 72074 Tübingen, Germany
3Department of Polar Science, SOKENDAI (The Graduate University for Advanced Studies), 10-3 Midori-cho, Tachikawa, Tokyo, 190-8518, Japan
4National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo, 190-8518, Japan
Abstract. Impurities control a variety of physical properties of polar ice. Their impact can be observed at all scales – from the microstructure (e.g., grain size and orientation) to the ice sheet flow behavior (e.g., borehole tilting and closure). Most impurities are likely to form micrometer-sized second phase inclusions. It has been suggested that these particles control the grain size of polycrystalline ice by the pinning of grain boundaries (Zener pinning), which should be reflected in the distribution of the inclusions in relation to the grain boundary network. We used an optical microscope to generate high-resolution large-scale maps (3 μm pix−1, 8 × 2 cm2) of the distribution of micro-inclusions in four samples from the EDML (Antarctica) and NEEM (Greenland) polar ice cores. The in-situ positions of more than 5000 μ-inclusions have been determined. A Raman microscope was used to confirm the extrinsic nature of a sample proportion of the mapped inclusions. A superposition of the 2D grain boundary network and μ-inclusion distributions show no significant correlations between grain boundaries and μ-inclusions. In particular, no signs could be found of grain boundaries harvesting μ-inclusions, no evidence of μ-inclusions inhibiting grain boundary migration by slow mode pinning could be detected. Consequences for our understanding of the impurity effect on ice microstructure and rheology are discussed.

Citation: Eichler, J., Kleitz, I., Bayer, M., Jansen, D., Kipfstuhl, S., Shigeyama, W., Weikusat, C., and Weikusat, I.: Location and distribution of micro-inclusions in the EDML and NEEM ice cores using optical microscopy and in-situ Raman spectroscopy, The Cryosphere Discuss., doi:10.5194/tc-2016-247, in review, 2016.
Jan Eichler et al.
Jan Eichler et al.
Jan Eichler et al.

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Short summary
This study contributes to investigations of the effect of impurities on ice microstructure and flow properties. For the first time we mapped over 5000 micro-inclusions in four samples from the EDML and NEEM polar ice cores. The particle distributions show no correlation with grain boundaries and thus we conclude that particle pinning plays only a secondary role for the microstructure evolution. Alternative mechanisms are discussed.
This study contributes to investigations of the effect of impurities on ice microstructure and...
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