Location and composition of micro-inclusions in deep ice from the EDML ice core (Antarctica) using optical microscope and cryo-Raman spectroscopy

• Main Authors: Eichler, Jan, Kleitz, Ina, Bayer, Maddalena, Jansen, Daniela, Kipfstuhl, Sepp, Shigeyama, Wataru, Weikusat, Christian, Wilhelms, Frank, Weikusat, Ilka
• Format: Conference Object
• Language: unknown
• Published: 2018
• Subjects: Antarc*; Antarctica; ice core
• Online Access: https://epic.awi.de/id/eprint/46796/; https://epic.awi.de/id/eprint/46796/1/PCI_Poster_Impurities_cmyk.pdf; https://hdl.handle.net/10013/epic.fd0ca8d6-00f8-433b-bf9d-4a5ea0af734b; https://hdl.handle.net/

The impurity content in meteoric ice from polar regions is relatively low compared to other natural materials. However, it controls a variety of physical properties of ice - from dielectric response to its mechanical behaviour. Links between impurity concentration, changes in ice micro-structure and deformation rate have been reported on several scales. In order to approach the responsible mechanisms, a better understanding is needed regarding the in-situ form, location, and distribution of the different species within the polycrystal. We used an optical microscope to generate high-resolution 2D-maps of micro-inclusions in deep ice from the EDML ice core (Antarctica). Superposition of the grain boundary network and micro-inclusion distributions shows no significant correlations between grain boundaries and micro-inclusions. Implications for the relevance of Zener pinning during grain boundary migration and redistribution of impurities by grain boundary drag are discussed. Raman spectra of micro-inclusions in selected regions were obtained using a confocal cryo-Raman system. Comparison with ion chromatography shows that most of the available ions in ice precipitate in form of micro-inclusions. However, indications were found that some of the residual components could coexist in form of solid solution.