Microstructure, micro-inclusions, and mineralogy along the EGRIP ice core – Part 1: Localisation of inclusions and deformation patterns

Abstract. Impurities deposited in polar ice enable the reconstruction of atmospheric aerosol concentration past. At same time they impact physical properties itself such as its deformation behaviour. are thought to enhance deformation, but observations ambiguous due a shortage comprehensive microstructural analyses. For first time, we systematically analyse micro-inclusions fast flowing ice, i.e. from East Greenland Ice Core Project core drilled through Northeast Stream. In direct relation inclusions derive crystal preferred orientation, fabric, grain size, and features at 10 depths, covering Holocene Late Glacial. We use optical microscopy create microstructure maps situ locations polycrystalline, solid samples. Micro-inclusions more variable spatial distribution than previously observed show various distributional patterns ranging centimetre-thick layers clusters solitary particles, independent depth. half all samples, often located or close boundaries by slight margin (in areas occupied boundaries). Throughout samples find strong indications dynamic recrystallisation, islands, bulging grains, different types sub-grain boundaries. discuss variability micro-inclusions, link between mineralogy, possible effects on behaviour ice. Our results emphasise need for holistic approaches future studies, combining impurity analysis.