Distribution and chemistry of micro-inclusions in the EPICA-DML deep ice core

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Deep ice cores have been drilled in Antarctica with the aim at reconstructing the history of Earth’s climate in the last million years. However, the interpretation of paleoclimatic records is severely entangled by perennial chemical reactions, mixing and diffusion processes involving many of the valuable climate proxies confined in polar ice. Particularly critical in this respect is the formation of micro-inclusions such as “black dots” and micro-bubbles, as well as possible veins of acid solutions at triple junctions. In spite of the abundance of the former and the menace to climate records represented by the latter, very little is known about them. We propose in this project to investigate the chemistry, distribution, frequency and evolution (relaxation) of micro-inclusions throughout the more than 2.7 km long EPICA-DML deep ice core extracted from Dronning Maud Land, Antarctica. In order to accomplish this challenging task we plan to combine an automated method of optical microscopy and digital image processing for statistical investigations called microstructure mapping (μSM) with an integrated micro-chemical analysis via micro-focus Raman spectrometry (μRS) and scanning electron microscopy (cryo-SEM) coupled with energy-dispersive X-ray spectroscopy (cryo-EDS) and electron backscatter diffraction (cryo-EBSD). The results of this study shall not only resolve the question about the nature of micro-inclusions and the occurrence of liquid veins but also serve as basis for new models of diffusion of dissolved gases and ions in Antarctic ice, to be developed in the course of the investigations.