ESR 7 – Microstructure and Air Inclusions in polar ice
Early stage researcher: Florian Painer (AWI, D)
Supervisors: I. Weikusat (AWI, D), M. Dury (Univ. of Ultrecht, NL)
Academic secondment: Univ. of Copenhagen (DK), Univ. of Ultrecht (NL); Non-academic secondment: Schäfter & Kirchhoff GmbH (D), PAGES (CH)
The climatic and environmental records in deep ice cores can be challenged when deformation is inhomogeneous and localised eventually leading to disturbances (e.g. folds) affecting the stratigraphy of the ice layers at large depths.
The effects on deformation by the presence and interaction of second phases (impurities and air inclusions) with the ice crystals can initiate and affect disturbances by, e.g. localised flow.
These effects are poorly understood and thus shall be investigated. On top of that deformation, at least partly by dislocation creep and thus resulting recrystallisation (e.g. grain boundary migration), has the potential to alter the original, depositional stratification. Further recrystallisation processes lead to growth of inclusions, such as air hydrates in the deep, old ice, which gives the potential of an independent dating tool.
ESR 7 will provide the basis using ice microscopic investigations for advising climate reconstruction through developing ideas and methods on the mechanisms sketched above. This will start with inspection of available micrographs, complemented by new discontinuous measurements of crystallographic-preferred orientations and second phase inclusions. Integration with available radio-echo sounding data on the large scale will round off the understanding we gain from ESR 7 inspection. Comparison of the obtained information with climate-related ice core data (water isotopes, impurities) and evaluation of the information on disturbances in the stratified ice will be ensured by a close integration into the DEEPICE cohort, as well as in AWI glaciology and Tübingen Structural Glaciology. The envisaged sample material is from existing ice cores (e.g. EDC) provided through sample requests from the BE-OIC Physical Properties consortium and the expected BE-OIC cores from Antarctica.
Key words: ice microstructure, crystal preferred orientation, stratigraphic sequence alteration, flow disturbances, impurity effects on deformation, recrystallisation
Credit: I. Weikusat (AWI)