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Ice Shelf Dynamics

This project is aimed at understanding the behaviour of grounded margins of ice shelves. Work in progress with Assoc. Prof. Gary Wilson of the Geology Department focusses on the processes of ice and sediment accretion at the thinning margin of the southern McMurdo Ice Shelf. Mapping of the ice shelf margin and ice cored moraines with a pulseEkko 100 Ground Penetrating Radar has revealed up glacier dipping layers of accreted ice and debris. The isotopic and ionic composition of the ice suggests it has a marine origin. Moreover, there is a systematic shift in the isotopic values that suggests near complete freezing of the water reservoir where sediment has been entrained.

Our previous experience in mapping the ice shelf at Minna Bluff has demonstrated that we are able to get up to 10 m penetration in ice-cored moraines on land but the signal is attenuated offshore. However, the power output of our upgraded pulseEkko Pro radar is programmable so the ice shelf substrate should be reached, at least in the landward few hundred metres. Future work will involve extraction of samples of the accreted ice using a series of cores to examine the composition of the ice. From this, further insight into the isotopic signatures of large scale conductive freezing events will be gained as will an increased understanding of the processes of debris entrainment.


© 2009 Department of Geography, University of Otago, Dunedin, New Zealand