Snow petrel stomach oil deposits (Antarctic mumiyo) as archives for the environmental history of terrestrial East Antarctica

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The Antarctic region is an important component in the Earth climate system, since the polar ice sheets and the surrounding ocean affect global sea level, ocean circulation and heat transport, marine productivity and albedo. Due to the remoteness of East Antarctica and the limited number of records many questions remain open concerning the important issue of Antarctic climate variability. For the establishment of an Antarctic-wide picture of ice sheet development and its link to the climatic and environmental variability, good records with a robust age control are a basic requirement. However, datable records are especially rare in the terrestrial areas of Antarctica. Snow petrels (Pagodroma nivea) are endemic to Antarctica. The birds exclusively breed on un-glaciated ice-free grounds along the coast and on nunataks in farer distance to the sea while their feeding grounds are located within the pack ice or open waters of the Southern Ocean. Around their nesting sites stomach oil, which is ejected as a defence against potential intruders, accumulates and fossilizes. The organic nature of these centimetre to decimetre thick deposits (called mumiyo) provides the rare opportunity for radiocarbon dating. Mumiyo deposits can therefore serve as archives for the reconstruction of the local glacial history, sea-level, and lake-level histories, and also provide a link to the marine environment, with respect to both ice coverage and oceanographic properties. Mumiyo has been used to constrain the timing of ice retreat in different parts of East Antarctica, however its potential as an archive for paleoenvironmental reconstructions has not been fully exploited. In the proposed project we want to systematically study the chronology of mumiyo deposits and to evaluate vertical changes in their composition. This will provide information on changes in the local conditions and in the paleodiet of the snow petrels, which has paleoceanographic implications. We use existing but yet unprocessed sample material from different sites in Dronning Maud Land. This will also give new insights in the deglaciation history of the East Antarctic Ice Sheet since the late Pleistocene in a region where chronological control is mostly not available.