Volcanological fieldwork in Antarctica

Posted by ga16 at Feb 04, 2015 12:25 PM |
Professor John Smellie has just returned from Antarctica, working on volcanoes with geologists of the Italian Antarctic Programme

Fig 1, Prof John SmellieI have just returned from several weeks working on volcanic rocks in northern Victoria Land. This was my third visit to Victoria Land and once more I participated as an invitee of the Italian Antarctic Programme (Programma Nazionale di Ricerche in Antartide). The area contains many very large shield volcanoes stretching along the coastal margin of the breathtakingly beautiful ice-clad Transantarctic Mountains .Transantartic MountainsThe volcanoes erupted beneath the East Antarctic Ice Sheet and together they contain a unique and valuable record of the physical state of the terrestrial ice sheet, particularly its thickness and thermal regime for the period between 10 million years ago and present. Thermal regime is especially important because it determines the relative stability or dynamism of the ice, which is crucial for assessing how sensitive it is to climate warmth and how rapidly it may contribute ice (and thereby water) to global sea levels. Our published regional assessment of thermal regime variations based on work during our first two seasons has already helped to resolve a 30 year old controversy about the thermal evolution of the ice sheet. The very fresh volcanic rocks are also easily dated isotopically by the 40Ar/39Ar method, which is a particular advantage over studies of glacial sedimentary rocks such as tills, which anyway are largely absent both onshore and offshore in the region for the period examined.
Antarctic HelicoptersAfter a hectic 2 days spent preparing field equipment at Mario Zuchelli Station, we were deployed at our remote field camp 250 km to the north and began work supported by helicopters. The volcanoes are extremely well exposed in awe-inspiring cliffs 500-1000 m high that individually stretch for a few tens of km for each volcano. Because of the lack of any obscuring vegetation and the effects of physical weathering much reduced by the very cold climate, the rocks are unusually fresh and reveal many pristine details down to a micro-scale. Antarctic VolcanoesAn exotic bonus of the fieldwork is the presence of a few rookeries of emperor penguins, including many freshly hatched chicks. We also took time out to fly far inland and up to an elevation of 2500 m to investigate and sample a series of very young scoria cones poking through the edge of the high polar plateau. The air temperature at the cones was an uncomfortable minus 30° C but our results from there and elsewhere in the region will considerably improve our understanding of how subglacially erupted volcanoes are constructed and what the physical state of the East Antarctic Ice Sheet was, mainly during the Miocene and Pliocene (10-2 million years ago), when the world was a much warmer place.

Emperor PenguinsHigh polar plateau

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