Five members of geology group G-097 arrived in McMurdo on Monday to begin preparations for a 10-week field season in Marie Byrd Land, West Antarctica. The group will be working in the Fosdick Mountains, which offer an exceptional exposure of intermingled networks of ‘migmatites’ – deep crustal rocks that have been heated to such a high temperature that they begin to melt – and granites – the final crystallized products of rock melting (see photo below). These rocks preserve a unique record of the linkage from partial melting of existing rock (migmatization) to granite formation, fundamental processes in the evolution and differentiation of the continental crust. During the last 400 million years, West Antarctica underwent two major cycles of mountain building events and crustal differentiation involving high temperature metamorphism and generation of granites, in the Devonian–Carboniferous (circa 375–345 million years ago) and in Jurassic–Cretaceous (circa 175–105 million years ago). These events promoted growth and stabilization along the Gondwana margin, and the Fosdick range represents a singular exposure of lower-to-middle crust that occurs within the little-studied, glaciated segment that bridges the geologic history preserved in the margin of South America to Australia. Their work will investigate the processes of melt generation, segregation and transfer through the crust during these two melting events through an integrated program of field work, structural geology, petrology, mineral equilibria modeling, geochronology and geochemistry.
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| Outcrop exposure of migmatites and granites at Bird Bluff in the Fosdick Mountains comprising layers of orthogneiss (gray-colored), paragneiss (brown-colored), leucogranite, and deformed mafic dikes (dark gray-colored). Two people for scale in bottom left of photograph. Bird Bluff is our first target site for field work this season! |
The group intends to deploy to the ‘deep field’ in the next week, and will collect data and samples based out of a self-sustaining, traditional-style camp. Due to the remoteness and style of field work, extensive preparation and training is required. Over the last week in McMurdo, the team has been packing food, testing gear, and conducting field safety training. In addition, they have been utilizing new high-resolution satellite imagery acquired just a few weeks ago, with geospatial support provided by the Polar Geospatial Center both on and off the ice. This amazing imagery is being used by all members of the team, including the team mountaineers to scout safe routes and traverses, the Air Guard to assess safe L-130 landing sites, and the team geologists to see rock detail and structural features (see photo below).
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| High-resolution imagery acquired by satellite on September 28, 2011 superimposed with geology. |
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