9702161 Siddoway Abstract This award allows a US investigator to join an Italian Antarctic Program geological field team in northern Victoria Land, Antarctica. The overall goal of the field program is to obtain detailed structural, petrographic, isotopic, and geochronological information that bears on the history of early Paleozoic magmatism in northern Victoria Land (NVL), and to relate this information to plate convergence during the Ross Orogeny. The group will test the hypothesis that high temperature-low pressure metamorphism in NVL occurred within the regional contact metamorphic aureole of fundamentally arc-related plutons, within a structural regime related to convergence. Detailed structural studies by the PI are expected to help characterize the dynamic setting in which the plutons were emplaced and correlate structural fabrics in host rock with changes in pressure- temperature conditions of metamorphic recrystallization in host rocks. The work will be used to verify the polarity of the magmatic arc during plutonism and establish the relationships with early Paleozoic plutons to the south. The results of this work will be used to infer the configuration of AntarcticaOs early Paleozoic active margin in NVL, for comparison with models developed in other parts of the Transantarctic Mountains. Interpretations developed in the course of this work will be integrated with tectonic and structural interpretations for other parts of the proto-Pacific margin of Gondwana. Methods used in the study will include structural mapping, structural and metamorphic petrology, and fluid inclusion analysis. The field program in centered on the Deep Freeze Range, with an additional possibility of examining sites in the vicinity of the Lanterman Range. The specific contribution supported by this award will be study and interpretation of the relations between deformation, magmatic pulses, and high temperature-low pressure metamorphic recrystallization.
