The Tectonomagmatic Setting of Early to Middle Jurassic Bimodal Volcanism in the Transantarctic Mountains

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The Beardmore Glacier region of the Transantarctic Mountains has the most complete Gondwana sequence (Victoria Group of the Beacon Supergroup) in Antarctica. This sequence is overlain by tholeiitic flood basalts of the Ferrar Group which are related to Gondwana fragmentation. The volcanism and flood basalt eruption reflect a major change in tectonic environment in the Transantarctic Mountains, from a foreland basin associated with an active plate margin to a continental rift related to Gondwana breakup. The objectives of this project are to: 1) establish a detailed stratigraphic framework for the volcanogenic rocks in order to assess the importance of regional thinning of units and of syndepositional extensional normal faulting; 2) investigate the paleovolcanology of this sequence, in particular that part of it formed by phreatomagmatic processes, in order to understand the physical environment in which the rocks were formed and the relations to the inferred tectonic setting; 3) further characterize the geochemistry of the volcanogenic rocks in order to better define time dependent changes in magma compositions and possible relations between the silicic and basaltic rocks; 4) attempt a preliminary assessment of possible source regions for the silicic magmas.