Thursday, 30 August 2007 - 4:00 PM
4.P2.B-2
"Thermochronologic constraints of the tectonic evolution of the western Antarctic Peninsula in late Meso- and Cenozoic times"
Manfred R. Brix1, Victor Faúndez2, Francisco Hervé2, Marcelo Solari2, Andrew Carter3, and Bernhard Stöckhert1. (1) Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Bochum, 44780, Germany, (2) Petrologia, Universidad de Chile, Santiago de Chile, Chile, (3) Birkbeck College, University of London, London, United Kingdom
West of the Antarctic Peninsula, oceanic lithosphere of the Phoenix plate is being subducted below the Antarctic plate. Subduction ceased successively from south to north over the last 65 Myr. An influence of this evolution on the segmentation of the crust in the Antarctic plate is disputed. Opposing scenarios consider effects of ridge crest – trench interactions with the subduction zone or differences in slip along a basal detachment plane in the overriding plate. Fission track analyses on apatites and zircons may detect thermochronologic patterns to test these hypotheses. The first results show zircon fission track ages between 80 and 90 Ma from different geological units over wide areas of the Antarctic Peninsula. They indicate a uniform regional cooling episode. Apatite fission track ages obtained so far show considerable regional variability.