Friday, 31 August 2007 - 2:10 PM
5.P1.B-3

Break-up of Gondwana and opening of the South Atlantic: review of existing plate tectonic models

Marta E. Ghidella1, Larry Lawver2, and Lisa M. Gahagan2. (1) Ciencias de la Tierra, Instituto Antártico Argentino, Cerrito 1248 C1010AAZ, Buenos Aires, Argentina, (2) Institute for Geophysics, University of Texas at Austin, 10100 Burnet Rd. - R2200, Austin, TX 78758-4445

The opening history the Weddell Sea and South Atlantic Ocean is critical to understanding the breakup of Gondwana and the evolution of Antarctica since Early Jurassic times. Unfortunately the tectonics of the region is difficult to resolve because of the paucity of data coverage and its inherent complexity. Although considerable progress has been achieved in the past 20 years, there are still several models which differ in crustal ages and schemes of opening. We present a review of four of those models. Focusing on poles of rotation, synthetic isochrons and flowlines, we show crustal age maps that display the estimated trace of the triple junction for each model, and plot reconstructions for comparison. The diverse simplifying assumptions used by the models, including plate fragmentation to account for the syn-rift basins and periods of stretching, are strong indicators that rigid plate tectonics is too simple a model for the present problem.