Oblique rifting of the Equatorial Atlantic: Why there is no Saharan Atlantic Ocean Christian Heine, EarthByte Group, School of Geosciences, University of Sydney, Sydney, NSW 2006, Australia, email@example.com; and Sascha Brune, Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Section 2.5, Geodynamic Modelling, Telegrafenberg, D-14473 Potsdam, Germany. Posted online 10 January 2014, http://dx.doi.org/10.1130/G35082.1.
During the final stages of fragmentation of the Gondwana supercontinent in the Early Cretaceous, vast continental rift systems extended between present-day South America and Africa and within the African continent. The South Atlantic and West African rift systems were about to split the African-South American part of Gondwana North-South into nearly equal halves, generating a South- and Saharan Atlantic Ocean. In a dramatic plate tectonic twist, however, a competing rift along the present-day South American and African Equatorial Atlantic margins, won over the West African rift, causing it to become extinct, avoiding the break-up of the African continent and the formation of a Saharan Atlantic ocean. Our work elucidates the reasons behind the success and failure of these rift systems by coupling plate tectonic and advanced 3-D numerical models of continental lithosphere deformation. We find that obliquity acts as a selector between successful and aborted rift systems, explaining why the South and Equatorial Atlantic Ocean basins formed and other rifts became aborted. Our modeling also sheds lights on the dynamics of rifting, suggesting that feedback loops caused a significant acceleration of the South American plate once the Equatorial Rift System had sufficiently weakened the last remaining continental bridge between both plates.
Contact: Kea Giles
Geological Society of America
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