Eric Salomon

Asymmetric continental deformation along southern Brazil and Namibia during South Atlantic rifting and its influence on Paraná-Etendeka Large Igneous Province emplacement

Plate restoration of South America and Africa to their pre-breakup position faces the problem of gaps and overlaps between the continents, an issue commonly solved with implementing intra-plate deformation zones within South America. One of these zones is often positioned at the latitude of SE/S Brazil. However, geological evidence for the existence of a distinct zone in this region is lacking. Obvious instead is that SE/S Brazil has been affected by the outpour of the voluminous Paraná-Etendeka Large Igneous Province. These lavas are closely linked to the South Atlantic opening, and of which 93 % are emplaced in and around southern Brazil and 7 % in Namibia on the African side.

In this presentation I will show, that combining published data on various geological aspects pictures a distinctive asymmetric deformation of the onshore passive margin of SE/S Brazil and its conjugate margin of NW Namibia. Whereas Namibia experienced margin-perpendicular extension during breakup, SE/S Brazil was subject to margin-parallel extension. Based on these observations, I will propose a breakup model that helps solving the apparent misfit in plate reconstructions in this region and at the same time explains the highly unequal distribution of the Paraná-Etendeka Large Igneous Province between South America and Africa.