Mesozoic epeirogeny at the South Atlantic margin and the Tristan hot spot

Epeirogenic structures of the eastern margin of Brazil's Paraná basin seem related to the position of the proposed Tristan hot spot in Early Cretaceous time. Several lines of evidence indicate that the hot spot was located offshore from a major structural depression, the Tôrres syncline, which is flanked by two structural arches about 750 km apart. Structural relief between the syncline and arches is estimated to be 4 km. Synchronism of the formative epeirogenic movements with proto-Atlantic continental rifting is indicated by the occurrence of a prominent Early Cretaceous basaltic dike swarm on the crest of one of the arches. The Tôrres downflexure might have originated through volcanic loading of the continental margin prior to formation of the Rio Grande Rise in the adjacent ocean basin.