The Luis Alves and Curitiba Terranes: Continental Fragments in the Adamastor Ocean

Abstract

The Luis Alves and Curitiba terranes represent pre-existent continental fragments of unknown origin involved in the Adamastor closure during the Western Gondwana assembly. These basement domains separate the low- to medium-grade Ribeira and Dom Feliciano belts that were generated as a result of the convergence of São Francisco, Paranapanema, Rio de la Plata, Congo and Kalahari Cratons. The Paleoproterozoic Luis Alves Craton is composed of a TTG suite, mafic-ultramafic bodies and a few paragneiss remnants representing a crustal block that had already been cold since the Paleoproterozoic. The Curitiba terrane comprises Paleoproterozoic migmatites and amphibole-gneissic rocks that underwent intense deformation and migmatization during the Neoproterozoic. The Pien magmatic arc was generated around 610 Ma as a result of the oceanic crust consumption that existed between the Luis Alves and Curitiba terranes. The culmination of the compressional process was the collision of these blocks in a few million years. The juxtaposition of the Luis Alves and Curitiba domains was already finished around 590 Ma when post-tectonic granitoids were emplaced. The northeast-trending Pien-Suture Zone is the limit between these crustal segments.