Sm-Nd isotopic data for metabasic rocks in central Brazil: constraints for the timing of mafic magmatism and regional magmatism

The tectono-sedimentary evolution of the Itararé Subgroup (Late Paleozoic) in the southern flank of the Ponta Grossa arch, States of Santa Catarina and Paraná, Brazil, is interpreted through stratigraphic analysis of outcropping beds.Its evolution seems to have been influenced by faulting causing rising and falling of the arch.The section analyzed runs some 50 km SE-NW, from Mafra (SC)-Rio Negro (PR) to Lapa (PR) and includes about 700 m thickness of glacio-clastic beds assigned to the Campo do Tenente and Mafra formations.Paleocurrent orientation, sense of the movement of the gravity driven Paraná glacial lobe, and stratigraphic data indicate a basin paleoslope initially dipping 7' N during deposition of the Campo do Tenente Formation.Isopach data shows that the unit fills a large trough trending NW, resting on abraded and striated rocks of the Paraná Group (Devonian).This interpretation implies a tecton-