Diques máficos de Minas Gerais do cretáceo inferior: idades ar-ar e correlaçãoes com a província ígnea Paraná - Etendeka

Abstract

An intense Lower Cretaceous magmatic event have been related to break-up of the western Gondwana supercontinent, initiating the development of basin with Brazilian and African continental margins and the opening of the South Atlantic Ocean. This magmatism is represented by flood basalts and mafic dykes swarms associated with 133-135 Ma Parana (Brazil) - Etendeka (Africa) large igneous province. Revealed by magnetometric images and with ages from Precambrian to the Lower Cretaceous, several dyke swarms occur in the State of Minas Gerais (MG). Crossing the São Fransisco Craton and its surrounding Brasiliano Mobile Belts, the Transminas mafic dykes and a group of Serra do Mar mafic dykes represent the youngerswarms of Minas Gerais. In Minas Gerais, plateau age of 124.56 ± 2.15 Ma and inverse isochron age of 131.92 ± 3.63 Ma for a Serra do Mar dyke and plateau age of 135.72 ± 4.35 Ma and inverse isochron age of 128.43 ± 8.46 Ma for a Transminas dike, obtained in this research by the Ar-Ar method, insert both Cretaceous mafic dyke swarms in the same intrusion tectonic context of Serra do Mar (outside Minas Gerais), Ponta Grossa (Paraná), Florianópolis (Santa Catarina) and Vitória-Colatina (Espirito Santo) mafic dyke swarms, all of them associated with Paraná-Etendeka igneous province.