Radiometric ages, aeromagnetic expression, and general geology of mafic dykes from southeastern Brazil and implications for African-South American correlations

Geological, geochronological, and magnetometric data pertaining to mafic dykes from southeastern Brazil, mainly with tholeiitic affinities, suggest eight distinct swarms. The major swarms, which encompass the giant Pará de Minas, appear in aeromagnetic maps. Seven are markers of important crustal extension events at 2.65, 1.72, approximately 1.25, 1.1-0.9, 0.22-0.17, 0.13-0.12, and 0.05 Ga, and a minor swarm shows intrusion and deformation interrelated with the development of vertical transcurrent shear zones active approximately 2.19 Ga ago. Because at least three or four swarms have African counterparts, they may be helpful in reconstructing paleocontinents.