Ion microprobe (SHRIMP) dates complex granulite from Santa Catarina, southern Brazil
AUTOR(ES)
HARTMANN, LÉO A., SANTOS, JOÃO O. S., McNAUGHTON, NEAL J., VASCONCELLOS, MARCOS A. Z., DASILVA, LUIZ C.
FONTE
Anais da Academia Brasileira de Ciências
DATA DE PUBLICAÇÃO
2000-12
RESUMO
Complex polymetamorphic granulites have been dated in the Santa Catarina granulite complex of southern Brazil through SHRIMP study of zircon. This complex is dominated by intermediate-acid plutonic rocks and contains small volumes of mafic and ultramafic rocks, and minor quartzite and banded iron formation. Porphyroblasts of orthopyroxene, clinopyroxene and plagioclase in mafic and acid rocks are interpreted as magmatic remnants in a volumetrically dominant granoblastic aggregate (M1) of the same minerals and hornblende. Hornblende formed during a later M2 metamorphic event constitutes rims around pyroxene, but the hornblende is also rimmed by granoblastic simplectites of orthopyroxene, clinopyroxene, hornblende and plagioclase in a second granulite facies event (M3). Chlorite and epidote occur in shear zones (M4). This granulite terrain is part of a Neoproterozoic craton, because it was little affected by the Brasiliano Cycle. The two granulite-facies events (M1 and M3) are dated by U/Pb zircon SHRIMP at about 2.68 and 2.17 Ga, while the magmatic protoliths formed at about 2.72 Ga. The amphibolite facies event (M2) probably occurred close to the 2.17 Ga granulitic metamorphism.
Documentos Relacionados
- Native understory palms (Arecaceae) of the Atlantic Forest in Santa Catarina, Southern Brazil
- The black flies (Diptera: Simuliidae) from Santa Catarina, Brazil
- SHRIMP U-Pb zircon dating of Pedras Grandes Suite, southern Santa Catarina State, Brazil
- Traditional Use of Palms (Arecaceae) in the Atlantic Forest in Southern Santa Catarina, Brazil
- Threatened flora from the State of Santa Catarina, Brazil: Arecaceae