info:eu-repo/semantics/article
A ASSOCIAÇÃO SHOSHONÍTICA DE LAVRAS DO SUL, RS
A ASSOCIAÇÃO SHOSHONÍTICA DE LAVRAS DO SUL, RS
Autor
NARDI, LAURO V. S.
LIMA, EVANDRO F . DE
Institución
Resumen
The Lavras do Sul Shoshonitic Association comprises volcanic and pyroclastic rocks which belong to the Hilário Formation, and granitoids occuring in the Lavras Granite Complex central zone. Such lithologies show Brazilian ages and characterize an extensional environment, probably close to an orogenic belt of similar age. These lithologies are geochemically characterized by trends similar to those observed in calc-alkaline and alkaline series as far as major elements are concerned. However, the high K2O, Ba and Sr, and the relatively low Zr, Nb and Ti contents are typical of shoshonitic associations. RE elements were determined in seven samples from the central zone of the Lavras Granite Complex. The REE patterns, normalized against chondrites, show relatively high fractination of heavy-REE in relation to light-REE and slight negative Eu anomalies. Gold-sulphide mineralization occurs in granitic and volcanic lithologies. The Lavras do Sul Shoshonitic Association comprises volcanic and pyroclastic rocks which belong to the Hilário Formation, and granitoids occuring in the Lavras Granite Complex central zone. Such lithologies show Brazilian ages and characterize an extensional environment, probably close to an orogenic belt of similar age. These lithologies are geochemically characterized by trends similar to those observed in calc-alkaline and alkaline series as far as major elements are concerned. However, the high K2O, Ba and Sr, and the relatively low Zr, Nb and Ti contents are typical of shoshonitic associations. RE elements were determined in seven samples from the central zone of the Lavras Granite Complex. The REE patterns, normalized against chondrites, show relatively high fractination of heavy-REE in relation to light-REE and slight negative Eu anomalies. Gold-sulphide mineralization occurs in granitic and volcanic lithologies.