info:eu-repo/semantics/article
THE NIQUELÂNDIA MAFIC-ULTRAMAFIC COMPLEX OF CENTRAL GOIÁS, BRAZIL: PETROLOGICAL CONSIDERATIONS
THE NIQUELÂNDIA MAFIC-ULTRAMAFIC COMPLEX OF CENTRAL GOIÁS, BRAZIL: PETROLOGICAL CONSIDERATIONS
Autor
RIVALENTI, G.
GIRARDI, V.A. V.
SINIGOI, S.
ROSSI, A.
SIENA, F.
Institución
Resumen
The Precambrian Niquelândia Complex displays, in the area examined, the following stratigraphy: a) Basal Gabbroic Zone (BGZ); b) Basal Peridotite Zone (BPZ); c) Layered Ultramafic Zone (LUZ); d) Layered Gabbroic Zone (LGZ). On the basis of field relationships, petrography, stratigraphy, bulk composition, mineral composition and equilibria it is concluded that: a) mantle tectonites likely do not occur at Niquelândia; b) the complex derives from the fractionation of a basaltic (pieritic) magma. The emplacement occurred under a 15-20 km thick crust and the complex re-equilibrated at 850-950°C under the same pressure regime. The Precambrian Niquelândia Complex displays, in the area examined, the following stratigraphy: a) Basal Gabbroic Zone (BGZ); b) Basal Peridotite Zone (BPZ); c) Layered Ultramafic Zone (LUZ); d) Layered Gabbroic Zone (LGZ). On the basis of field relationships, petrography, stratigraphy, bulk composition, mineral composition and equilibria it is concluded that: a) mantle tectonites likely do not occur at Niquelândia; b) the complex derives from the fractionation of a basaltic (pieritic) magma. The emplacement occurred under a 15-20 km thick crust and the complex re-equilibrated at 850-950°C under the same pressure regime.