Sm-Nd isotope systematics and REE data for leucotroctolites and their amphibolitized equivalents of the Niquelandia Complex upper layered series, central Brazil: further constraints for the timing of magmatism and high-grademetamorphism
Cf. Ferreira et Mm. Pimentel, Sm-Nd isotope systematics and REE data for leucotroctolites and their amphibolitized equivalents of the Niquelandia Complex upper layered series, central Brazil: further constraints for the timing of magmatism and high-grademetamorphism, J S AM EART, 13(7), 2000, pp. 647-659
The Barro Alto, Niquelindia, and Cana Brava Complexes are major Proterozoic
layered intrusions in central Brazil that were affected by high-grade meta
morphism with associated ductile deformation during the Neoproterozoic (770
-795 Ma). Recent studies recognized that the Niquelandia Complex comprises
two petrologically distinct and tectonically juxtaposed magmatic systems: a
younger Upper Layered Series to the west and an older Lower Layered Series
to the east. Previous geochronological studies on Lower Series rocks sugge
sted a Paleoproterozoic (ca 2.0 Ga) age for the Lower Series magmatic event
, New trace element data matched with Sm-Nd isotope data for Upper Series s
amples yielded well-constrained and original geochronological information,
The 1.35 Ga age of the Upper Series magmatism reported in this paper indica
tes a much younger age of the Upper Series compared with the Lower Series,
The tectonic contact between these two distinct magmatic systems is now rai
sed to the category of a major Paleo-Mesoproterozoic crustal discontinuity.
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