Article
Evolution of polycyclic basement complexes in the Aracuay Orogen, based on U–Pb SHRIMP
Registro en:
NOCE, Carlos M; PEDROSA-SOARES, Antônio Carlos; SILVA, Luiz Carlos da; ARMSTRONG, Richard; PIUZANA, Danielle. Evolution of polycyclic basement complexes in the Aracuay Orogen, based on U–Pb SHRIMP. Precambrian Research, v.159, p.60-78.
Autor
NOCE, Carlos M
PEDROSA-SOARES, Antônio Carlos
SILVA, Luiz Carlos da
ARMSTRONG, Richard
PIUZANA, Danielle
Institución
Resumen
Paleoproterozoic basement of the Arac¸ua´ı Orogen is composed of amphibolite and granulite facies orthogneiss units known as
Mantiqueira and Juiz de Fora complexes. Six U–Pb SHRIMP crystallization ages for the Mantiqueira Complex range from 2137±19
to 2041±7 Ma. Studied samples are characterized by the abundance of inherited Archean zircon grains, TDM model ages ranging
from 2.9 to 3.2 Ga, and strongly negative εNd(t) (−9 to −13). Gneiss protholits were mainly generated by partial melting of older
continental material, and the Mantiqueira Complex is related to active margin and syn-collisional magmatism. High-grade gneiss
samples of the Juiz de Fora Complex yields crystallization ages of 2119±16 and 2084±13, and inherited zircon grains are absent.
This plutonic unit much probably evolved within an oceanic magmatic arc setting, or on a very stretched continental crust.
The Mantiqueira and Juiz de Fora complexes, together with the Kimezian basement of the West Congo Belt, were parts of
a Paleoproterozoic orogenic system disrupted and deeply reworked during the evolution of the Arac¸ua´ı–West Congo Orogen.
Neoproterozoic metamorphic overprint is dated at ca. 590–574 Ma.