U–Pb and Sm–Nd geochronology of amphibolites from the Curaçá Belt, São Francisco Craton, Brazil: Tectonic implications

Autor: Luiz José Homem D´El-Rey Silva, Jorge Henrique Laux, Maria da Glória da Silva, João Batista Guimarães Teixeira, Elton Luiz Dantas
Rok vydání: 2007
Předmět:
Zdroj: Repositório Institucional da UnB
Universidade de Brasília (UnB)
instacron:UNB
ISSN: 1342-937X
Popis: The Curaca terrane is part of the Itabuna–Salvador–Curaca (I–S–C) Paleoproterozoic orogen in the Sao Francisco craton, northeastern Brazil, and comprises supracrustal rocks, gneisses of their probable basement, amphibolites, and mafic-ultramafic Cu-bearing bodies (including the Caraiba Cu-Mine), all affected by D1-D3 deformation events associated to M1-M3 metamorphism under high-T granulite and amphibolite facies, and assisted by G1-G3 tonalitic-granodioritic-granitic intrusions. U–Pb and Sm–Nd Thermal Ionization Mass Spectrometry (TIMS) isotopic data from amphibolite, tonalite, and granite, sampled in a well-known outcrop, indicate partial reset and heterogeneous modification of the original isotopic systems, attributable to deformation and metamorphism. The ages obtained from these systems agree with each other, and also with other previously published U–Pb data, and imply that 2.6 Ga is the crystallization age of the protolith of the amphibolite. Together with key structural relationships, they also indicate a 2.08–2.05 Ga interval for M3 metamorphism, and make even a less precise age (2.2–2.3 Ga) acceptable, as it suggests contamination in the amphibolite with material in a syn-D2 tonalite crystallized 2248 ± 36 Ma ago. The new data demonstrate the existence of Neoarchean fragments of both oceanic and continental crusts and constrain the Archean-Paleoproterozoic development of the Curaca belt, the I–S–C orogen, and the Sao Francisco craton.
Databáze: OpenAIRE
Externí odkaz: