Title of article :
Sedimentary provenance in the central Ribeira belt based on laser-ablation ICPMS207Pb/206Pb zircon ages
Author/Authors :
Valladares، نويسنده , , Claudia Sayمo and Machado، نويسنده , , Nuno and Heilbron، نويسنده , , Monica and Duarte، نويسنده , , Beatriz Paschoal and Gauthier، نويسنده , , Gilles، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2008
Pages :
11
From page :
516
To page :
526
Abstract :
207Pb/206Pb ages from 420 zircons from 9 upper amphibolite and granulite facies quartzites of the post-1.8 Ga metasedimentary cover from the Occidental and Oriental terranes from the Neoproterozoic central Ribeira belt, in eastern Brazil, are discussed. Ages from the Occidental terrane show that Proterozoic ages predominate with a modal class at 2.1–2.2 Ga and that Archean ages are less common and lie within the 2.5–3.6 Ga range. A wider dispersion on Proterozoic ages down to 1.1 Ga and youngest Neoproterozoic ages (550–700 Ma) were also observed and could be related to the Brasiliano/PanAfrican metamorphic events. The data show that detrital sediments of the Occidental terrane were derived predominantly from erosion of a 1.8–2.2 Ga Paleoproterozoic terrane with a small proportion of a 2.6–3.6 Ga Archean crust. Ages from the Oriental terrane are greatly dispersed, but show a significant proportion of ages between 1.7 and 2.1 Ga, although the great majority are between 0.5 and 1.6 Ga. Only 3 out of 144 grains yield Archean ages, between 2.5 and 2.9 Ga. Based on the greatest errors observed on the data from the Oriental Terrane (100–300 Ma), and a continuum of obtained ages between 2072 Ma (Paleoproterozoic) and 517 Ma (Cambrian), the more plausible interpretation is that the dispersion of ages results from partial resetting of the U–Pb system by Brasiliano metamorphism in Proterozoic–Archean zircons, although a Mesoproterozoic source could not be discarded.
Keywords :
Inductively coupled plasma 207Pb/206Pb ages , Ribeira belt , Archean , Paleoproterozoic , zircon
Journal title :
Gondwana Research
Serial Year :
2008
Journal title :
Gondwana Research
Record number :
2363653
Link To Document :
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