| Texto completo | |
| Autor(es): |
Henrique-Pinto, R.
[1]
;
Janasi, V. A.
[2]
;
Vasconcellos, A. C. B. C.
;
Sawyer, E. W.
[1]
;
Barnes, S. -J.
[1]
;
Basei, M. A. S.
[2]
;
Tassinari, C. C. G.
[2]
Número total de Autores: 7
|
| Afiliação do(s) autor(es): | [1] Univ Quebec Chicoutimi, Dept Appl Sci, Chicoutimi, PQ - Canada
[2] Univ Sao Paulo, Inst Geociencias, BR-05508 Sao Paulo - Brazil
Número total de Afiliações: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Precambrian Research; v. 256, p. 271-288, JAN 2015. |
| Citações Web of Science: | 19 |
| Resumo | |
Detrital zircons from quartzites of the Sao Roque Domain were subject of studies of crystal growth and stratigraphy, using in situ LA-ICPMS trace element geochemistry and U-Pb dating to deduce their provenance and contribute to understand the tectonic evolution of the Proterozoic metasedimentary successions of southeast Brazil. Trace element chemistry of most detrital cores indicates derivation from plagioclase-rich felsic rocks (e.g., tonalites to granodiorites); however, a small proportion may derive from gabbroic sources, as indicated by a combination of features (strong positive Ce anomaly, high Lu-N/Sm-N, low U/Yb; concave-down shape of the intermediate REE patterns). Thin metamorphic overgrowths are chemically distinct (e.g., enriched in several trace elements, especially the LREE), and were dated at 584 +/- 47 Ma, reflecting the Ediacaran metamorphism and granite magmatism that affected the Sao Roque Domain. The detrital zircon U-Pb ages for five quartzite samples from different stratigraphic positions within the Sao Roque Domain are restricted to the Paleoproterozoic and Archean (similar to 1730-3440 Ma). A striking feature of the dataset is a main peak at similar to 2.2 Ga which is characteristic of all samples; the age and abundance of Archean peaks allow distinguish two groups of samples: Jaragua and Japi, with 41-43% Archean zircons and a peak at 2.6-2.7 Ga; and Voturuna, Pirucaia and Serra da Viuva, with 16-21% Archean zircons and a peak close to the Archean-Paleoproterozoic boundary (2.4-2.5 Ga). A limited contribution of late Paleoproterozoic (Statherian) sources places an upper limit for the deposition of the sedimentary successions that is consistent with the estimated age of the metaconglomerate-metarkose rift sequence of the Sao Roque Group (Boturuna Formation), based on U-Pb dating of interlayered meta-trachydacites (1.75 Ga). Our data demonstrate that the different sedimentary successions of the Sao Roque Domain have an essentially continental (cratonic) provenance which is very similar to those of other sequences in the Ribeira Belt (Acungui and possibly also Embu Domain). The similar to 2.2 Ga age of the volumetrically most important sources, also indicated by the age of granite pebbles in metaconglomerates, is a diagnostic signature, consistent with the age of regional basement (e.g., orthogneisses from few basement nuclei in the Acungui Domain). Similarities in provenance and tectonic evolution of the metasedimentary sequences are consistent with the interpretation that the Ribeira Belt is part of the reworked border of the sao Francisco Paleoplate, displaced southwestward as a result of significant dextral orogen-parallel tectonics during the Neoproterozoic collision, and may imply that a suture zone between this paleoplate and another stable continental area to the SW lies below the Phanerozoic sediments of the Parana Basin. (C) 2014 Elsevier B.V. All rights reserved. (AU) | |
| Processo FAPESP: | 12/04148-0 - Evolução geológica do domínio São Roque: uma contribuição a partir da geocronologia do magmatismo granítico e da proveniência de metassedimentos psamíticos |
| Beneficiário: | Valdecir de Assis Janasi |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |