Zircon provenance in meta-sandstones of the Sao Roque Domain: Implications for the Proterozoic evolution of the Ribeira Belt, SE Brazil

Author(s)

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]

Affiliation

^[1] Univ Quebec Chicoutimi, Dept Appl Sci, Chicoutimi, PQ - Canada

^[2] Univ Sao Paulo, Inst Geociencias, BR-05508 Sao Paulo - Brazil

• Document type: Journal article
• Source: Precambrian Research; v. 256, p. 271-288, JAN 2015.
• Web of Science Citations: 19

Abstract

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)

• FAPESP's process: 12/04148-0 - Geological evolution of the são Roque domain: a contribution from geochronology of the granitic magmatism and provenance of psammitic metasediments
• Grantee: Valdecir de Assis Janasi
• Support Opportunities: Regular Research Grants