U-Pb dating, Lu-Hf isotope systematics and chemistry of zircon from the Morro do Polvilho meta-trachydacite: constraints on sources of magmatism and on the depositional age of the São Roque Group

Authors

  • Renato Henrique-Pinto Département de Géologie et de Génie Géologique, Faculté des Sciences et de Génie, Université Laval
  • Valdecir de Assis Janasi Instituto de Geociências, Universidade de São Paulo - USP
  • Ginaldo Ademar da Cruz Campanha Instituto de Geociências, Universidade de São Paulo - USP

DOI:

https://doi.org/10.11606/issn.2316-9095.v18-125793

Keywords:

Polvilho, Meta-trachydacite, High-temperature melts, Reducing conditions, São Roque Group.

Abstract

We present new in situ geochronological data of controversial silicic metavolcanic rocks from the lower terrigenous-metavolcanic sequence of the São Roque Group, Ribeira Belt, confirming that they are older than the rocks of higher-metamorphic grade sequences of the Serra do Itaberaba Group. The age of the Polvilho meta-trachydacite was established at 1760 ± 17 Ma, furthermore the results suggest that the bi-modal volcanism of the Boturuna Formation has parent melts from an old (Archean to Paleoproterozoic) continental crust that was melted in a within-plate environment. Trace-element chemistry of zircon, suggests similarities with high-temperature melts (T Zrsat = 900–915ºC) similar to A-type granites (high negative EuN/EuN* and moderate positive CeN/CeN*) from continental sources under reducing conditions.

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Published

2018-07-24

Issue

Vol. 18 No. 2 (2018)

Section

Articles

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How to Cite

Henrique-Pinto, R., Janasi, V. de A., & Campanha, G. A. da C. (2018). U-Pb dating, Lu-Hf isotope systematics and chemistry of zircon from the Morro do Polvilho meta-trachydacite: constraints on sources of magmatism and on the depositional age of the São Roque Group. Geologia USP. Série Científica, 18(2), 45-56. https://doi.org/10.11606/issn.2316-9095.v18-125793