The Morro do Resende orthogneiss: mineralogy, petrography, geochemistry and geochronology

Authors

  • Fabiana Franco de Vasconcelos Universidade Federal do Rio de Janeiro – UFRJ, Instituto de Geociências.
  • Ciro Alexandre Ávila Universidade Federal do Rio de Janeiro – UFRJ, Museu Nacional.
  • Reiner Neumann Centro de Tecnologia Mineral – CETEM
  • Wilson Teixeira Universidade de São Paulo – USP, Instituto de Geociências.
  • Everton Marques Bongiolo Universidade Federal do Rio de Janeiro – UFRJ, Instituto de Geociências.
  • Natali Barbosa Universidade Federal do Rio de Janeiro – UFRJ, Instituto de Geociências.
  • Beatriz de Oliveira Camara Universidade Federal do Rio de Janeiro – UFRJ.
  • Victor Hugo Riboura Menezes Universidade Federal do Rio de Janeiro – UFRJ.
  • Fernanda Caetano de Mattos Cunha Universidade Federal do Rio de Janeiro – UFRJ.

DOI:

https://doi.org/10.11606/issn.2316-9095.v17-285

Keywords:

Orthogneiss, Mineralogy, Petrography, Rhyacian, Mineiro Belt.

Abstract

The Morro do Resende orthogneiss is a hololeucocratic to leucocratic, fine-grained body with monzogranitic to granodioritic composition, cropping out near the Volta Grande mine in Nazareno County, State of Minas Gerais, Brazil. It bears xenoliths of metamafic rocks of the Rio das Mortes metavolcano-sedimentary sequence and yields a U-Pb SHRIMP crystallization age of 2174 ± 4 Ma, relating it to one of the magmatic pulses of the Mineiro Belt. The primary mineralogy includes quartz, albite, microcline, biotite, allanite, zircon, magnetite, titanite and apatite, while sericite, epidote, zoisite, clinozoisite, carbonate and chlorite are metamorphic minerals. Maghemite, barite, fluorite, monazite, xenotime, garnet and REE fluorides (possibly gagarinite) are hydrothermal, as they fill the fractures, intergrow or replace the primary and metamorphic minerals. Fluid interaction was not homogeneous throughout the body. Metamorphic paragenesis points to greenschist facies conditions, which could be related to the Paleoproterozoic II event of the Mineiro Belt, which lasted from 2131 to 2101 Ma. The Morro do Resende orthogneiss is distinguished by significant REE enrichment, as well as a negative Eu anomaly linked to the magmatic crystallization and a negative Ce anomaly related to oxidizing hydrothermal fluids circulation.

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Published

2017-04-18

Issue

Vol. 17 No. 1 (2017)

Section

Articles

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How to Cite

Vasconcelos, F. F. de, Ávila, C. A., Neumann, R., Teixeira, W., Bongiolo, E. M., Barbosa, N., Camara, B. de O., Menezes, V. H. R., & Cunha, F. C. de M. (2017). The Morro do Resende orthogneiss: mineralogy, petrography, geochemistry and geochronology. Geologia USP. Série Científica, 17(1), 143-164. https://doi.org/10.11606/issn.2316-9095.v17-285