GEOCHRONOLOGY OF S-TYPE PERALUMINOUS ORTHOGNEISSES ASSOCIATED WITH THE ARAXÁ GROUP IN SOUTHEASTERN GOIÁS STATE, BRASÍLIA BELT: CRYSTALLIZATION VS. INHERITANCE AGES

Geochronolgy os S-Type peraluminous orthognaisses ssociated with the Araxá Group in southeastern Goiás state, Brasília Belt: crystallization vs. inheritance ages

Authors

  • Guillermo Rafael Beltran Navarro Instituto de Geociências e Ciências Exatas, Departamento de Geologia, Universidade Estadual Paulista, Campus de Rio Claro
  • Thaís Güitzlaf Leme Universidade Federal do Rio Grande do Sul. 
  • Antenor Zanardo Instituto de Geociências e Ciências Exatas, Departamento de Geologia, Universidade Estadual Paulista, Campus de Rio Claro

DOI:

https://doi.org/10.5016/geociencias.v45i1.19706

Abstract

In the southeastern region of Goiás state, near the municipalities of Mairipotaba and Cromínia, orthogneiss bodies occur interlayered with metasedimentary rocks of the Araxá Group. These bodies are regionally grouped under the designation of Aragoiânia-type granitoids and are informally referred to as the Mairipotaba, Cromínia–Prof. Jamil Safady, and Rochedo orthogneisses. This study presents new U–Pb zircon and Sm–Nd whole-rock isotopic geochronology data, along with whole-rock geochemical analyses from four of these occurrences. The orthogneiss bodies are elongated in an E–W direction, concordant with the main regional foliation, and consist predominantly of (biotite)-muscovite and muscovite orthogneiss with granodioritic to tonalitic compositions. These rocks were affected by the main regional deformation. Whole-rock geochemical data indicate orthogneisses composition similar to plutonic rocks generated in magmatic arc settings. They are classified as S-type granitoids, generated through partial melting of Araxá Group metasedimentary rocks. Zircon crystals predominantly show oscillatory zoning. Most of the 206Pb/238U ratios did not yield isochronous ages but showed concordant ages ranging from 563 to 2,121 Ma. Ages older than 670 Ma are interpreted as inherited ages from the granitic magma source rocks. The younger ages (ranging from 603 ±10 to 621 ±12 Ma) are interpreted as the metamorphic age (main regional metamorphic event) and likely represent the granitoids crystallization interval. Sm–Nd isotopic data yielded model ages (TDM) ranging from 1.69 to 1.94 Ga. These model ages, along with the inherited zircon age populations, are comparable to detrital zircon ages from the Araxá Group, supporting the interpretation that the zircon crystals were derived from the metasedimentary protolith and do not represent the crystallization age of the orthogneisses.

Author Biographies

  • Guillermo Rafael Beltran Navarro, Instituto de Geociências e Ciências Exatas, Departamento de Geologia, Universidade Estadual Paulista, Campus de Rio Claro

    Instituto de Geociências e Ciências Exatas,

    Departamento de Geologia, Universidade Estadual Paulista,

    Câmpus de Rio Claro.

    Avenida 24-A, 1.515. Bela Vista – Rio Claro – SP

  • Thaís Güitzlaf Leme, Universidade Federal do Rio Grande do Sul. 

    Universidade Federal do Rio Grande do Sul. 

    Instituto de Geociências, Departamento de Mineralogia e Petrologia,

    Avenida Bento Gonçalves, 9500 / Prédio 43126. Sala 107 - Bairro Agronomia,

    Porto Alegre, RS

  • Antenor Zanardo, Instituto de Geociências e Ciências Exatas, Departamento de Geologia, Universidade Estadual Paulista, Campus de Rio Claro

    Instituto de Geociências e Ciências Exatas,

    Departamento de Geologia, Universidade Estadual Paulista,

    Câmpus de Rio Claro.

    Avenida 24-A, 1.515. Bela Vista – Rio Claro – SP

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Published

2026-03-31

Issue

Vol. 45 No. 1 (2026)

Section

Artigos