THE OH COMPONENTS IN GARNETS FROM DIFFERENTGEOLOGICAL ENVIRONMENTS: P-T AND BULK COMPOSITION CONSTRAINTS

Auteurs

  • Danielle Piuzana Instituto de Humanidades, UFVJM.
  • Cristiane Castañeda Centro de Pesquisa Manuel Teixeira da Costa/IGC/UFMG, Brasil.
  • Sigrid Griet Eeckhout European Synchrotron Radiation Facility, Grenoble, France
  • Eddy De Grave Department of Subatomic and Radiation Physics, Ghent University, Belgium

DOI :

https://doi.org/10.18285/geonomos.v17i1.82

Mots-clés :

Garnet, petrogenetic indicator, hydroxyl, Mössbauer spectroscopy

Résumé

Metamorphic garnet from the Anápolis-Itauçu Complex (AIC), central Brazil, were investigated by electron microprobe analyses and Mössbauer spectroscopy, in order to contribute on their geological history. The data were further extended by magmatic samples from complex and simple pegmatites, as reported by Eeckhout et al. (2002). Three clear chemical tendencies within garnets from AIC rocks were revealed. From Mössbauer spectroscopy data it is obvious that ferrous iron is present at dodecahedral site. Very small amounts of ferric iron at octahedral site of garnet structure are additionally present in garnets from sample of ultra-high temperature (UHT) granulites from AIC, implying slightly oxidizing conditions during this metamorphicevent. In addition, a higher degree of structural disorder has been discerned in these samples.

Keywords: Garnet, petrogenetic indicator, hydroxyl, Mössbauer spectroscopy.

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Publiée

2013-02-15

Numéro

Geonomos - v.17 n. 1 (2009)

Rubrique

Artigos

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The copyrights of the works published in Geonomos are those of the author, with rights of first publication for the journal.