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| Bühn,Bernhard; Pimentel,Márcio M.; Matteini,Massimo; Dantas,Elton L.. |
| Age determinations using the 235U and 238U radioactive decay series to the daughter isotopes 207Pb and 206Pb, respectively, using the mineral zircon (ZrSiO4), are widely used to decipher geological processes. A new method developed in the last couple of years, the laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS), overcomes previous laborious sample preparation, and yields isotopic ratios and age data with a high spatial resolution of ten of microns. The present study describes the analytical set-up and data reduction process as presently applied at the Laboratory for Geochronology of the University of Brasília. It explores the precision and accuracy of the method by cross-analysing three international zircon... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geochronology; U-Pb isotopes; LA-MC-ICP-MS; Zircon; Age dating. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652009000100011 |
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| Pimentel,Márcio M.; Silva,Maria da Glória. |
| The Fazenda Brasileiro gold mineralization is hosted by a gabbroic sill, intrusive into metavolcanicmetasedimentary rocks of the Rio Itapicuru Greenstone Belt, São Francisco Craton. The 2.05 Ga old mineralization is associated with intense shearing and hydrothermal alteration, and the host gabbro is altered to a series of rocks rich in sericite, chlorite, actinolite, carbonate and quartz. Twelve whole-rock samples of the gold mineralization, representing varied degrees of alteration, from rocks with preserved igneous textures to the ore (quartz-carbonate-sulfide-chlorite), were studied by the Sm-Nd method. All analytical points resulted in an isochron (MSWD = 1.9) indicating the age of 2142 +/- 47 Ma (1s) and Epsilon Nd (T) of +1.2.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Rio Itapicuru greenstone belt; Fazenda Brasileiro; Paleoproterozoic; Gold mineralization; Sm-Nd; Hydrothermal alteration. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652003000300009 |
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