Oxygen fugacity of Alto Paranaíba kimberlites and diamond instability: Três Ranchos IV and Limeira I intrusions

dc.contributoren-US
dc.contributorpt-BR
dc.creatorColdebella, Bruna
dc.creatorAzzone, Rogério Guitarrari
dc.creatorChmyz, Luanna
dc.creatorRuberti, Excelso
dc.creatorSvisero, Darcy P.
dc.date2020-05-11
dc.date.accessioned2022-12-15T20:11:33Z
dc.date.available2022-12-15T20:11:33Z
dc.identifierhttps://ppegeo.igc.usp.br/index.php/bjg/article/view/13554
dc.identifier10.1590/2317-4889202020190087
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/5360144
dc.descriptionOxygen fugacity (ƒO2) conditions were established for Três Ranchos IV (TR-IV, diamond-bearing) and Limeira I (LM-I, barren) kimberlite intrusions, in Alto Paranaíba Alkaline Province, to constrain a possible correlation between f O2 and diamond instability. Temperature and pressure estimates obtained from the xenocryst assemblage composition are compatible up to garnet lherzolite levels. It suggests that both intrusions could cross the diamond-stability field. The ƒO2 of the TR-IV constrained by perovskite oxygen barometry presents an average value of -2.4 for ΔNNO, with standard deviation of 1.30 (n = 120), whereas those calculations for LM-I have an average value of -1.31 for ΔNNO, with standard deviation of 1.38 (n = 81). Considering these uncertainties, there is an important superposition of fO2 values for both intrusions, in which there is higher tendency of more reduced conditions for TR-IV. For the LM-I, an oxybarometer based on the composition of monticellite yielded a similar ΔNNO range: -4.2 and +2.5. Some crystals and samples present trends towards more reduced conditions, while others display more oxidized conditions for each intrusion. Due to the superposition of ranges and absence of a preferential trend, the influence of f O2 for the possible instability of diamonds in the study area remains uncertain.en-US
dc.descriptionpt-BR
dc.formatapplication/pdf
dc.languageeng
dc.publisherSociedade Brasileira de Geologiapt-BR
dc.relationhttps://ppegeo.igc.usp.br/index.php/bjg/article/view/13554/13149
dc.rightsDireitos autorais 2020 Brazilian Journal of Geologypt-BR
dc.sourceBrazilian Journal og Geology; v. 50, n. 1 (2020); 1-15en-US
dc.sourceBrazilian Journal of Geology; v. 50, n. 1 (2020); 1-15pt-BR
dc.source2317-4692
dc.source2317-4889
dc.subjectKimberlites; Alto Paranaíba Province; Intensive parameters of crystallization; Oxygen fugacity.en-US
dc.subjectpt-BR
dc.titleOxygen fugacity of Alto Paranaíba kimberlites and diamond instability: Três Ranchos IV and Limeira I intrusionsen-US
dc.titlept-BR
dc.typeinfo:eu-repo/semantics/article
dc.typeinfo:eu-repo/semantics/publishedVersion
dc.typeen-US
dc.typept-BR


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