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Formation and evolution of the chromitites of the Stillwater Complex : a trace element study

Pagé Philippe, Barnes Sarah-Jane et Zientek Michael L.. (2011). Formation and evolution of the chromitites of the Stillwater Complex : a trace element study. Dans : 11th Biennial SGA meeting: Let's Talk Ore Deposits. The Society for Geology Applied to Mineral Deposits (SGA), Antofagasta, Chile , 26–29 September 2011, Antofagasta, Chile.

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Résumé

Large layered intrusions, such as the Stillwater Complex, contain cyclic units of chromite-rich layers (cm to m thick) having kilometre-scale lateral extension. Chromite cumulates are among the first to form after new primitive melt injections into the magma chamber. Therefore, chromite cumulates could be used to investigate the nature of the parental magma, given the fact that chromite preserves its primary original magmatic composition. The cooling and crystallization history of large layered intrusions is long, complex, and involves multiple injections of hot primitive magma into an evolving and fractionating magma chamber. Our study on Stillwater chromites shows that the early crystallized chromite experiences various post-cumulus processes with the interstitial silicate melt, such as the precipitation of chromite overgrowths on early formed cumulus chromite and/or the reaction - reequilibration of early formed cumulus chromite. These processes have modifed the primary magmatic composition of the chromite making it difficult to identify the parental magma. Moreover, mineralogical evidence for chromite - interstitial melt interactions have probably been obliterated during late post-magmatic textural maturation and recrystallization which tends to homogenize chromite grain size and composition.

Type de document:Matériel de conférence (Article)
Date:2011
Sujets:Sciences naturelles et génie > Sciences naturelles > Sciences de la terre (géologie, géographie)
Département, module, service et unité de recherche:Départements et modules > Département des sciences appliquées > Unité d'enseignement en sciences de la Terre
Mots-clés:chromite, Stillwater Complex, LA-ICPMS trace element, crystal-melt interaction, parental melt
Déposé le:12 déc. 2016 17:22
Dernière modification:12 déc. 2016 17:22
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