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| HAL : hal-00195655, version 1 |
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| American mineralogist 92 (2007) 1978-1989 |
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| Dissolution of radiation-damaged zircon in lateritic soils |
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| Simon Delattre 1, 2Satoshi Utsunomiya 1 |
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| (2007) |
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| Zircon crystals from lateritic soils at Nsimi, Cameroon, were investigated using electron microprobe analysis (EMPA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Raman spectroscopy to determine the extent of radiation damage from alpha-decay events. The soils belong to a small watershed developed on granitic rocks of the Congo craton (2.9 Ga). Interactions with fluids are evidenced by significant CaO (up to 1.5 wt%), Al2O3 (up to 2.9 wt%), and Fe2O3 (up to 2.9 wt%) concentrations in UO2 rich regions (0.05 to 1 wt%) of the zircon. Regional heating up to 500 °C, related to the Pan-African orogeny about 0.6 Ga ago, has lead to the recrystallization of the radiation-damaged grains and the formation of a nanoporous microstructure. The correlation observed between the presence of dissolution features and the actual damage state of zircon shows that zircon dissolution occurs under tropical weathering conditions and with preferential dissolution of the highly radiation-damaged regions. Congruent dissolution of zircon and the limited mobility of Zr are supported by the absence of zirconium oxide precipitates in the fractures of weathered grains of zircon. |
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| 1 : | Department Geological Sciences University of Michigan |
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University of Michigan |
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| 2 : | Institut de minéralogie et de physique des milieux condensés (IMPMC) |
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CNRS : UMR7590 – IPG PARIS – Université Pierre et Marie Curie [UPMC] - Paris VI – Université Paris VII - Paris Diderot |
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| 3 : | Laboratoire des Mécanismes et Transfert en Géologie (LMTG) |
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CNRS : UMR5563 – Observatoire Midi-Pyrénées – Université Paul Sabatier [UPS] - Toulouse III – Institut de recherche pour le développement [IRD] : UMR154 |
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| 4 : | Centre européen de recherche et d'enseignement de géosciences de l'environnement (CEREGE) |
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CNRS : UMR6635 – Institut de recherche pour le développement [IRD] – INSU – Université de Provence - Aix-Marseille I – Université Paul Cézanne - Aix-Marseille III |
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| Domaine | : | Planète et Univers/Sciences de la Terre/Minéralogie |
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| Zircon – Nsimi – laterite – nanopore – zirconium – metamict – radiation damage – TEM |
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| hal-00195655, version 1 | |
| http://hal.archives-ouvertes.fr/hal-00195655 | |
| oai:hal.archives-ouvertes.fr:hal-00195655 | |
| Contributeur : Danielle Thomas | |
| Soumis le : Mardi 11 Décembre 2007, 11:50:11 | |
| Dernière modification le : Mardi 11 Décembre 2007, 11:50:11 | |
