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Université de Provence - Aix-Marseille I Hyper Articles en Ligne |
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Université de Provence - Aix-Marseille I Hyper Articles en Ligne |
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| HAL : hal-00330850, version 1 |
| Code IRD Horizon : PAR00007505 |
| Fiche détaillée |  Récupérer au format |
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| Hydrology and Earth System Sciences Discussions 8, 1 (2004) 35-46 |
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| 234U/238U Disequilibrium along stylolitic discontinuities in deep Mesozoic limestone formations of the Eastern Paris basin: evidence for discrete uranium mobility over the last 1–2 million years |
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| P. Deschamps 1, 2C. Hillaire-Marcel 1 |
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| (2004) |
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| The (234U/238) equilibrium state of borehole core samples from the deep, low-permeability limestone formations surrounding the target argilite layer of the Meuse/Haute-Marne experimental site of the French agency for nuclear waste management -ANDRA- (Agence nationale pour la gestion des déchets radioactifs) was examined to improve understanding of naturally occurring radionuclide behaviour in such geological settings. Highly precise, accurate MC-ICP-MS measurements of the (234U/238U) activity ratio show that limestone samples characterised by pressure dissolution structures (stylolites or dissolution seams) display systematic (234U/238U) disequilibria, while the pristine carbonate samples remain in the secular equilibrium state. The systematic feature is observed throughout the zones marked by pressure dissolution structures: (i) the material within the seams shows a deficit of 234U over 238U ((234U/238U) down to 0.80) and (ii) the surrounding carbonate matrix is characterised by an activity ratio greater than unity (up to 1.05). These results highlight a centimetric-scale uranium remobilisation in the limestone formations along these sub-horizontal seams. Although their nature and modalities are not fully understood, the driving processes responsible for these disequilibria were active during the last 1–2 Ma. Keywords: uranium isotopes, multiple-collector ICP-MS, waste management, remobilisation, migration |
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| 1 : | GEOTOP-UQAM-McGILL |
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GEOTOP-UQAM-McGill |
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| 2 : | 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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| 3 : | Laboratoire Magma et Volcan (LMV-ENSMSE) |
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CNRS : UMR6524 – École Nationale Supérieure des Mines - Saint-Étienne – SPIN |
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| 4 : | Agence Nationale pour la Gestion des Déchets Radioactifs (ANDRA) |
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ANDRA |
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| Domaine | : | Planète et Univers/Interfaces continentales, environnement Sciences de l'environnement/Milieux et Changements globaux Planète et Univers/Océan, Atmosphère Planète et Univers/Sciences de la Terre |
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| hal-00330850, version 1 | |
| http://hal.archives-ouvertes.fr/hal-00330850 | |
| oai:hal.archives-ouvertes.fr:hal-00330850 | |
| Contributeur : Publication EGU | |
| Soumis le : Jeudi 1 Janvier 2004, 08:00:00 | |
| Dernière modification le : Vendredi 12 Décembre 2008, 12:41:21 | |
