Manioc : Portail | resultats 1 - 20 pour la recherche: Engines ( lc )

Les colonies françaises : un siècle d'expansion coloniale
Auteur(s) : Terrier, Auguste (1873-1932) Dubois, Marcel (1856-1916)
Auteurs secondaires : France. Ministère des colonies (1894-1946)
Année de publication :

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Old French Decauville Engine near Frijoles ; 204-C - Old French Decauville Engine near Frijoles. - Oct., 1908
Auteur(s) : Hallen, Ernest ( Photographer )

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Dictionaire francois-caraibe
Auteur(s) : Breton, Raymond (1609-1679)
Année de publication :

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Notice sur la transportation à la Guyane française et à la Nouvelle-Calédonie pour les années 1884.
Auteur(s) : Aube, Hyacinthe Théophile (1826-1890) La Porte, Jean Roger Amédée de (1848-1900)
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Anecdotes américaines ou Histoire abrégée des principaux événements arrivés dans le nouveau monde, depuis sa découverte jusqu'à l'époque présente
Auteur(s) : Hornot, Antoine (17..-....)
Année de publication :

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Preservation of Permian allanite within an Alpine eclogite facies shear zone at Mt Mucrone, Italy: Mechanical and chemical behavior of allanite during mylonitization
Auteur(s) : Cenki-Tok, Bénédicte Oliot, Emilien Rubatto, D. Berger, A. Engi, M. Janots, Emilie Thomsen, T.B. Manzotti, P.
Auteurs secondaires : Institute of Geological Sciences ; University of Bern Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Laboratoire Chrono-environnement (LCE) ; Université Bourgogne Franche-Comté (UBFC) - Centre National de la Recherche Scientifique (CNRS) - Université de Franche-Comté (UFC) Research School of Earth Sciences [Canberra] (RSES) ; Australian National University (ANU) University of Copenhagen (KU) Minéralogie et environnements ; Institut des Sciences de la Terre (ISTerre) ; Université Joseph Fourier - Grenoble 1 (UJF) - Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR) - Institut national des sciences de l'Univers (INSU - CNRS) - Institut de recherche pour le développement [IRD] : UR219 - PRES Université de Grenoble - Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]) - Centre National de la Recherche Scientifique (CNRS) - Université Joseph Fourier - Grenoble 1 (UJF) - Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR) - Institut national des sciences de l'Univers (INSU - CNRS) - Institut de recherche pour le développement [IRD] : UR219 - PRES Université de Grenoble - Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]) - Centre National de la Recherche Scientifique (CNRS) James Cook University, School of Earth and Environmental Sciences ; James Cook University, School of Earth and Environmental Sciences Financial support from Swiss National Fund for our work in the Western Alps (Grants 200020-109637, 200021-117996/1). The electron microprobe at the University of Bern is also partly funded by SNF (Grant 200021-103479/1).

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This study addresses the mechanical and chemical behavior of allanite during shear zone formation under high-pressure metamorphism. Understanding physico-chemical processes related to the retention or resetting of Pb isotopes in allanite during geological processes is essential for robust petrochronology. Dating of allanite in meta-granodiorite showing variable amounts of strain (from an undeformed protolith to mylonite) at Monte Mucrone (Sesia Zone, NW Italy) gave surprising results. Based on structural and petrographic observations the shear zones at Mt Mucrone are Alpine, yet allanite located within an eclogite facies mylonite yielded Permian ages (208Pb/232Th average age: 287 ± 7 Ma). These mm-sized allanite grains are rimmed by an aggregate of coarse-grained garnet + phengite, thought to derive from former epidote. These aggregates were immersed in a weak matrix that experienced granular flow, and they were thus chemically and mechanically shielded during Alpine mylonitization. In undeformed samples (8a and 8b), two populations of epidote group minerals were found. Allanite forms either coronas around Permian monazite or individual grains with patchy zoning. Both types yield Permian ages (208Pb/232Th age: 291 ± 5 Ma). On the other hand, grains of REE-rich clinozoisite of Cretaceous age are found in undeformed rocks. These grains appear as small fragments with embayed surface outlines and minute satellites or rims around Permian allanite. These (re)crystallized grains are Sr-rich and show mosaic zoning. These results indicate that allanite crystals retained their chemical and isotopic characteristics, and thus their Permian age, as a result of strong strain partitioning between the epidote group porphyroclasts and the eclogite facies matrix in HP-mylonites. The observed partial mobilization of Pb isotopes, which lead to the Cretaceous-aged rims or grains in undeformed samples was facilitated by (re)crystallization of allanite and not by mere Pb diffusion alone under the HP conditions.
ISSN: 0024-4937

insu-00679730
https://hal-insu.archives-ouvertes.fr/insu-00679730
DOI : 10.1016/j.lithos.2011.01.005

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