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	Provedor de dados ArchiMer (2) Autor Barrat, Jean-alix (1) Brasseur, R (1) Chaussidon, Marc (1) Dosso, Laure (1) Fagel, N (1) Hamelin, Cedric (1) Hillaire-marcel, C (1) Humblet, M (1) Maury, Rene (1) Seitz, Hans-michael (1) Stevenson, R (1) Weis, D (1) Mais... Palavra-chave Nd and Pb isotopes (2) Clay-size fraction (1) Deep circulation (1) Labrador Sea (1) North Atlantic (1) Sedimentary mixings (1) Sr (1) Trachytes Basalts HIMU Assimilation and fractional crystallization (AFC) Lower crust Li (1) Mais... Tipo do documento Text (2) Ano 2009 (1) 2004 (1) País France (2) Idioma Inglês (2)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 2 Primeira ... 1 ... Última Nd and Pb isotope signatures of the clay-size fraction of Labrador Sea sediments during the Holocene: Implications for the inception of the modern deep circulation pattern ArchiMer Fagel, N; Hillaire-marcel, C; Humblet, M; Brasseur, R; Weis, D; Stevenson, R. Nd and Pb isotopes were measured on the fine fraction of one sediment core drilled off southern Greenland. This work aims to reconstruct the evolution of deep circulation patterns in the North Atlantic during the Holocene on the basis of sediment supply variations. For the last 12 kyr, three sources have contributed to the sediment mixture: the North American Shield, the Pan-African and Variscan crusts, and the Mid-Atlantic Ridge. Clay isotope signatures indicate two mixtures of sediment sources. The first mixture (12.2-6.5 ka) is composed of material derived from the North American shield and from a "young'' crustal source. From 6.5 ka onward the mixture is characterized by a young crustal component and by a volcanic component characteristic of the... Tipo: Text Palavras-chave: Clay-size fraction; Sedimentary mixings; Deep circulation; Nd and Pb isotopes; North Atlantic; Labrador Sea. Ano: 2004 URL: https://archimer.ifremer.fr/doc/00226/33731/32199.pdf A low delta7 Li lower crustal component: Evidence from an alkalic intraplate volcanic series (Chaine des Puys, French Massif Central) ArchiMer Hamelin, Cedric; Seitz, Hans-michael; Barrat, Jean-alix; Dosso, Laure; Maury, Rene; Chaussidon, Marc. The intraplate volcanic suite of the Chaine des Puys (French Massif Central) shows a complete petrologic range, from alkali basalts to trachytes. The significant variations of trace elements and radiogenic isotopes along the series strongly support the occurrence of crustal assimilation associated with fractional crystallization (AFC). The least contaminated basalts are clearly related to a HIMU-type reservoir (Pb-206/Pb-204>19.6; Sr-87/Sr-86<0.7037; epsilon(Nd)>+4). The behavior of radiogenic isotopes suggests that the most likely crustal contaminants are meta-sediments located in the lower crust. The Li isotopic compositions of the lavas range from high delta Li-7 (> + 7 parts per thousand) in basalts to lighter values in more evolved lavas... Tipo: Text Palavras-chave: Trachytes Basalts HIMU Assimilation and fractional crystallization (AFC) Lower crust Li; Sr; Nd and Pb isotopes. Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6853.pdf Registros recuperados: 2 Primeira ... 1 ... Última

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