A study of the formation and history of a piece of continental crust by 87Rb-87Sr method: The case of the French oriental Pyrénées |
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Authors: | Annie Vitrac Michard Claude J Allègre |
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Institution: | 1. Laboratoire de Géochimie et Cosmochimie, Institut de Physique du Globe, Université Paris VI, France 2. Département des Sciences de la Terre, Université Paris VII, France
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Abstract: | Rb-Sr whole rock data for gneisses and granites from the oriental Pyrénées yield cadomian ages for the basement gneisses and hercynian ages for the granites. Granites occur in two generations. An alkaline granite dated at 335±15 m.y. is syn.—or slightly post-tectonic, and a later calcalkaline granite dated at 275±12 m.y, is clearly intrusive and marks the end of hercynian tectono-metamorphism. Initial 87Sr/86Sr ratios of the granites put limits on the proportion of juvenile contribution from the mantle to their formation. Petrogenetic models are tested using Rb and Sr as tracers. |
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