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Apports d'une étude intégrée sur les relations entre granites et minéralisations filoniennes (Au et Sn-W) en contexte tardiorogénique (Chaîne Hercynienne, Galice centrale, Espagne).

Abstract : The “Domaine Schisteux de Galice Centrale“ (DSGC) is located within the NW Spain (Galicia), within internal part of
the Hercynian domain. The late-orogenic evolution is characterized by the emplacement of four granites called G1
(335 Ma), G2 (322 Ma), G3 (318 Ma) and G4 (303 Ma). Pegmatite and granite dykes and sills associated with gold
and Sn-W lodes are found around the intrusions. Gold-bearing lodes are linked to the G3 and Sn-W ones to G2.
Structural data demonstrated that deformation is continuous since granite emplacement until mineralization. The
mineralogical and textural characteristics are similar for Au and Sn-W systems. Fluid inclusion study reveals that
aquo-carbonic fluids are dominant although high-salinity fluids are found. The Ar/Ar dating of granites and orebearing
veins (ca. 300 Ma) were interpreted to traduce the effects of Ar resetting or, alternatively, to record cooling
through temperatures of 300-400°C. The age of mineralization remains unknown but certainly close to those of the
neighbouring granite, based on petro-structural arguments.
A general model of evolution of the study area is proposed and discussed in conclusion. This model implies that the
granites were emplaced during an unique and continuous tectonic event characterized by EW shortening and Northdirected
shearing. It has been interpreted as the result of lateral escape, coeval with the ongoing EW hercynian
compression, and control by a half spoon-shape geometry, limited to the East by a dextral shear zone (G3 granites “en echelon” alignment) and, to the west, by the left-lateral shear zone of Couso. Mineralizations were formed in favour of mechanical instabilities developed on top of the granite. Indeed, granites play a thermal, rheological and also chemical role in ore concentration, as the nature of the granite infer on the nature of the mineralization (i.e., Au or Sn-W).
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Contributor : Nathalie Pothier <>
Submitted on : Wednesday, October 18, 2006 - 2:55:20 PM
Last modification on : Thursday, March 5, 2020 - 6:48:49 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 8:04:30 PM

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  • HAL Id : tel-00107391, version 1

Citation

Eric Gloaguen. Apports d'une étude intégrée sur les relations entre granites et minéralisations filoniennes (Au et Sn-W) en contexte tardiorogénique (Chaîne Hercynienne, Galice centrale, Espagne).. Minéralogie. Université d'Orléans, 2006. Français. ⟨tel-00107391⟩

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