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Les minéralisations sulfurées associées aux ophiolites de Corse : un exemple de système hydrothermal de sous-plancher océanique

Abstract : Sulfide mineralizations associated with the Corsican ophiolites appear at different levels of the ophiolitic sequence from peridotites (often transformed to serpentinites) to basalts through gabbros. Textures and metallic paragenesis show that mineralization deposition occurs in two stages. The first one is quantitatively predominant and it is characterized by a primary paragenesis of high temperature (300 to 400 °C). In this stage, iron sulfides (pyrite in basalts and gabbros ; hexagonal pyrrhotite in serpentinites) predominated the paragenesis. The second stage is characterized by low temperature paragenesis dominated by copper sulfides (mainly chalcopyrite and cubanite) indicating that a rich-copper latest fluids are invoqued.
The emplacement of mineralizations is related to a convectif hydrothermal system established in the oceanic crust. The sea water-rocks interaction lead to the transformation of the rocks at different degrees of metamorphism. The mineralogical and paragenetic studies of these transformations show that the hydrothermal system has been evolved in two stages with lowering temperature. Near the mineralized sills, quartz is abondant and secondary phases are iron-rich minerals. The fluids penetration up to the mantle is facilitated by the rock cracks related to the intraoceanic deformation.
The responsible hydrothermal system of sulfide mineralization deposition is related to the late magmatism of the Rospigliani serie. This serie shows magmatic, tectonic and sedimentary particular characters which allowed us to locate its genesis at the transform zone. This magmatism come before another one of Inzecca serie which presents some resemblances with tholeiites recently recognized at the straight above of the normal oceanic ridges. The genetic model of sulfide mineralizations associated with the Corsican ophiolites is comparable to that developped into the actual oceanic ridges and ophiolites of Cyprus and Oman.
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https://tel.archives-ouvertes.fr/tel-00276213
Contributor : Mohamed El Gadarri <>
Submitted on : Monday, April 28, 2008 - 7:18:38 PM
Last modification on : Thursday, March 5, 2020 - 6:49:00 PM
Long-term archiving on: : Friday, May 28, 2010 - 5:56:53 PM

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  • HAL Id : tel-00276213, version 1

Citation

Mohamed El Gadarri. Les minéralisations sulfurées associées aux ophiolites de Corse : un exemple de système hydrothermal de sous-plancher océanique. Minéralogie. Université d'Orléans, 1995. Français. ⟨tel-00276213⟩

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