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Evidence for Fe-sulfide and Fe-Ti oxide liquid immiscibility in the Itsindro gabbro Complex, Madagascar

Abstract : The petrology and mineralogy of the Itsindro complex, SW Madagascar has been investigated through samples coming from a borehole drilled, in the early 70’s, in a geophysical and Ni-,Cu-geochemical anomaly. The host rocks are represented by a pyroxenite unit with interbedded gabbro layers and a gabbro unit. A decrease of the Mg number of CPX, independent of the lithology, is observed from the deepest samples (316 m) up to 163 m suggesting a regular fractional crystallization process. The evolution of this parameter is more erratic in the upper part of the bore hole. The mineralisation consists in Fe-Ti-P oxides and Fe-(Cu-Ni) sulfides. The ilmenite-magnetite±apatite and pyrrhotite±chalcopyrite ±pent-landite assemblages are always observed in interstitial position. The contemporaneous character of the oxide and sulfide assemblages strongly suggests a two stages evolution of the tholeitic magma, a first immiscibility process between a Si-rich and a Fe-Ti-P liquids followed by a sulfide contamination of the latter giving way to massive Fe-rich over Cu- Ni sulphides.
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Contributeur : Thierry Augé Connectez-vous pour contacter le contributeur
Soumis le : mardi 26 juillet 2022 - 12:11:49
Dernière modification le : mercredi 3 août 2022 - 04:06:20
Archivage à long terme le : : jeudi 27 octobre 2022 - 18:19:44


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  • HAL Id : hal-01157670, version 1



Thierry Augé, Laurent Bailly, Jean-Yves Roig. Evidence for Fe-sulfide and Fe-Ti oxide liquid immiscibility in the Itsindro gabbro Complex, Madagascar. SGA 2015 : Ressources minérales dans un monde durable, SGA (Society for Geology Applied to Mineral Deposits), Aug 2015, Nancy, France. ⟨hal-01157670⟩



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