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.
Type de document :
Communication dans un congrès
SGA 2015 : Ressources minérales dans un monde durable, Aug 2015, Nancy, France. 2015
Liste complète des métadonnées

https://hal-brgm.archives-ouvertes.fr/hal-01157670
Contributeur : Thierry Augé <>
Soumis le : jeudi 28 mai 2015 - 13:08:15
Dernière modification le : jeudi 10 septembre 2015 - 01:03:34

Identifiants

  • HAL Id : hal-01157670, version 1

Collections

Citation

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, Aug 2015, Nancy, France. 2015. 〈hal-01157670〉

Partager

Métriques

Consultations de la notice

123