Mafic magmatism in the Central Iberian Zone: Towards a better understanding of Sb mineralization?
Résumé
This work presents the geochemical and geochronological characterization of mafic sills of the Central-Iberian Zone, in order to unveil their possible relationships with Sb mineralization. These sills are located within three different synclines where several Sb mineralization are observed: La Codosera Syncline (CS) hosts the largest Sb mineralisation in Europe; Almaden Syncline (AS) hosts a world-class Hg deposit and some small Sb deposits; Guadalmez Syncline (GS) hosts several Sb +/- Hg deposits. Whole rock geochemistry of the mafic rocks and U-Pb dating on apatite reveal several differences among the three areas. The rocks from the CS present a sub alkaline affinity, whereas the rocks from AS and GS have an alkaline affinity. Primitive mantle normalized diagrams of the CS mafic samples show E-type MORB patterns with Cs and Pb positive anomalies and K, Ba, and Rb negative anomalies that are more marked in samples spatially related to Sb mineralization. The geochronological data allow to propose the existence of a mafic magmatic event that took place around 357 +/- 13Ma in the CIZ. Our data is temporarily concordant with a mafic event reported in the Armorican Massif, which is genetically associated with Sb mineralization in the same domain.