Hydrothermalisme anté-Hercynien en Sud-Ibérie : apport de la géochimie isotopique du plomb

Lead isotope study has been performed on massive sulphide deposits of Ossa-Morena and Aracena Belt (South Iberia). Results suggest the existence of at least two ancient hydrothermal events. The first one, Upper Brioverian in age (～600–570 Ma), gave birth to Maria-Luisa and Puebla de la Reina massive sulphide deposits; it thus confirms the existence of a Cadomian orogen in South Iberia. Isotopic compositions indicate a local contribution of mantle-derived material (Maria Luisa mine), confirming the presence of ancient oceanic crust in Aracena Belt. This mineralising event seems to extend till the Armorican Massif. The second episode, Eo-Hercynian in age (～400–350 Ma) has allowed genesis of massive sulphide deposits of la Nava Paredon and Aguas Blancas, and could be coeval with the emplacement of South-Iberian massive sulphide ore deposits in the neighbouring South-Portuguese Zone. A more continental crustal source for later ore deposits could explain the much more important metal accumulation in this zone. To cite this article: É. Marcoux et al., C. R. Geoscience 334 (2002) 259–265.