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New U-Pb zircon ages from the Santa Olalla Igneous Complex have been obtained, which improve the knowledge of the precise timing of Variscan magmatism in the Ossa-Morena Zone, SW Iberia. This complex has a special relevance as it hosts the most important Ni-Cu-platinum group element (PGE) mineralization in Europe: the Aguablanca deposit. U-Pb zircon ages have been obtained for seven samples belonging to the Santa Olalla Igneous Complex and spatially related granites. With the exception of the Cala granite (352 AE 4 Ma), which represents an older intrusion, the bulk of samples yield ages that cluster around 340 AE 3 Ma: the Santa Olalla tonalite (341.5 AE 3 Ma), the Sultana hornblende tonalite (341 AE 3 Ma), a mingling area at the contact between the Aguablanca and Santa Olalla stocks (341 AE 1.5 Ma), the Garrote granite (339 AE 3 Ma), the Teuler granite (338 AE 2 Ma), and dioritic dykes from the Aguablanca stock (338.6 AE 0.8 Ma). The Bodonal-Cala porphyry, which has also been dated (530 AE 3 Ma), comprises a group of sub-volcanic rhyolitic intrusions belonging to the Bodonal-Cala volcano-sedimentary complex, which hosts the igneous rocks. The knowledge that emplacement of the Aguablanca deposit was related to episodic transtensional tectonic stages during the Variscan orogeny will be fundamental in future mineral exploration in the Ossa-Morena Zone.

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SummaryThe Aguablanca Ni-Cu-(PGE) magmatic sulphide deposit is associated with a magmatic breccia located in the northern part of the Aguablanca gabbro (SW, Iberia). Three types of ores are present: semi-massive, disseminated, and chalcopyrite-rich veined ore. The principal ore minerals are pyrrhotite, pentlandite and chalcopyrite. A relatively abundant platinum-group mineral (PGM) assem blage is present and includes merenskyite, melonite, michenerite, moncheite and sperrylite. Moreover, concentrations of base and precious metals and micro-PIXE analyses were obtained for the three ore-types. The mineralogy and the mantle normalised chalcophile element profiles strongly suggest that semi-massive ore represents mss crystallisation, whereas the disseminated ore represents an unfrac tionated sulphide liquid and the chalcopyrite-rich veined ore a Cu-rich sulphide liquid. Palladium-bearing minerals occur commonly enclosed within sulphides, indicating a magmatic origin rather than hydrothermal. The occurrences and the composition of these minerals suggest that Pd was initially dissolved in the sul phides and subsequently exsolved at low temperatures to form bismutotellurides.Negative Pt and Au anomalies in the mantle-normalised chalcophile element pro files, a lack of Cu-S correlation and textural observations (such as sperrylite losing its euhedral shape when in contact with altered minerals) suggest partial remobi lisation of Pt, Au and Cu by postmagmatic hydrothermal fluids after the sulphide crystallisation.