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 ± 4 Ma), which represents an older intrusion, the bulk of samples yield ages that cluster around 340 ± 3 Ma: the Santa Olalla tonalite (341.5 ± 3 Ma), the Sultana hornblende tonalite (341 ± 3 Ma), a mingling area at the contact between the Aguablanca and Santa Olalla stocks (341 ± 1.5 Ma), the Garrote granite (339 ± 3 Ma), the Teuler granite (338 ± 2 Ma), and dioritic dykes from the Aguablanca stock (338.6 ± 0.8 Ma). The Bodonal–Cala porphyry, which has also been dated (530 ± 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.

A model is proposed for the origin and emplacement of the ca. 341 Ma Aguablanca magmatic Ni-Cu-(platinum group element [PGE]) sulfi de deposit (SW Iberia) integrating petrological, geochemical, structural, and geophysical data. The Aguablanca deposit occurs in an unusual geodynamic context for this ore type (an active plate margin) as an exotic , magmatic subvertical breccia located at the northern part of the coeval gabbronorite Aguablanca stock (341 ± 1.5 Ma). Structural and gravity data show that mineralized breccia occurs inside the inferred feeder zone for the stock adjacent to the Cherneca ductile shear zone, a Variscan sinistral transpressional structure. The orientation of the feeder zone corresponds to that expected for tensional fractures formed within the strain fi eld of the adjacent Cherneca ductile shear. Two distinctive stages are established for the origin and emplacement of the deposit: (1) initially, the ore-forming processes are attributed to magma emplacement in the crust, assimilation of crustal S, and segregation and gravitational settling of sulfi de melt (a scenario similar to most plutonic Ni-Cu sulfi de ores), and (2) fi nal emplacement of the Ni-Cu sulfi de-bearing rocks by multiple melt injections controlled by successive opening events of tensional fractures related to the Cherneca ductile shear zone