Publication: The Aguablanca Cu–Ni ore deposit (Extremadura, Spain), a case
of synorogenic orthomagmatic mineralization: age and isotope
composition of magmas (Sr, Nd) and ore (S)
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Publication Date
2001
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Elsevier Science B.V., Amsterdam
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Abstract
The Aguablanca Cu–Ni orthomagmatic ore deposit is hosted by mafic and ultramafic rocks of the Aguablanca stock,
which is part of the larger, high-K calc-alkaline Santa Olalla plutonic complex. This intrusive complex, ca. 338 Ma in age, is
located in the Ossa-Morena Zone (OMZ) of the Iberian Variscan Belt. Mineralization consists mainly of pyrrhotite,
pentlandite and chalcopyrite resulting from the crystallization of an immiscible sulphide-rich liquid. Isotope work on the host
igneous rocks (Sr, Nd) and the ore (S) suggests that contamination with an upper-crustal component took place at some depth before final emplacement of the plutons (εNd338= -6 to -7.5; Sr(338)=0.7082 to 0.7100; δ34(sulphides) near + 7.4‰). Assimilation–fractional crystallization (AFC) processes are invoked to explain early cumulates and immiscible
sulphide-magma formation. Intrusion took place at the beginning of the type-A oblique subduction of the South Portuguese
Zone under the Ossa-Morena Zone and was probably driven by transpressive structures (strike-slip faults). The mineralization
is thus synorogenic.
Aguablanca is probably the first case referred to in the literature of a magmatic Cu–Ni ore deposit hosted by calc-alkaline
igneous rocks.