The Argemela mineralized area (AMA), central Portugal, exhibits a nearly continuous magmatic to hydrothermal ore-forming sequence typical of Variscan granite-related rare metal deposits. Disseminated and vein-type mineralization are distributed in two systems, the Argemela Mine (AM) and the Cabeço da Argemela (CA). Disseminated mineralization includes montebrasite, cassiterite and columbite-tantalite dispersed in rare metal granites. Vein-type mineralization occurs both in granites and country rocks. The CA system exposes three generations of intragranitic veins with montebrasite in the two earliest and montebrasite, wolframite, cassiterite and columbite-tantalite in the latest. Country rock veins include a swarm of cassiterite and montebrasite veins (AM) and rare isolated wolframite veins (CA). Disseminated cassiterites are enriched in Ta 2 O 5 and Nb 2 O 5 compared to vein cassiterites. Disseminated columbite-tantalites evolve toward Mn-and Ta-rich chemistries that contrast with the more Fe-and Nb-rich compositions in intragranitic veins. In the CA system, both intragranitic and country rock veins crystallize early Mn-rich wolframites followed by late more Fe-rich compositions associated with Nb-, Ta-poor cassiterite, the later replaced by stannite. Field relations, structural, mineralogical and geochemical data suggest that the disseminated and vein-type mineralization are expressions of a continuous metallogenic evolution initiated at the magmatic stage, pursued during the magmatic-hydrothermal transition and ended with hydrothermal circulations in country rock. The two mineralized systems share similarities, but they also show major differences. Structural analysis demonstrates that the intragranitic veins in the CA and the country rock veins in the AM were emplaced under the same tectonic regime. Therefore, the two systems are variants of the same local metallogenic evolution. Sn and W show markedly contrasted behaviors. Both have a magmatic source but only Sn reaches concentrations leading to saturation of the melt with cassiterite. W is deposited later and preferentially to Sn in intragranitic veins. At the hydrothermal stage, cassiterite and wolframite deposition are disconnected and, overall, wolframite occurs only in minor amounts. The metallogenic model proposed for the AMA emphasizes magmatic rare metal concentration processes, exsolution of magmatic fluids and selective deposition of metals during the magmatic-hydrothermal and later hydrothermal stages. The Sn-Li-(Nb-Ta)-dominated, and W-poor signature of the AMA makes it similar to LCT pegmatites of the Central Iberian Zone but is distinctive from the world class W-(Sn-Cu) Panasqueira deposit nearby.

Understanding wolframite deposition mechanisms is a key to develop reliable exploration guides for W. In quartz veins from the Variscan belt of Europe and elsewhere, wolframites have a wide range of compositions, from hübnerite-(MnWO 4 ) to ferberite-rich (FeWO 4 ). Deposition style, source of Mn and Fe, distance from the heat/fluid source and temperature have been proposed to govern the wolframite H/F (hübnerite/ferberite ratio) defined as 100 at. Mn / (Fe + Mn). The Argemela mineralized district, located near the world-class Panasqueira W mine in Portugal, exposes a quartz-wolframite vein system in close spatial and genetic association with a rare-metal granite.Wolframite is absent as a magmatic phase, but W-rich whole-rock chemical data suggest that the granite magma is the source of W. Wolframite occurs as large homogeneous hübnerites (H/F = 64-75%) coexisting with montebrasite, K-feldspar and cassiterite in the latest generation of intragranitic veins corresponding to magmatic fluids exsolved from the granite. Locally, early hübnerites evolve to late more Fe-rich compositions (H/F = 45-55%). In a country rock vein, an early generation of Fe-rich hübnerites (H/F = 50-63%) is followed by late ferberites (H/F = 6-23%). Most Argemela wolframites have H/F ratios lower than at Panasqueira and other Variscan quartz-vein deposits which dominantly host ferberites. In greisens or pegmatitic veins, wolframites generally have intermediate H/F ratios. In those deposits, fluid-rock interactions, either involving country rocks (quartz-veins) or granite (greisens) control W deposition. In contrast, at Argemela, wolframite from intragranitic veins was deposited from a magmatic fluid. Differentiation of highly evolved peraluminous crustal magmas led to high Mn/Fe in the fluid which promoted the deposition of hübnerite. Therefore, the H/F ratio can be used to distinguish between contrasted deposition environments in perigranitic W ore-forming systems. Hübnerite is a simple mineralogical indicator for a strong magmatic control on W deposition.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.