Highly fractionated granites and related magmatic-hydrothermal ore-forming processes can be traced by elemental ratios such as Nb/Ta, K/Rb, Y/Ho, Sr/Eu, Eu/Eu*, Zr/Hf, and Rb/Sr. The lanthanide “tetrad effect” parameter (TE_1,3) can also be a useful geochemical fingerprint of highly fractionated granites. This work assesses its application as an exploration vector for granite-related mineralization in the Central Iberian Zone by examining TE_1,3 variations with different elemental ratios and with the concentrations of rare metals and fluxing elements (such as F, P, and B). The multi-elemental whole-rock characterization of the main Cambrian–Ordovician and Carboniferous–Permian granite plutons and late aplite–pegmatite dykes exposed across the Segura–Panasqueira Sn-W-Li belt show that the increase in TE_1,3 values co-vary with magmatic differentiation and metal-enrichment, being the Carboniferous–Permian granite rocks the most differentiated, and metal specialized. The Argemela Li-Sn-bearing rare metal granite and the Segura Li-phosphate-bearing aplite–pegmatite dykes deviate from this geochemical trend, displaying TE_1,3 < 1.1, but high P₂O₅ contents. The results suggest that mineralized rocks related to peraluminous-high-phosphorus Li-Sn granite systems are typified by TE_1,3 < 1.1, whereas those associated with peraluminous-high-phosphorus Sn-W-Li (lepidolite) and peraluminous-low-phosphorus Sn-Ta-Nb granite systems display TE_1,3 > 1.1, reaching values as high as 1.4 and 2.1, respectively.

The Segura mining field, the easternmost segment of the Góis–Panasqueira–Segura tin–tungsten metallogenic belt (north–central Portugal), includes Sn-W quartz veins and Li-Sn aplite-pegmatites, which are believed to be genetically related to Variscan Granites. Sediment geochemistry indicates granite-related Ti-enrichments, locally disturbed by mineralization, suggesting magmatic and metamorphic/metasomatic titaniferous phases. Therefore, Segura alluvial samples and the geochemistry of their TiO₂ polymorphs (rutile, anatase, and brookite) were investigated, and their potential as exploration tools for Sn and W deposits was evaluated. The heavy-mineral assemblages proved to be good proxies for bedrock geology, and TiO₂ polymorph abundances were found to be suitable indicators of magmatic and/or metasomatic hydrothermal processes. The trace element geochemistry of Segura’s alluvial rutile, anatase, and brookite is highly variable, implying multiple sources and a diversity of mineral-forming processes. The main compositional differences between TiO₂ polymorphs are related to intrinsic (structural) factors, and to the P-T-X extrinsic parameters of their forming environments. Anomalous enrichments, up to 9% Nb, 6% Sn and W, 3% Fe, 2% Ta, and 1% V in rutile, and up to 1.8% Fe, 1.7% Ta, 1.2% Nb, 1.1% W 0.5% Sn and V in anatase, were registered. Brookite usually has low trace element content (<0.5%), except for Fe (~1%). HFSE-rich and granitophile-rich rutile is most likely magmatic, forming in extremely differentiated melts, with Sn and W contents enabling the discrimination between Sn-dominant and W-dominant systems. Trace element geochemical distribution maps show pronounced negative Sn (rutile+anatase) and W (rutile) anomalies linked to hydrothermal cassiterite precipitation, as opposed to their hydrothermal alteration halos and to W-dominant cassiterite-free mineralized areas, where primary hydrothermal rutile shows enrichments similar to magmatic rutile. This contribution recognizes that trace element geochemistry of alluvial TiO₂ polymorphs can be a robust, cost- and time-effective, exploration tool for Sn(W) and W(Sn) ore deposit systems.