| Summary: | 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<sub>1,3</sub>) 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<sub>1,3</sub> 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<sub>1,3</sub> 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<sub>1,3</sub> < 1.1, but high P<sub>2</sub>O<sub>5</sub> contents. The results suggest that mineralized rocks related to peraluminous-high-phosphorus Li-Sn granite systems are typified by TE<sub>1,3</sub> < 1.1, whereas those associated with peraluminous-high-phosphorus Sn-W-Li (lepidolite) and peraluminous-low-phosphorus Sn-Ta-Nb granite systems display TE<sub>1,3</sub> > 1.1, reaching values as high as 1.4 and 2.1, respectively.
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