Geochronology and decoupling controls of Sn-(Ta-Li) and W-(Sn) mineralization in the Iberian Variscan Massif, Spain and Portugal

The image on the left shows selected Sn-(Ta-Li) deposits, Black circles, and W-(Sn) deposites, white circles. in the Iberian Peninsula for Ar/Ar in muscovite, Re-Os in molybdenite and U-Pb in zircon dating. The ages obtained, along with those already reported in the literature (image to the left) suggest a temporal decoupling between Sn-(Ta-Li) and W-(Sn) mineralizatin. Deposits rich in Sn and poor in W are related to S1 granites in the northern Iberia zone and to S2 in the southern zone. In contrast, W-(Sn) mineralization includes deposits rich in both metals which occur related to S1 and S2 granites, and other deposits enriched in W and depleted in Sn associated with type I-type granitoids. 1- Arteixo, 2-Santa Comba, 3- Amparo, 4- Fontao, 5- Casaio, 6- Valtreixal, 7- Calabor-Montesinho, 8- Las Sombras-Carris, 9- Golpejas, 10- Lumbrales, 11- Torrecilla de los Ángeles, 12- Las Navas, 13- Valdeflores, 14- La Parrilla, 15- San Nicolás. • Sn-W deposits in Iberia are link to Variscan granites from 330 to 280 Ma. • Sn-(Ta-Li) deposits correlate with S 1 and S 2 granites. • W-(Sn) mineralization is related to S 1 and S 2 granites and I-type granitoids. • Decoupling of Sn and W is related to late magmatic and hydrothermal processes. Sn-W mineralization in the Iberian Variscan Massif (corresponding with the western zone of the Iberian Peninsula, in Spain and Portugal) occurs closely related to metaluminous to peraluminous granitoids of Variscan age. The deposits are grouped into two main styles of mineralization; Sn-(Ta-Li) and W-(Sn) deposits. Within this work we present a first attempt to correlate timing of W-Sn mineralization and plutonic events at a regional scale. We report new 40 Ar/ 39 Ar dates of muscovite related to the quartz-muscovite alteration of eleven deposits, molybdenite Re-Os dates from six deposits and two new zircon U-Pb dates of granitoids genetically related to the mineralization. The dates obtained support the relationship between W-Sn mineralization with specific, but not uniquely just one, granite suites. The dominant S-type peraluminous Variscan granitic suites in Iberia, the S 1 -type dated at ca. 330–311 Ma and the S 2 -type at ca. 314–296 Ma, are related to both, Sn-(Ta-Li) and W-(Sn) mineralization. A subgroup of deposits of the W-(Sn) group, generally enriched only in W but not in Sn is associated with the youngest but volumetrically less abundant I-type (ca. 303–280 Ma) metaluminous magmatism. The relationship of both the Sn-rich and W-(Sn)-rich deposits with the highly peraluminous S-type granites suggest that the ultimate source of the melts is not related to the decoupling between Sn and W. Therefore, the causes of W and Sn separation may be related to late-stage magmatic and magmatic-hydrothermal processes.