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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. [Display omitted] • 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 40Ar/39Ar 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Critical raw materials are essential for the development of our society. However, most shallow ores have already been exploited and only deep targets remain unexplored. This work aims to apply indirect geophysical techniques to the San Finx Sn-W deposit (A Coruña) in order to get further constrains of its deep structure and geometry. Accordingly, a magnetic and a gravity survey have been carried out in the area (SE of Noia, A Coruña), at the southern part of the Malpica-Tui Complex. The resulting absolute magnetic anomaly and the relative gravity anomaly have been studied analytically and through 2-2.75D forward modeling. Results indicate that, the sampling interval (~1 km) is too high to characterize the anomalies related to the Sn-W mineralization. Contrarily, they show the potential field imprint of the regional Variscan tectonics. To better assess the relationship between the regional Variscan tectonics and the mineralization, a higher resolution survey should be acquired to detect this deposit.

The Badzhal tin magmatic-fluid system of the eponymous volcanoplutonic zone in the Middle Amur Region has been studied to reveal special characteristics of the transition from granite crystallization to rare-metal deposition. Therefore, the authors have conducted an in-depth study of melt, fluid-melt, and fluid inclusions and oxygen isotope composition of minerals from granitic rocks of the Verkhneurmiisky pluton within the Badzhal volcanoplutonic zone and minerals of the Pravourmiisky and Blizhnee Sn-W deposits. Greisen alteration and hydrothermal veins at the Pravourmiisky and Blizhnee deposits resulted from a single magmatic-fluid system related to the Verkhneurmiisky granite pluton, which is one of domes of the Badzhal batholith. The transition has been traced from magmatic crystallization of granite to hydrothermal ore formation and evolution of magmatic fluid from its separation to Sn and W deposition. Mixed fluid-melt inclusions directly support tin-bearing fluid separation during melt crystallization. The glass compositions indicate that granite and porphyry granite crystallized from felsic metaluminous to peraluminous melts with an ASI index and alkali content ranging from 0.95 to 1.33 and from 6.02 to 9.02 wt %, respectively. The Cl and F concentrations in glasses are 0.03–0.14 and 0.14–0.44 wt %, respectively, and are higher than those in the bulk rock compositions, 0.02 and 0.05–0.13 wt %, respectively. These differences indicate that Cl and F could have been removed from a granitic melt during its crystallization and degassing. The H2O concentration estimated based on the electron deficiency of summed microprobe analyses is 8–11 wt %. This was estimated taking into account the possible effect of "sodium loss" (Nielsen and Sigurdson, 1981) when analyzing hydrated glasses. Taking into account the high uncertainty of such estimation (Devine et al., 1995), this value is extremely uncertain and the studied melts should be considered as containing 9.5–10.0 wt % H2O. The melt inclusion study shows that some of the magmatic rocks of the Badzhal ore-magmatic system formed at approximately 650°C. The melt from which these rocks crystallized was felsic, moderate in fluorine, and meta- and peraluminous. Low-temperature crystallization is probably caused by high water pressure and elevated fluorine content. These inclusions most likely characterize the final stage of the pluton, at which crystals, residual melt, and magmatic fluid phase coexist. Fluid responsible for the formation of greisens at the Pravourmiisky deposit has features very close to those of supercritical fluid trapped by magmatic minerals. Its salinity, ranging from ∼9 to 12 wt % NaCl equiv., and maximal temperature of 550°C (taking into account pressure correction for ∼1 kbar) are close to those of magmatic fluid. This makes it possible to relate the origin of the fluid to cooling of the pluton. Greisen and quartz-cassiterite-topaz veins of the Pravourmiisky deposit formed from magmatic fluid at a decreased temperature from 550–450 to 480–380°C. The fluid responsible for the formation of quartz-cassiterite veins at the Blizhnee deposit also separated from magma as indicated by the oxygen isotope composition ( δ 18 O H 2 O ~ 8.5 ‰ ), which evolved in a shallower environment under much lower pressure. This resulted in fluid with a salinity of ∼13 wt % NaCl equiv. at 420–340°C being separated into a low-density low-saline vapor and brine with a salinity of 33.5–37.4 wt % NaCl equiv. The oxygen isotope composition of the mineralizing fluid was governed by equilibrium with granite within a wide temperature range (from ∼700°C to the onset of greisen crystallization). The agreement between the measured data and those calculated based on the suggested model indicates that a significant volume of external fluid having different isotopic features and not in equilibrium with the Verkhneurmiisky granite did not enter the magmatic-fluid system. The revealed differences in the physicochemical formation conditions of the two studied deposits are not critical and support their formation within a single magmatic-fluid system. [ABSTRACT FROM AUTHOR]

• Zircon and cassiterite U–Pb isotopic dating obtained Permian age of granites related the Sn mineralization in the Eastern Belt of Peninsular Malaysia. • I-type granites are identified by partial melt of the Proterozoic meta-igneous rocks. • Granites were formed in the island-arc environment of an active continental margin. The Guposhan ore field, located in the central part of the Nanling Range and close to the giant Central South Peninsula tin ore belt, is well-known for its large-scale Sn (W) mineralization and hosts a series of middle to large scale Sn (W) deposits. In this study, medium to fine grained biotite granite, outcropped in the mining area, have zircon U–Pb ages of 162.8 ± 1.3 Ma (MSWD = 0.54) and 162.7 ± 1.2 Ma (MSWD = 0.66), respectively. These zircon ages are consistent to the Sm–Nd isotopic age of minerals (garnet, hornblende, clinopyroxene and orthopyroxene) from the skarn-type ores, which is 160.4 ± 4.8 Ma (MSWD = 1.3). These granites are characterized by high content of SiO 2 , K 2 O, Na 2 O and REEs, and high Ga/Al ratios, indicating that they belong to highly fractionated A-type granites with high-K calc-alkaline and aluminous-peraluminous signatures. The zircon Lu–Hf isotopes of these granites have ε Hf (t) values and T DMC ages of −2.66 to −1.71 and 1.32–1.38 Ga, respectively. Combined with the previous studies, it was proposed that the magma was formed by the mixing of crust-mantle components (ca. 50 and ca. 50%, respectively). In addition, magmas are characterized by low temperatures of ca. 710 °C and oxygen fugacity (log(f O 2) values of −18.5 to −16.4. Formation of these granites were likely related to an intraplate extensional tectonic setting, triggered by roll-back of the subducted Paleo-Pacific plate beneath the South China Block (SCB). These granites are in favor of the Sn (W) mineralization, making the Guposhan ore district a large-scale Sn (W) mineralization ore field in the Nanling Range. [ABSTRACT FROM AUTHOR]