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Tin (Sn) and tungsten (W) mineralization are often associated with each other in relation to highly evolved granites, but economical ore grades are restricted to rare global occurrences and mineralization styles are highly variable, indicating different mechanisms for ore formation. The Sn-W Zinnwald deposit in the Erzgebirge (Germany/Czech Republic) in the roof zone of a Variscan Li-F granite hosts two contrasting styles of mineralization: 1) cassiterite (Sn) in greisen bodies and 2) cassiterite and wolframite (W) in predominantly sub-horizontal quartz-rich veins. The relative timing and causes for ore formation remain elusive. Studies of fluid inclusion assemblages in wolframite, cassiterite and quartz samples from greisen and veins by conventional and infrared microthermometry and LA-ICP-MS analyses have revealed compelling evidence that all elements required for the formation of the Zinnwald Sn-W deposit were contained in a single parental magmatic-hydrothermal fluid that underwent two main processes: 1) fluid-rock interaction during Sn-greisen formation and 2) depressurization and vapor loss leading to ore precipitation in quartz-Sn-W veins. The results also show that fluid inclusion assemblages in ore minerals can document fluid processes that are absent in the fluid inclusion record of gangue minerals. The study further highlights the role of phase separation in the formation of W-rich Sn-deposits and indicates that W-deposits in distal parts of evolved granites may be restricted to fluids derived from deeper-seated plutons.

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Fluid inclusions studies in quartz and calcite in samples from the ICDP‐Chicxulub drill core Yaxcopoil‐1 (Yax‐1) have revealed compelling evidence for impact‐induced hydrothermal alteration. Fluid circulation through the melt breccia and the underlying sedimentary rocks was not homogeneous in time and space. The formation of euhedral quartz crystals in vugs hosted by Cretaceous limestones is related to the migration of hot (>200 °C), highly saline, metal‐rich, hydrocarbon‐bearing brines. Hydrocarbons present in some inclusions in quartz are assumed to derive from cracking of pre‐impact organic matter. The center of the crater is assumed to be the source of the hot quartz‐forming brines. Fluid inclusions in abundant newly‐formed calcite indicate lower cyrstallization temperatures (75–100 °C). Calcite crystallization is likely related to a later stage of hydrothermal alteration. Calcite precipitated from saline fluids, most probably from formation water. Carbon and oxygen isotope compositions and REE distributions in calcites and carbonate host rocks suggest that the calcite‐forming fluids have achieved close equilibrium conditions with the Cretaceous limestones. The precipitation of calcite may be related to the convection of local pore fluids, possibly triggered by impact‐induced conductive heating of the sediments.

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