Abstract

Thermometric and salinity data are presented for fluid inclusion populations in samples of hydrothermal vein material (quartz intergrown with wolframite, cassiterite, stannite, arsenopyrite, pyrite/chalcopyrite, hematite and limonite) and in metasomatic quartz over-growths in granite, greisen and kaolinized granite. These data indicate that multistage high temperature (Th 200– 400°C) and single or multistage low temperature (Th 70–150°C) hydrothermal events occurred within the Cligga Head granite stock and its environs. Although fluid inclusion salinities were low (2–12 equiv, wt. % NaCl) throughout the hydrothermal history of the stock, there is a general tendency for the salinity of the vein fluids to decrease with decreasing temperature. The homogenization temperature and salinity of the vein fluids of the wolframite-cassiterite mineralization are similar to those of another Cornish Sn-W deposit at St Michae¾s Mount. Low to moderate salinity fluids in the Th range 300–400°C appear to be a characteristic of the cassiterite-wolframite mineralization in the Cornubian metallogenic province.

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