Origin and Evolution of Hydrothermal Fluids Associated with Granitoid-Hosted Tungsten Mineralization at Degana, Rajasthan

The Degana tungsten deposit is found genetically and spatially related to the post-Delhi granite. Hydrothermal fluids associated with this granitic magmatism have evolved in three stages. Early greisenization stage took place in the temperature range 480°-260°C. Brecciation followed by boiling and emplacement of quartz sheets responsible for most of the wolframite mineralization occurred in the temperature range of 270°-350°C. In the last stage, addition of meteoric water took place in the temperature range of 130°-260°C. Salinity of mineralizing hydrothermal fluids ranges fiom 67-9 eq. wt % NaCI. Evidence of fluid boiling suggests a depth of mineralization at 600-1250 m, consistent with a range of hydrostatic pressure for about 60-300 bars.