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 t he post-Delhi granite. Hydrothermal fluids associated with this granitic ma gmatism have evolved in three stages. Early greisenization stage took place in the temperature range 480 degrees -260 degreesC. Brecciation followed b y boiling and emplacement of quartz sheets responsible for most of the wolf ramite mineralization occurred in the temperature range of 270 degrees -350 degreesC. In the last stage, addition of meteoric water took place in the temperature range of 130 degrees -260 degreesC. Salinity of mineralizing hy drothermal fluids ranges from 67-9 eq. wt % NaCl. 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.