Although granitic magmas are often invoked as sources of hydrothermal ore solutions, very little direct evidence exists for a genetic link between a specific mineral deposit and a specific magmatic body. This link may be provided by studying the Capitan Pluton and its associated quartz-allanite mineralization. The evolution and composition of the magmatic fluid phase can be modeled using the constraints provided by the existing detailed geochemistry of the Capitan pluton. This will be compared with the composition of the actual magmatic fluids which were responsible for mineralization. Vein minerals (quartz, allanite and titanite) and their trapped fluid inclusions will be analyzed for stable isotope, elemental and gas compositions. Comparison of the measured fluid composition and the computer-modeled composition should provide insight into the processes involved in magmatic aqueous fluid evolution.
