The Geochemistry of the Platinum Group Elements, Copper, Rhenium and Gold in Granitic Rocks

We have developed an analytical technique that allows us to make the first systematic low-level analyses of the platinum group elements (PGEs) in granitic rocks. The significance of the PGEs is that they partition into immiscible sulfide melts much more strongly than other chalcophile (S loving) elements, such as copper and nickel, making them highly sensitive indicators of sulfide saturation in fractionating granitic magmas. Sulfide saturation, once it occurs in evolving granitic magmas, controls the subsequent evolution of the chalcophile elements. The proposed study will allow us to identify onset of sulfide saturation and monitor its effect on the chalcophile elements, including the important ore elements copper and gold.