Controls on the porphyry Cu-Au mineralizing potential of magmas in continental collision settings

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The aim of this project is to evaluate the influence of magmatic factors on the porphyry Cu-Au mineralizing potential of magmas in continental collision settings. A popular view is that the high fertility of postcollisional, potassium-rich magmas stems from the partial melting of sulfide-rich cumulates that were deposited in the lower crust during a previous stage of subduction-related magmatism. This hypothesis will be tested using a dual approach that involves both experiments and studies on natural samples. In the experiments, natural, sulfide-bearing cumulates will be subjected to high pressures and temperatures to induce partial melting, and the obtained run products will be thoroughly characterized with regard to their composition, the oxygen fugacity, and the abundances of sulfur, H2O and metals in the silicate melt. The studies on natural samples aim at: (1) characterizing additional lower crustal cumulates that can be used as starting materials for the experiments, and (2) reconstructing the composition, formation conditions and metal content of a number of natural, postcollisional magmas associated with both mineralized and barren systems, such that the results can be directly compared with those obtained from the experiments.