Experimental Study of Silver in High-Temperature Magmatic-Hydrothermal Systems

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EAR-0309967CandelaMagmatic-hydrothermal ores, such as many porphyry, skarn and related ores, as well as many epithermal deposits, are related spatially and temporally to intermediate to felsic intrusive igneous rocks. We propose to establish a preliminary baseline for the physical chemistry of silver in magmatic-hydrothermal systems by examining the partitioning of silver among coexisting melts, crystalline sulfide, metal and oxides phases. These data will allow the estimation of a model activity ratio of Ag:Au:Cu in high-temperature porphyry type fluids. Additionally, these data can be used to estimate how the crystallization of Cu-Fe sulfides from a hydrothermal fluid changes the ratio of Ag to Au in the fluid, and how the crystallization or destruction of magmatic sulfide or oxide phases might modify the silver content of high-level magmas. This will allow more quantitative testing of hypotheses such as the suggestion that pulses of saline magmatic fluids into the epithermal environment can supply significant quantities of silver, or that the gold and silver budgets of porphyry type ores is controlled by the temperature dependent partitioning of Ag and Au into Cu-Fe sulfides. Volatile phases will be trapped in quartz fluid inclusions and analyzed by LA-ICPMS. These data will serve as a basis for the construction of exploration models for both gold and silver deposits. Further, our group has a track record involving a mix of high school, undergraduate, masters and doctoral students in our research. All of our graduate students are involved in undergraduate teaching. Furthermore, we actively participate in outreach in a variety of formats (e.g. Partners in Education Program (PEP) sponsored by GSA; training for the Ranger Interpreter Program in Yosemite National Park for the National Park Service; and visits to elementary schools).