BUILDING A FRAMEWORK FOR INTERPRETING MOLYBDENUM ISOTOPE RATIOS IN ORE DEPOSITS

Molybdenum (Mo) is a metal with a role in our daily lives and has many essential industrial uses. It is used as a lubricant and a steel alloying agent, which improves its strength and resistance to corrosion and heat. The behavior of molybdenum in low temperature environments has been extensively studied, however little work has focused on its behavior in high temperature environments like magmas and their associated systems. Outstanding questions include: What is the source of molybdenum in ore deposits, and how is it transported in geologic fluids? This research will analyze and compare Mo and sulfur (S) isotope ratios in molybdenite samples from a variety of ore deposit types including porphyry, epithermal, skarn, and metamorphic systems. Since each type of deposit is formed by the combination of specific geologic processes and conditions (e.g., temperature, redox), we can analyze Mo and S isotopes in molybdenite to characterize variations between ore deposit types. Preliminary samples come from seven locales and represent all four targeted deposit types. The pairing of Mo and S stable isotopes will determine if Mo isotopes and/or Mo-S isotope pairs is a useful geochemical tool to illuminate the geological origin (fluid versus melt; conditions) of molybdenite ore. Such a detailed dataset will provide a framework for this novel geochemical approach to understanding Mo-rich ore deposits.