Re-Os Dating of Molybdenites from the North American Cordillera and Crustal/Mantle Contributions to Metallogenesis

辉钼矿有两种多型；六角形（2H）和更罕见的菱形（3R）。本研究的目的是确定哪种辉钼矿多型在沉积后最有可能保持Re-Os交换。项目拟从已知年龄的不同类型矿床中获得辉钼矿，采用XRD分析确定多型，采用ICP-MS同位素稀释分析其Re-Os丰度。本工作的第二个目的是确定亚利桑那州、新墨西哥州、墨西哥北部、内华达州和犹他州斑岩型铜/钼矿床硫化物的Re-Os同位素系统，以限制金属进入这些系统的地壳/地幔输入。

The are two molybdenite polytypes; a hexagonal (2H) and the more rare rhombohedral (3R). The purpose of this study is to determine which molybdenite polytype is most likely to remain closed to Re-Os exchange after deposition. The PI proposes to obtain molybdenites from different types of ore-deposits of known age, and determine the polytype by XRD analysis and analyze the Re-Os abundances by isotope dilution using an ICP-MS. The second purpose of this work is to determine the Re-Os isotope systematics of sulfides from porphyry copper/molybdenum deposits from Arizona, New Mexico, northern Mexico, Nevada and Utah in order to constrain the crust/mantle input of metals into these systems.