RE-OS DATING OF MOLYBDENITE FORMATION AT THE HAILE GOLD MINE, LANCASTER COUNTY, SOUTH CAROLINA

New Re-Os measurements from molybdenite from three samples of mineralized drill core at the Haile Gold Mine, SC have yielded ages of 548.7 ± 4.2, 549.0 ± 3.1, 548.4 ± 2.4 and 541.2 ± 2.3 Ma. These combined ages suggest molybdenite formation at Haile occurred between approximately 540 and 552 Ma. The very fine-grained nature of molybdenite made it impossible to obtain pure, non-magnetic, mineral separates from the Haile samples. Two Re-Os ages reported outside of the 540-552 time window are interpreted as inaccurate, based on low Re abundances and relatively high common Os, indicating low purity molybdenite separates having ages that may have been significantly influenced by Re and Os in contaminant minerals. Broadly correlative Mo and Au abundances in drill samples produced during the recent phase of exploration at Haile, and the common presence of molybdenite in Au-bearing horizons indicate that Au mineralization at Haile probably also occurred in the 540-552 time window. The Re-Os molybdenite ages reported here establish a close chronological association between Au mineralization and the time of peak magmatism in the Haile area in the 545-558 Ma time window (Ayuso et al., 2005 – Econ Geol). These results indicate the hydrothermal systems that produced the Haile deposit were driven by volcanism at a time when the Carolina Slate Belt, which is exotic to North America, was still in a peri-Gondwana location. The new ages appear to rule out models that associate mineralization at Haile with metamorphism during accretion of the Slate Belt to Laurentia, which postdates molybdenite formation by more than 200 Ma.