TRACE ELEMENT GEOCHEMISTRY OF SPHALERITE: IMPLICATIONS ON MINERALIZING EVENTS AT THE CUMBERLAND MINE, CENTRAL TENNESSEE, USA

Sphalerite ore samples were collected from the Cumberland Mine in central Tennessee, USA, to determine trends in trace element distribution. Mineralization is classified as Mississippi Valley Type and is hosted in Lower Ordovician carbonate platform rocks situated along the paleostructural highs of the Nashville Dome and Cincinnati Arch. Sphalerite is the dominate ore mineral along with minor amounts of galena, pyrite, calcite, barite, and fluorite. Mineralization occurs primarily in two forms: open space fillings in collapsed dolomite breccias and as sulfide replacement of limestones. Samples of sphalerite in breccia and replacement ores were cut and polished and then analyzed with a scanning electron microscope with an energy dispersive system. Detectable elements include Zn, Fe, Ge, Ga, Cd, and Cu with the highest concentrations of Ge, Ga, Cd, and Cu occurring in sphalerite collected from breccia ore. Significant positive correlations exist between Ge and Cd, Fe and Ge, and Fe and Cu in replacement ore and between Ge and Cu in breccia ore indicating a relationship between these elements in the different ore types. The analyses suggest that sphalerite may have been precipitated from different compositional fluids or formed during different mineralizing events from a single evolved fluid.