BRECCIATION, ALTERATION, AND MINERALIZATION IN CENTRAL TENNESSEE ZINC DISTRICT

Major zinc deposits have recently been discovered in stratabound breccias in the Mascot Dolomite of the upper Knox Group in Central Tennessee and southern Kentucky. The Mascot Dolomite is a Lower Ordovician sequence of very finely crystalline dolostone units with interbedded limestones and coarsely crystalline dolomitized equivalents of these limestones. The breccias are similar to those of the well-known zinc deposits within the Knox Group of East Tennessee but with some distinct differences. The dominant minerals in Central Tennessee are reddish brown sphalerite, barite, fluorite, galena, and calcite. In East Tennessee pale yellow sphalerite and dolomite are the only major minerals cementing the breccias. Sulfide mineral deposition in Central Tennessee was significantly later than breccia formation and may have been as late as late Paleozoic. Refs.