GEOLOGY AND PETROLOGY OF THE FLETCHER MARBLE, FLETCHER, NORTH CAROLINA

Several discontinuous, lenticular carbonate bodies occur within the Brevard Fault Zone of southwestern North Carolina. The Fletcher quarry, one of the larger marble occurrences, is currently exploited by the Fletcher Limestone Company for various industrial carbonate products. A 1:2500 scale geologic map of the quarry illustrates the structural relationship of the marble with respect to the encompassing phyllonitic rocks of the Brevard Fault Zone. The quarried marble is generally white with blue-gray laminations, medium to finely crystalline, dolomitic (95.3-66.9%) to calcitic (70-58.3%) with few impurities. It is texturally massive, but exhibits several distinct sets of crosscutting macro-scale joint-like spaced cleavage foliation planes. Three deformational events were identified through petrographic thin section examination. Microscopically, the marble exhibits a continuum of microtextures, ranging from protomylonite to porphyclastic mylonite. Extensive microbrecciation crosscuts these microtextures, however macro-scale cohesiveness was retained. Late-stage dolomite and calcite filled veins and open fractures crosscut the entire rock mass. Microfabric within the marble records a ductile to brittle deformation path. Stable isotope results of ¹⁸O (18.55-21.78‰V-SMOW) and ¹³C (1.11-0.64‰ V-PDB) are documented for dolomitic samples taken from the quarry. The entire marble body is surrounded by graphitic phyllonite and chlorite phyllonitic schist of the Brevard Fault Zone, and is interpreted to be a tectonic horse block. Kinematic indicators within the phyllonite schist suggest a westward-southwestward movement of the marble body along the Brevard Fault Zone.