MAPPING AND KINEMATIC INTERPRETATION OF THE FRIES AND GOSSAN-LEAD FAULTS IN NORTHWEST NORTH CAROLINA

Mapping and structural analysis was conducted to investigate the kinematics and relationships between the Fries and Gossan-Lead faults in northwest North Carolina. The mapping was done in the northern portion of the Jefferson quadrangle and the northern and central sections of the Warrensville quadrangle in Ashe County and was a continuation of previous mapping done in the Grassy Creek and Mouth of Wilson quadrangles. The sections of the Fries fault and Gossan-Lead fault mapped in this project were previously proposed as continuations of the Fries thrust fault and the Burnsville strike-slip fault, respectively. During mapping the mineral assemblages, structural orientations, and kinematic indicators were identified in order to determine the distribution and type of motion along the faults. We determined that both the faults are kilometer-scale ductile shear zones and mylonites are pervasive in both the hanging wall and footwall. The Gossan-Lead fault is distinguished by the Ashe Metamorphic Suite in the hanging wall and basement gneisses in the footwall, whereas the Fries fault is characterized by a mylonite zone entirely within the basement. The Ashe Metamorphic Suite contains meta-sedimentary and meta-igneous rocks including graphitic schist, metagreywacke, pelitic schist, chlorite actinolite schist, and amphibolites. Rocks of the basement include granitic and biotite gneisses. Both the Gossan-Lead and the Fries faults dominantly strike northeast and dip southeast. We determined top to the northwest hanging wall displacement in the Ashe Metamorphic Suite based on SE-plunging mineral lineations, S-C fabric, and tails on garnet porphyroblasts in the amphibolites that are consistent with top to the northwest thrusting. Kinematic indicators in the basement associated with both the Fries and Gossan-Lead faults include SE-plunging mineral lineations, an S-C fabric, and occasional feldspar augen that indicate top to the northwest motion. Our mapping and kinematic analysis indicates that the Gossan-Lead fault is unlikely to be a continuation of the Burnsville fault because of the lack of evidence we found for strike-slip motion.