DETAILED GEOLOGIC MAPPING, BRUSHY MTNS, NC: KEY TO TIMING AND KINEMATICS OF A TERRANE BOUNDARY

The Brushy Mountains are located in the Inner Piedmont (IP), North Carolina, W and NW of Winston-Salem. Previous EDMAP-supported mapping in the SW Brushy Mountains has revealed a new terrane boundary, the Brindle Creek fault (BCF). It juxtaposes polydeformed Silurian-Devonian sillimanite I and II pelitic schist and biotite gneiss, and Devonian-Carboniferous anatectic granitoids of the eastern IP, against western IP Cambrian-Ordovician Tallulah Falls/Ashe Formation metasedimentary rocks, Poor Mountain Formation metavolcanics, Ordovician Henderson Gneiss, and other Ordovician-Silurian granitoids. New EDMAP-supported mapping in the NE Brushy Mountains has traced the BCF to near the end of the Brushy Mountains south of Call, NC. Footwall lithologies and hanging-wall rock units are also continuous to the NE, but the BCF is folded, exposing several truncated units in the hanging wall and footwall. The folded BCF truncates the 427 Ma Brooks Crossroads Granite, indicating a mid-Paleozoic or younger emplacement of the BCF. Truncation of several linear NE-SW-trending 366 Ma Walker Top Granite bodies by the BCF confirms Devonian-Mississippian emplacement of the BCF, consistent with 350-360 Ma zircon rims. This mapping also will help identify new stone and other resources and provides structural data that can be used for investigation and accessing groundwater resources. Detailed knowledge of the distribution of rock units will facilitate making better decisions about the locations of first and second-home and recreational-home sites in an area undergoing rapid development by anyone who chooses to use this information.