GEOLOGIC MAP OF THE NORT HALF OF THE HAZELWOOD 7.5” QUADRANGLE, WESTERN NORTH CAROLINA: EXTENT OF THE OLDEST GRENVILLE BASEMENT COMPONENT IN THE SOUTHERN APPALACHIANS

Xenolith-bearing felsic orthogneiss of Amazonian affinity discovered in Dellwood quadrangle in the eastern Great Smoky Mountains basement complex represent the oldest crustal component of the southern Appalachians (1.33-1.37 Ga: Quinn et al., 2012). Detailed mapping was conducted to determine whether this old crustal component extends farther south into the adjoining Hazelwood 7.5” quadrangle. The map area is dominated by the Copper Hill Fm. (Great Smoky Gp. of the western Blue Ridge), Cartoogechaye terrane, and Otto Formation of the Dahlonega Gold Belt. In the study area the folded contact zones strike NE-SW. The Copper Hill Fm. makes up the northeastern portion of the map area and is comprised of variably migmatic metapsammitic gneiss interlayered with metapeltic schist (qtz+plg+ms+bt±ky/sil ±grt±st). The Cartoogechaye terrane southeast of the Copper Hill is primarily migmatitic biotite paragneiss (bt+qtz+kfs+pl±ms±grt) with some areas containing small layers, lenses and pods of amphibolite, primarily in the southwestern portion of the map area. Stromatic, schileren and agmatite structures were observed. Parallelism of leucosomes and biotite grain orientation define the dominant steep to subvertical fabric. Felsic orthogneiss is not observed in this portion of the Cartoogechaye terrane. The Otto formation consist of homogeneous, massive, mild to moderately foliated metasandstone and lesser interlayered metapeltic shist. The distribution of map units correlates well with published larger scale maps (e.g. Southworth et al., 2012). A less prominent unit is augen orthogneiss associated with the Coleman Creek anticline in the northwest corner of the area, and is a southwestward extension of augen gneisses in the Dellwood quad. This unit yielded a concordant SIMS U-Pb zircon age of 1140 ± 11 Ma. Samples were collected from each map unit for petrographic analysis, bulk rock geochemistry, and U-Pb detrital zircon geochronology. These data will aid in characterizing the origin and tectonic setting of the units as well as determining the nature of the contacts.