Southeastern Section–56th Annual Meeting (29–30 March 2007)

Paper No. 10
Presentation Time: 1:00 PM-5:00 PM


MERSCHAT, Arthur J.1, HATCHER Jr, Robert D.2, STAHR III, Donald W.1, CYPHERS, Shawna R.1 and ECKERT Jr, James O.3, (1)Earth and Planetary Sciences, University of Tennessee, 306 Earth and Planetary Sciences Bldg, Knoxville, TN 37996-1410, (2)Earth and Planetary Sciences, University of Tennessee, 1412 Circle Park Dr, Knoxville, TN 37996, (3)New Haven, CT 06520-8109,

In southwestern NC the central Blue Ridge consists of a polydeformed, synformal thrust stack of amphibolite to granulite facies rocks of the Cartoogechaye (CRT), Cowrock, and Dahlonega gold belt (DGB) terranes, truncated and overlain by the eastern Blue Ridge. Detailed geologic mapping of an ~850 km2 area between Waynesville and Highlands, NC in the Great Balsam and Cowee Mountains, attempts to resolve fundamental tectonic problems existing between central and eastern Blue Ridge terranes. The highest thrust sheet, CRT, consists of upper amphibolite to granulite facies migmatitic biotite gneiss with map- to mesoscale lenses and pods of migmatitic amphibolite. Various ultramafic bodies occur throughout, including the dome-shaped Webster-Addie body. The ~1.10 Ga Trimont Ridge complex is the only documented Grenville basement massif, but several other migmatitic felsic orthogneisses exist in the CRT. Below the CRT, the Cowrock terrane consists of metasandstones and schist of the Coleman River and Ridgepole Mountain Formations intruded by the ~468 Persimmon Creek Gneiss. Pelitic schist and metagraywacke of the DGB occur in the footwall of the folded, steeply NW-dipping Soque River fault, and in Great Balsam Mountains window (GBM) extending from Sylva to Canton, NC. Metamorphic grade of the DGB remains kyanite-staurolite grade in GA and increases to sillimanite grade in the GBM. SHRIMP U-Pb ages of metamorphic rims on detrital zircons suggest peak metamorphism in the CRT and DGB occurred ~460 Ma, suggesting the western and central Blue Ridge comprise the Taconic metamorphic core. The Chattahoochee fault juxtaposes migmatitic Tallulah Falls Formation metagraywacke, amphibolite, and schist of the Tugaloo terrane (Tt) against central Blue Ridge terranes, and truncating the Soque River fault. Truncation of the Miss. Rabun Granodiorite indicates final movement of the Chattahoochee fault was post 335 Ma. Evidence for multiple tectonothermal deformation events in the Tt include (1) Taconic (~460 Ma); truncation of folded amphibolite layers by the ~466 Ma Whiteside Granite; (2) Neoacadian (360-350 Ma); reported metamorphic rims on zircon; and (3) Alleghanian (~330 Ma); truncation of ~335 Rabun granodiorite, parallelism of magmatic and country rock fabrics, and Ar/Ar cooling ages.