ALLEGHANIAN DEXTRAL MOTION ALONG A RECENTLY IDENTIFIED SHEAR ZONE NEAR WEAVERVILLE, NC

Recent compilation and remapping of the western half of the Asheville, NC 1:100,000-scale quadrangle (Merschat et al., 2008) has identified four discontinuous exposures of mylonite and ultramylonite within the Western Blue Ridge Mesoproterozoic basement of the Earlies Gap granulitic/biotite gneiss near Weaverville, NC. Where exposed, these outcrops define a <20 m-wide belt that trends northeast-southwest for about 6 kms and contains a mylonitic foliation that strikes 040-050 with a sub-vertical dip; mineral-stretching lineations plunge 55-65 degrees to the southwest. Outcrop-scale structures in the mylonites include shear-zone folds and grain-tail complexes that indicate dextral shear. Kunk et al. (2006) obtained a 40Ar/39Ar muscovite cooling age of 335 Ma for a mylonite within this outcrop belt. Based upon our preliminary work, we hypothesize that these outcrops define a larger Alleghanian shear zone that affected principally the Mesoproterozoic basement in the vicinity of Weaverville. The Holland Mountain fault, located about 2 kms to the southwest of this outcrop belt, does not show evidence of reactivation. Detailed mapping along the trend of the outcrop belt and sample collecting for additional cooling ages is ongoing.