MAPPING AND STRUCTURAL ANALYSIS ACROSS EMUCKFAW GROUP-WEDOWEE GROUP CONTACTS IN THE EASTERN BLUE RIDGE OF ALABAMA

The Early-Middle Ordovician Wedowee and Emuckfaw Groups in the middle-upper amphibolite facies Ashland-Wedowee-Emuckfaw belt (eastern Blue Ridge) of Alabama-Georgia have been the focus of numerous geologic studies over the past few decades. The Wedowee Group has generally been mapped as highly graphitic and garnetiferous metapelite (schist) interlayered with subordinate metagraywacke and orthoamphibolite, while the structurally and stratigraphically higher Emuckfaw Group has typically been mapped as non-graphitic/graphite-poor garnetiferous metapelite interlayered with subordinate metagraywacke and orthoamphibolite. The Emuckfaw Group has been further subdivided into the lower Josie Leg Formation consisting of non-graphitic garnet mica schist and subordinate metagraywacke and orthoamphibolite (e.g. Beaverdam Amphibolite) and the upper Timbergut Formation consisting of variable, but slightly graphitic garnet mica schist with subordinate metagraywacke, metaconglomerate and rare kyanite schist. The Wedowee-Emuckfaw contact has been interpreted as an unconformity, a polydeformed stratigraphic contact, a sheared stratigraphic contact, and a major thrust fault outlining the “Dog River Window”. Within the Emuckfaw Group, the contact between the Josie Leg and Timbergut Formations has been defined locally by the presence of a megacrystic orthogneiss and an absence of amphibolite in the Timbergut Formation. Our preliminary mapping is supportive of interpretations of the Wedowee-Emuckfaw contact as a locally sheared stratigraphic boundary, but suggests that delineation of the Josie Leg-Timbergut contact based on the presence or absence of amphibolites and/or megacrystic orthogneiss may not be useful. In addition to examination of these boundaries, we have been able to refine and revise map relationships between the Emuckfaw, Wedowee and pre-kinematic plutons (Zana and Kowaliga gneiss) which intrude both units.