TECTONIC EVOLUTION OF THE WEDOWEE AND EMUCKFAW GROUPS OF THE SOUTHERN BLUE RIDGE OF EAST CENTRAL ALABAMA

The Ashland-Wedowee-Emuckfaw Belt is a metamorphic composite terrane found in the southernmost Appalachians of the northern Piedmont (southeastern Blue Ridge) in east central Alabama and west central Georgia. In the Graham 7.5 minute quadrangle of Celbrune and Randolph Counties in east-central Alabama and Carroll and Heard Counties in west-central Georgia these metasedimentary units have previously been studied in reconnaissance, with no clear understanding of unit contacts or structural features. The nature of the major contacts and correlations between the various units have been in debate. Recent detailed mapping of this quadrangle was conducted under the guidelines of the Educational Mapping Cooperative agreement (EdMAP) between the Alabama Division of the U.S.G.S. and Florida State University which has provided a better understanding of the lithologic and unit contacts, as well as the structural evolution of the Wedowee and Emuckfaw Groups. The rocks that make up these units have recently been shown to contain Middle Ordovician detrital zircons with age ranges of 460 Ma to 1475 Ma and are correlated with the units in Georgia which contain Middle Ordovician bimodal metavolcanic . The Wedowee and Emuckfaw Groups are composed of metapelites, metaturbidites, and metavolcanic rocks. Based on regional geologic relationships and geochemical studies of the metavolcanic rocks, these two units have been interpreted to have formed in a Laurentian margin back-arc basin. The Wedowee Group lies stratigraphically and structurally above the Ashland Supergroup and below the Emuckfaw Group. The Emuckfaw Group lies stratigraphically and structurally above the Wedowee Group. It has been previously purposed that the contact between the Wedowee and Emuckfaw Groups is a fault contact along an unconformity. The contact between these two units in the mapping area is interpreted to be gradational in nature based on the absence of fault related structures, and the absence of opposing facing data. Both units are at the same metamorphic grade and there is no discordance of planar or linear fabrics across the boundary.