Southeastern Section - 61st Annual Meeting (1–2 April 2012)

Paper No. 17
Presentation Time: 8:00 AM-12:00 PM


GILMER, Jess and BARINEAU, Clinton I., Earth and Space Sciences, Columbus State University, 4225 University Avenue, Columbus, GA 31907-5645,

In the southernmost Appalachians of Alabama and Georgia, the eastern Blue Ridge composite terrane has traditionally been mapped as two separate lithotectonic belts: the Ashland-Wedowee-Emuckfaw belt (AWEB) and the Dahlonega Gold belt (DGB). Both terranes lie northwest of the northeast striking Brevard Zone and southeast of the northeast striking Hollins Line fault system and younger Allatoona fault, although the Chattahoochee fault is the bounding fault for much of the DGB northeast of the Cartersville transverse zone. The amphibolite facies AWEB is composed primarily of metasedimentary rocks, with minor amounts of intercalated amphibolite, and has been intruded by a number of Devonian/Carboniferous and older(?) granitoids. These amphibolite/metasedimentary sequences are thought to have formed along the post-Rodinian Iapetus rifted margin of Laurentia. Lying along strike of the AWEB to the northeast, the DGB in northwestern GA consists of metasedimentary (New Georgia Group) and metavolcanic rocks (Pumpkinvine Creek Formation). The Pumpkinvine Creek Formation, a bimodal metavolcanic sequence with suprasubduction geochemical characteristics, is interpreted to have formed in a Middle Ordovician back-arc basin on the Laurentian margin, suggesting that at least portions of the New Georgia Group strata originated as sediment interlayered with the volcanic sequences. Similar interpretations have also been made for the correlative Otto Formation farther to the northeast in the DGB. In northwest GA, at the juncture of the two belts, their similar structural positions and lithologic character have led some workers to suggest that rocks of the Wedowee and Emuckfaw Groups (AWEB) can be correlated with those of the New Georgia Group (DGB). Other workers, however, have suggested that one or more major faults separate the two terranes. Detailed geologic mapping southwest of Carrollton, GA, at the location of one of the proposed faults, suggests that rocks of the AWEB and DGB are stratigraphically continuous and not in faulted contact. Correlation of stratigraphy across the two belts suggests that they should be considered a single terrane consisting of Laurentian early Paleozoic rifted-margin sequences and younger Ordovician back-arc volcanic and intercalated sedimentary rocks.