DETAILED GEOLOGIC MAPPING OF THE EASTERN/ WESTERN BLUE RIDGE TERRANE BOUNDING ALLATOONA FAULT OF NORTHWESTERN GEORGIA

The Allatoona Fault in northwestern Georgia represents the fundamental terrane boundary between rocks of the eastern Blue Ridge (EBR) and those of the western Blue Ridge (WBR) and its southwestern extension, the Talladega belt (TB). This northeast-southwest trending fault formed very late in the kinematic sequence and designates a metamorphic break between the lower greenschist facies WBR/TB bound to the northwest and the amphibolite facies EBR bound to the southeast. Structurally, the typically metavolcanic, metasedimentary and metaplutonic, sequences of the EBR in the southeastern hanging wall of the fault are thrust over the allochthonous Laurentian cover sequence of the WBR/ TB. The WBR/TB cover sequence represents the western Iapetan margin of the southeastern Laurentian craton, rests nonconformably upon the Grenvillian crystalline basement, and consists of mainly siliciclastic (and minor metavolcanic) rift-to-drift facies successions and younger successor basins, in all spanning the late Proterozoic to Middle Paleozoic. The EBR Rocks are thought to represent an accreted terrane(s) emplaced against Laurentia during the Paleozoic closing of the Iapetus Ocean. Multiple terranes may be represented within the study area and include a possible arc (Pumpkinvine Creek formation), a largely metasedimentary sequence (Sandy Springs group), and an undifferentiated metaplutonic sequence. Presently, detailed geologic mapping (1:24,000) at the latitude of Cartersville and directly southwest is being employed to gain a better understanding of this poorly understood fault system. Combined with prior completed research by the Structural Geology and Tectonics group at Florida State University, a detailed geologic map of the Allatoona Fault, from Cartersville, GA to the Alabama border (~100 km), with structural and stratigraphic data, is compiled to provide an in depth view of the Allatoona fault, the immediate terranes bound by it, and an overall understanding of the assembly and tectonic history of the southern Appalachian orogen.